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1st International Conference on Rain Water Cistern Systems
Honolulu, Hawaii, USA - June 1982

Section 1: History Of Cisterns

Paper 1.1

Lessons of History in the Design and Acceptance of Rain Water Cistern Systems

George W. Reid
University of Oklahoma, USA

Introduction

Technology is the application of science to the resolution of a current problem. There are several sub-classifications, such as intermediate technology, appropriate technology, retrogressive technology. If one were to advocate the use of cisterns today, it would be retrogressive technology because in early times-about 2000 B.C. - in the Middle East (Ancient and Medieval), typical middle class dwellings stored rain water in cisterns; irrigation works were used as a domestic supply, private bathing facilities for the wealthy, and sewage and solid wastes deposited in streets and open spaces. During the 8th century, the Greeks (Olynthus) used aqueducts of terra-cotta pipes; houses with bathrooms, cisterns, lavatories, and a waste pipe running through the outside wall to the street; a central alley in each block for drainage; and covered brick masonry drains.

Hippocrates advocated boiling water for disinfection and prevention of odors, as did the Egyptians (47 B.C. Alexandria) where prominent families were provided with cisterns.

Thus, one can envision technology being applied and perfected, as required by one's environment. This leads to the conclusion that the technology used is also a function of socioeconomic conditions. Historically, most development has been associated with socioeconomic growth. The concepts of technological growth are shown in Table 1 and that of life style in Table 2. A third variable would be time (Table 3).

Now one might reflect on these ideas, first as one's life style shifts from hunting and fishing, to agriculture, industry and to mass production. One progresses (if that's the word) from rural to urban life, increased services, ultimately 70 to 80% urbanization, 70 to 75% service employment and 3 to 5% in agriculture; and develops progressively, resource strains, pollution and scarcities. Water requirements escalate from 1 to 2 litres/person/day to 8000 litres/person/day because of large irrigation and industrial components. Water service increase needs in the home from 7 to 8 litres to 400 to 500 litres/day. Eighty to 90% of the water used is contaminated, and needs treatment before recycling can occur. Thus, in successive order, water requires treatment, then is discharged as sewage, and finally is a reuse product.

Paper 1.2

Outlook on Ancient Cisterns in Anatolia, Turkey

Professor Unal Ozis
Ege University, Turkey

Introduction

Evidence of human civilization in Anatolia goes back to millions of years: remains of civilization date back to the VII millennium B.C.; those of water works to the II millennium B.C. These ancient water works also included cisterns which played a certain role in water supply throughout the entire history of our country either as the only source or as an emergency water system.

Present day efforts in collecting rainfall precipitation directly into cisterns is somewhat similar to the harnessing of solar energy. Almost one third of the solar radiation reaching the earth's crust drives the hydrological cycle and thus creates renewable fresh water and water power potential. Although actually only one-fifth of the economically feasible hydroelectric potential is exploited, with regard to spatial distributions of the water power potential and to time projections of energy needs, man actually tried to directly exploit solar energy.

Similarly, the need for fresh water in areas of scarce surface water or groundwater resources may be met by direct collection of precipitation and storage in cisterns. Besides the opportunities lying in modern mathematical methods to deal with the hydrological process involved, the physical application of this mode of water supply is thousands of years old.

In this respect, Anatolia was the crossroads of civilizations and can perhaps be considered as an open air museum of ancient water works, showing the greatest richness and variety on earth.

During the seminar session concerning ancient hydraulic works of the XVII I.A.H.R. Congress, nine contributions dealing with historical water works in Anatolia were presented (I.A.H.R. 1977); the same subject was also part of the IXIII I.A.H.R. Congress and included new contributions (Ozis et al. 1979). The author presented a key paper at the opening of the sixth T.B.T.A.K. Science Congress (Ozis 1978), a special bi national symposium held in Istanbul, Turkey (Braunschweig 1979). It should be noted that the History of Hydraulic Engineering is offered as an elective course in the Civil Engineering Faculty of Ege University.

So, like all ancient water works in Anatolia, cisterns too deserve special interest. This paper is intended to provide a brief outlook on ancient cisterns in Anatolia.

Paper 1.3

History of Yucatan Cisterns

Tuchee Gordillo
University of Yucatan, Mexico

Ernesto Gonzalez L.
Instituto Regional de Antropologia e Historia, Mexico

Salvador Gaona V.,
Universidad Nacional Autonoma de Mexico, Mexico

Introduction

The development of civilizations is always associated with sources of fresh water - the more usual sources being natural rivers or lakes. In some cases, the state of technical development permits the settlement of cities where only rain water is available. The systems constructed to collect and store rain water are historically the oldest hydraulic works. This system is practiced all over the world under the same principles: a catchment area that collects rain water, a transport system that conducts the collected water and a storage vessel where the water remains until needed. The differences vary according to the type of material, ecological/economic conditions and the state of the architecture or design. Here is a brief presentation of the ways developed by the Yucatecans settled in the Peninsula of Yucatan - the Mayas and modern inhabitants. The observations and data were obtained from different studies and direct observations and measurements of the authors. The presentation covers the beginning of the classical Maya period (300 A.D.) to the present.

Paper 1.4

Present and Past Development of Catchment Areas in the Mediterranean Coastal Desert of Egypt

Abdu A. Shata
Desert Institute, Egypt

Introduction

The Mediterranean Coastal Desert of Egypt comprises a narrow zone having an east-west length of about 1,000 km and a north-south width of about 20 km. This coastal desert, located between the Cyrenaican Massif (+700 m) to the west and the Negev-Lebanon Massif (+2 000 m) to the east, occupies a portion of the great Sahara Desert of Africa and extends northward to the Mediterranean Sea (Fig. 1). The climate of this coastal desert differs from the inland desert areas to the south, and is characterized by winter rainfall of 150 to 300 mm frequent and comparatively high periods of humidity, and small diurnal temperature variations.

This paper deals with the western portion of the coastal area, which is historically known as the Mareotis District. The district extends westward to the Libyan border and was once an area of prosperous cultivation. But by the 10th century, the area gradually declined and changed into an almost desert tract. As discussed by Kassas (1972), it is "unlikely that there have been major climatic changes during the last 2000 years that could have caused the deterioration of this area." Facts obtained from the work carried out in connection with the dating of groundwater using carbon 14 techniques (Shata et al. 1962) support this conclusion and show that the last rainy interval coincided with the "Late Wurme" some 7000 years before. The coastal area "must have depended for its cultivation on dry farming that included methods of water management and conservation."

In this paper on the development of catchment areas, emphasis will be given to the following tow methods used since Roman times in the Mediterranean Coastal Desert area: (1) cisterns and (2) Karms or vineyards. Before describing the details of such systems based on personal experiences and on information available in the literature (Hume and Hughes 1921; De Cosson 1935; Shafie 1952; Paver and Pretorius 1954; Murray 1955; Kassas 1972), the physiographic features and the water resources of the area will be discussed.

Paper 1.5

Rain Water Cistern Systems for the Himalayan Region

Raj Kumar Gupta & Vidya Sagar Katiyar
Central Soil and Water Conservation Research and Training Institute, India

Introduction

The Himalaya receives very heavy to heavy rainfall during the monsoon months of July to September. The annual rainfall varies from 900 to more than 2 000 mm in the western Himalaya, and even more in the eastern Himalaya of Assam, the location of Chirapunji, which means "always raining". During the monsoon months, the region receives more than 80% of the total rainfall.

Most of the rainfall is lost as runoff into streams and rivers and causes problems of flooding in the lower reaches of the rivers. Acute scarcity of potable water is experienced in the region. Rural women are the worst sufferers because they have to walk long distances to fetch drinking water from far-off streams and springs. Due to heavy deforestation in the catchment areas, perennial springs supplying potable water have dried. Rainwater cistern systems could easily meet drinking water requirements in many areas, while in others, water could be harvested for livestock and life-saving protective irrigation.

Paper 1.6

Carthaginian-Roman Cisterns in Sardinia

Francesca M. Crasta, Costantino A. Fasso, Francesco Patta and Giorgio Putzu
University of Cagliari, Italy

Abstract

The island of Sardinia remained a Phoenician-Carthaginian colony for about a millenium. The Phoenicians first began to settle on the island during the 9th to 7th century B.C., founding several ports of call to carry out trade by sea. Of these ports, Cagliari, Nora, Bithia and Tharros are evidence of the role that the island's southern coast played in supporting the commercial routes of the Mediterranean.

The types of rain water cisterns most commonly used in the period considered here are the "bath-tub" and "flask" cisterns. Some examples of large cisterns, which will be referred to as "cave" cisterns, have also been discovered in Cagliari.

Section 2: Rainfall Analysis

Paper 2.1

Stochastic Dynamic Models for Rainfall Processes

Samir A. Ahmed
Oklahoma State University, USA

Yu-Si Fok
University of Hawaii at Manoa, USA

Introduction

In recent years, there has been a revival of interest in using rain water cistern systems (RWCS) as a supplement to rural and urban residential water supply (Fok et al. 1980; Fok, Murabayashi, and Fong 1979). The reasons for this have been the increasing demand for water and the lack of adequate supply. Curtailment of new urban developments and limits on new house-building permits because of water shortages have been reported in many areas, such as Orange County, California and all the counties o£ Hawaii. In addition, it may not be feasible in some areas-the Hawaii Volcanoes National Park, for example - to install pipelines for water supply (Wentworth 1959). Fok, Murabayashi, and Fong (1979) find that for residential houses located in areas with an annual rainfall of about 508 mm (20 in.), RWCS's may be feasible and cost effective as their main or supplemental source of water supply.

To properly design and operate a RWCS, it is necessary to understand the dynamic and stochastic nature of rainfall processes. These processes evolve continuously in time, thus suggesting models of differential equation form to describe their characteristics. However, since rainfall data are often collected at a series of discrete points in time, differential equation models can be directly used to fit such data. The parameters of the estimated discrete model can then be used to construct continuous time models if the data have been obtained through uniform sampling of the continuous process. The details of such a procedure for modeling, predicting, and simulating rainfall processes are explored in this paper.

Paper 2.2

Stochastic Model of Daily Precipitation using the Time Series Methodology

Silvia Vega,
University of Yucatan, Mexico

S. Gaona V.
Universidad Nacional Autonoma de Mexico

Introduction

The Yucatan Peninsula, situated in the eastern part of the Mexican Republic (Fig. 1), has geological conditions that necessitate the proper management of its water resources. The aquifer of this peninsula is of the calcareous type (Lesser 1976). Here, the limestone in the study area is covered in some places by just a few centimeters of soil (Gaona, Gordillo, and Villasuso 1980). The area is relatively flat, and there are no rivers and lakes. For this reason, groundwater and precipitation are the only sources of water that can be considered.

In this region, the groundwater has a high content of carbonates and is frequently contaminated by injections of municipal and industrial wastes that infiltrate to the groundwater table. It is for this reason that we consider precipitation as the most viable way to obtain potable water for human consumption. Although rainfall catchment was a very common source of water in the past, the actual design of an adequate system for catchment storage and the management of pluvial water requires more scientific studies.

The first of these studies consists in the development of a statistical model of rainfall by using historical data to plan the tank volume and their catchment areas.

Presented here is the statistical analysis of the data and the way in which it will be used to design the cistern, including the results.

The data consist of the daily rainfall-depth measurements corresponding to the past twenty-five years from one of the forty meteorological stations that exist in the Yucatan Peninsula-that which is situated in the city of Merida. A microprocessor Radio-Shack TRS-80 model was used for the analysis, which was done on a daily basis, to obtain results that can be used in other areas even though it was not necessary for our purpose.

Paper 2.3

Estimation of Extreme Point Rainfall Over Peninsular India

O.N, Dhar, P.R. Rakhecha and A.K. Kularni,
Indian Institute of Tropical Meteorology

Introduction

In November 1980, the United Nations launched International Drinking Water and Sanitation Decade (1981-1990) to focus world-wide attention on providing safe drinking water. In India there are still villages and towns in various parts of the country where people have to carry water from long distances for their daily use in spite of the fact that we have tremendous water resources which are replenished year after year by rainfall during the monsoon months.

It has been estimated that the average annual rainfall of the contiguous Indian area is about 117 cm of which about 76% is received during the four monsoon months of June to September (Dhar, Rakhecha, and Kulkarni 1979). This much rainfall is estimated to generate annually a surface flow on the order of 1 881 bil m3 (Murthy 1977). Apart from this, this country has groundwater resources which are on the order of 350 mil m3.

Because the main goal of the International Drinking Water and Sanitation Decade is to provide safe drinking water in sufficient quantity, an attempt has been made in this study to find out what the maximum probable rainfall or the extreme rainfall is that a station can get in the peninsular region of this country. This information, would not only be useful in knowing the extreme amount of rainfall that is physically possible over a station or a basin, but is also useful for the safe design of hydraulic structures that may be constructed for conservation of water in this region of India.

Paper 2.4

Frequency Distribution of Weekly Rainfall at Bahadrabad, India

S.M. Seth
National Institute of Hydrology , India

Jagdish Mohan & S.S. Tiagi
U.P. Irrigation Research Institute, India

Introduction

The state of Uttar Pradesh, which is extremely diverse in topography, climate and vegetation, ranks fourth in area and first in population in India. Because of the rapid growth in population, intensive urbanization and industrialization is taking place in the basically agricultural areas in the foothill regions of the Himalayas. Rainfall in this region occurs during the monsoon months of June to October with most of it occurring July and August, with some rainfall during the non-monsoon months. During the monsoon season, there is considerable variation in rainfall in time and space. To provide information regarding expected levels of rainfall at different time for planning drainage requirements, the analysis of statistical characteristics of rainfall in the area is necessary.

The meteorological observatory at Bahadrabad, established in 1952, is situated at 29°55.5' east latitude and 78°2.25' north longitude at an elevation of 275 m above mean sea level. Its climatic observations are representative of the foothill region of the Ganga-Yamuna interbasin. The observatory is equipped with recording and non-recording types of rain gauges. The weekly rainfall for 1955 to 1980 for the monsoon season (1 June-1 November) has been used in the present study. The maximum weekly rainfall of 395.7 mm during this period occurred in the week of 3 to 9 August 1978.

Paper 2.5

General Methodology for the Characterization of Rainfall Time Distribution

Van-Thanh-Van Nguyen
University of Quebec, Canada

Introduction

Information on variations in rainfall time characteristics is always necessary in various types of hydrologic studies concerning the planning, design and operation of water resources systems.. Most previous research on the time distribution of rainfall usually involved the study o temporal distributions of "rainfall exteriors" characteristics, such as total event depth, total event duration and time between events, but very few studies deal with the time distribution of rainfall within each individual vent or the temporal pattern of each event.

The objective of this study is to provide basic information on the variability of temporal patterns based on the probabilistic characteristics of an actual rainfall record. Information concerning the nature of the temporal distribution of rainfall within a rainfall event is usually presented as a mass curve of accumulated depth as a function of time. The purpose here is to ascertain the probability distributions of rainfall accumulated at the end each time unit within such a total rainfall event representation.

First, a general theoretical model will be proposed, and then a numerical application will be presented by using a 32-year record of daily rainfall at Dorval Airport on Montreal Island (Canada). In the numerical example, the daily precipitation is selected because relatively long and reliable records are readily available and such data are frequently sufficient for many practical problems. The model, however, might be used for hourly rainfall (Nguyen and Rouselle 1981) and for rainfall durations of one ay or longer.

Paper 2.6

Deterministic and Probabilistic Processes of Weekly Rainfall

Yu-Si Fok, Ronald H.L. Fong, Edwin T. Murabayashi and Andrew Lo
University of Hawaii at Manoa, USA

Introduction

In the design of rain water catchment cistern systems, the following design variables are considered essential:

  1. Input (weekly rainfall) 
  2. Catchment area (roof-top area) 
  3. Storage capacity (cistern volume) 
  4. Output (withdrawal/use).

Of these, the weekly rainfall is the only design variable that is uncontrollable and unpredictable. Thus, to design an adequate water catchment cistern system, the weekly rainfall must be estimated, using available statistical methods from existing rainfall records. In this paper, the deterministic and probabilistic processes of weekly rainfall data are discussed and presented for design purposes.

Paper 2.7

Computerized Methods in Optimizing Rainwater Catchment Systems

Eric J. Schiller & Brian Latham
University of Ottawa, Canada

Use of rainwater Collection Systems in Canada

Rainwater collection systems (RWCS) have been widely used in Canada from the time of the early settlers. The tradition was brought from Europe and fitted well with the needs here. In the older farm areas, such as that around Ottawa, a cistern was a common part of a farmhouse as it provided soft water for washing and bathing- a necessity with natural soaps. Drinking water was obtained from a well or spring, if available, because of the mineral content which "quenched" thirst.

Presently, RWCS's are still in use on farms in Ontario and on the prairies of the west where groundwater may be saline and farmhouses are separated by great distances. In many coastal areas, such as the Atlantic area of Nova Scotia, the terrain is rocky with little or no soil cover. A central water system is difficult and prohibitively expensive to install. However, coastal areas have high, consistent rainfall and moderate temperatures which make a RWCS an attractive drinking water source.

Another area for use of RWCS's that may show great promise in the future is the northern regions of Canada. During the warm season, RWCS's could provide safer drinking water. Fully reliable, year-round systems would not be practical because of the long freeze up during the winter period.

In all of these remote areas, a RWCS represents a least-cost option because of the isolation of individual users, the unsuitable quality of groundwater or the sheer unavailability of fresh water. Estimates o£ costs for setting up a system will depend on many factors, but are reduced because of the nature of Canadian houses. Much of what is required is already constructed in the house and cannot be charged exclusively to the RWCS. Roofs are generally large and pitched (to carry away the rain and snow). A sealed basement with poured concrete floor and walls and plumbing is standard. Hence, one and possibly two walls are available for use in tank construction. In areas without a central water system, a pump and pressure tank are standard equipment and are not an additional cost due to the RWCS.

Paper 2.8

Hydrographs for Roof-Top Runoff Under Varying Rainfall Conditions

Bhaskar Datta
Flood Control Dept. Gauhati, INDIA

G.C. Mishra
University of Roorkee, INDIA

Introduction

With increasing population, water supply systems may fail to satisfy the demand for water. In arid and semiarid regions, especially, the source of water is often depleted. Rain water collected from roof surfaces and utilized through cistern systems can augment the usual domestic supply without large expenditures or energy and can thus meet water shortages.

To design gutters and a cistern system, knowledge of the water surface profile and flow hydrograph is necessary. The kinematics of flow over roof surfaces can be determined from available studies of overland flow. Many investigators have dealt with the problem of overland flow under uniform, excess rainfall either by using the method of characteristics (Behlke 1957; Henderson 1964; Wooding 1965; Morgali and Linsley 1965; Abbott 1966; Brakensiek 1966) or by solving the mass balance equation by assuming a linear relationship between outflow and storage (Horton 1938; Izzard 1944). Wooding (1965) has dealt with the problem of overland flow under a constant, uniformly distributed rainfall of finite duration with an analytical solution for a hydraulic model based on the method of characteristics for flow over a plane, which is part of a V-shaped catchment. In reality, the rainfall intensity is not uniform; instead, the distribution is skewed. The typical time variant design of rainfall distribution patterns described by Rodda, Downing and Law (1976) for a 10-year, 5-year and annual return frequencies are shown in Figure 1. Water surface profiles and flow hydrographs for roof surfaces for such design storms can be determined for different intervals of time by using the characteristics equations.

Section 3: Design, Cost, And Policy

Paper 3.1

Design Strategy for Domestic Rainwater Systems in Australia

S.J. Perrens
University of New England, Australia

Abstract

Any closed rainwater supply system involving a sealed or almost impervious catchment, a storage and a linked supply point may be characterized by some general relationships regardless of the size of the system. This paper presents the results from a simulation model of the operation of such water supply systems at four locations in New South Wales, which are representative of the range of rainfall regimes in Australia. The results are presented in the form of generalized design graphs. Although this study refers particularly to Australia, the principles involved are applicable to any rainwater supply system.

Paper 3.2

Feasibility Analysis of Rain Water Cistern Systems as an Urban Water Supply Source

Shuichi Ikebuchi
Kyoto University, Japan

Seiji Furukawa
New Japan Engineering Consultant Company, Japan

Introduction

In the past, dam reservoirs were constructed to meet the increasing water supply demand as a result of the growth in population and urbanization. In recent years, however, social pressures and environmental controls have made it more difficult to construct dam reservoirs; thus, a comprehensive water supply system has become an increasingly important planning guide. With this in mind, we propose the integration of rain water cistern systems into existing water supply systems.

In Japan, there are a few examples of rain water cistern systems that are limited to the roof catchment and storage of rain on individual buildings or houses. Judging from the scale effect and the operation and maintenance of this system, the collective form seems to be more efficient and effective than small, individual rain water cistern systems. As presented in this paper, the collective form of rain water cistern systems relates to the expansion of roof catchment areas of many buildings in the urban area. The assets of this sort of system are threefold: (1) a supplemental source of potable water to the existing water supply system, (2) a means of diminishing and utilizing storm runoff, and (3) a method of decreasing the amount of treatment necessary for the combined sewer system.

Paper 3.3

Determining The Desirable Storage Volume Of A Rain-Catchment Cistern System: A Stochastic Assessment

PingSun Leung & Yu-Si Fok
University of Hawaii at Manoa, USA

Introduction

The four major design factors for rain-catchment cistern systems are rainfall, catchment area, storage capacity and water demand. Of these, only rainfall is uncontrollable by the system designer. In most cases, the size of the catchment area or roof is largely predetermined for an existing structure. The initial basic decision for the cistern owner is to determine the minimum storage capacity which can satisfy the water demand. The minimum storage capacity can be easily determined if given a set of deterministic rainfall for a fixed planning horizon. Most studies (Fok et al. 1980; Wentworth 1959) used the worst rainfall occurrence for the design of the storage capacity without looking into the impact of the stochastic nature of rainfall on storage capacity design. The present study suggests using computer simulation to determine the probability distribution of the minimum storage capacity required. This will provide additional information to the cistern owner in deciding on the necessary storage capacity. The historical rainfall pattern at the Manoa Tunnel station on the island of Oahu was analyzed and used as a case study.

Paper 3.4

Optimal Catchment Design by Marginal Analysis

Richard J. Heggen
The University of New, USA

Rainwater Catchment Design

In many regions, roofing and cisterns provide a simple hygienic household water supply (Black and Popkin 1967; Bonilla 1967; Gillis 1967; McJunkin 1969; Ree 1976; Roberts 1967; Wagner 1959; Watson 1915, pp, 278-279; Watt 1978; USPHS 1962). An optimal allocation of resources for construction of such household rainwater catchment systems may be determined from basic engineering principles. Computer simulation may be used to investigate the effect of alternative combinations of rainfall, catchment area, storage volume, and water use rate on the adequacy of supply. Marginal economic analysis may be used to find that scale of facilities maximizing net benefits. Optimal system design includes: (1) precipitation synthesis, (2) water deficit calculations, (3) isodeficit curve construction, (4) isoquant analysis, and (5) optimal scale identification.

Paper 3.5

Design And Calculation Of Rainwater Collection Systems

C.L.P.M. Pompe
West Java Rural Water Supply, Indonesia

Introduction

Dry seasons occur even in monsoon areas. If there are no nearby wells or rivers, people will walk long distances t o obtain water. A solution to this problem may be the catchment of rain water-an ancient custom still practiced in many countries in the world where rainfall is collected during the wet season t o use in the dry season. The questions are (1) what should the volume be of such a rainwater collection system and (2) how should such a collector be designed?

Paper 3.5

Application of Gould Matrix Technique to Roof Water Storage

Terry L. Piggott
Queensland Institute of Technology, Australia

Ian J. Schiefelbein
Gutteridge, Haskins & Davey, Australia

Mark T. Durham
Telecom, Australia

Introduction

The dependence of many Australian homes on roof and tank rainwater collection systems. has been discussed in detail by Perrens (1975), Perrens used a monthly simulation model to relate roof area, storage capacity and demand to probability of failure at Armidale in New South Wales. He drew economic comparisons between extending the system capacity and buying water when the system failed to meet the required demand.

Durham (1980) and Schiefelbein (1981) used the Gould matrix technique (McMahon and Mein 1978) to determine probabilities of failure of a roof-tank system, rather than to rely on critical period methods. These studies were initially made for Brisbane and subsequently for a number of selected climatic zones within Queensland as part of a continuing programme.

This paper covers some aspects of the work initiated by Durham (1980) and continued by Schiefelbein (1981):

Paper 3.6

Assessment Of Rainwater Catchment and Storage Systems on Majuro

Rebecca A. Stephenson, Hiro Kurushina, & Stephen J. Winter
University of Guam, USA

Introduction

This paper focuses on a discussion of freshwater supply systems in Micronesia. Particular attention is paid to the conditions within a small Micronesian atoll environment of the Marshall Islands, the village of Laura on Majuro atoll.

Initial fieldwork during July to August 1981 revealed that a paradox exists between the abundant availability of fresh water as rain water and ground-water on the one hand, and frequent shortages o£ fresh water, on the other. In the course of earlier field research by Winter and Stephenson (1981) in the Eastern Caroline Islands, Micronesia, the same paradoxical condition was found to exist.

We suggest that the paradox exists because of an inadequate management of water supply and water storage systems in Micronesia. We further suggest that economic, technical and social factors may be related to this phenomenon. The paper describes the study area in the Marshalls, discusses local water supply and storage systems, examines attitudes towards the use of groundwater versus rainwater catchment, and attempts to explain why rain water is not utilized , more extensively than it is. The paper concludes that, as water consumption is most likely to increase along with modernization in Micronesia, government plans should provide for increased water supply.

Paper 3.7

Adjusting Operation Policy for a Rain Water Cistern System

Andrew Lo & Yu-Si Fok
University of Hawaii at Manoa, USA

Introduction

Rain water cistern systems have long been a water supply source in many countries. In some rural areas where municipal water is limited or unavailable, rain water for domestic use is caught on roofs and stored in water tanks. To design an efficient catchment system, adequate catchment area and cistern capacity in relation to water demand are factors that have to be carefully selected and designed to suit the rainfall pattern of the design area. If the average rainfall could be daily obtained, only enough catchment and storage would be needed to satisfy respectively the daily water demand and peak loads. However, there are many areas with frequent droughts that can last for months. Severe water shortage problems emerge even with extremely large catchment and storage. To alleviate such problems, the operating rule of the catchment system must be modified. Appropriate water use reduction imposed prior to the onset of dry weather may save enough water to last through the drought.

The following sections describe a linear and a non-linear reduction strategy, and their performance is compared to the classical unadjusted operating policy.' Conclusions are then drawn in relation to the proper form of rain water cistern system operation policy.

Paper 3.8

Reliability of Roof Runoff in Selected Areas of Indonesia

J.L. Irish
UNESCO, Indonesia

Sukarna
Meteorological and Geophysical Service, Indonesia

D. Murdiyarso
Institut Pertanian Bogor (Agricultural University), Indonesia

Introduction

Indonesia, an archipelago of about 12,000 islands spread 4 000 km east-west across the equator (Fig. 1), has a population approaching 160 million, with an estimated $350 (1970) per capita gross domestic product, of which oil production represents about 18% and agriculture about 32%. Approximately 65% of the population lives on the island of Java (including the adjacent island of Madura), which has an area of only 132 000 km2, or less than 7% of the total land area. Other densely populated areas include Bali and Lombok, and the province of Lampung at the southern tip of Sumatra. More than two-thirds of the population live in rural areas, generally in villages or small towns, and engage principally in subsistence agriculture. Rice is the main crop; others of importance are maize, cassava, soya beans, copra, tea, coffee, rubber, palm oil and sugar.

The mean annual rainfall ranges from less than 1 000 mm in a few small areas (e.g., Palu Valley, Saluwest) to over 4 000 mm in exposed coastal areas and parts of Kalimantan and Irian Jaya. Estimates of mean annual rainfall and per capita water availability for each of the main island groups are shown in Table 1.

The population is largely concentrated on islands with water resources below the national average. This situation is aggravated by the seasonal pattern of rainfall that is most marked in the southeastern islands of Indonesia: Timor, Nusa Tenggara (Flores, Sumba, Sumbawa, Lombok, among others), Bali and Java, which have a "dry" season from May/June until September/October. Rarely does a month receive no rain at all, even in the dry season, except in Timor and the lightly populated parts of Nusa Tenggara where the wet cultivation of rice is only possible during the wet season and transition periods, unless advanced irrigation is practiced. Elsewhere in Indonesia, rainfall has a less marked seasonal pattern, and cropping throughout most of the year is possible in many areas (Oldeman, Las, and Darwis 1979; Oldeman and Syarifuddin 1977). Surface water resources are consequently more reliable in those areas than in Java and the islands to the southeast.

Rain generally occurs about 120 days per year, typically, as intense bursts. Pan evaporation is relatively uniform-spatially and temporally-being about 1 500 mm/yr.

Public water supply is reticulated only in the largest towns and cities of Indonesia; elsewhere, the source of water is from streams or wells, or from stored roof runoff. During the dry season, people walk several kilometres or more in many parts of southeastern Indonesia to obtain water.

The Indonesian government is implementing a series of five-year development plans. The current plan, REPELITA III, emphasizes the goal of equitable social development as a result of the rapid growth in the value of exports (oil, timber, tin, rubber), an expanding manufacturing sector, and improvements in agricultural productivity. Transmigration from Java and Bali to the outer islands is being encouraged, and a successful family planning program hopefully will limit the population explosion. In line with the United Nations' International Drinking Water and Sanitation Decade, Indonesia is promoting the improvement of water supplies as a basic step toward better health and welfare. Many of these projects are small in scale and geared to rural villages, where the majority of the population lives, and to which special programs are directed. One such program involves UNICEF (a UN agency concerned with the welfare of women and children) and the government of Indonesia for selected regions, mainly the poorer and relatively dry areas of Yogyakarta, Madura, East Java and Lombok.

Little in the way of hydrological studies has been done to support the current program to increase the use of roof-runoff systems in villages. Instead, the approach has been to improve access to potable water and to allow villages to determine the safe yield from experience. The United Nations Educational and Cultural Organization (Unesco) decided to support a hydrological study, financed from its regional component of the International Hydrological Programme (IHP), to demonstrate technology transfer and the methods of applying technology appropriate to the needs of a developing country. This is consistent with the rational use and management of national water resources emphasis in the later phases of the IHP, and extends and is consonant to the synthesis of scientific knowledge, education and training of the International Hydrological Decade and the first phase of the IHP.

Village water supply projects are being implemented at numerous sites throughout the nation. This hydrologic network, which should cover a broad area, is based on planning that recognizes the large gradients of mean annual rainfall in the typical mountainous terrain of much of the highly populated areas.

A large quantity of daily and monthly rainfall data are available in Indonesia: the Dutch colonists were pioneers in the collection and study of such data. There are at present over 3000 sites (whose station density roughly approximates the population) that regularly report daily rainfall to the national Meteorological and Geophysical Service. By 1922, there were already 2800 stations with. five or more years of data; by 1941, this had increased to 4400 stations. The Pacific War, the disruption during the struggle for independence and the political turmoil of the 1950s and the early 1960s reduced the number of stations making regular climate or rainfall reports; however, this has been redressed in the last decade. A computer has recently been installed to store and retrieve climatological data, and monthly rainfall has been published in yearbooks for more than 80 years, However, the shortage of trained personnel in the provinces, and especially outside the cities, means that these data are hardly accessible to many potential users.

It was therefore decided to carry out a regional study based on the UNICEF-GoI programme of village improvement. The techniques developed might then be applied elsewhere in Indonesia and generally in Southeast Asia by using local data to obtain relevant statistical relationships. The area selected for study is broadly from Yogyakarta to Surabaya (parts of Central and East Java), the island of Madura, the drier parts of the island of Bali, Lombok and all of Sumbawa, an area of about 50 000 km2 with a population of about 20 million.

Paper 3.9

Rain Water as a Water Supply Source in Bermuda

D.H. Waller
Technical University of Nova Scotia, Canada

Introduction

Any description of rain water supply systems in Bermuda must take into account the geography and history of this small mid-Atlantic country.

The island of Bermuda is located at 32° north latitude, 65° west longitude, 917 km east of the North American coast. The "island" is actually a . series of seven small islands, joined by bridges, that are the unsubmerged portion of limestone deposits, approximately 100 m from the sea floor. The aeolean limestones, laid down during glacial advances and retreats of the Pleistocene era, are loosely cemented and extremely permeable. The rock is covered by a soil layer approximately 15 cm thick.

The island is 30 km long, with a mean width of approximately 1.5 km and.a maximum width of 3 km. The total area is 53.1 km2. The elevation of most of the land mass is less than 30 m above sea level, rising to a maximum of less than 100 m.

The climate is semitropical and frost free. Mean monthly temperatures approximate 20°C in winter and 30°C in summer. The average annual rainfall, based on records since 1886, is 146.8 cm (Vatcher 1974); minimum and maximum 12-month rainfalls are respectively 77.0 and 227.6 cm. Rainfall is fairly uniform during the year, but onlthly average values for April through July are lower than the annual mean.

One result of the high permeability of soil and rocks is the absence of freshwater streams and lakes. Groundwater underlies 20% of the land area, in five lens. The largest lens, with a mean thickness of 7.6 m, represents two thirds of the total area. Brackish water (1-10% sea water) underlies another 23% of the island (Vatcher 1974).

Bermuda today is a self-governing British colony.

The island was uninhabited until its discover in 1503. It has been continuously occupied since 1609, when it was settled by English colonists who also colonized Massachusetts and Virginia in the United States.

The first Bermuda houses were similar to those in England, but construction quickly adapted to indigenous materials of cedar and limestone. Native cedar was in short supply as early as 1620, and stone buildings were encouraged, using cedar for framing and trim. The native limestone, which can be cut with a saw and which hardens on exposure to the atmosphere, was cut into blocks for walls. Roofs, supported on cedar framing, were formed of overlapping limestone slates, 30.5 cm x 45.7 cm x approximately 3.8 cm. Limestone, burned in kilns, also provided the mortar used to assemble both walls and roofs. This form of construction is basically the same as that used today, except that concrete block walls have replaced limestone in recent construction: in 1980, 95% of households lived in houses with outer walls of limestone ("Bermuda stone") or cement block (Statistical Department 1980).

A unique feature of Bermuda roofs has been their role in water supply. Until the 1930s, rain water provided the only source of potable water. Water was collected on roofs, where wedge-shaped limestone "glides" were laid to form sloping gutters on the roof surface, diverting rain water into vertical leaders and thence into storage tanks.

Early storage tanks were rum puncheons or cisterns made of cedar. Others were formed by excavation into rock and made tight with mortar. Prior to the 20th century, tanks were located at the outside rear of dwellings, partly or entirely above ground. Water was removed from tanks by bucket or hand pump and carried indoors. In some later systems, hand pumps transferred water to elevated indoor storage tanks. Current systems include storage tanks under buildings with electric pumps and pneumatic tanks. Today, 96% of households are provided with piped indoor water supplies (Statistical Department 1980).

Rain water was also collected from "artificial catches" created by removing thin hillside soil and sealing the rock surface with mortar. Water from large artificial catches continues to provide significant quantities of water, e.g., an estimated 13.6 million l/yr from a catchment developed for a British military installation, and 45.5 million l/yr from a catchment serving a major hotel (Thomas 1980).

Roof water systems with adequate storage were not systematically encouraged until the 20th century. Prior to adoption of current public health regulations in 1951, storage capacities of 1400 to 22,000 l were common (previous public health regulations required up to 6800 l per occupant, although 13,000 litres per occupant were recommended), compared with typical storage today of 68,000.l.

Water was imported from North America during a five-year period from 1938 to 1968.

In 1932 a private company, Watlington Waterworks, began development of the largest of the groundwater lenses, providing up to 3.5 million k/day of brackish water for non-potable uses (primarily flushing) through a distribution system serving the central part of the island. Part of this water fed a desalination plant that provided potable water to several major tourist facilities. In 1979, the Bermuda Public Works Department and Watlington Waterworks commenced a joint venture aimed at rational development of the groundwater resource, involving new wells in the central lens and delivery of potable water through. the Watlington system.

By the 1960s, desalination plants had been installed by several major hotels, industry, and government. At present (June 1981) a government sea water distillation plant is reaching the end of its useful life, and a brackish water reverse osmosis plant is being brought on-line, by the Public Works Department.

Paper 3.10

Design And Calculation Of Rainwater Collection Systems

C.L.P.M. Pompe
West Java Rural, Indonesia

Introduction

Dry seasons occur even in monsoon areas. If there are no nearby wells or rivers, people will walk long distances to obtain water. A solution to this problem may be the catchment of rain water-an ancient custom still practiced in many countries in the world where rainfall is collected during the wet sea-. son to use in the dry season. The questions are (1) what should the volume be of such a rainwater collection system and (2) how should such a collector be designed?

This paper deals mainly with the first question: the calculation of the volume of the rainwater collector.

H.M.C. Satijn (1979), who was a former project participant, analyzed the problem and designed a computer simulation model of the rainwater collection system. Because computers are not widely available, I was asked to review Satijn's work and to develop a slide rule-calculation method that could be used by regional technicians. Thus, a step-by-step method was designed to enable technicians to calculate the volume of rainwater collectors by using available monthly rainfall data.

The results of the calculation are not sacrosanct because, first of all, the variables of themselves vary widely, such as consumption or the water demand. Thus, if 5 litres/person/day is the basis for calculating drinking water needs, there is no way of knowing the actual use and the variation in conservation and utilization. What must be borne in mind in the statistical calculation of rainwater catchment systems is that its accuracy will depend on correct input. It is also important to be realistic in using the statistical calculation method, rather than concentrating on complicated statistical computations.

The vital question is "Who pays?" If the farmer (user) pays, he will construct a 15-m3 collector and in the dry season will be conservative in using his water while praying to Allah that rain will soon fall again. When the government or an international organization pays, the designer might think of future users and design a 20- or even 25-m3 collector.

The basic principle of this: method is the importance of calculating storage to provide enough water of the period of the year when there is no rainfall or when it is insufficient to meet water needs. In the following sections the step-by-step method and the theoretical background of the method are presented, and the last section includes some design criteria for the rainwater collection system.

Paper 3.11

Rain Water Collection and Utilization at Tamil Nadu Agricultural University, Coimbatore, India

R.K. Sivanappan,
Tamil Nadu Agricultural University, India

Introduction

"As free as the land, air and water" is an age-old expression, which men have used for hundreds of years to signify the things that nature has bountifully provided, as contrasted to the type of wealth that has a tangible value, usually as a result of human efforts in reworking natural elements. But today the old phrase is largely empty. It has lost most of its original significance and at present water has become such a scarce resource that it is called "Liquid Gold" in many parts of the world, especially in the Coimbatore District of Tamil Nadu, India. It is needless to say that man simply cannot live without water. He must have it to drink, to meet domestic needs, to raise crops and to cooperate his manufacturing industries. And the demand for water is steadily increasing as civilization becomes more and more industrialized.

The place of water in the agricultural and in the overall economy is clearly established. It is indispensable to any form of life and action. It can be man's greatest friend or one of his most destructive enemies. Under control, it performs a host of vital tasks in addition to achieving its final and supreme purpose in providing man with a resource necessary to life itself. Uncontrolled, it wreaks havoc with floods and carries our most precious top soil out to sea.

Taking all these elements into account and in looking to the future to 2000 A.D. and beyond, we must carefully plan and harness every drop of available water in the dry areas. If we should fail to act now, with intelligence and decision, we would place our children in a position of deadly peril. There are several avenues of approach and all of them must be explored and used to the fullest practicable extent. One technique among these is water harvesting.

Paper 3.12

Rain Water as an Alternative Source in Nova Scotia

D.H. Waller
Technical University of Nova Scotia, Canada

D.V. Inman
Nova an Alberta Corporation, Canada

Introduction

The Canadian province of Nova Scotia includes a population of 856,600 persons in an area of 52,840km2. Approximately one-half of this population is served by municipal water distribution systems. Most of the remainder are served by private wells. Groundwater in some parts of the province is inadequate in quantity, or is made undesirable or completely unacceptable for domestic uses because of excessive mineral concentrations.

Arsenic and uranium have recently been added to a list of natural contaminants that includes iron, manganese, and hardness. In one small municipality, 294 wells were tested for arsenic. Arsenic concentrations exceeded 0.01 mg/l in water from 130 wells of which 51 had concentrations greater than 0.05 mg/l (Division of Public Health Engineering 1979), compared with a recommended objective concentration equal to or less than 0.005 mg/k and a maximum acceptable level of 0.05 mg/l (Health and Welfare Canada 1978).

In another area, water in 101 of 299 wells tested for uranium contained an excess of the maximum acceptable concentration of 0.02 mg/l, and water in a further 58 wells contained concentrations between 0.01 and 0.02 mg/l (Bower 1981).

For many years-, rain water collected on roofs has served as a complete or a supplementary domestic water source in parts of Nova Scotia where water quantity or quality is inadequate, but no documented evidence of roof water systems was available. In 1977, the authors undertook an exploratory study of roof water use in Nova Scotia. The study was initiated with a newspaper enquiry and followed by a questionnaire, personal interviews, limited water quality analysis and analysis of precipitation data.

Paper 3.13

Cost Analysis of Rain Water Cistern Systems

Yu-Si Fok & PingSun Leung
Univer ty o£ Hawaii at Manoa, USA

Introduction

The economic feasibility of rain water cistern RWC) systems is an important factor in its acceptance in the scheme of water resources planning and development. A cost analysis of this water supply system is complex because socioeconomic conditions vary in different countries. To present an unbiased cost analysis of a RWC system, a case-by-case format is preferable and, if possible, a cost comparison with the existing public water supply system should be also included. In general, RWC systems are financed with private funds, and public water supply systems with public funds. However, their costs to users may not differ too much. In addition, the cost of labour is another factor that should be considered in the cost analysis. It is this amount of labor that owners contribute to their own RWC systems that is difficult to document as a cost item. Thus, these factors should be considered by the readers of this paper.

Paper 3.14

Some Aspects of Roof Water Collection in a Subtropical Region

Adhityan Appan
Nanyang Technological Institute, Singapore

Introduction

The ever-increasing demand for water is making man look towards different means of conservation and new methods of abstracting water. The concept of collecting and storing rain water, an age-old practice, could prove to be an encouraging additional source that could very well enhance the limited and apparently dwindling supply of water.

In a city-state like Singapore, there are competing demands for use of limited land area and, with the added rapid economic grow and industrial development, there is an even greater demand for water. Singapore lies 8° north of the equator, has an average ambient temperature of 26°C and a population of 2.3 million. With the twin assets of 70% of the population living in high-rise flats and an average annual rainfall of 2 230mm , it would appear to augur well for the harnessing of roof water as a supplementary source of water.

Paper 3.15

Rain Water Cistern System Impact on Institutional Policy

Yu-Si Fok
University of Hawaii at Manoa, USA

Introduction

The adaptation of the rain water cistern system ill have a definite impact on institutional policy. To promote the adaptation of this type of system, Fok and Murabayashi (1979) indicated that, in water shortage areas, some incentive measures-such as tax credits-would produce results and require a new institutional policy.

Another impact is related to cistern water quality, which is a matter of concern to many public health officials. Because the cistern catchment area could be polluted by natural or artificial pollutants the rain water collected and stored in the cisterns may not be fit for human consumption. Therefore, Fok (1980) reported that in California a ruling as made that prohibited the use of roof-catchment cistern water for drinking for other human consumption uses.

Because rain water cistern systems are considered structures, the safety of these systems is another matter of concern. Thus, their impact on existing building codes, which may not be applicable to cisterns imposes another impact on institutional policy.

The impact of cistern systems on institutional policies and their acceptability to users requires investigation. In this paper, examples of rain water cistern system impacts on institutional policies are discussed and presented as suggestions for further investigation and consideration.

Section 4: Water Quality

Paper 4.1

Quality of the St. Thomas, US. Virgin Islands Household Cistern Water Supplies

G. Fred Lee & R. Anne Jones
Colorado State University, USA

Abstract

A study was conducted in December 1972 to determine the characteristics of individual household cistern water supplies locate on St. Thomas in the U.S. Virgin Islands. Twelve cistern supplies as well as several other water sources, including the domestic water supply for Charlotte Amalie, St. Thomas and several well water supplies, were sampled. Measurements were made of specific conductance, alkalinity, pH, Ca, Mg, Na, K, Cl S04, total P, N02, N03 NH4, organic N, F, Zn, Ca, Cd, Pb, Cr, Ni, Fe, Mn an Hg. It was found that all of these contaminants' concentrations were below U.S. EPA water quality criteria except for Hg, whose concentrations exceeded the U.S. EPA regulations.

Individual household cistern water supplies did of appear to be contaminated to a significant extent by materials of construction or painting of the rooftop collection system. While the chemical characteristics of the cistern water supplies were in general satisfactory in terms of drinking water quality, other studies have shown that these systems tend to be contaminated with faecal coliforms and that large amounts of decomposing organic materials, such as leaf litter, tend to accumulate in the storage tank. A recommended maintenance program is presented, which includes disinfection with chlorine, periodic removal of accumulated debris from the bottom of he tank, and periodic sampling for measurement of sanitary and chemical quality.

Paper 4.2

Effect of Acid Rain Upon Cistern Water Quality

Thomas L. King & P.B. Bedient
Rice University, USA

Introduction

As consumption of water increases, surface water supplies are unable to meet the current demands and the receding groundwater table reflects the pressure placed on groundwater reserves. One potential source of water is precipitation. The use of rainfall catchment-cistern systems is not a new concept, but can be an old approach to an emerging need. Cisterns superficially appear to be a simple means to obtain water; however, cisterns require capital expense for the construction of the system, system maintenance and a means of assuring cistern water quality. Current and future use of cisterns requires an evaluation of precipitation quality in addition to water, quality degradation in cisterns. This paper addresses the impact of acid rain on cistern water quality.

Paper 4.3

Occurrence of Selected Heavy Metals in Rural Roof-Catchment Cistern Systems

William E. Sharpe & Edward S. Young
The Pennsylvania State University, USA

Introduction

Roof-catchment cistern systems consist of a roof, usually the house roof, which serves as an impervious catchment for precipitation, and a cistern to store the collected water. The stored water is pumped from the cistern to points of use within the house. Very little is known about the prevalence of this type of water supply in the United States or the quality of drinking water obtained from such systems. A recent paper by Kincaid (1979) cites Ohio Department of Health records that reported a total of 67,000 cistern systems in the state of Ohio alone. A company owned and operated by Mr. Kincaid specializes in providing service to cistern owners in Ohio. The company handles approximately 800 requests for assistance each year and provides specialized water treatment equipment to its customers. Since mot of this equipment is designed to remove particulates and disinfect cistern water, it may be concluded that these are important cistern water quality problems. However, the relatively new phenomenon of acid rain (Cogbill and Likens 1974). and the deposition of toxic metals such as lead (Lazrus et al. 1979; Hutchinson 1973) in roof-catchment cistern systems have not been previous investigated.

Roof-catchment cisterns are common in regions of the United States where groundwater supplies are either unavailable or unusable. Cisterns are present in the coal mining regions of Pennsylvania where ground water has been polluted by mining and public water supplies are unavailable. Additional concentrations of these systems occur where groundwater has not been successfully developed and surface water sources are either polluted or nonexistent. The former case generally prevails in rural areas of Clarion on and Indiana Counties, Pennsylvania and in much of southeastern Ohio.

Although each cistern system was unique, most cisterns were constructed of concrete or cinderblock coated with a waterproof cement-base sealant. Sixteen of the 40 systems evaluated in 1980 incorporated sand and gravel filters to remove particulates from incoming precipitation. In those systems with sand and gravel filters, CaC03 may have also been added as the precipitation passed through the filter.

A study was designed to survey water quality in roof-catchment cistern water systems to determine the occurrences of the toxic metals, lead, cadmium and copper. A related objective involved the evaluation of the corrosivity of the water being collected and stored in roof-catchment water systems and its relationship to plumbing type, cistern construction materials and water treatment devices.

Paper 4.4

A Water Quality Argument For Rain Water Catchment Development In Belau

Charles Romeo
University of Guam, USA

Introduction

Summary of Problem.

The quantity and quality of fresh water for human use has been a critical area of development in the Republic of Belau, formerly Palau, in the Western Caroline Islands. In an area which receives about 3 810 mm (150 in.) of rainfall per year, development of water resources has lagged behind demand and use. The primary emphasis for the last thirty years has been on the development of a centralized water system utilizing the impoundment of surface water. Resulting water hours from an insufficient quantity of water and delivery problems plus poor quality have limited the effectiveness of the municipal system in meeting the needs of the consumer. Because of these quantity and quality problems, rain water has been extensively utilized for human consumption. Yet, there has been little organized effort to develop this resource beyond a rudimentary level. Thus, rainwater catchments are often inadequate during certain times of the year.

With increased growth and development and a need to be self-sufficient, a sound water resources development policy that include rainwater catchment should be considered for the Republic of Belau. The high quality of rainwater in this geographic area should be an important actor in this choice.

Paper 4.5

Rain Water Cistern Utilization In Selected Hamlets Of The Republic Of Belau, Western Caroline Islands

Christine O'Meara
University of Hawaii, USA

Introduction

An examination of water procurement through the use of rain water cisterns should include not only rainfall data and the mechanical and the technical aspects of catchment systems, such as their design r operation, but equally important is the utilization of this water resource. The true test of the effectiveness of a rain water cistern system rests with those persons who will utilize the contained water supply. Fresh water usage is the result of deliberate human action and it is not surprising to find that particular types of water, depending upon its source, its quality, its quantity or availability, and its accessibility, have specific uses.

The following report summarizes the more salient pints regarding rain water catchment utilization based on a recent investigation o£ fresh water usage in the Republic of Belau, formerly Palau. Entitled "An Investigation of Social Aspects of Fresh Water Use in Selected Hamlets of Belau" (O'Meara, in press) and conducted by the author, that study serves as the basis of this report. While the aim of the previous study was (1) the identification and mapping of traditional, historical, and modern freshwater sites and (2) the broader examination of freshwater utilization, the information presented here concerns rain water cistern systems and includes a description of historical and modern catchment systems, their utilization, and their water quality.

Paper 4.6

Roof Catchments: The Appropriate Safe Drinking Water Technology For Developing Countries

B.Z. Diamant
Ahmadu Bello University, Nigeria

Introduction

Water is one of the major components in the structure of the human environment; it comprises nine tenths of our body and coves three quarters of our world. However, as much as water can, support and preserve life, it can also damage and destroy it when this basic commodity is contaminated prior to consumption. There are various sources of water contamination, but the most dangerous source is considered to be human waste originating from sick people infected mainly with intestinal diseases, like typhoid f ever and cholera, or from healthy carriers of these diseases. History, in particular medieval history, has been recording numerous outbreaks of water-borne diseases that wiped out whole communities.

Unfortunately, despite the remarkable technologic l achievements of our era, dangerously contaminated water supplies still pose a serious threat for a large portion of the world's population. Salas (1981) of the United Nations Fund for Population Activities, has estimated the 1980 world's population at 4.4 billion. According to recently released World Heath Organization (WHO) figures (World Water 1981), the number of people that lived without access to safe drinking water in 1980 has been estimated at 1,32 million, comprising 30% of the world's population (the ratio is actually higher because the WHO figures did not include China). Almost all these less privileged people resided in developing countries where they comprised more than half of the population. In this respect, it has been further conclude that mostly affected were the rural areas where an overwhelming majority of developing countries people live.

These distressing environmental facts were among the main reasons leading to the recently inaugurated International Drinking Water Supply and Sanitation Decade (IDWSSD) 1981-1990 aimed at "providing safe water and proper sanitation for all by the year 1990." It is universally hoped that this most human expectation will come true but, meanwhile, together with the time consuming, large-scale water resources development activities connected with the IDWSSD, it is essentially important to embark as soon as possible on ways and means aimed at providing immediate, though limited, solutions for the steadily growing safe drinking water problem in the developing world. A large-scale development of roof catchment drinking water supplies can be the appropriate answer for this problem due to the relatively low costs of the method, but mainly because it provides an almost entirely safe, raw drinking water supply that does not require costly and complicated purification processes.

Section 5: Current And Future Practices

5.1

Recent Initiatives in Raintank Supply Systems for South Australia

Peter J. Hoey & Stephen F. West
Engineering and Water Supply Department of South Australia

Introduction

Much of Australia is arid and experiences a high evaporation rate (Fig. 1). In these areas, lack of rainfall combined with high potential evaporation results in a scarcity of surface water in the form of permanent lakes and streams.

With a population of 14 million concentrated in large coastal cities, domestic water supply in Australia is most commonly provided by conventional reticulated systems, which draw water from large surface storages or from groundwater.

Besides being a necessity in many country areas, rainwater tank/roof collection systems have been and still are popular as adjuncts to urban water supplies in Australian towns and cities. This is particularly so in areas where the quality of aesthetic properties of the reticulated supply are poor. Adelaide, the capital city of South Australia is one such city.

A large proportion of Adelaide's water supply is drawn from the River Murray, a river beset with the problems familiar throughout, the world today, of rising salinity levels, increasing nutrient loads, turbidity, and algal blooms. The Australian media has for many years publicized the Murray's plight, with interest rising dramatically in recent years as the result of widespread drought conditions.

The South Australian Government and the public are concerned about deteriorating reticulated water quality, particularly that originating from the River Murray. There is a growing awareness of the benefits of rainwater systems in terms of water conservation and quality.

This paper discusses two recent government initiatives: a rainwater tank promotion campaign, its aims, its strategy and its results; and research work undertaken to gain a better understanding of raintank processes and demands, for incorporation into improved computer models design d to predict the reliability of rainwater tank/roof catchment systems.

Paper 5.2

Rural Rainwater Cistern Design in Indonesia

Winarto
Yayasan Dian Desa, Indonesia

Introduction

Water is difficult to obtain in some areas, such as the region of Gunung Kidul, which is located to the southeast of Yogyakart in Java. The main source of water in this area is rainfall. During the dry season, villagers spend much time and labor fetching water over great distances for domestic use.

In Yogyakarta, several ponds serve as catchment basins for rainfall that accumulates during the rainy season. This water is used for drinking, cooking, bathing, washing and also for livestock watering. Some of these ponds, which dry up during the dry season, are several kilometres away from the people who use them. Under such conditions, it is common for local inhabitants to search for water several kilometres from their homes.

In the Gunung Kidul region, the water table is quite deep – up to 160 m (525 ft), thus making it difficult to hand dig wells o exploit the groundwater. And because of poor economic conditions, local people traditionally catch rain water in jugs as it flows from the roof.

It is especially true that Indonesians living in villages place great importance on the joy and value of working together. This belief in solidarity is quite widespread for, within the activities of day-to-day living, there is constant contact and cooperation between neighbors. From this point of view, we believe that there is much to gain if a rural program for constructing rainwater cisterns of ferrocement and bamboo cement is encouraged especially in developing countries.

Paper 5.3

Rainwater Collectors for Villages In West Java, Indonesia

Ron van Kerkvoorden
Rural Water Supply West Java Project 0-9(a), Indonesia

Introduction

The West Java Rural Water Supply Project is jointly sponsored by the governments of Indonesia and The Netherlands. The International Water Supply Consultants IWACO B.V. was appointed to provide consultant services, part of which included the development of simple techniques for water supply systems and the transfer of this information to the rural population so the villagers could construct their own rainwater collection systems.

This paper presents the use of local building materials, the value of close cooperation of local authorities and the rural population and how people can build their own drinking-water system.

Paper 5.4

Effect of Rationing on Reliability of Domestic Rainwater Systems

S.J. Perrens
University of New England, Australia

Introduction

In a companion paper, Perrens (1982) presented the elements of a simulation model which has been used to study the main design parameters of rainwater supply systems at four locations in Australia. For that study, the model was run assuming that no rationing policy was opted when supplies were low. The results showed, however, that for all but the areas of subtropical rainfall with a mean annual greater than 1500 m, inadequate supply would-be available from all the roof areas on a typical farm or "station" to allow a reasonable standard of living for a family of four people. Under these circumstances, two strategies are commonly employed:

  1. Overall reduction in the demand for rain water either by lowering expectations or by seeking an alternative source of water to meet an element of the demand, for the use of water from a farm dam for toilet flushing or, with minor treatment, for clothes washing 
  2. Acceptance of a short-term reduction in demand by accepting a rationing policy which will increase the reliability of the supply for a given demand or, alternatively, allow increased demand for the same reliability.

The problem of allocating the rainwater resource given certain practical constraints on the physical elements of the system (storage size and catchment area) is one which regularly faces many Australian homesteads. Rationing may therefore be seen as an alternative to increasing the size of the physical components of the system. To make rational decisions about rationing, the user will need to know:

  1. The rationing policy to apply (duration of rationing and reduction of demand) 
  2. The effect of a particular policy on the reliability of the supply  
  3. The frequency with which rationing will be imposed under a particular policy.

This paper presents some preliminary analysis of these factors which have received very little attention to date.

Body (1968a, b) studied a range of rainwater supply systems in Australia and examined the effect of rationing policy on the reliability of supply. His work was never completed, however, and the results have not been made generally available. Body adopted more complex rationing rules than those used in this study and examined a three-stage rule requiring successive reductions of demand to 75, 50 and 25% of full demand when particular storage levels were reached. The study took the percentage of time that rationing could be accepted as one of the criteria for design and examined the probability of achieving this. The study also examined the variability of rationing with particular historic sequences of rainfall.

Like many engineering design tasks, the analysis can be made as complex as desired. The main factor requiring judgement is the appropriate level of sophistication required for the task in hand. In this apex, which is based on a study primarily aimed at domestic rainwater system, one simple rationing rule has been examined.

Paper 5.5

Integrating Rain Water Cisterns with Public Water Supply Systems

Yu-Si Fok
University of Hawaii at Manoa, USA

Introduction

In recent years, many metropolitan centers have experienced water shortages, due partly to droughts as well as rapid urbanization. The latter has resulted in an oversubscription of existing water supplies. As a result, moratoriums on building permits have been reported in Orange County (Los Angeles, California) and in several counties in Hawaii. Developers in these areas were denied building permits and told to develop their own water source before building permits could be issued. As a result, many developers suffered losses in time, money, and business opportunities.

Thus, it is evident that alternative water sources must be found to alleviate water shortage problems in urban areas. Rain water-cistern systems are practical alternative or supplemental water supply systems which have long been used prior to the development of public water supply systems. During the 1977 California drought, Monterey peninsula residents recycled their limited 50 gal/person/day water rations to irrigate their gardens and lawns, and utilized rain cisterns to supplement their recycled water. These emergency water management practices reportedly reduced revenues to the water supply agencies, thus creating a financial problem for the water supplier, Therefore, when a potential, alternative water supply system is contemplated, related problems discussed in this paper should be solved before the alternative is integrated into the existing water supply system.

Paper 5.6

Cistern Systems: The California Perspective

Alan Thane Ingham & Charles Franklyn Kleine
Department of Water Resources, State of California, USA

Introduction

The California drought of 1976-1977 focused attention on the limits of conventional water supplies at the state and the local levels. Most of the rainfall occurs in the northern. portion of the State, whereas the principal metropolitan developments are in Southern California. To provide water supply for these developments and for agriculture, largely in the San Joaquin Valley of Central California, the State Water Project (SWP) was developed to collect water in reservoirs in Northern California, and to transport this water to Southern California using pumping plants and over 64.36 x 104 m (400 miles) of aqueduct. The system is currently supplying about 60% of its contracted entitlements. As originally planned, the ultimate development of the system would require construction of new reservoirs and canals beyond those now constructed. In many developed areas of the state, natural surface and groundwater sources are fully developed. The 1976-1977 drought reinforced California's recognition that her water resources were limited; this; coupled with increasing energy costs for pumping water to major urban areas and political and environmental changes occurring in the last 10 years, encouraged the development of statewide programs to expand existing conventional supplies by reclaiming municipal waste waters and to promote conservation practices fox both urban and agricultural water users. Sometimes these programs involved the investigation into the potential for innovative development of water supplies, such as coastal fog recovery and cistern technology. California's program to develop cistern systems is unique. In this paper will be discussed the background, elements, and benefits of cistern technology and California's program encouraging the development of these systems. It is hoped that this program will serve as a model fox other states when they plan their overall water development programs.

The technical discussion presented in this paper will address the State's residential usage of water, the advantages of grey water as an alternative supply of landscape irrigation water, and the typical elements of cistern systems used in California. Attention will then be directed to reviewing the regulations and management of cistern systems; California's tax incentive program for developing residential cistern water supplies; and a program for implementing demonstration cisterns for planners, engineers, health officials, and the general public. The paper will close with a presentation of cistern benefits to the individual region and the state; and hence, governments' responsibility to encourage this worthwhile technology.

Section 6: Related Topics

Paper 6.1

The Terrace-Cistern System: New Perspectives in Soil and Water Management

Ulpio Nascimento
Laboratorio Nacional de Engenharia Civil, Portugal

Introduction

The basic idea presented in this paper is the combination of two very old techniques- land cultivation in terraces and rainwater catchment in cisterns -to form a terrace-cistern system whose potentialities are expected to exceed that of either technique by itself.

Such a system can open new prospects for land and water management. In the case of soil management, rainwater catchment for irrigation will make possible the reclamation of waste land and/or the introduction of new crops with higher yields. And for water management, a direct benefit will be the increase in the available water resources as a result of the collection and utilization of runoff; indirect benefits include the diminishing of soil erosion, and consequently, improving the operation of reservoirs and channels.

One may ask in what circumstances the implementation of this system becomes practicable from the technical and economic points of view. To throw light on this question, the Laboratario Nacional de Engenharia Civil recently started the research project reported here and which will require further research to solve some of the problems. That such research is needed is beyond question. In some of the most recent literature on water management, Cunha et al. (1980) concluded that research is not only necessary but also urgent.

This paper is presented to the International Conference on Rain Water Cistern Systems to profit mainly from any criticism and comments and to hopefully elicit cooperation in the pilot studies and the work to be done.

Paper 6.2

Underground Pipes to Recharge Rainwater Storage in Aquifers

Katsuyoshi Ishizaki, Fumio Yoshino & Akira Terakawa
Ministry of Construction, Japan

Introduction

Rainwater cistern systems have high potentialities to supplement and thus reduce the demands on public water supply systems if the storage tank cost can be made more feasible. In general, the cost of water tanks is relatively high in comparison to other components of the total rainwater cistern system. Thus, an underground aquifer can be considered as one method to minimize the total. cost of rainwater cistern systems if an aquifer, rather than a storage tank, can be used to store rain water. Using underground pipes as an infiltration technique is a possible solution.

Underground pipes, which are permeable and buried in the topsoil, are being used for crop irrigation and also for drainage. They were recently found to be also useful in the field of groundwater recharge (Ishizaki, Kitagawa, and Terakawa 1981). Because ordinary methods to recharge groundwater, such as well injection and ponding, have common problems of clogging, considerable design and cost studies will be necessary to maintain them as infiltration facilities (Ishizaki and Kitagawa 1981). Because of aerobic conditions, underground pipes used for irrigation have little chance of clogging. Also, the cost of these pipes is relatively low because of their simple structure. Thus, we discuss the possibility of using an underground aquifer as the storage element and underground pipes as the catchment and conduit for rainwater into the aquifer.

Paper 6.3

Rain Water Cistern Systems in China

Jiaxiang Zheng
East China Normal University, China

Introduction

Rain catchment systems have long been used in China. People like to drink rain water because it is cleaner than river or well water and does not have the bad odor and taste of river or well water.

In the vast area south of the Yangtze where rainfall is abundant, rain water cistern systems have been a common means of water supply in past years.

The method of collecting and storing rain water was rather simple. The most available material that people used for making rain water gutters was mao bamboo, which is very common in South China and has a thick stem, which can be hallowed out and split into two halves for use as gutters. Since the introduction of tin plate and galvanized iron, people have liked to use them instead of bamboo for making gutter systems, although they are susceptible to rusting and are more expensive. Earthenware, a traditional material used for making vessels in China, is also available for making rain water cisterns. People use large earthenware vats as storage cisterns. The vats have various sizes, but the largest one has a volume of about one cubic meter. 'In appearance it is like a bowl, with an upper diameter of about one meter or more Although earthenware is fragile, it is an ideal material for a rain water cistern because it is less expensive and has no effect on water quality.

In rural areas of China, an ordinary household usually has a small yard where large earthen vats used as rain water cisterns are placed just under the gutter systems to receive the rain water from above. When it -rains and the vats are filled with water, wooden covers are put on them to avoid contamination and to shut out the sunlight to prevent algae growths. No filtering process is needed, but some alum as coagulant is generally added to remove the suspended solids. The impurities on the bottom of the vat should be regularly cleared away. Because mosquito larvae sometimes breed in the water, a goldfish is placed in the water to feed on them.

In China, an average peasant may have a commodious house with a total roof area of 50 to 100m2. As a catchment area, it is broad enough to receive rain water for drinking, but still inadequate to provide water for other domestic uses. Thus, river or well. water must be used for washing and other domestic uses. Since the annual rainfall in subtropical and tropical areas of China generally exceeds 1 000 mm, and in many regions over 1 500 mm, most of the domestic demand for water can be very likely technically improved by using rain water cistern systems with larger catchment areas.

In recent years, tap water has become an increasingly common source of water in small cities and towns of China, while rain water cisterns have decreased. However, people do not like chlorinated water for drinking because of its odor, and some people still collect rain water for drinking.

Paper 6.4

Water Demand Analysis for Agricultural Watersheds

Prabhat K. Chowdhury
Indian Institute of Technology Kharagpur, India

Introduction

Agriculture cannot exist without water. And without the required quantity of water, especially during critical periods, agriculture fails. If farmers cultivate crops without a clear picture of the amount of water needed during the growth period, two problems can occur: either crop damage because of a water shortage or a decrease to some extent in net returns because of improper and underutilization of the available water.

Farmers sometimes grow a single crop, paddy, for example, an their entire land holding. If there is a shortage of water in such cases, it is possible to overcome the problem by planting some other crops, such as wheat and pulses, in addition to paddy during the same season without causing damage to the crops because of a water shortage or diminishing the net returns. One means of increasing the per capita income of farmers is the selection of the right combination of crops, whose water demands remain well within the available water resources during a given season and which result in maximum net return and which fulfil food-grain requirements and yet remain within their investment potentialities. How and why water demand analysis is used for agricultural watersheds are dealt in detail in this paper and a water demand analysis case study is presented for small farmers.

Paper 6.5

Transient Mixed-Flow Models for Storm Sewer Systems

Charles C.S. Song
University of Minnesota, USA

Introduction

The traditional role of a sewer network has been primarily that of conveyance of waste water and storm water. A common design criterion was to ensure an adequate hydraulic capacity to convey a maximum design flow at a steady rate without surcharging the sewer. The design objective and criterion of a sewer network have undergone a fundamental change in recent years due to upgraded pollution control rules. To meet these goals, it has become increasingly clear that a substantial saving can be achieved by utilizing the in-line storage capacity of a sewer network. Most existing sewer networks have enough capacity to store the entire runoff due to a storm equal to or less than the one-year storm. The majority of storm runoffs can thus be stored for future treatment if there are provisions for a suitable control mechanism or some precautions against transient pressure.

A sewer network designed to store as well as convey storm water would undergo changes in flow regimes following a large storm event. Typically, the flow would initially be free surface flow and then begin to pressurize starting at the downstream end of the sewer system. At this time there would be a combined flow regime consisting of free surface flow and pressurized flow separated by one or more moving surge fronts. The magnitude of such a surge may build up to a significant amount as it moves upstream, and would generate severe water-hammer pressure upon collision with an upstream boundary. Clearly, a steady state or a kinematic wave type model, such as the SWMM model, is not suitable for a sewer network used as a storage-conveyance system. A complete dynamic model capable of simulating unsteady mixed-flow is necessary.

This paper describes some experiences with two dynamic models: (1) the Priessmann-Cunge-Wagner model and (2) the Song-Cardle-Leung model developed at the St. Anthony Falls Hydraulic Laboratory.

Paper 6.6

Flood Routing Through A Series Of Detention Ponds

Rong-Shun Liu & Johnny R. Barker
Lichliter/Jameson & Associates, Inc., USA

Introduction

In recent years, storm water detention has become a more popular and acceptable flood preventative measure used by planners in government agencies in the United States. The main purpose of a detention pond is to attenuate the peak flow produced upstream and to release only the maximum discharge which is equal to the existing condition. Liu and Barker (1981) developed a computer program which routes a flood hydrograph through a single storm water detention pond based on the effect on downstream receiving waters in areas with relatively small relief or coastal zones. The routing procedure becomes more complicated when a series of two or more detention ponds is required because of physical or economical limitations.

The computer program for a flood hydrograph has been revised to route the flow of flood waters through a series of two ponds by taking into account the variations of headwater and tailwater discharged at each pond, as well as by balancing the storage routing equation to determine the sizes of the ponds and their outlet structures.

Paper 6.7

Rain and Waste Water Reuse for Toilet Flushing: A Simulation Model

A. Fewkes & S.A. Ferris
Trent Polytechnic, UK

Introduction

The reuse of rain and domestic waste water for water closet flushing has an effect on the water resources of a country: this conservation may have a particular impact in areas where the carrier for the waste water is salt water or where the potable water carrier is in short supply. In the United Kingdom, 30% of the, potable water supplied to the domestic sector is used for the transportation of waste water; however, the advantages of a reuse system are unlikely to be relevant here because of the abundance of cheap potable water.

This paper considers two water closet [WC] supply systems: one is rain water collected from the roof and the other combines rain and domestic waste water. The stochastic nature of the rain and waste water time series have been simulated using the Monte Carlo method. Subsequently, the operation o£ each system is modelled to determine the percentage of WC water conserved per annum for a range of tank capacities, roof area and family sizes.

Paper 6.8

Rain Water Cistern Systems in Indonesia

Srimoerni Doelhomid
Universtiy of Indonesia

Introduction

In Indonesia, villagers obtain their domestic water from springs, shallow wells, rivers or lakes. The fast coastal. areas have brackish surface water, groundwater and intermittent rivers. In such areas, rain water is collected from roofs for domestic purposes.

From about three to four years ago, the Indonesian government has constructed, with some financial aid from UNICEF, nearly a thousand rain water cistern (RWC) systems in Gunung Kidul, Madura, Lombok and Nusa Tenggara. A program has been established to train groups of villagers to build bamboo cement cisterns and to construct roof gutters and other component structures. Unfortunately, the storage capacity of the cisterns is not large enough to provide enough water for the very long, dry season demands. H.R. Doelhomid, a University of Indonesia student, conducted a study in which she presented nomograms for the volume of cisterns based on the roof area and family size for the Gunung Kidul area.

In a large-scale, Dutch-aided program now underway in the north coast of West Java, high quality and low quality cisterns of bricks, ferroconcrete, concrete without reinforcement, bamboo cement and ijuk (palm fibre) cement are being constructed.

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