湖南省水库与干旱情势空间匹配关系研究

Spatial matching relationship between reservoirs and drought situation in Hunan Province

根据湖南省地质、地形等条件,以县域为单元将湖南省划分为9个区域,对省内14000多座各类型水库开展空间统计,分析了水库空间分布规律,并采用SPI-3指数法计算得到4-9月重旱及以上干旱频率的空间分布,对比研究了水库分布与干旱的空间匹配关系。结果表明:湖南省水库分布具有明显的空间分异特征,丘陵区水库数量密度一般要大于山地区,但受大型水库不足的影响,库容密度一般要小于山地区。洞庭湖平原腹地水库密度极低,而外围岗地区则拥有全省最大的水库分布密度。不同分区水库供水能力与人口、耕地的匹配关系也有很大差异。湘东南罗霄-南岭山地区单位面积兴利库容和人均兴利库容最大分别可达54397.32 m^(3)/hm^(2)和3286.53 m^(3),而在湘中南岩溶丘陵区、洞庭湖区等地区则分别不大于3450 m^(3)/hm^(2)和210 m^(3)。湖南省水库的空间分异特征主要受地质、地形等地理条件控制,山地区水库规模大、数量少,而丘陵区水库小、数量多。总体上看,湖南省水库供水能力与干旱的空间分布存在明显的失衡错位,如衡邵盆地不仅年均降雨量少、重旱频率高,而且水库供水能力也处于全省较低水平,再加上岩溶区“保水难”的特性,该区成为省内干旱情势最为严重的地区。

Based on the geological,topographical and other conditions,Hunan Province was divided into nine regions by counties for statistic purposes.More than 14,000 reservoirs of various types in the province were investigated to analyze the spatial distribution pattern of reservoirs and the spatial distribution of drought frequency of severe droughts and above from April to September using SPI-3 index method,so as to conduct a comparative study on the spatial matching relationship between reservoir distribution and droughts.The results show that the reservoir distribution in Hunan Province is obviously spatially differentiated.The number density of reservoirs in hilly areas is generally greater than that in mountainous areas,and the reservoir capacity density is generally smaller than that in mountainous areas due to the shortage of large reservoirs.The density of reservoirs in the hinterland of the Dongting Lake Plain is extremely low,but that in the periphery of the plain ranks first in the whole province.The matching relationships between reservoir water supply capacity and population,reservoir water supply capacity and cultivated land in different regions are also differentiated.The maximum reservoir capacity per unit area and per capita in the southeastern Luoxiao-Nanling mountainous area of Hunan reached 54,397.32 m^(3)/hm^(2) and 3,286.53 m^(3) respectively,whereas in central Hunan karst hilly area and Dongting Lake area,they were not higher than 3,450 m^(3)/hm^(2) and 210 m^(3) respectively.The spatial differentiation characteristics of reservoirs in Hunan Province are mainly under the influence of geological and topographical conditions,with large scale but small quantity of reservoirs in the mountainous area,and small scale but large quantity of reservoirs in the hilly area.In general,the spatial distribution of reservoir water supply capacity and drought situation in Hunan Province are obviously unbalanced and dislocated.For example,the Hengshao Basin is not only afflicted by low average annual rainfall,but also frequent severe droughts,and its reservoir water supply capacity is also at a low level compared to the other areas in the province.In addition,karst areas are difficult to retain water,now this basin has the most severe drought situation in Hunan Province.