Quantitative Study Of Cotton Grey Water Footprint Based On SWAT Model

Cotton is an important economic crop.During the planting process,its irrigation system is complicated and its management methods are diversified.As a result,cotton crops lack reliable water footprint quantification methods and cannot be certified for low-water footprint cotton.It draws a lot of attention in research field.Grey water footprint is a component of water footprint and there is few research on grey water footprint accounting.In our study,model was used for grey water footprint according to cover the shortage.In my study the grey water footprint was mainly quantified in the cotton growing process(bearing and non-bearing)in Xinjiang.Xinjiang is the main cotton producing area in China and there are some differences in climate and planting management between the northern and southern Xinjiang.Therefore,the cotton districts of Yuli in southern Xinjiang and the cotton districts of Shihezi in northern Xinjiang were selected as the representative districts.The date of climate,environment,soil,social conditions,and water were collected to compare the characteristics of the cotton district of Weili County,southern Xinjiang and Shihezi cotton district of northern Xinjiang.And use the elevation data,soil raster data,land use type raster data,and cotton management operating resources of the two places to construct models of a grey water footprint quantification model for cotton in the Yuli County cotton area in southern Xinjiang and Shihezi cotton area in northern Xinjiang based on the water consumption mechanism of cotton planting,and account the direct gray water footprint of cotton under different standards(total nitrogen,total phosphorus,COD).Find the most unfavorable indicators and combine the indirect gray water footprint generated by energy consumption during cotton planting to calculate the total nitrogen in Xinjiang as the standard.The research results of gray water footprint are as follows:The elevation,climate,soil,land use types,cotton planting characteristics,operation management and other data in the cotton area of Weili County,southern Xinjiang and Shihezi cotton area of northern Xinjiang were collected and organized.The southern Xinjiang is relatively dry,with high solar radiation and higher temperature.Constructed SWAT models for cotton and cotton areas in Weili County,including the construction of a preliminary spatial database and attribute database,recalculation of soil attributes,construction of a soil attribute database,and input of crop management operational data.Directly calculated the direct gray water footprint of cotton production based on indicators including total nitrogen,total phosphorus,and COD.The direct gray water footprint of cotton planting in cotton areas in Weili County is in range of 732.19 m~3/ha-1242.26 m~3/ha,the total phosphorus timing is is in range of 376.21 m~3/ha-628.31m~3/ha,the COD timing is in range of 452.34 m~3/ha-793.45 m~3/ha.The direct gray water footprint of cotton planting in Shihezi cotton area is in range of 573.21 m~3/ha-826.21m~3/ha.The total phosphorus timing is in range of 278.32 m~3/ha-494.26 m~3/ha;the COD timing is in range of 432.21 m~3/ha-698.71 m~3/ha.According to the calculation results,the value of gray water footprint was the largest when the total nitrogen was used as the standard.Taking into account the grey water footprint(in terms of total nitrogen)generated by the energy consumption during cotton planting and harvesting,the total grey water footprint and its distribution when total nitrogen was used as the standard in cotton production in Xinjiang were calculated.