Near-natural Diagnosis Theory And Its Application In Water Environment Of Suburb Stream In Beijing

Because of unreasonable exploitation and uses, the water environment has suffered severe disturbance. Aimed at understanding water environment problems and its impact factors to provide information support for water environment restoration and sustainable management in suburb of Beijing, the theoretical framework, methodological system and case application on diagnosis of water environment of suburb streams in Beijing have been studied in this paper based on stress state-response mechanism. The results were expected to provide reference for effective protection and therapy of water environment of suburb streams in Beijing. The main works and conclusions are as following:(1) The near- natural diagnosis theory of water environment of suburb streams in Beijing was established. Conception framework of near- natural diagnosis for water environment of suburb streams in Beijing was brought forward, which consisted of hydrology, configuration, water quality, riparian zone, aquatic organisms and landscape.(2) The comprehensive diagnose indicators system of water environment of suburb streams in Beijing was constructed based on the six elements introduced above. Corresponding field investigation method and procedure for each indicator was ascertained.(3) The near- natural diagnosis model and method were set up. Three models including conception model, mathematic model and foundation model of near- natural diagnosis were explained. After diagnosis method was determined, each indicator's measuring value and diagnose standard were built comparing the reference status. The naturality of suburb streams were divided into four classes:Natural state, near natural state, degraded state and artificial state.(4) SAS 9.0 was used to analyze diagnosed factors and the plot indicated that lands for tourism had greater effect on benthic macroinvertebrates species and concentration of phosphorus in water than lands for transportation; Lands for inhabitancy can increase concentration of nitrogen in stream; farmland primary affected phytoplankton species, PH value and concentration of dissolved oxygen.(5) Three typical suburb streams of Beijing were selected as research areas. According to the actual value of diaginose indicators after conducting field surveys on research areas during four yeas, the naturalitis of water environment of research stream were calculated. Then the main pressures and factors that induced degradation of water environment were analysed based on the diagnose results. Different control measures were brought forwarded for corresponding naturality states.(6) The decision support system of water environment based on the Visual Basic language was further developed, which realized the visual drawing of diagnostic results.