International Rainwater Catchment Systems Conference
Mannheim, Germany - September 2001
Rainwater Catchment in Humid and Arid Regions
Value of Rainwater for Domestic Use in the Uphill Settlements in Sri Lanka
Hector Kobbekaduwa Agrarian Research and Training Institute
Although Sri Lanka's climate is in the Monsoon zone and therefore with
ample water resource in its wet zones, recent studies show that there
are wide temporal and spatial variations of water availability and demand.
If the current trend of water use efficiency continues, there will be
a severe scarcity of water in several districts of the country in the
near future (Amarasinghe et. al, 1999). In addition, 43% percent of rural
population are deprived of safe water for drinking purpose (UNDP, 2000).
Scarcity in water availability will be more aggravated with the economic
development and implementation of free market policies, where demand for
water for industries and domestic use will increase. Therefore the envisaged
water crisis will be a significant constraint for the country's socio-economic
The community Water Supply and Sanitation Project (CWSSP) was an innovative
project started in 1993 and aiming to establish an alternative system
of water supply and sanitation delivery in rural Sri Lanka. The project
was implemented based on the needs and aspirations of the people though
community initiated projects. The project mainly used the following technologies
to achieve domestic water security at household level. These include,
Gravity Water Supply Systems, shallow dug wells, hand pumps/bore holes
and pumped pipe systems. However, these conventional technologies were
not suitable to supply safe water for the communities living in uphill
settlements. In hilly areas the ground water table is very deep and most
springs and wells dry out quickly during the dry season. In addition to
the uphill areas, some places in the dry zone of Sri Lanka also have water
problems for domestic use, particularly those areas where groundwater
sources are not reliable throughout the year and the available water has
problems of salinity, hardness and high concentration of other elements.
A technology for systematic rainwater harvesting (RWH) was proposed
and successfully implemented in the uphill areas and dry zone of Sri Lanka
by CWSSP with community participation and contribution. The difficulties
and time involved in fetching water, uncertainty in available water, rising
costs in water fetching and low quality of available water sources provided
a greater incentive to beneficiaries to adopt rainwater harvesting technology.
The main components of the rainwater harvesting systems are catchment
surface for water collection (mainly domestic roof), gutter system for
water delivery and a tank for water storage. Although Sri Lanka is a country
with an annual average annual rainfall of nearly 2000mm, spatial and temporal
variations in rainfall make it necessary to adopt a technology for systematic
collection of rainwater.
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