Study On Health Evaluation And Water Ecological Restoration Of Pingchuan Section In Han River

The Han river is the biggest in the middle reach of Yangtze river tributaries,is the largest river in southern shaanxi,but also in hanzhong city people’s "mother river" of the heart,would hanzhong city in the north qinling mountains,south of bashan mountains,the land is fertile,superior natural conditions,is the most developed area of grassland,economy and society.Along with the social economy rapid development,the industrial scale,emissions increased year by year,lead to regional water ecological problem increasingly prominent,has become an important factor of restricting the sustainable development of regional economy.Based on this,this article from the angle of river health assessment and ecological restoration,this paper studies the effect of land use change on the river landscape,evaluated the would section of river water quality present situation,while fully the field investigation of river health based on the analytic hierarchy process(AHP)was used to construct the evaluation model and evaluation would section of river health,and used the MIKE21 simulates the effect of sand mining behavior for fish survival environment,provide the ecological health of the corresponding suggestions and measures.The research results are as follows:(1)from the analysis of land use landscape data,it can be seen that the land use and ecological landscape changes in pingchuan section are the time nodes divided by the front and back stages in 2000.Before 2000,due to the accelerated impact of economic and social development,the impact of construction land was increasing,the extent of regional landscape fragmentation,was increasing,and the ecological environment was deteriorating.2000 years later,with the development of the han river wetland ecological management project,the regional landscape patch types of richness,landscape heterogeneity increases unceasingly,the han river in hanzhong city would strengthen the ecological regulating function.Aiming at the problems of regional landscape pattern,landscape pattern optimization,on the basis of establishing large vegetation patches,build ecological corridor,realize the continuity between the plaque,at the same time identify as ecological corridor on the ecological function of weak ecological node.(2)Cross the three monitoring cross section from 2006 to 2015 water quality indexes such as average,maximum and which to statistics,since 2010,three section of ammonia nitrogen values are appear to exceed bid,become the main factors affecting water quality.According to principal component analysis results of water quality in different seasons each season factor composite scores from upstream Jinniuyi section to the downstream section showing a rising trend,the east village shows that water quality gradually from upstream to downstream,the low water during the month peace hidden from section to section water town hanzhong city comprehensive factor score were particularly evident increase amplitude;Due to the large amount of water,the pollutant was diluted and the score of the comprehensive factor was not obvious.(3)Using analytic hierarchy process(ahp),a total of 20 indexes of four criteria layers were selected to construct a river health evaluation model of pingchuan section.Among the four criterion layers(assigned 0～25),aquatic animals and plants were the most disturbed,and the range of section scores was between 9.4 and 20.6.The score of hydrological index,river geomorphic index and water quality index is about 20.Based on four criterion layer index evaluation results,according to the health index of wujiang river(assigned 0～100),the results show that in hanzhong city would river between 67～80 basic belongs to sub-health state,The scores on the section of the section show the distribution of high middle and low sides,and the partial health of the main urban area is obviously affected,and the improvement measures need to be taken.(4)According to the fish area statistics,all kinds of traffic situations,sand mining area after mining will cause fish habitats around by the high-grade environment into a medium or low habitats,severely compressed fish living area,reduce the fish species.During the minimum flow in the dry period,the river sand mining has the greatest impact on the habitat environment of the fish.The habitat area of the high quality fish in the river area is reduced by 42%,which has a very serious impact.According to the water ecological research,due to the large amounts of sand mining activities,basic destroyed the spawning grounds,could become a battlefield,80%of the spawning grounds or sediment water into the river,affecting fish breeding incubator.