A study about the influence of human activities on water quality in a closed water area―A case study in Baiyangdian, China—

Abstract

Water quality in Baiyangdian lake, which is located in North China Plain encountering rapid urbanization, reflects the human activity in the watershed. We define such a lake as an Environmental Lake . Human factors in the formation of water quality and ecosystem services as a resilience of the lake, are made clear based on the relationship between characteristics of spatio-temporal distribution of water quality, especially nutritive salt, and land use as an index of human activities.Land use change maps in the Baiyangdian watershed and surroundings in the laks, are created for different periods. Expanded urban areas and farmland-discharged waste water to the lake cause the deterioration of water quality. Drying up of surface waters by dam construction and leakage of water by ground water extraction also cause the deterioration of water quality.Long term decrease of annual precipitation leads to decrease of inflow to the lake, and causes the deterioration of water quality. On the other hand, water purification in the lake is recognized along the direction from upper to lower lake-flow, and water quality is improved in September compared to other seasons. In Baiyangdian Lake, the spatio-temporal distribution of water quality is created by both human activities in the watershed and water purification function by ecosystem services of lake water and wetland vegetation.