土地利用变化对茂名市降水入渗补给量的影响

Effect of Land Use Changes on Precipitation Infiltration Recharge in Maoming

大气降水是地下水补给的主要来源,确定降水入渗补给量对地下水资源管理和规划有着重要意义。以茂名市为研究区,基于Wet Spass分布式水文模型及Geo SOS-FLUS模型,结合GIS技术,估算2010年的降水入渗补给量,分析未来土地利用变化及其对降水入渗补给的影响。结果表明,(1)降水大部分转化为蒸散发量,入渗补给量次之,年平均降水入渗补给量为684.63 mm;不同土地利用类型下,径流量、蒸散发量和降水入渗补给量存在显著差异性,由于城市规划的作用和区域土壤质地的差异,林地、居民用地的降水入渗补给能力较大,高达800 mm,荒地最小。(2)近20年来,居民大量开垦荒地,草地转变为耕地和林地,有利于降水入渗的土地利用类型面积减少,使得降水入渗补给量减少,土地利用变化影响着地下水的水量平衡。(3)到2050年,各类土地利用类型在区域上的分布更加集中,水域面积大量减少,耕地面积普遍大于其他类型土地,导致大部分面积的降水入渗补给量将呈现减少的趋势,全年、丰水期的降水入渗补给量变化较相似,与枯水期的变化相差较大;到2100年则偏向于林地和草地的增加,降水入渗补给量呈增加趋势。可见,在未来一段时期内,茂名市在追求经济高速发展的同时,应加强对生态环境的保护,加大绿化面积,使地下水得到一定量的补给。本研究结果可为茂名市未来土地规划提供一定依据,以进一步加强对地下水的管理和保护。

Precipitation is the main source of groundwater recharge, and it is important to determine the quantity of water supply to management and planning of groundwater resource. Maoming was taken as research area. Based on WetSpass and GeoSOS-FLUS model, combined with GIS technology, this paper estimated the precipitation infiltration recharge for the year 2010, and analyzed future change of land use and its effect on the precipitation infiltration recharge. The results showed that the precipitation was mostly converted into evapotranspiration, and precipitation infiltration recharge was the second, and the annual average precipitation was 684.63 mm. Under different land use types, the surface runoff, evapotranspiration and recharge were obviously different. Owing to the different urban planning, the rainfall infiltration capacity of forest and urban was larger, as high as 800 mm, and the barren was minimal. Over the past 20 years, the residents had reclaimed the barren and then a large number of grasslands had been transformed into farmland and forest. The decrease of these land areas resulted in the reduction of recharge. By 2050, distribution of all land use types was more concentrated, a substantial reduction in water area, cultivated land area was generally greater than other types of land, causing most of the precipitation infiltration recharge area to decrease, and the change of annual and seasonal recharge would be the similar. By the year 2100, there will be an increase in forest land and grassland, and the supply of precipitation will be increasing too. In a period of the future, Maoming should strengthen the protection of the ecological environment, increase the green area and make the groundwater get a certain amount of supply. The research results could provide some basis for the future land planning of Maoming, so as to further strengthen the management and protection of groundwater.