Assessment Of Water Conservation Function And Analysis Of Influencing Factors In Zoige

Zoige is located on the northwest edge of Sichuan,and has become one of the important water conservation and biodiversity reserves in Sichuan Province with its important ecological status and rich species type,as well as one of the most important water conservation areas in the Yellow River and the upper reaches of the Yangtze River.As the largest "solid plateau reservoir" in the world and the most important ecological barrier in the upper reaches of the Yangtze River and the Yellow River,Zoige is known as the "reservoir" of the Yellow River,which plays an important role in water conservation and soil and water conservation of the Yangtze River,the upper reaches of the Yellow River and its tributaries.Accurately assessing the water conservation function of Zoige and revealing its temporal and spatial characteristics and influencing factors are of great significance for guiding local ecological protection work.Based on the principle of water balance and SCS-CN model,with the landsat satellite remote sensing image data,MODIS meteorological data,soil data,and statistical Yearbook,with the support of GIS and remote sensing image processing(RS).The main research results of this paper are as follows.First,the evaluation method of water conservation is proposed.Through a large number of literature research,it is found that the current water conservation function evaluation method relies too much on the empirical coefficient instead of some parameters,which is easy to ignore the spatial heterogeneity of the parameters,and the evaluation scale is mostly formulated in accordance with the river basin or provincial or national administrative divisions.In order to accurately assess the water conservation capacity at the county level and provide decision support to local governments,this paper comprehensively considers the data availability and accuracy of county scale data,couples the formation mechanism of water conservation process,and uses the powerful spatial analysis function of GIS technology to comprehensively analyze resources,environment,ecology,The intrinsic spatial characteristics of human activity and its interaction and relationship on geographical space,the quantitative evaluation method of county water conservation function based on SCS-CN model and water balance equation is proposed.Second,carry out the evaluation of water conservation function in Zoige.Based on the multi-source data of landsat satellite remote sensing images,meteorology and soil,the water conservation function of Zoige from 2000 to 2019 was evaluated by using the method proposed in this paper.The temporal and spatial variation characteristics of water conservation in Zoige were analyzed.The results show that: in space,the water conservation function of Zoige shows the distribution trend of south high and north low;in time,from2000 to 2019,the water conservation quantity of Zoige has increased;in administrative scale and pixel scale,the water conservation capacity of Tangke Town is the strongest,the jurisdiction of Man Town and Maixi Township is stronger,and the three towns are located in the west of Zoige,indicating that the overall water conservation capacity of the west of Zoige is stronger and more stable;the water conservation capacity of Axi Town,Brazil Town and Dazasi Town is grassland,woodland and shrubland;In Tangke Town,jurisdiction Man Town,Nenwa Township,the water conservation capacity is grassland and shrub land;in Hongxing Town and Maixi Township,the water conservation capacity is grassland and cultivated land;in Baozuo Township,Jiangza Township,Qiuji Township,Tiebu Town,Zhanwa Township,the water conservation capacity is cultivated land and woodland.Third,explore and analyze the influence factors of water conservation function in Zoige.Based on the annual average data,the influence of water conservation function on environmental factors in Zoige was analyzed from two aspects: underlying surface factor and meteorological factor by using trend analysis method and spatial correlation analysis method.The results show that the forest land water conservation capacity is the best in Zoige,and the grassland is the second.The artificial surface produces more surface runoff and the water conservation capacity is extremely poor.In the past 19 years,the forest land and shrub land have been greatly reduced,and the increase of artificial surface and bare land area has led to the increase of total runoff in Zoige in 2019;The water conservation capacity of each kind of soil in Zoige is calcareous cinnamon soil > dark brown soil > cold soil > brown soil > grass felt soil > meadow soil > peat swamp soil > calcareous meadow soil,black felt soil > brown black felt soil > leaching cinnamon soil > marsh soil > meadow swamp soil >low peat soil,coarse bone soil,soil texture type medium loam ratio is more than 85%,The effect of topography fluctuation on water conservation function is also very significant.With the increase of elevation and slope,water conservation capacity is weakened;more than 90%of regional rainfall is positively correlated with water conservation,and when rainfall is between 620-670 mm,water conservation increases fastest;more than 85% of regional evapotranspiration is negatively correlated with water conservation,and water conservation decreases fastest when evapotranspiration is between 500-600 mm.