The Study Of Water Environmental Capacity Estimation And Total Load Allocation In Jinjiang River Of Jiangxi Province

In recent years, water pollution problem is getting worse and even affect people's life with the development of economy. Water environmental capacity was estimated with choosing Chemical Oxygen Demand(COD) and NH3-N (ammonia nitrogen) as the main factors in Jinjiang river (in 2008), and the allocation equality of initial water environmental capacity was evaluated with Gini coefficient, finally the industrial structure adjustment scheme was propounded according to the area which exceed the environmental capacity, the research get the following results:(1) According to the national "11th five-year plans" and "12th five-year plans", total amount of Jinjiang River was estimated with choosing COD and NH3-N as the main factors on the basis of one-dimensional water quality model. Design flow was the traditional 30Q10 (the withered monthly average flow in nearly ten years), when the flow was zero or rarely in dry season, the design flow was the selection of the driest season with the average flow, and the flow velocity was the one which corresponded with the design flow. The analogy method was used for the degradation coefficient, the degradation coefficient of COD and NH3-N were 0.2d-1, 0.1d-1.(2) Total amount of Jinjiang River were estimated with choosing the flow of the driest month and the driest season, meanwhile with choosing different flow and flow velocity on the premise of other conditions remained the same. The COD capacity of the driest month was 102811 t/a, and the capacity of NH3-N was 2294 t/a, the COD capacity of the driest season was 101181 t/a, the capacity of NH3-N was 2640 t/a. The flow of the driest month was less than the flow in the driest season, but there were some differences between them, the water capacity of COD in the driest month was more than the capacity in the driest season. According to the formula of water environmental capacity with one-dimensional water quality model, the design of hydrological condition was the key factor which effects water environmental capacity, and it explained that the flow and the flow velocity had an important role in the estimation of COD capacity.(3) There were differences in different season apparently in the Jinjiang River. So the total load was allocated with using the driest season capacity, and the population, GDP, sewage discharge, and the land area were selected for the effect factors of the allocation. The distribution model was chose for the initial allocation of capacity, however, the weight coefficient was the key factor, and the coefficient was determined on the basis of equally distribution with raising the population and the GDP weight appropriately. The distribution result was evaluated with choosing the Gini coefficient method for the fairness. It was explained that the distribution was more equitable when the Gini coefficient was smaller. Overall, plan b was the optimal scheme, namely, the allocation was more equitable when the main influencing factors were the population and GDP. The results showed that, the Gini coefficient of the scheme b in the point source pollution were smaller than 0.10, and the Gini coefficient of the scheme b in the total source pollution were smaller than 0.12.(4) The COD distribution results of each unit in point source pollution were 20171 t/a,39036 t/a,24149 t/a,17825 t/a, and the NH3-N were 520 t/a,1025 t/a,626 t/a,469 t/a. The COD distribution results of each calculation unit in total pollution were 21372 t/a,36642 t/a,24321 t/a,18847 t/a. The NH3-N distribution results of each calculation unit in total pollution were 569 t/a,935 t/a,621 t/a,515 t/a.(5) Compared with the pollutant emissions, the COD capacity of each calculation unit in basins also had remaining capacity, and the capacity utilization of NH3-N were 96.0%,78.7%,103.5%,108.9% respectively. The NH3-N were Mainly from the breakdown products of microbes in sewage,some industrial waste water and drainage. It was observed that non-point source pollution of the Jinjiang River was serious, the non-point source pollution should be controlled, the source of pollution was the livestock and poultry breeding and urban life in the city of GaoAn, the county of XinJian and the city of FengCheng. The industrial structure type was changed from "two, one, three" to " two, three, one" in Jinjiang River, the proportion of the first industry should be reduced, and the proportion of the second industry can be increased appropriately for accelerating the development of the economy in the basin.