环洞庭湖丘岗地区水资源平衡及其管理

Equilibrium and Management of Water Resources in Hilly Are a Around Dongting Lake

对环洞庭湖丘岗生态系统水环境要素的定位观测和小流域水平衡监测研究表明 :环洞庭湖丘岗地区水资源总量丰沛 ,可利用的集雨水量为现今农业用地最大灌溉水需求量的 2 .4 1倍 ,可维持生态系统的水量平衡。但由于雨水的季节性配置差异 ,系统水分有季节性富余与亏缺 ,一般年份 3月中旬至 7月上旬水富余 3 11.3 mm ;8月上旬至 9月下旬水亏缺 13 4 .7mm。天然降水大约 76%产生派生资源参与系统水分循环 ,其余部分主要以径流形式溢泄入下游水域。这一过程使该地区每年流失或向洞庭湖水域输送水 1.3 1× 10 1 0 m3、泥沙 1.64× 10 4 m3、养分 ( N,P,K)0 .89× 10 4 t。该地区土类多属红壤 ,持水能力强 ,但有效含水量低 ,凸现出涝渍、湿害和干旱双重农业水问题。本地区水平衡管理应注重两个方面 ,一是加强集雨水利工程建设 ;二是合理构建坡地农林复合生态系统。

Location observation on water environmental elements in the ecosystem and monito ring and research on water equilibrium in the minor valley in the hilly area aro und Dongting lake have been carried out, the results show that the area is rich in water resources,the utilizable rainwater is 2.41 times as much as maximum re quirement of irrigation for agricultural land at present, and can maintain wat er equilibrium in the ecosystem, but because of differences of seasonal disposit ion of rainfall there is a seasonal surplus and a shortage of water in the syste m, usually with a surplus of 311.3 mm from the middle ten days of March to the first ten days of July, and a shortage of 134.7 mm from the first ten days of Au gust to the last ten days of September, about 76% of precipitation produces der ivative resources to participate in water cycling in the system, and the other p art overflows to lower water area mainly in the form of runoff and 1.31×10^( 10)m^3 of water,1.64×10^(4) m^3 of silt and 0.89×10~4 t of nutrient ( N,P,K) in the area bleeds or are transported into Dongting lake by the course each year. Most of the soil in the area belongs to red soil with strong water re tention ability and low available water content resulting in double problem of a gricultural water of waterlogging and wet harm and drought. We should pay attent ion to two aspects for water equilibrium and management in the area: one is stre ngthening the construction of water conservancy project for rainfall collection, and the other is rational construction of agro-forest compound ecosystems on h illside fields.