An Assessment of Ecosystem Health in Dongxi River Basin based on PSR Framework

In this paper,an indicator system based on the Pressure-State-Response(PSR) model proposed by the OECD and UNEP is developed to evaluate ecosystem health for River basin.The indicator system of the ecosystem health for the River basin is composed of the pressures from nature and humans,the status of the ecosystem and the responses of human society.Located in the coastal zone of southeast China,the economy of Dongxi River basin is relatively developed,the population density there is relatively higher,and natural resources is correspondingly indigent.The ecosystem health in the River basin is very important for sustainable development of the local social-economy.In a healthy River basin,ecosystem provides such services for human being as water resources supply,fish resources,flood diversion and storage,hydro-power,recreation,culture and scientific research,environmental purification,wildlife habitat,CO_2 fixation,nutrient cycling etc.In this paper,such indicators as population density,annual GDP growth,water resource per capita,annual precipitation,rate of forestland coverage,the rate of industrial waste water treatment were selected to reflect the pressure,the state and the response of the River basin firstly.Secondly,the weight of the indicators was confirmed by experts,and the assessment criteria were based on related national standard.Thirdly,the integrated assessment method for the healthy assessment of the River basin was proposed and the status of ecosystem health in Dongxi River basin was evaluated through this model.Lastly,five grades of ecosystem health status were classified,which are very good,good,moderate,low and very low.The status of ecosystem health in Dongxi River basin was evaluated.The results show that the ecological health index of Dongxi River basin is 0.5898,which is in the moderate condition.Some strategies for improving ecological environment of Dongxi River basin were put forward: Firstly,the control of population growth and environmental regulations enforcement should be enhanced.Secondly,use of pesticides and fertilizers should be reduced.Thirdly,wastes treatment and ecological restoration project should be conducted particularly in the upper and middle streams of the River basin.