论文部分内容阅读
基于稳定同位素技术研究了河西走廊中部典型荒漠区土壤水分对降水脉动的响应。结果表明:降水分布及其δ18 O值都存在显著的季节变化特征,降水事件多发生在夏季,且有较高的δ18 O值,而冬季降水稀少,且δ18 O值偏低。降水以脉动方式输入土壤中,不同量级的降水事件会导致土壤含水量和δ18 O值不同程度的响应。降水入渗后不同深度的土壤含水量和δ18 O值的响应程度和响应时间不同,土壤深度越大,响应程度越小且响应时间越滞后。对比降水δ18 O值和降水后不同深度的土壤水δ18 O值的变化发现,表层土壤能够迅速的对降水做出响应,下层土壤的响应具有滞后性。即这种自上而下的活塞式下渗是该区主要的降水入渗方式。荒漠区土壤水分受降水的调节和控制,但是深层土壤水受小降水事件的影响较小,大降水事件虽然发生频率较小,但是能够对深层土壤水形成有效的补给,对整个荒漠生态系统的可持续发展都具有十分重要的意义。
Based on the stable isotope technique, the response of soil moisture to precipitation fluctuation in a typical desert area in central Hexi Corridor was studied. The results show that there is a significant seasonal variation in precipitation distribution and δ18O value. Precipitation events occur mostly in summer with high δ18O value, but scarce in winter and low in δ18O value. Precipitation is input into the soil in a pulsating manner. Precipitation events of different magnitudes lead to different degrees of response to soil moisture and δ18O values. After the rainfall infiltration, the response and response time of soil moisture and δ18O values at different depths were different. The greater the soil depth, the smaller the response and the lagged the response time. Comparing the δ18O value of precipitation with the δ18O value of soil water at different depths after precipitation, it is found that the surface soil can respond quickly to precipitation and the response of the lower soil has a hysteresis. That this top-down piston infiltration is the main rainfall infiltration. Soil moisture in the desert area is regulated and controlled by precipitation, but the deep soil water is less affected by the small precipitation event. Although the occurrence frequency of the large precipitation event is small, it can form an effective supply to the deep soil water and contribute to the entire desert ecosystem Sustainable development is of great importance.