基于地下水动态和经验模型的巴丹吉林沙漠潜水蒸发量级——以苏木吉林湖区为例

Magnitude of groundwater evapotranspiration in the Badain Jaran Desert based on groundwater dynamics method and empirical model:A case study of the Sumujilin Lake Area

为确定巴丹吉林沙漠腹地湖区潜水蒸发对地下水排泄的贡献量级,以沙漠腹地的苏木吉林湖区为研究区,使用高分辨率影像、DEM和实测的地下水埋深提取了研究区湖泊水面、不同类型植被区及不同地下水埋深区的范围,基于地下水动态信息法和潜水蒸发经验模型分别计算了植被覆盖区和裸地的潜水蒸发量。结果表明:(1)同时期内芦苇观测点潜水蒸发量大于芨芨草-白刺观测点,且两者分别在生长中期、前期达到峰值。(2)同等大气蒸发条件下,苏木吉林湖区有植被覆盖的潜水蒸发总量比无植被覆盖条件下多16%~18%,仅使用裸地潜水蒸发经验模型计算会产生较大误差。(3)苏木吉林湖区潜水蒸发总量占湖区地下水排泄总量的11.3%~13.2%,证明潜水蒸发是巴丹吉林沙漠湖区水量平衡研究中不可忽略的关键因素之一。

The Sumujilin Lake Area was taken as a study case to determine the contribution of evapotranspiration to groundwater drainage in the Badain Jaran Desert hinterland.Using high-resolution remote sensing image,digital elevation model(DEM),and field-measured groundwater depth,we extracted the ranges of lake water surface,different types of vegetation coverage areas,and groundwater depth hierarchic areas in the study area.Meanwhile,the evapotranspiration of vegetation coverage area and bare land wererespectively calculated on the basis of the groundwater dynamic method and the groundwater evapotranspiration empirical model.The results showed that the evapotranspiration from the Phragmites australis observation area is larger than that from the Nitraria tangutorumAchnatherum splendens observation area during the same period.There are differences in the evapotranspiration patterns of the two types of observation areas.The former reaches the peak of the evapotranspiration rate during the middle stage of the growing season,whereas the latter reaches the peak during the earlystage.Under the same atmospheric conditions,the total amount of groundwater evapotranspiration with vegetation cover in the Sumujilin Lake Area during the growing season is 16%to 18%more than that without vegetation coverage.Therefore,using only bare land groundwater evapotranspiration formulas or models to calculate the groundwater balance of the lake basin would produce large errors.Finally,the total amount of groundwater evapotranspiration in the Sumujilin Lake Area,including vegetation coverage and bare zone with shallow groundwater depth,accounts for 11.3%to 13.2%of the total groundwater drainage in the lake area,which proves that groundwater evapotranspiration is one of the key items of the water cycle of Badain Jaran Desert lakes and could not be negligible in the water balance studies.