基于塘坝淤积的黑土丘陵区小流域侵蚀产沙时空变异研究

Pond dam is recognized as one of the most important engineering measures for soil and water conservation. The sediments trapped within the pond dam can record the process information of soil erosion and sediment yield from the pond-controlled catchment. In this project, alluvial sediments within the pond dams and their controlled catchments located in the Shuangyang River basin of the rolling hilly area in Southeast Baiquan County of the black soil region will be selected as our research objects.The research will be conducted by integrated methods, including direct measurments and calculations of the trapped sediments within the selected pond dams, using 137Cs and 210Pbex tracers to analyze the deposited sediment profiles for several representative pond dams, and soil erosion prediction with the Universal Soil Loss Equation (USLE) for the selected dam-controlled catchments.The dynamic processes of catchment erosion and sediment yield rates and the relative contributions of sediemnts from different sediment source areas will be studied, and the spatio-temporal variations of soil erosion and sediment yield rates for the dam-controlled catchments will be discussed.The factors influencing catchment erosion and sediment yield rates, such as land use and cover change, soil, topography, precipitation, and the catchment areas will be analyzed. The response mechanism of spatio-temporal variations of soil erosion and sediment yield characteristics for the study catchments to the influencing factors as well as their changes will also be disclosed in this project. The research will provide scientific evidence for the effect of the conducted soil and water conservation measures on catchment erosion and sediment yield, and then provide rational implementation of soil and water conservation measures for the small catchments of the black soil region, Northeast China.

塘坝是水土保持治理的重要工程措施之一，坝内淤积的泥沙记录了塘坝控制流域侵蚀产沙过程信息。本研究以拜泉县黑土丘陵沟壑区双阳河流域塘坝内淤积的泥沙及塘坝控制控流域为研究对象，采用众多塘坝的淤积泥沙测算、典型塘坝淤积泥沙复合核素（137Cs与210Pbex）示踪辅以坡面侵蚀USLE模型相结合的方法，研究坝控流域侵蚀产沙速率、不同泥沙来源地相对来沙量的动态变化过程，探讨坝控流域侵蚀产沙时空变异特征，分析坝控流域侵蚀产沙影响因素及其变化，揭示坝控流域侵蚀产沙、不同泥沙来源地相对来沙量时空变异对侵蚀产沙影响因素及其变化的响应机制。本研究将为黑土区小流域水土保持治理效应评价及其合理实施提供科学的理论指导。

黑土区是我国重要的商品粮基地，近年来土壤侵蚀严重，威胁到我国的粮食安全。然而，黑土区土壤侵蚀研究起步较晚、有水沙监测的小流域少及监测时间短，小流域侵蚀产沙变异及因素影响机制研究亟待深入开展。本项目利用水库/塘坝的泥沙淤积信息，结合核素（137Cs和210Pbex）示踪技术和模型（WaTEM/SEDEM）模拟，阐明了黑土区典型水库/塘坝控制小流域泥沙来源时间特征及不同泥沙源地相对来沙量变化过程，发现齐心水库流域耕地来沙贡献约为50.87%，非耕地（林地和草地）贡献为5.22%，而沟道侵蚀贡献约为43.91%。在量化流域产沙影响因素的基础上，揭示了小流域侵蚀产沙时空特征及变异机制，发现土地利用和流域地形是流域产沙的主要影响因素，它们对流域产沙的贡献率分别为45.6 %和22.4 %。利用土壤侵蚀产沙模型（WaTEM/SEDEM）模拟，发现自1954年以来，流域减沙的80%是由水土保持措施的实施和土地利用变化引起的。在本基金的资助下，发表论文18篇（其中SCI论文8篇），超额完成了研究任务（基金预期发表10-12篇，其中SCI论文4-6篇）；培养硕士研究生2名。该基金研究成果可深化黑土区小流域侵蚀产沙机理研究，为黑土区合理实施水土保持措施提供科学依据。