Shaanxi Section Of Weihe () Health Evaluation

With the rapid development of economy, human activities frequently interfere the eco-environmental system, the structure and function of river has been destroyed, all the factors harmfull to the river health. Hence, advanced theories and methods are used to evaluate the health of Weihe River which would be of great significance to river health research in the aspects of theory and practice. So many scholars both at home and abroad make great progress in the assessment of river health. Weihe River (Shaanxi Section) is face with a great number of ecological and environmental problems. Based on this condition, a method combine data collection with site survey is developed to appraise Weihe River health. The data used to assess river health is selected at the year of2007. Several steps which including identifying evaluation principles, proposing assessment index system, choosing the evaluation criteria, and calculating the indicators’weight are taken to made a preliminary study on the health status of Weihe River. The main contents and innovation findings of this treatise are as follows:(1) The average annual runoff of Weihe River shows a downward trend, but the uneven distribution during a year on the contrary. The result of spearman rank correlation test analysis shows that the runoff sharply decline from midstream to downstream.(2)About70%of the river water is severely polluted and hard to meet the need of river functional criteria every year. The downstream flood plain continuing rise, the main channel increasing shrinkage, and the channel gradient ratio becoming lower and lower, which sharply drop the flood capacity in river.(3) The model named Analytic Hierarchy Process-fuzzy comprehensive evaluation model is developed to implement river health assessment, and the results show that the health level of the five sections as follows:midstream is "middle", from Xianyang to Lintong is "sick" and below is "bad". The health of the lower reaches showing downward trend along the river, but there are some improvement at the estuary.(4) The conclusion of index sensitivity analysis demonstrated that the sensitive indicators including water quantity, water quality, flood discharge capacity, bank-full discharge and river bed gradient from midstream to downstream. (5) For the sake of solving problems confronted by Weihe River, some measures which include improving water use efficiency, preventing water pollution, control flood disasters, and reinforcing the administration are proposed to preserve the health of Weihe River.