The Water Environment Evolution And Capacity Calculation Of Guanting Reservoir

Guanting reservoir is an important large-scale reservoir in Yongding River Basin.With the rapid development of social economy in the upper reaches of the reservoir,pollution discharge and water demand are increasing day by day,leading to many problems in the water environment of Guanting reservoir.This paper analyzes the hydrological and water quality change process of Guanting reservoir,This paper analyzes the hydrological and water quality change process of Guanting reservoir,and studies the evolution characteristics of the reservoir water environment by establishing water balance model and water quality evolution trend.On this basis,a steady-state algorithm model is established to calculate the pollutant capacity of Guanting reservoir,and the inflow and outflow pollutant fluxes of the reservoir are analyzed and calculated.The main contents and conclusions of this paper are as follows:(1)This paper introduces the general situation of the reservoir basin,analyzes the balance of the hydrological process of the reservoir,and obtains the composition of each component and the proportion in the balance.The reason of water level change and the influence of each component on the water level of Guanting reservoir are analyzed.(2)Using the comprehensive pollution index method,the comprehensive pollution index of each section control factor is calculated,and the water quality of each section of the reservoir is evaluated.Based on the analysis of the water quality evolution process of the reservoir,the water quality evolution trend of the eight bridge section,HeKou section and the Yong1000 section is judged by the method of cumulative leveling.From the perspective of trend,the overall water quality of Guanting reservoir from 2010 to 2017experienced a process from good to bad,then to good,and from fluctuation to stability.(3)Based on the water balance equation,daily inflow and outflow discharge data,water level-area-volume curve and spatial interpolated daily meteorological data of Guanting reservoir.The calculation model of water balance and reservoir regulation process is developed and then the model is applied to solve the temporal process of water level,water area and volume in the reservoir during the 2012-2016 and the predicted water level is fit well with the measured data.The flow discharge budget and component ratio among the directly inflow,outflow,the local precipitation,evaporation and leakage are analyzed in details under the original reservoir operation condition.The new scenarios are setup according to the recent water diversion project from Yellow river and minimum ecological flow control method using the hydrological series from 2002 to 2016,the related scenario simulation shows:1)If there is no outer-basin water transfer,the outflow process from the Guanting reservoir can’t satisfy the requirement of the minimum ecological flow discharge,meanwhile,the downstream of Yongding river will dry out at dry season;2)With 1.0×108 m~3 additional input water from Wanjiazhai reservoir in Yellow river and 0.5×108 m~3 water into Guanting reservoir,the outflow of Guanting reservoir can satisfy the requirement of the minimum ecological flow discharge on the hydrological condition during 2002-2016.(4)T In this paper,the steady-state algorithm is used to calculate the allowable pollutant carrying capacity of Guanting reservoir and calculated the inflow and outflow pollution fluxes load of the reservoir:The allowable pollutant carrying capacity of the outlet reservoir is 2709.7t/a,ammonia nitrogen 362.9t/a,TP 36.5t/a,TN 361.2t/a.By comparing the inflow fluxes(COD3562.1t,ammonia nitrogen 58.6t,TP32.4t)in 2016,it can be concluded that only cod needs to be reduced by 24%,ammonia nitrogen and TP are less than the allowable inflow.