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10th International Rainwater Catchment Systems Conference
"Rainwater International 2001"
Mannheim, Germany - September 2001

Section 4: Rainwater Catchment in Agriculture

Paper 4.13

Effects of Rainwater Harvesting on Dry Farming

Zhu Qiang and Li Yuanhong
Gansu Research Institute for Water Conservancy
Lanzhou 730000


The middle and eastern part of Gansu, one of China's driest and poorest provinces, is a typical dry farming region. Most of the area is mountainous, crisscrossed by ravines and gullies and covered with deep loess soil. The annual precipitation is only 330 mm with unfavourable distribution within the year. Due to the climatic and geological conditions, the runoff coefficient is as low as 0.05 and there's a lack of groundwater. Frequent droughts made the agriculture production a very low level. Serious water scarcity caused food insecurity and inadequate drinking supply for the people. In the past decades, people have made many efforts within the conventional measures of dry farming, including the cultivation measures such as deep ploughing and harrowing, mulching, breeding of varieties adapted to water stress, etc. The soil and water conservation measures such as terracing, contour planting and constructing fish scale pits are also adopted to retain rainfall-runoff. All these measures have proven to be effective in raising crop yield, however, the effects are limited especially in the dry years. They could not bridge the gap between the time rainfall occurs and the time when crops demand water. Figure 1 shows the water demand versus rainfall in the crop periods for winter wheat. We can see that crop water deficit is mainly owing to the rainfall distribution rather than the yearly water shortage. The soil porosity is far from enough to store all the excessive water in summer and autumn for the next spring.

PDF of full document (4pp, 59kb)

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