The Simulation Of Emergent Water Pollution In River-Type Drinking Water Sources

In recent years,the people's demand for water security has become increasingly high.The party and the state have attached great importance to it and taken a number of measures to strengthen the governance and protection of drinking water sources.Nanchang,with more than 5.4 million permanent residents,its 97%drinking water is from Ganjiang River.with the booming of China's economy,the living places of residents are increasingly gathering,the loads of water pollution are highly heavier and the events of sudden water pollution are happening frequently.Following the development of Nanchang's economy,the coastal traffic lines of Ganjiang River are getting much more complex and complicated.Although the water and land transportations are much more convenient there,the rate of traffic accidents and the potential risk of water pollution climb higher.What's more,as one of the few provincial capitals with a single source of drinking water.The present researches seldom focus on the sudden water source pollution events whose water sources are rivers in the Nanchang section of Ganjiang River.In this paper,based on the analysis of the natural and social conditions of this section,the distributions of the waterworks,the categories of source and the figures of the pollution,we concluded that the main pollution sources are hazardous chemicals and oil caused by the water and land transportation.Furthermore,this provides evidence for the model researches of the Nanchang Section of the Ganjiang River.Taking various water quality models into consideration,the hydrodynamic forces and water quality models of this section were established by sampling MIKE21 model according to the river characteristics of it.To explore the migration and diffusion rules of these two types of pollutants there,and to predict the changes of pollutants concentration in the emergency response time of four water plants within the region.We draw conclusions as following:(1)Flow has the greatest effect on the response time and concentration of pollutants.In wet season,the water works'response time is limited and meanwhile the stay time is short.It only takes the pollution balls 1.3 hours to arrive at Qingyun water plant and after 10 hours,all pollutants could flow out the four water plants.On the other hand,during dry season,the response and stay time are much longer.To arrive at Qingyun water plant,the pollution balls need 4.8 hours,which is much longer than that of wet season.And the pollutants could flow out completely in 48 hours.In addition,it takes 14 hours for all pollutants to flow out of the water intake of the water plant during the normal water period.(2)Speed and direction of wind also influences the pollutants.High winds effect the concentration,moving trail,and arriving time of the pollutants more obviously than light wind or when there is no wind especially in dry seasons.Take the Qingyun water plant as an example,the maximum concentration of the hazardous chemical pollution group is 0.34 mg/L at the wind speed of 5 m/s from Southwest,while the maximum concentration is reduced to 0.21 mg/L and 0.23 mg/L when the wind speed is 5 m/s from the Northeast and North.(3)Different pollutants have different moving trail and response time.The hazardous chemical pollution group would affect all the four water works;however,to some extent,the oil spill pollution group wouldn't flow through these areas because of the figures of wind,flow and pollutants themselves.Nevertheless,these four water works are in the first-level drinking water protection areas,and the pollution clusters would flow through there.We assume that there still exists high risk of pollution and needs to check and manage them though the pollution wouldn't reach the water intakes.(4)Based on 2013 kan chau station hydrological data,at 500 m3/s--7700 m3/s flow range,We have observed the response time of each water plant with the 25 flowing results,and then obtained a formula to quickly calculate the response time for emergencies of each water plant:(?) When the flow and distance from the pollution source to the water plant are known,we could get the response time for emergency by calculating using this formula.We advise government to enhance the supervision of the water source in dry season and the traffic of Shengmi Bridge.It would be good to the water source if the government let the vehicles of hazardous chemical run through Yingxiong Bridge instead of Shengmi Bridge.Besides,check more frequently in wet season to prevent or lessen these kinds of events and operate the vehicles and boats in dry season within land and water transportation in order to prevent or reduce these sudden water pollution events.