Study On Ecological Water Replenishment Scheme In The Middle And Lower Reaches Of Naoli River

Wetland is one of the most important ecosystems on the earth,which plays an important role in conserving water sources,regulating runoff,improving water quality and so on.However,due to the development of economy and society,the area of wetland has been reduced year by year,and the ecological structure has been seriously damaged.In this paper,the wetland group in the middle and lower reaches of the Naoli River is selected as the research object.The purpose of this paper is to get the water demand and replenishment amount through the calculation of ecological water demand.Then,through the comparison of the water replenishment effect of different water replenishment schemes,the suitable schemes are determined,and the future years are predicted and the water replenishment effect is evaluated.Through this study,we can get the following results:(1)The ecological water demand of wetland is an important basis for artificial water supply.In this paper,ecological method is used to calculate the ecological water demand of wetland group.Among them,the ecological water demand is divided into four parts:vegetation transpiration water demand,water surface evaporation water demand,soil water demand and water demand of animal and plant habitat.The year of 75%water frequency is selected as the level year for ecological water supply.According to the calculation,the ecological water demand of the middle and lower reaches of Naoli River Wetland group is 1.11 billion m~3,the non-consumption water demand is 163 million m~3,the consumption ecological water demand is 304 million m~3,and the non-consumption water demand is 216 million m~3.(2)Based on the EFDC model,this paper designs two kinds of artificial water replenishment schemes:one-time water replenishment and multiple water replenishment.Among them,the annual contribution of one-time make-up water,NH4-N,TN and TP are 555million m~3,58 tons,224 tons and 41.7 tons respectively,and the annual contribution of multiple make-up water is 550 million m~3,16 tons,149.3 tons and 24.6 tons.According to the simulation results,seven elements such as the coverage area under different water depths,the coverage area and net flux under different NH4-N/TN/TP concentrations are selected,and ten different importance combinations are designed.The two schemes are compared by AHP.The results show that 29/30 of the results show that the comprehensive score of multiple water replenishment in the whole year is higher than that of one-time water replenishment in the whole year.Therefore,the best water replenishment scheme is multiple water replenishment in the whole year.(3)In this paper,ARIMA model is established to forecast the main tributaries of Naoli River Basin.The accuracy coefficient R2 of the forecast results is about 75%or above,which reaches the level of class B forecast.This result can be used.The forecast results show that2020 is a wet year and the frequency of incoming water is about 30%.According to the prediction results,the wetland groups in the middle and lower reaches of Naoli River were artificially supplemented with water.Through EFDC simulation,the results showed that the contribution of NH4-N,TN and TP to the wetland was 6 tons,42.6 tons and 6.4 tons respectively.