Evaluation Of Sustainable Utilization Of Water Resources Based On Improved Ecological Footprint Model

Understanding sustainable utilization of water resources is of great guiding significance to human survival,social development and coordinated development of ecological environment in arid areas.In order to objectively and accurately evaluate sustainable utilization of water resources,introducing the calculation method of vegetation ecological water demand recommended by FAO to improve the relevant parameters of ecological footprint model.Firstly,land classification of Minqin Oasis was carried out based on the remote sensing data of Landsat5 in 2008 and Lnadsat8 in 2013 and 2016.According to meteorological data,evapotranspiration ET0 of reference crops in Minqin oasis was calculated,and the formula recommended by FAO was used to calculate the ecological water demand of Minqin oasis,and the relevant empirical coefficients in the ecological footprint model were improved accordingly.Finally,according to the improved ecological footprint model,the sustainable utilization of water resources in Minqin Oasis from 2007 to 2018 was evaluated.The main research results are as follows:(1)According to the daily meteorological data of Minqin Oasis from 2007 to 2018,the reference crop evapotranspiration ET0 was calculated.During the growth period of natural vegetation(April-October),ET0 changes greatly and is consistent with each other,with the highest value appearing in May and the lowest value appearing in October.From 2007 to 2018,ET0 in Minqin Oasis showed a significant growth trend,from the lowest value of 1614.24mm in 2007 to the maximum value of 1732.3mm in 2018,with an increasing of 118.06mm and an increasing of 7%.(2)The vegetation coefficients of forest land,desert and grassland in Minqin Oasis in different growth periods were calculated,and the results showed that grassland had the smallest change range with a fluctuation value of 0.14 in the whole growth period,while forest land had the largest change range with a fluctuation value of 0.47.During the vegetation development period and the end of vegetation growth period,the change rate of forest land is the largest,reaching a monthly growth rate of 0.235 and 0.23 respectively,while the change rate of grassland and desert is close and small,reaching a monthly growth rate of 0,02.(3)Based on Landsat 5 and Landsat 8 remote sensing images,the land classification of Minqin Oasis was carried out,and the vegetation area of each classification was obtained.From the perspective of land use types,the order of coverage area from large to small is grassland>cultivated land>desert>construction land>forest land>water.Among the natural vegetation,grassland has the largest distribution range,accounting for 47%of the total area,followed by desert,accounting for 9.6%of the statistical area,and forest land has the smallest distribution range,accounting for 4,6%of the statistical area.From 2008 to 2016,the change trend of the coverage area of the same land use type is different:the areas of water,desert,forest land and grassland are increasing,but the areas of cultivated land and construction land are decreasing.(4)The ecological water demand of natural vegetation was calculated by using the calculation method recommended by FAO.The maximum ecological water demand of natural vegetation in Minqin Oasis in wet year is 163 million m3,followed by that in dry year(140 million m3),while the minimum ecological water demand in nomal year is only 128 million m3.The ecological water demand of natural vegetation in Minqin Oasis ranges from 128 to 163 million m3,(5)According to the calculated ecological water demand of natural vegetation in Minqin Oasis,the applicability of correlation coefficient 0.4 in ecological footprint model to Minqin Oasis is verified.The research results show that this coefficient is suitable for Minqin Oasis.The coefficient a is 0.45.(6)Based on the improved ecological footprint model,the ecological footprint and ecological carrying capacity of water resources in Minqin Oasis from 2007 to 2018 were calculated,and the indicators of sustainable utilization of water resources were used for evaluation.The water resources in Minqin oasis are in an unsustainable state with the sustainable utilization level increasing year by year.There is a significant positive correlation between ecological carrying capacity and rainfall(P<0,01),and the correlation coefficient is 0,61;The primary industry accounts for the largest proportion of the total ecological footprint of water resources,but its water use efficiency is the lowest,which makes the contradiction between supply and demand of water resources more serious;There is a very significant negative correlation between the ecological footprint of the primary industry and the urbanization rate,and the correlation coefficient is 0 81,The improvement of urbanization rate can obviously reduce the ecological footprint of primary industry.