The Driving Mechanism Of Lake Fluctuation In Hetao Irrigation Area,Inner Mongolia

Hetao irrigation area is located in the northwest of Inner Mongolia autonomous region,which is in the transition zone of agriculture and animal husbandry in China.Because the Yinshan mountains is located in the north of study area weaken the Mongolian cold high in winter to a great extent,and the south adjacent to the Yellow River irrigation conditions are superior,so it has gradually become an important oil and grain production areas in China.Water resources play an irreplaceable role in the sustainable development of the region,among which the lake fluctuation in hetao irrigation area reflects the process of ecological and hydrological changes in the region most directly,which has a high reference value and practical significance for the evaluation of ecological water balance and food production security in the region.In hetao irrigation area,the yellow water diversion,groundwater depth,precipitation,temperature,farmland planting scale and other important indicators all have an impact on the lake swelling.In this paper,based on 2000-2018,April 15 every year solstice on 31 May and September 15 to November 15 day of MODIS data and 1999-2018 Landsat spatial data and field survey data in 2017,in the platform of ArcGIS space composite analysis,statistics algorithm spatio-temporal data acquisition in hetao irrigation area nearly 20years of lakes,and combining the meteorological,hydrological and agricultural planting area and other data,the main driving factors in hetao irrigation area and lakes up elimination of relationship is analyzed.In order to accurately grasp the changes and response mechanism of lake flood in hetao irrigation area,it provides a scientific basis for the rational allocation of water resources and the maintenance of stable water supply in farmland ecosystem.The main research results are as follows:（1）The lakes in hetao irrigation area of Inner Mongolia are obviously rising.Based on MODIS spatial data,the maximum lake area in the past 20 years reaches4068.75 hm²（2002）,and the minimum value is only 1218.75 hm²（2009）,with the number of lakes ranging from 183（2002）to 34（2009）.From the perspective of the whole irrigated area,the area and quantity of lakes in the east and west are higher than that in the central region,but the spatial differentiation in the south and north is not obvious.（2）In hetao irrigation area of Inner Mongolia,the amount of yellow water diversion,groundwater depth,temperature,precipitation and farmland planting scale all show great changes.Among them,the farmland planting scale and groundwater burial depth showed an upward trend,with slopes of 7689.4（Sig=0.001）and 0.018（Sig=0.034）,respectively.（3）From 2000 to 2018,the groundwater burial depth,annual average temperature,farmland planting scale and the area and quantity of lakes in Hetao Irrigation Area changed in reverse;the relationship between lake area and groundwater burial depth in Hetao Irrigation Area reached a significant level（P=0.047<0.05）;The reason why the various factors can cause the lake to rise and fall is mainly reflected in the incoming water and water consumption.（4）In the past 20 years,large lakes（with an area greater than 100 hm²）and small lakes（with an area less than 100 hm²）in the southeastern margin of ulan bubu and the irrigation region were dominant in area,while small lakes（with an area less than 100 hm²）were dominant in quantity.Trend analysis showed that the area and number of large lakes showed a significant decreasing trend(the correlation coefficientsignificancetestwasR=0.624>R_18,0.01=0.561and R=0.648>R_18,0.01=0.561).The decrease trend of small lakes was not significant.In the spatial distribution pattern,the central part of the study area is the stable distribution area of large lakes,and the number of large lakes varies from 11 to 23.The area varies from 2208 to 4581 hm².The growth and decline of lakes in the study area are mainly affected by the actual annual yellow water diversion,farmland area and groundwater depth.Among them,the actual amount of yellow water diversion affected all lakes（P≤0.01）,while the farmland area and groundwater depth had significant effects on large lakes（P≤0.01）and small lakes（P≤0.05）.The multiple regression model constructed with the above three factors shows that the accuracy of the prediction of the area and quantity of large and small lakes reaches over 75.7%and 60.5%respectively.（5）Through research,this paper finds that for the lake information extracted based on MODIS and Landsat remote sensing data,there will be differences in the analysis results of the swelling mechanism,which is mainly related to the difference in resolution resulting in the extraction of many small lakes.