塔里木河下游荒漠河岸林地下水蒸散发

通过对塔里木河下游4个观测点地下水位的监测和地下水蒸散发的估算，分析荒漠河岸林地下水位月和日的波动、地下水蒸散发（ETg）的时空变化及其主要影响因素。结果表明：①在生态输水前（7月21日至8月12日），4个观测点地下水位呈整体下降趋势；而生态输水后，水位保持稳定上升趋势。在整个观测期内，地下水位都表现出明显的昼夜波动现象。② ETg 均呈现出单峰变化特征，8:00开始快速增加，在12:00—16:00维持在一个较高水平上，18:00以后快速下降，最高值出现在当地时间14:00。③ ETg随着植被类型、覆盖度的不同而存在显著差异，同时又受地下水位埋深的影响。④太阳辐射、温度和饱和水气压差是影响塔里木河下游地下水蒸散发日变化的主要因素，风速对其无显著影响。

Groundwater Evapotranspiration in Desert Riparian Forest in the Lower Reaches of the Tarim River

In this study, the groundwaterlevel at four observation sites in the lower reaches of the Tarim River wasmonitored, and the values of groundwater evapotranspiration were estimated. Thepurposes of the study were to analyze the fluctuations of groundwater level andthe groundwater evapotranspiration (ET_g) as well as theirmain affecting factors. The results showed that: ① A drawdown of groundwater level occurredholistically at the four observation sites before implementing the project of ecologicwater conveyance; after implementing the project from July 21 to August 12,however, the groundwater level was in a steady rising trend. There was a diurnal-nocturnalfluctuation of groundwater level during the study period; ② The curve of ET_g was unimodal, ET_g began to rapidly increase from 08:00, maintained at ahigh level from 12:00 to 16:00, and rapidly decreased after 18:00. The highestvalue appeared at 14:00 local time; ③ ET_g varied significantly withdifferent vegetation types and coverage, and was also affected by groundwater depth; ④ Solar radiation, temperature and vapor pressuredeficiency were the main factors affecting the daily variation of groundwaterevapotranspiration in the lower reaches of the Tarim River, and the effect ofwind speed on it was not significant.