干旱区生态环境知识资源中心

Low rainfall, water scarcity and land degradation severely intimidate the production capacities of the rangelands in the arid environments. Water harvesting focuses on improving the productive use of rainwater on the local scale (field to subcatchment scale) before the runoff water leaves the geographical unit in question. The aim is to mitigate the effects of temporal water shortages to cover both domestic and agricultural needs. This paper provides a review on water harvesting techniques focusing on microcatchment methods, and information on performance of a small-basin water harvesting system (negarim) under a typical arid environment in Turkey as a case study. In the negarim case study, we analysed rainfall, runoff, catchment area, soil water storage and crop evapotranspiration. The microcatchment area (36m(2)) included five surface treatment methods (natural, plastic cover, stone cover, hay cover and compaction), which were studied in a pistachio plantation by monitoring soil water balance in the root zone. The overall efficiency of the water harvesting system was determined as the ratio of the amount of water stored and used by the crop to the amount of rainfall received in the catchment area. It was demonstrated that the overall efficiency of the system varied from 2.9% to 79% depending on the surface treatments and the root zone capacity. Plastic cover had the greatest efficiency. Gains in runoff improvement were lost when the soil moisture in the cultivated area was near field capacity. Surface treatments had a significant effect on plant height and stem diameter. Plant height with different treatments was 158cm with plastic cover, 128cm with surface compaction, 121cm with hay cover, 117cm with stone cover and 102cm of control. Among the surface treatments, plastic cover was superior to the other treatments on plant growth, but the use of plastic may cause environmental problems.