巴音河中下游农业灌溉对地下水补给量与排泄量的影响

Effects of Agricultural Irrigation on Groundwater Recharge and Discharge in the Middle and Lower Reaches of Bayin River

为揭示农业灌溉对柴达木盆地东北部内陆河—巴音河地下水补给量与排泄量的影响,采用SWATMODFLOW耦合模型,在保证其模拟精度的前提下,模拟了巴音河中下游有无农业灌溉条件下的地下水循环。结果表明,空间上,持续灌溉使得下游的地下水向地表水排泄比例从0.32%增加到0.70%,并持续到灌溉停止后的第3个月。季节尺度上,农业灌溉使研究区地下水补给量和排泄量增加,农业灌溉对地下水补给量的影响夏季汛期时较小,秋季河道径流量较小时最大,冬季最小。农业灌溉对地下水的补给作用具有一定滞后性,停止灌溉后3个月内补给仍在进行。相对于地下水补给量,地下水排泄量受农业灌溉影响亦在增加,但增量较稳定,稳定在60000~70000 m^(3)/d之间。年际尺度上,地下水补给量和排泄量在农业灌溉影响下均有所增加。其中,降水量较多年份农业灌溉对地下水补给量影响较小。农业灌溉影响下地下水向地表水排泄量的年际变化不大,变幅为-2%~2%。

To reveal the impact of agricultural irrigation on the groundwater recharge and discharge in the inland river-Bayin River in the northeastern QaidamBasin,the SWATMODFLOW coupling model was used to simulate the groundwater circulation in the middle and lower reaches of the Bayin River with/without agricultural irrigation under the premise of ensuring the simulation accuracy.The results show that in space,continuous irrigation increased the discharge rate of downstream groundwater to surface water from 0.32%to 0.70%,and continued until 3 months after the cessation of irrigation.In the seasonal scale,agricultural irrigation increased the groundwater recharge and excretion in the study area.The effect of agricultural irrigation on groundwater recharge was small in summer flood season,the maximum in autumn when river runoff was small,and the minimum in winter.Agricultural irrigation had a lag effect on groundwater recharge,and the recharge was still going on within 3 months after the last irrigation.Compared with the groundwater recharge,the groundwater discharge affected by agricultural irrigation was also increasing,but the increment was relatively stable,which was between 60000 and 70000 m3/d.In the interannual scale,both groundwater recharge and excretion increased under the impact of agricultural irrigation.In the years with more precipitation,agricultural irrigation had less impact on groundwater recharge.Under the impact of agricultural irrigation,the annual variation of groundwater discharge to surface water was not obvious,with a range of 2%-2%.