The Calculation Method Research Of The Runoff Pollution In The Rice-Growing Area Of The Southern

Rice is the main grain varieties in our country and its planting area accounted for a large. The pollution problems in the process of rice planting is one of the important environmental problems. Simulation and experimental study was applied to Hunan rice planting runoff loss in our study. At the same time, we established the calculation model. Load and mobility patterns of Hunan rice planting non-point source surface runoff pollutants is studied. We summed up the calculation method of the non-point source runoff pollution in the rice-growing area of Hunan province. Providing the technical support for the Hunan rice planting pollution monitoring calculation and the calculation method for the improvement of Hunan rice planting system. The main results in this experiment are showed as follows.(1) The runoff and rainfall significantly positive correlation, the relationship is not linear. Runoff (Y/L·m-2) and rainfall (X/mm) relationship equation was Y=1.078e0.053X, R2=0.952, significantly stronger. Equation is applicable to the generally paddy soil paddy field in the south, and the rainfall intensity shoud below 4.5mm/5min.(2) The total nitrogen in surface water of paddy field was higher within 15 day after application of fertilizer and the total phosphorus in surface water of paddy field was higher within 30 days after application of fertilizer. We can according to the changes in the concentration of pollutants in surface water of paddy fields and timely fertilization. At the same time, we can control the production activities such as irrigation and drainage and the others which may cause the total nitrogen and total phosphorus loss.(3) When the time is more than 7 days after the application of basal fertilizer, surface water total nitrogen was calculated as Y(Tn)=764.2e-129X, and after fertilizer surface water total nitrogen was calculated as Y (TN)=8.433X-0.51. After the application of basal fertilizer, surface water total phosphorus was calculated as Y (TP)=14.82e-0.63X. When the time is less than or equal to 7 days after the application of basal fertilizer, surface water total nitrogen was calculated as Y(Tn)=4.180X2-22.94X+179.2, and after fertilizer surface water total nitrogen was calculated as Y (Tn)=0.249X2-3.257X+12.44. After the application of basal fertilizer surface water total phosphorus was calculated as the Y (Tp =-0.102X2+1.456X+1.021. Y(TN)for the total nitrogen concentration (unit:mg/L), Y(Tp) for total phosphorus concentrations (unit:mg/L), X for measuring time (unit:day). Equation is applicable to the generally paddy soil paddy field in the south, with common rice varieties and MNK fertilizer level, the rain did not occur when the surface water concentration calculation.(4) Runoff concentration and before rainfall field surface water concentrations were positively correlated, but they were not a simple multiple relationship. Runoff concentration and runoff generation was negatively correlated, and they were not a simple multiple relation. The runoff water total nitrogen concentration was calculated as Z=1.141X-0.056Y, the runoff water total phosphorus concentration was calculated as Z=0.78X-0.002Y. Z for the runoff total nitrogen or total phosphorus concentration, unit:mg/L. X for the total nitrogen or total phosphorus concentration before rainfall in the surface water, unit:mg/L. Y for the volume of runoff, unit:L. Equation is applicable to the generally paddy soil paddy field in the south, with common rice varieties and MNK fertilizer level.(5) Under the condition of natural rainfall, the runoff pollution amount and rainfall have no obvious correlation, its value is affected by surface water concentrations before rainfall (rainfall time) and rainfall (runoff production quantity). The ratio of theory loss and actual loss basically stable at around 1.5 for the total nitrogen, and the ratio of theory loss and actual loss basically stable at around 1.3 for the total phosphorus. The correlation coefficient of total nitrogen was 1.5732, the correlation coefficient of total phosphorus was 1.3672.(6) The calculation formula of loss of total nitrogen and total phosphorus are as follows after correction and summary. TN= 1.229998αNYSe0.053x-0.0650767αNS2e0.106x TP= 0.84084αPYSe0.053X-2.324168x10-3αpS2e0.106xThe TN for the total nitrogen loss and the TP for the total phosphorus loss, unit:mg. The x for the rainfall, unit:mm. Y for the surface water concentration before rainfall (its value calculated by calculation formula in Chapter fourth), unit:mg/L. S for the paddy field area, unit:m2. a N for the correlation coefficient of total nitrogen and a P for the correlation coefficient of total phosphorus, no unit. The e for constants. Equation is applicable to the generally paddy soil paddy field in the south, with common rice varieties and MNK fertilizer level.