基于环境同位素的洛川塬区地下水补给机制研究

发布时间：2018-04-18 16:06

本文选题：水汽来源 + 地下水补给　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：地下水资源是水资源的重要组成部分,在用水结构中占很大比重。在水资源匮乏的黄土塬区,地下水资源更加珍贵。而塬区降水对地下水的补给机制及土地利用方式变化对其影响还不明确。本研究以黄土高原中部洛川塬区为研究区域,利用氢氧稳定同位素技术和氯元素质量平衡法相结合对不同水体(降水、土壤水、地下水)同位素组成和氯离子浓度进行分析。探究塬区降水水汽来源、地下水补给机制和土地利用方式对地下水补给造成的影响。1.阐明了黄土塬区降水氢氧稳定同位素特征及水汽来源。研究区降水同位素在不同时间段受到不同环境因素和不同来源的水汽影响而存在季节效应、雨量效应和温度效应。对区域大气降水线方程和氘盈余的分析得出洛川塬区降水水汽来源较多,存在年内和年际差异。降水水汽会受到西风环流、印度洋季风和太平洋季风等的影响,又以西风环流的影响为主。2.揭示了黄土塬区土壤水分状况和土壤水分运移方式。浅层土壤水分受降水补给和蒸发作用影响较大;深层土壤受到土地利用方式影响。土壤剖面同位素组成特征验证了土壤水分下渗补给和降水直接补给深层土壤这两种水分运移方式的存在。土壤剖面氯离子浓度受土地利用方式影响有限,深层氯离子较为稳定。3.阐明了黄土塬区地下水补给机制及土地利用方式对其影响。研究区降水对地下水的补给以深层土壤水下渗补给为主,也存在降水对地下水的直接补给。氯离子质量平衡法计算出的总补给速率为120 mm/yr,占全年降雨量的20%。土地利用方式变化形成的生物利用干层阻碍了土壤中下渗水对地下水的补给。
[Abstract]:Groundwater resources is an important part of water resources, which accounts for a large proportion in the water use structure.In the loess plateau where water resources are scarce, groundwater resources are more precious.However, the recharge mechanism of precipitation to groundwater and the change of land use mode are not clear.In this study, the isotopic composition and chloride ion concentration of different water bodies (precipitation, soil water and groundwater) were analyzed by using hydrogen and oxygen stable isotope technique and chlorine mass balance method in Luochuan tableland of central Loess Plateau.This paper explores the influence of water vapor source, groundwater recharge mechanism and land use mode on groundwater recharge in the tableland.The stable isotope characteristics of hydrogen and oxygen and the source of water vapor in precipitation in Loess Plateau are expounded.The precipitation isotopes in the study area are affected by different environmental factors and different sources of water vapor in different time periods, and there are seasonal effects, rainfall effects and temperature effects.Based on the analysis of regional precipitation line equation and deuterium surplus, it is concluded that there are many sources of precipitation water vapor in Luochuan tableland, and there are intra-annual and inter-annual differences.The precipitation vapor will be affected by the westerly circulation, the Indian Ocean monsoon and the Pacific monsoon, and the westerly circulation.The soil moisture status and the soil moisture migration patterns in the loess plateau were revealed.Shallow soil moisture was influenced by precipitation recharge and evaporation, and deep soil was influenced by land use pattern.The isotopic composition of soil profile verifies the existence of two water transport modes: soil water infiltration recharge and precipitation direct recharge to deep soil.The concentration of chlorine ion in soil profile is limited by the land use mode, and the chloride ion concentration in the deep layer is relatively stable. 3.The recharge mechanism of groundwater and the influence of land use mode on groundwater recharge in loess tableland are expounded.The main recharge of groundwater in the study area is subaqueous infiltration of deep soil, and there is also direct recharge of precipitation to groundwater.The total recharge rate calculated by the chloride mass equilibrium method is 120 mm / yr, accounting for 20 times of the annual rainfall.The dry layer of biological utilization caused by the change of land use mode hinders the recharge of groundwater by the infiltration of water in the middle and bottom of the soil.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P641

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