永定河上游水量水质耦合模拟研究

Affected by climate change and human activities, water shortage and water deterioration pose serious challenges to the rational use of water resources and ecological security at basin scale. Therefore, a joint simulation of water quantity and quality is highly required due to the uncertainty of the water cycle and the complexity of water quality changes. In recent years, the Yongding River is confronted with severe water shortage and water deterioration. Characteristics of water quantity. Quantifying water quality and the mechanisms of their changes at basin scale are therefore critical for the sustainability of water resources and have a profound and far reaching practical significance for water conservation in northern Beijing and national ecological barrier, and therefore have for coal safety production. This project coupled modelling of water cycle and non-point source pollution in the headwaters of Yongding River basin based on a distributed hydrological model by integrating remote sensing, meteorological and eco-hydrological multi-source datasets, the spatial-temporal variation of water balance and runoff components in the upper reaches of the Yongding River is simulated and analyzed. Based on the water balance, a coupled non-point source pollution process model was developed to study the spatial-temporal variation of solute transport. Furthermore, the scenarios of land use change will be set to quantitative assessment of the impacts of human activities on water quantity and quality based on coupled simulation. This project and possible findings are expected to provide scientific evidences for the development, utilization and protection of water resources and the construction of ecological civilization.

受气候变化及人类活动影响，水量短缺和水质恶化给流域水资源合理利用及生态安全带来严重挑战。由于水循环的不确定性及水质变化的复杂性，需要对水量水质进行联合模拟。近年来，永定河面临径流量减少、水质恶化等生态问题。因此，理清流域水量平衡及水质变化的机理，对水资源可持续利用及建设首都水源涵养区和生态屏障的国家需求具有重要的理论与实践意义。本项目以永定河上游水源保护区为研究区，在整合遥感、气象、生态水文等多源数据基础上，基于分布式水文模型，模拟分析永定河上游流域水平衡及各径流分量的时空变化规律；在水平衡基础上，耦合流域面源污染过程模型，研究溶质运移的时空变化规律。基于耦合模型，设置土地利用变化情景分析，定量评估人类活动对流域水量水质的影响，揭示永定河流域水量水质变化规律。本研究将为实现流域水资源合理开发、利用、保护及流域生态文明建设提供科学依据。

受气候变化及人类活动的影响，永定河上游流域面临径流量减少、水质恶化等生态环境问题，理清流域气象、水文等要素变化特征及水量、水质变化的机理，对水资源可持续利用及建设首都水源涵养区和生态屏障的国家需求具有重要意义。本项目以永定河上游流域为研究区，对永定河上游典型流域土壤剖面、土壤质地及水质进行了野外采样和定位监测，并开展了流域土地利用分类；利用统计分析、同位素和水化学、水热耦合模型、流域水文模型及机器学习模型、流域污染负荷模型，揭示了永定河上游流域气候、水文、土地利用的时空变异特征，评估了气候变化和人类活动对流域径流减少的影像贡献，评估了典型流域不同土地利用对流域总氮、总磷负荷的影响。研究发现：1）永定河上游流域气温突变型升高，最低气温及冬季气温上升显著，降水量呈现不显著下降趋势但夏季降水下降趋势明显，土地利用变化剧烈且2000年以后变化最显著，以林地和建设用地增加，耕地、未利用地和水体面积减少为主要特征；2）高强度人类活动是导致永定河上游流域径流减少的主要原因，人类活动对永定河上游不同流域径流减少的贡献率约为84.3%~97.6%；3）受自然因素及人类活动的共同影响，洋河和桑干河流域水化学类型差异显著，地表水离子浓度表现为桑干河>洋河，影响地表水水化学的自然因素主要为矿物溶解和蒸发，但人类活动却体现出流域差异，桑干河的主要影响因素为支流的工业废水排放，而洋河流域为农业生产和城市。4）清水河典型流域各月径流均呈显著减少趋势，年内分布的不均匀程度增加；土地利用类型中耕地对水体总氮、总磷浓度的贡献最大，分别占60.8%和54.3%。本项目成果可为永定河上游流域水资源量质演变的评估提供科学依据。

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