地下水水位对灌溉的响应——以北京南部灌区为例

Response of Groundwater Level to Irrigation

北京地区的地下水为满足农业灌溉,保障粮食生产起到了至关重要的作用。但是随着开采的急剧增加,地下水位出现了连续下降的趋势。为掌握地下水水位对农业灌溉的响应,选取了主要受农业灌溉影响为主的一眼地下水监测井,通过对比地下水水位的日变化量与大气降水以及本地区冬小麦降水耦合度之间的关系,得出了地下水水位与冬小麦灌溉之间的关系。研究发现,冬小麦灌溉各个阶段,地下水水位相应下降,显示出两者之间存在密切关系。冬灌后至返青前,地下水得到了充分有效的补给,水位可以恢复到冬灌之前的水平;但是由于返青-拔节和灌浆期灌溉需水量较大而且降水量较少,地下水不能得到充分有效补给,静储量被消耗,地下水位持续下降。研究结果表明,如果在返青-拔节和灌浆期采用节水措施或者引用其他水源,减少地下水的开采量,可以达到采补平衡,实现地下水的持续利用。

Groundwater in Beijing is essential for achieving demand of agriculture irrigation and guaranteeing grain production. However, groundwater level is continuously decreasing with the overexploitation of groundwater. In order to find the response of groundwater level to agri- culture irrigation, a monitoring well mainly affected by agriculture irrigation was selected to find out relationship between groundwater and win- ter wheat irrigation by analyzing relationship between daily change of groundwater level, precipitation and coupling degree between rainfall and water requirement of winter wheat. As concluded from the study, a close relation between groundwater level and winter wheat irrigation was in- dicated by groundwater level decrease corresponding to every irrigation period. Groundwater rose to the level before winter irrigation when striking root irrigation started due to abundant and effective recharge by precipitation infiltration; however, groundwater level continuously de- creases with consumption of static reserve of groundwater due to ineffective and incomplete recharge because irrigation requirement was greater and precipitation was smaller during striking root-jointing stage and filling stage irrigation. Exploitation and compensation balance can be ob- tained to achieve sustainable development of groundwater if groundwater pump rate is reduced by water saving irrigation methods or alternating water source during striking root-jointing stage and filling stage irrigation.