Effects of land use/cover change on lake water quality in the semi-arid region of northern China: A case study in Lake Daihai Basin (2000-2018)

Abstract

土地利用/覆被变化对明晰气候变化和人类活动对湖泊水环境的影响有重要作用.以北方典型农牧交错的岱海流域为研究对象，基于遥感解译技术、马尔可夫转移矩阵、综合污染指数法等方法，对2000—2018年岱海流域土地利用/覆被和湖泊水质的变化进行分析，并结合冗余分析法和计量分析模型探究长时间序列尺度下土地利用/覆被变化对湖泊水质的影响.结果表明：近20年来，岱海流域的土地利用/覆被类型以耕地和草地为主，其变化特征主要是草地和林地转化为耕地，水域转化为季节性河流，岱海转化为内陆滩涂、沼泽草地和灌丛沼泽；岱海湖泊水质因子高锰酸盐指数、五日生化需氧量、总磷和总氮浓度存在不同程度的超标现象；岱海、湿地、林地对水质具有积极的改善作用，耕地、草地、建设用地是加剧水质污染的主要原因.该研究为岱海湖泊流域土地资源合理利用、湖泊水质改善和生态保护提供了一定的科学理论依据.;Land use/cover change plays an important role in clarifying the impacts of climate change and human activities on lake water environment. This paper takes Lake Daihai Basin, a typical agro-pastoral region in north China, as the research object and analyzes the changes of land use/cover and lake water quality in the Lake Daihai Basin from 2000 to 2008, which is based on remote sensing interpretation technology, Markov transfer matrix, and comprehensive pollution index method. At the same time, the method of redundant analysis and econometric analysis model are used to further reveal the impact of land use/cover area change on lake water quality under long-term time scales. The results show that the land use/cover type in the Lake Daihai Basin is dominated by cultivated land and grassland in the past 20 years. The characteristics of their changes are mainly the conversion of grassland and woodland to cultivated land, the waters to seasonal rivers, and Lake Daihai to inland beaches, marshy grasslands, and thickets of swamps, respectively. The water quality factors including COD_Mn, BOD₅, total phosphorus and total nitrogen have different degrees of exceeding the standard in Lake Daihai. Moreover, Lake Daihai, wetland, and forestland play a positive role in improving water quality and cultivated land, grassland, and construction land are the main reasons for aggravating water pollution. This research provides some scientific theoretical basis for rational utilization of land resources of Lake Daihai Basin, improvement of lake water quality, and ecological protection.