Health evaluation and risk factor identification of Urban Lakes-A case study of Lianshi Lake

Abstract

Health assessment and risk factor identification represent the premise and foundation of scientific management and ecological restoration of urban lakes. Based on in-depth understanding of the nature-society duality of urban lakes, a framework for evaluating urban lake health was constructed, including four modules, namely, establishing an index system; determining the index weight; identifying risk factors; and a comprehensive lake health evaluation. Employing this framework, we evaluated Lianshi Lake, Beijing, classifying the lake condition as "sub-healthy". Based on the evaluation data, we identified the health risk factors of the lake. We applied standard difference rate (SDR) and risk degree (Rd) (safe degree (Sd) concepts, and classified the indices of risk areas employing the Pareto analysis method. Finally, we identified the lake residence period, landscape connectivity, and eutrophication as the major risk factors in Lianshi Lake. Three factors constitute the basis of ecosystem health and are key targets of ecological restoration: the lake residence period represents the hydrological and hydrodynamic characteristics of the lake; landscape connectivity is described from an ecological perspective, and represents the integrity of the lake ecosystem; and the eutrophication states describe the water quality characteristics and represent the availability of lake water. The results contribute to decision-making for comprehensive urban lake management.