Research On Water Environment Analysis And Safety Assurance Decision-making In The Core Area Of ​​the Winter Olympics

The Beijing-Zhangjiakou Winter Olympics will be held in 2022,and the practical implementation of the "green Olympics" concept is of great significance to the successful hosting of the Olympic Games.The Water environment pollution control in the core area of the Zhangjiakou Winter Olympic Games plays an important role in the safety of the river water environment.Assessing the pollution load level of the entire Donggou watershed to which the core area of the Winter Olympics belongs,and predicting the water environment pollution status of the Taizicheng River in the core area of the Winter Olympics is a necessary prerequisite to ensure the safety of the water environment.This paper calculates the pollution load of the Donggou Basin and predicts the water environment pollution status of Taizicheng River.The main work and conclusions are as follows:(1)Based on the improved export coefficient method considering rainfall and terrain factors,the export coefficients of Donggou watershed are determined after comprehensively comparing and analyzing non-point source export coefficients of different properties.We revealed the spatiotemporal distribution of point source pollution load according to relevant data.At the same time,the point source pollution load was calculated based on field survey data,and the contribution of different types of pollution load was analyzed.The results show that the inter-annual variation of non-point source pollution load in the entire Donggou watershed is obvious;the spatial distribution of pollutant output load also embodies non-uniform characteristics that the sub-watershed output load is relatively high.(2)Combined with the one-dimensional water quality model,the distribution of pollutants under the conditions of sudden pollution accidents was analyzed,and the effects of water quality guarantee measures under the conditions of emergencies were simulated.Based on the measured rainfall and water quality monitoring data in the core area of the Winter Olympics,the relationship between rainfall and water quality is established,the pollution load of the core area watershed during the flood season is assigned,and the water quality of the Taizicheng River exit section is predicted.There is a clear non-linear relationship between rainfall and water quality:the relationship between rainfall and total nitrogen(TN)concentration is:,the relationship between rainfall and chemical oxygen demand(COD)concentration is:The relationship between rainfall and ammonia nitrogen(NH4+-N)concentration is:.The pollution load was the highest in July during the high water period,and the total nitrogen,COD,TP and ammonia nitrogen pollution loads were 62.73kg,1251.72kg,29.93kg and 2.07kg,respectively.The pollution load in May and October was relatively low.From the perspective of the spatial distribution of the pollution load in each month,the pollution load of the sub-basins 1,5 and 6 of the Taizicheng River is relatively high,and the upstream.sub-basin is relatively low.The COD concentration at the outlet section of the Taizicheng River can basically reach the surface water classⅢ standard,which is slightly higher than the surface water class Ⅲ in June;the ammonia nitrogen concentration at the outlet section can reach the surface water class Ⅲ.(3)In the case of sudden pollution in the core area,the concentration of pollutants from the leakage point to the exit section of the Taizicheng River Basin has a certain downward trend.However,the pollutant concentrations at the exit of the Taizicheng River Basin still cannot meet the surface water class Ⅲ water standard,which has a serious impact on the downstream water environment.Therefore,a diversion scheme was designed,and pollutants were diluted with clean water that the COD background concentration of 10 mg/L.The decision to ensure water quality at the exit section of the Taizicheng River Basin in different periods was analyzed.The results show that during the current high-water season,the river hydrological conditions can reduce the pollutant concentration after the dilution with fresh water at a flow of 17.45m3/s,7.29m3/s,3.77m3/s,and 5.33m3/s,respectively.And the COD concentration at the exit section of the Taizicheng River Basin can reach surface water class Ⅲ water standards.