基于MODFLOW的山区地下水径流数值模拟

Preliminary simulations of the groundwater flow within the mountain ranges by MODFLOW

以祁连山大都麻河流域上游为研究区域,采用等效多孔介质的方法,利用DEM以及其他的降雨径流资料,尝试利用MODFLOW模拟山区地下水径流.考虑到山区地形复杂,地下水变化大,本文将河流概化为排水渠边界,设置两个模型分别代表不同的地下水活动层厚度.通过查阅资料及模型调试,得到模型a,b的山区基岩补给量分别为降雨量的2.762%,0.103%,模型a,b的年基流量分别为地表径流量的79.307%,77.57%,地下水蒸散发都为潜在蒸发量的36%,模型a,b的降雨补给量分别为降雨总量的67%,21%.本文利用有限的水文地质资料概化了缺乏资料山区的地下水运动,并模拟得到山区基岩补给量及基流量,为未来山区地下水勘探提供参考.

The upper reach of the Daduma River located in the Qilian Mountains was choosen as the study area. The MODFLOW model was applied to simulate the groundwater flow in the mountainous region using the equivalent porous medium based on DEM and some other hydrological data. Considering the complex topography and large fluctuations of groundwater table, we took the rivers as ＂leaky” boundaries and built two models representing different thickness of the active layer of groundwater. The model was first calibrated qualitatively through the review of literature and the scattered local hydrological data. Preliminary results showed that the ratio of mountain block recharge to the precipitation of model a and model b is 2.76% and 0.103% respectively. The ratio of the base flow to the surface runoff of model a and model b is 79.307% and of 77.570% respectively. The evaporation and precipitation recharge of the two models are 36% and 67%. The simulations enabled us to understand the groundwater flow in fractured rock in the data-lacking high elevation mountain watersheds, which can provide a reference for further study.