40年来洞庭湖流域耕地利用变化及其水分平衡效应

Cultivated Land Use Induced Moisture Balance Effect in Dongting Lake Basin in Recent 40 Years

明确我国关键粮食产区水土资源平衡状况,有利于粮食生产结构调整及保障国家粮食安全。以南方洞庭湖流域为研究区,在多期土地利用数据、常规气象站点数据和DEM数据支持下,从耕地的新增、类型转换、存续和灭失4方面系统识别耕地利用变化特征,并运用Penman-Monteith公式、有效降水量模型等揭示其气候水分平衡特征及耕地利用下水土资源平衡效应。结果表明:(1)40年间,洞庭湖流域的水田处于较为稳定的空间分布状态,而旱地重心向西北方向移动了17.36 km~2。耕地存续的相对面积比例达到70.63%,灭失类型多分布于怀化、湘西州等地,新增的耕地来源主要是林地,内部转换集中于衡邵娄等地;(2)流域南端以及洞庭湖区的蒸散能力较强,而西部至西北端偏弱,有效降水量呈西北至东南逐渐增大的特点;(3)1980年水分亏缺区面积比例仅为1.79%,至2020年该比例已增至32.84%,洞庭湖区以及永州市等地水分亏缺风险较高;(4)耕地的气候水分平衡历经了以水分盈余为主到水分亏缺与盈余并存阶段,亏缺区主要分布于洞庭湖区、湘江流域西北部以及永州等地,且亏缺区扩张更多围绕以水田为核心的耕地利用变化类型进行。研究结论可为该流域的耕地合理开发与利用提供决策支持。

Understanding the water and soil resource balance in China's critical grain-producing regions is essential for optimizing grain production structure national food.This study focuse on the Dongting Lake Basin in the southern and utilize multiple sets of land use data,conventional meteorological station data,and DEM data to systematically identify changes in cultivated land use land addition,type conversion,persistence,and loss.Additionally,the Penman-Monteith equation and the effective precipitation model employed to reveal the climate water balance characteristics and the impact of cultivated land use on water and soil resources.The results indicate:1)Over the past 40 years,paddy fields in the Dongting Lake Basin maintained a relatively stable spatial distribution,while dryland shifted northwestward by 17.36 km2.The relative proportion of persistent cultivated land reached 70.63%,and areas with lost cultivated land primarily distributed in regions Huaihua and Xiangxi Prefecture.The newly added cultivated land s converted from forest land,conversions concentrated in areas Hengyang,Shaoyang,and Loudi;2)The southern and Dongting Lake regions exhibit higher evapotranspiration capacity,while the western to northwestern regions lower capacity.Effective precipitation gradually increase from northwest to southeast;3)The proportion of water-deficient areas was only 1.79%in 1980 but increased to 32.84%by 2020.The Dongting Lake region and Yongzhou face a higher risk of water deficit;4)The climate water balance of cultivated land shifted from a surplus to a coexistence of deficit and surplus.Water-deficient areas mainly distributed in the Dongting Lake region,the northwestern part of the Xiangjiang River Basin,and Yongzhou.The expansion of water-deficient areas s mainly concentrated around changes in cultivated land use,with paddy fields as the core.Thfindings provide valuable insights for making informed decisions on the sustainable development and utilization of cultivated land in the studied basin.