Assessment And Zoning Management Of Non-point Source Pollution Based On "Source-sink" Pattern In Mountain River Watershed

As the degree of intensive management of agriculture has been improved,the problem of non-point source pollution has been highlighted,and the landscape pattern is closely related to the change of non-point source pollution.The relationship between landscape pattern and non-point source pollution is of great significance to the prevention and control of non-point source pollution.This paper takes Qixia City as a case which located in Jiaodong peninsular(typical for mountains and hills)?Firstly,61 water samples were collected by field sampling in May and September of 2016,total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),ammonium nitrogen(NH4-N),electrical conductivity(EC)concentration of each sample were acquired through laboratory experiment.Secondly,SPSS and GIS techniques were used to analyze the temporal and spatial differences of water quality of different sub-watersheds and tributaries.Thirdly,the river water quality indicators were used as indicators of non-point source pollution.And the relationship between landscape heterogeneity and non-point source pollution was analyzed by correlation analysis.Finally,the location-weighted landscape contrast index which reflects ecological process was introduced,and analyzing the relationship between LWLI and non-point source pollution.Through the zoning management,measures was put forward to provide theoretical basis for the city non-point source pollution.The main results are as follows:(1)The water quality indexes of six major rivers in Qixia City showed different degrees in different periods,among which TN was the most serious,which was much higher than that of surface water.The concentration of pollutants in different sections of the same river showed a certain time and space The water quality of Qixia City was generally better than that of the comprehensive pollution index,and 94.73% were in the section ? and above.The water quality of rivers and tributaries did not differ significantly between May and September,The average of the various water quality indicators in May is greater than the tributary of the mainstream,in September on the contrary,the tributary is greater than the mainstream.(2)The proportion of land area of 21 small watersheds in Qixia City is quite different,and the area of forest land is 38.43%,which is the most land use type in Qixia City.The proportion of land use area has a certain correlation with non-point source pollution index.There is a positive correlation between the cultivated land,the garden land,the construction land and the unused land area,and the main "source" landscape in the basin.Forest land,grassland and water area have a negative correlation with each nutrient quality index,which is the main "sink" type in this basin.There is a positive correlation between cultivated land and garden land and water quality index,and the negative correlation between forest land and water quality index is large.(3)The correlation between the landscape pattern and the water quality index is related to the water quality index.The correlation shows that the landscape type and the landscape shape are more complicated,and the nutrient index has a certain ability of interception,and the water is more polluted.The dominant landscape in this area is And the landscape heterogeneity is bigger,the effect of the landscape type of forest land is weakened,and the source landscape of cultivated land and garden is strengthened.(4)The spatial load comparisons of the source and sink landscape show significant spatial autocorrelation in the region,and there is a significant positive correlation with the water quality indexes in the basin,and TN,COD and conductivity have significant correlation in both periods.LWLI was as an indicator of non-point source pollution indicators.(5)Based on the non-point source zonation of the watershed,the non-point source pollution zoning map is similar to the ecological division map of Qixia city,showing the southwest-northeast direction and the severe pollution area in the hilly grain-fruit comprehensive utilization area in the southwest,The area of Qixia City,1/7,the potential pollution area located in the town of Tingkou,the town after the town and the town of low mountain forest protected areas,and mild pollution,moderate pollution area accounted for the total area of Qixia City 80%,indicating that the overall situation of Qixia City is better.(6)Compared with the two partition patterns,it can be found that there is the same distribution trend on the whole,but the amount of data needed to partition the index based on the landscape space load is much lower than that of the multi-criteria analysis,which can be more convenient Source pollution zoning and governance to provide theoretical basis.Based on the landscape to match the index of the partition map,according to local conditions put forward various measures.In the high LWLI area of the river exit,should strengthen the "sink" the type of landscape protection,increase vegetation buffer,planting trees and grass on the slope,the precipitation carried by the sediment,nutrient load play a certain obstacle to strengthen Protection of water bodies.