腾格里沙漠宁夏回族自治区中卫市沙层水分入渗研究

为查明腾格里沙丘沙层水分渗透性及其原因,在该地区进行了沙层水分入渗试验。结果表明,在稳定前,流动沙丘入渗率最大,半固定沙丘次之,洼地最小。在达到稳定入渗后,半固定沙丘的入渗率较流动沙丘略大,洼地则最小,它们的平均稳定入渗率分别为16.8,16.2,12.0 mm/min。不同地貌类型的沙层达到稳定入渗的时间在6.3～8.8 min之间。流动沙丘与半固定沙丘水分入渗量基本相同,入渗量均较大,洼地入渗量最小。沙层具有入渗率高,达到稳定入渗快和入渗率变化小的突出特点,沙层粒度较粗,组成均一和孔隙连通性好,是其主要原因。沙层入渗率高为沙漠地区大气降水向地下水的转化创造了非常有力的条件。研究结果表明,在常用的3个入渗计算公式中,Koctakob公式最适用于沙丘水分的入渗研究,Horton公式也较适用沙层水分的入渗研究,通用经验公式不适于沙层水分的入渗研究。

Sand Layer Water Permeability of Tengger Desert in Zhongwei City,Ningxia Hui Autonomous Region

In order to explore the water permeability of sand layer and its controlling factors in the Tengger Desert,an infiltration experiment was carried out in the region.The results show that during the first stage before a steady infiltration rate was reached,the moving sand dunes have the highest starting infiltration rate,followed by the half-fixed sand dunes and low-lying-lands in order. After about 6.3~ 8.8 min, the infiltration rate of sand layers became stable.The saturated infiltration rate of half-fixed sand dune was slightly larger than that of the moving sand dune, while the rate of the low-lying-land remained the smallest.The moving sand dune and the half-fixed sand dune had almost same high infiltration capacities and the low-lying-land has the smallest infiltration capacity.As typical characteristics,the sand layers had high and steady infiltration rates and need only a short period from start to approch steady infiltration rates,owing to the coarse but uniform texture and good pore connectivity.The high infiltration rates provided very good conditions for the transformation from rainfalls to groundwater.For the three infiltration models,the Koctakob formula was the best in describing the water permeability of sand layers,the H orton formula the second,and the general formula the most unfavourable.