Study On Water Environmental Carrying Capacity Based On BP Neural Networks

As a Continental semi humid and semi-arid climate types in Ningxia area,dry climate,large evaporation,shortage of water resource and deterioration of water environment have become one of the problems of impeding the development of the region.The research of regional water environmental carrying capacity has produced great significance for reasonable development and effective protection of water resource,and ecological environmental restoration.On the basis of study on Tengger Lake in Zhongwei,temporal and spatial variation characteristics of water environmental factors from 2013 to 2015 were studied,and the main influence factors,water quality and eutrophication status of water body were explored to structure index evaluation system of water environmental carrying capacity in Tengger Lake,and artificial neural network model was established to analyze(WECC)water environmental carrying capacity.Finally,theoretical basis of ecolog:ical environment protection and sustainable development was informed in Tengger Lake.The main results are organized as the following:(1)The water environmental main factors followed by the importance which had affected on water quality of Tengger Lake in 2013 were ranged as follows:(TP)total phosphorus,(COMMn)Permanganate index,pH,(CODcr)chemical oxygen demand,(NH3-N)ammonia nitrogen,(DO)dissolved oxygein,(Chl.a)Chlorophyll a,(TN)total nitrogen and(SD)transparency;and in 2014,the water environmental mian factors were ranged as follows:NH3-N,SD,TP,Chl.a,DO,TN,pH,CODcr and COMm.;and in 2015,the water environmental mian factors were ranged as follows:TP,DO,Chl.a,TN,NH3-N,CODcr,SD,COMmn and pH,and nitrogen and phosphorus nutrient salts were regarded as main functito on in Tengger Lake.(2)The water quality level from spring winter in Tengger Lake in 2013 were ? class,V class,V class and ? class;and the water quality level from spring to winter in Tengger Lake in 2014 and 2015 were:? class,IV class,IV class and ? class.Eutrophic state from 2013 to 2015 in Tengger Lake in spring was mild eutrophic,and the summer and autumn was middle eutrophic or mlid eutrophic state,and the winter was medium eutrophic state.The degree of pollution for Tengger lake in summer was moderate pollution state,and in spring or autumn was light pollution or general cleanliness state,and in winter was cleanliness state or general cleanliness state.(3)The nine indicators from water quality subsystem and aquatic ecological subsystem were selected to structure evaluation index system of water environmental carrying capacity in Tengger Lake,and artificial neural network model was used to analyze and study water environmental carrying capacity in Tengger Lake.Water environment carrying capacity index from 2013 to 2015 in Tengger Lake was 0.69,0.63 and 0.46,which showed that water environment carrying capacity of Tengger Lake was in a state of basic bearing capacity.