渭河流域地下水系统对气候变化的响应研究

In recent years, extreme climate and hydrological events initiated by global climate change restrict regional social and economic development. As a part of climate system, groundwater characteristics will be influenced by climate changes (such as precipitation, temperature etc,.). However, because lack of researching works that combined climate change and groundwater system，the mechanism is still not known for groundwater system respond to climate change. In this work, we choose Weihe River Basin as a study area. Based on historical data analysis, field sueveying, field experiment and numerical simulating, relationship between groundwater system and climate will be studied. The aims of these works is to discriminate the influence degree of groundwater systems influenced by climate change and human activities, which will reveal evolution mechanisms of groundwater systems in Weihe River Basin. Consequently, we can construct a numerical model that combined climate change and groundwater system, which can help us to predicting evolutionary trend of the Weihe River groundwater systems influenced by future climate change and human activities, to put forward the groundwater resources development and utilization contingency plans under the extreme climatic conditions, raising awareness on climate changeability and adapt to the Weihe River economic sustainable development.

近年来全球气候变化引发的极端气候和极端水文事件已成为区域社会经济发展的制约因素。地下水作为气候系统的组成因子，随气候因子（降水、温度等）的变化亦会做出相应响应，由于缺乏将气候变化和地下水系统作为统一体来研究，地下水系统对气候变化的响应机制尚不清楚。本项目选择渭河流域作为研究区，立足史料分析、野外调查、原位试验和数值模拟，研究地下水系统与气候变化之间的关系，甄别气候变化和人类活动对地下水系统的影响程度，揭示渭河流域地下水系统对气候变化的响应机制，构建渭河流域气候变化-地下水动力场耦合的数值模型，预测未来气候变化和人类活动影响下渭河流域地下水系统的演化趋势，提出极端气候条件下地下水资源开发利用的应急预案，提高对气候变化的适应能力，实现渭河流域经济可持续发展。

本项目选择渭河流域作为研究区，依托原位试验和数值模拟，研究了地下水系统与气候变化之间的关系。系统研究了不同粒径土壤水分特征曲线的影响因素与物理意义，发现了Arya-Paris模型适合用来预测中等质地土壤，模型参数a进行非线性拟合，预测结果最为精确。发现水体温度存在日分层现象，水体面积和蒸发量呈负相关关系。受城市用地面积和耕地面积的影响，西安市热岛效应强度呈现上升趋势，升温速度为0.193℃/5年。关中盆地年降水量呈减少趋势，存在3年、5年，20年、35年左右的周期。平均气温呈现上升趋势，存在15年、30年左右的周期。1980-2000年地下水水位整体呈波动下降，2000年后部分地区水位出现回升。建立了关中盆地SWAT和MODFLOW耦合模型，研究了不同气候变化情景地下水位的变化特征。