灌区稻田控制排水对排水量及盐分影响的试验研究

宁夏银南灌区每年从黄河引水约16亿m3,其中超过一半的水量以排水形式退回黄河或湖泊湿地。监测数据显示目前排水的含盐量较低，排水过量现象严重，不仅导致了水资源的浪费，而且加剧了黄河及湖泊湿地的污染。造成这种现象的主要原因之一是现有灌区排水系统能力过剩。本文介绍了在该灌区水稻田进行的一项控制排水试验，研究了在生长期内抬高排水沟出口对田间排水和盐分变化的影响。试验结果表明，将深度为1m的排水农沟控制到60cm时，生长期内农沟地下排水量减少了50%左右。排水量减少后，田间地下水含盐量增长幅度仅为3.7%，远远低于影响作物生长的临界含盐量。因此，控制排水措施具有节约灌溉用水和减少农业非点源污染的重要意义。

Effect of drainage control on salt and water balance in rice field

The Yinnan Irrigation District, in Ningxia Hui Autonomous Region discharges a large amount of drainage water into the Yellow River each year and influences the water quality of the River. A field experimental study on the effect of drainage control on salt and water balance in rice fields was carried out in summer, 2004. Controlling weirs were installed at the field ditch outlets to raise water level during the growing season. Flow measurement data showed that when the depths of drainage ditches were reduced from lm to 60cm by the weirs, the subsurface drainage water amount was reduced by 50%, but the salt content in the controlled fields increased merely by 3.7 %. It may conclude that the drainage control plays a significant role in water saving and non-point source pollution reduction.