Effects Of Paddy Fields Transformed From Dry Fields On Water Environment In Jiangchuan Irrigation Area And Control Countermeasures Research

Heilongjiang Province enlarged the rice planting area and changed dry lands to paddy lands in order to make full use of the advantage of natural condition. Changing dry lands to paddy lands makes fundamental changes of local agricultural production features, not only the grain production is greatly increased, but also influence on the ecological environment. Paddy fields and dry fields both can pollute the surface water to some extent, But at present, it is very lack of qualitative or quantitative research for the effects of changing from dry fields to paddy fields in the water. especially in northeast of China.First, set up the database of model: spatial database included digital elevation map ?DEM?, land use map and soil map, attribute database included the meteorological data in research area, soil attribute data, agricultural management data, etc.; Aimed at the feature of natural rivers distributing on the edge of the irrigation area, using "burn-in" algorithm to make artificial canal system network as water system, then divided the area in46sub basin and177HRUs.Then, use LH-OAT method of SWAT model to analyzes parameter sensitivity, and sift the important factor for the model result, then aooly the measured data of runoff, TN and TP with2008-2009as calibration period,2010-2013as validation period to explore the model applicability in the research area. It shows that the model has good applicability in the study area, and then analyzes the jiangchuan irrigation non-point pollution distribution characteristics of spatial and time. It is concluded that different land use non-point output are different, and cultivated land output is most serious.Next, based on the above research, remain the arable land areas and change the proportion of paddy field and dry field to set different scenes. Then reveal influence of changing from dry fields to paddy fields on water environment, Last, put forward control counterplans and protective measures. It is concluded that after changing from dry fields to paddy fields, the runoff, TN and TP load gradually increased, and produced adverse effect on water environment.Last, use SMS software to forecast the migration and transformation of paddy field non-point source pollution in water environment, analyzes the time and space distribution and diffusion degree of nitrogen and phosphorus pollutants to look for regularities of distribution. Last, visual chart is given by the software. Last, using a two-dimensional steady-state mixed attenuation model to estimate the contribution concentration of paddy field nonpoint source pollution to the water quality of Songhua river, the results showed that the pollutants concentration is not big, and discharge flow is small, so it has small negative influence on water environment. Although changing dry lands to paddy lands promoted the agriculture technology greatly and improve the life's quality of local people, it had negative effect on water environment. So on the basis of actual situation, some control measures were put forward, on the premise of ensuring the output of grain, reduced the influence of non-point source pollution on water environment, and promoted sustainable development of local irrigated agriculture, realized win-win situation of environment and economy.