Research Of Water Environment Capacity Of Jianghan Plain River Network

Jianghan plain is developed by Yangtze river and Han river alluvialing foryears and frequent floods since ancient time.Our county had adjusted theoriginal river system by excavating lots of drain and irrigate channels sothat drought and flood events can be reduced and river network system inthe plain was formed.With the economic growth in the place, more andmore pollution is discharged.Water quality condition of manual graffscannot be optimistic since they’re the main pollution accepted waterbodies.The calculation of water environment capacity is the base work of waterpollution prevention plan. A good deal of manual structures in the plainhave made the water network’s graffs effected by both nature andman-made.The graffs can be roughly divided into brake-shut time anddrain-irrigate time on the basis of different fuction and flow states.Sotheir water environment capacity calculation is special in somedegree.Therefore, to calculate the water environment capacity ofjianghan plain river network’s graffs properly has important theorymeanings and practical value.This paper has taken Qianjiang water network which has the classicJianghan plain water network characteristic for example and proceeddemonstration research.Proper water quality mathematical model andwater environment capacity model are chosen and optimized based on thewater environment characteristic and practical research condition, waterenvironment capacity and water quality forecast is calculated in bothbrake-shut and drain-irrigate time, and it calculated the whole yearpractical water environment with time distribution andcomposition.According to the calculation results analyzed the rationalityof available water pollution prevention scheme. Put forward the amountcontrol suggesting index and cutting down scheme.Then made waterquality forecast with mathematical model and analyzed water quality reachability of river network so that the feasibility of the suggestion canbe confirmed.Considering the effect of “Water Diversion into City”project on Qianjiang river network，it put forward water diversionsuggestion and calculated the water environmental capacity of everypollution accepting graff.So it can discuss the effect of water diversionproject on water environment capacity of river network.According to the research result, under the available planning condition, water environment capacity of pollution accepting graffs is smaller inbrake-shut time.After deducting the discharged pollution, remainingwater environment capacity of Shangdonggan graff, Zonggangraff, Xinglong river and Chengnan river is negative；the water qualityforecast results are roughly coincide with water environment capacitycalculation results.Water quality in brake-shut time are worse than thosein drain-irrigate time.The amount of pollution which is discharged intoShangdonggan graff, Zonggan graff, Xinglong river and Chengnan rivershould be cut down;Chose water environment capacity calculationresults in drain-irrigate time as the amount control index formulatingbase.The suggested Index showed that the discharged pollution amountinto Shangdonggan graff, Chengnan river can be controlled below theindex with strengthening comprehensive improvement the two availablepollution source in Qianjiang.Zonggan graff and Xinglong river shouldcomprehensively deal with the upriver water pollution source whileoptimizing available planning drain outlet.Especially for the Zonggangraff, long-term corporation with the department concerned in Jingzhou isnecessary, in order to deal with the Zonggan graff pollution managingwork.Besides, with a proper "Water Diversion into City" scheme, waterenvironment capacity of every pollution accepting graff is increasedgenerally.Water environment capacity of Shangdonggan graff, Xinglongriver and Chengnan river in both time is nomore negative and waterforecast can reach the standard.But water quality of Zonggan graffupstream is still too bad to fulfil the relevant function demand.