宁夏银南灌区排水现状分析及计算

作为灌溉农业的一项保障措施，农田排水在维持田间水盐平衡的同时，也向下游输送了大量可能成为地表水污染源的物质。位于黄河上游的宁夏银南灌区由于历史原因形成的“大引大排”积习，每年将过量的农田排水排入黄河，成为下游水质污染源，同时也浪费了宝贵的水资源。该文针对宁夏银南灌区过量排水问题，对灌区排水现状进行了详细的分析和计算。结果表明，在现有灌排制度下，生长期内水田的农沟排水量约56 cm，占地下排水总量的58%；旱田的农沟排水量较少，只有1.0 cm，占地下排水总量的4%。建议在水田农沟上加筑控制性建筑物，如堰等，对排水量进行控制，达到节约灌溉用水和减少农田排水对下游河道污染的目的。

Analytical study on current drainage condition in the Yinnan Irrigation District in Ningxia Hui Autonomous Region of China

The Yinnan Irrigation District is located in the upper reaches of the Yellow River in China. Due to historical reasons, the district diverts a large amount of irrigation water from the Yellow River and consequently discharges a relatively large amount of drainage water to the downstream river. In order to mitigate the negative impact of the current water management practice on water quality of the Yellow River, a comprehensive analysis was conducted on the drainage system of the irrigation district. The calculation results showed that, for the paddy fields, the annual drainage through field ditch was as high as 56 cm, accounting for 58% of total subsurface drainage; for the dryland crop fields, the annual drainage through field ditch was only 1.0 cm, accounting for 4% of the total subsurface drainage. Therefore, it is feasible to implement controlled drainage practice in the rice growing areas in order to reduce drainage discharge and save irrigation water.