Research On The Supply-demand Balance Of Water Resources And The Water Seepage From Canal Systems In Qingtongxia Irrigation District

Qingtongxia Yellow-River Irrigation District (QYRID) is located at the lower section of the upper reach of the Yellow River. It is one of the large-scaled traditional irrigation districts in China. With the inflow reduction in the Yellow River and the rapid social-economic development in Ningxia, the supply-demand conflict of water resources in QYRID is becoming serious and the traditional patterns of water use in agricultural irrigation can no loner accord with the new situation of the local development. The application of water-saving irrigation and the development of water-saving agriculture have become a must to make sure of the harmonized development among the population, resources, economy, ecology and environment in QYRID.In order to find out the exploitable potential of water saving, quantitative analysis was employed in the researches on the supply-demand balance of water resources in QYRID. Under the condition that the water supply from the Yellow River is becoming less, it is recommended to reduce the water use in agriculture through the adjustment of cropping structure and to exploit the underground water for supplementary resources. In this way, it is expected that the supply-demand conflict of water resources in QYRID will be alleviated, and it is predicted that water requirement in agriculture in 2005will be 25% less. The saved water will be used mainly to satisfy the water requirements in the local social-economic development and ecological improvement. The balances among the water diversion, drainage and consumption were analyzed to meet the challenge of water use restriction in QYRID.The water seepage from canal systems was one of the major factors in the analysis of water supply-demand balance. Through the analysis of the monitoring data on water delivery in the canal systems, a generalized model of water loss at a unit length of canal and a mathematic model of canal percolation replenishment to the moving table of underground water were recommended. The results of correlation comprehensive array analysis indicated that the water seepage from canal systems was the main cause resulting in the uprising of underground water table and the increase of soil salinity in QYRID.