1986—2019年河套灌区土壤盐渍化动态变化规律及成因

Dynamic Changes and Driving Forces of Soil Salinization in Hetao Irrigation District from 1986 to 2019

内蒙古河套灌区是我国最大的自流型灌区,位于干旱内陆区,土壤盐渍化问题突出,监测和治理灌区土壤盐渍化演变迫在眉睫。以内蒙古河套灌区为研究区,利用Landsat系列遥感数据对1986—2019年研究区不同季节的土地类型进行分类,结合当地水文气象资料和工程建设发展,探讨该地区土壤盐渍化的变化规律和影响因素。结果表明:整体上研究区春秋两季盐渍化土地面积呈下降趋势,其中1995—2005年是这两个季节盐渍化土地面积明显下降的时期,其前后两个时间段为盐渍化土地面积变化较稳定的时期,各个季节的景观格局指数下降趋势先快后缓,盐渍化土地先破碎后稳定,盐渍化土地的主要去向和来源为农业用地;1986—2003年间地下水水位埋深是研究区春季、夏季和秋季三个季节盐渍化土地面积的主要影响因素(相关系数r分别为-0.62、-0.80、-0.72);2005—2019年间研究区春季盐渍化土地面积受上一年灌溉水量的影响最大(相关系数r为0.78),夏季盐渍化土地面积与年均降雨量有关(相关系数r为-0.48),秋季盐渍化土地面积受地下水水位埋深的影响而下降(相关系数r为-0.57)、受当年灌溉水量的影响而上升(相关系数r为0.48)。该研究结果可为内蒙古河套灌区土壤盐渍化控制措施的制定提供依据。

Hetao Irrigation District in Inner Mongolia is the largest gravity flow irrigation area in China,Which is located in the arid inland area.The problem of soil salinization is prominent,so it is urgent to monitor and control the evoluation of soil salinization in the irrigation area.With Hetao Irrigation District of Inner Mongolia as the research area,the Landsat series remote sensing data were used to classify the land types in the study area in different seasons from 1986 to 2019,and to explore the changing laws and influencing factors of soil salinization in the district by combining local hydro-meteorological data and engineering construction development.The results of the study are as follows:overall the salinized land area in the study area shows a decreasing trend in spring and autumn,among which 1995-2005 is the period of obvious decrease in these two seasons,the two periods before and after which are more stable changes in salinized land area,the decreasing trend of landscape pattern index in each season is fast and then slow,the salinized land is first fragmented and then stable,and the main destination and source of saline land is agricultural land;from 1986 to 2003,the depth of groundwater table burying is the main influencing factor of saline land area in spring,summer and autumn(correlation coefficient is-0.62,-0.80 and-0.72 respectively);from 2005 to 2019,the saline land area in spring is most influenced by the irrigation water of the previous year(correlation coefficient is 0.78),summer salinized land area is related to the average annual rainfall(correlation coefficient is-0.48),and the fall salinized land area is affected by the depth of buried groundwater table and decreases(correlation coefficient is-0.57)and the increase in the amount of irrigation water in the current year(the correlation coefficient is 0.48)This study can provide basis for the design of soil salinization control measures in Hetao Irrigation District.