【摘要】 以湖南省桃源县 (总土地面积 4 4 5 8.4 km2 )为代表 ,采集该县 196 0～ 2 0 0 1年的气象资料 ,结合有关科研成果 ,深入研究我国典型红壤丘陵区季节性干旱的成因、发生规律及其合理调蓄利用水资源的依据 ,提出了抗御该区季节性干旱的指导思想与基本对策。研究结果表明 ,7月～翌年 2月份是该区季节性干旱的易发期 ,年发生概率在 85 %以上 ,中等和中等以上干旱的年发生概率在 5 0 %左右 ,7～ 8月份和 11～ 12月份为年内的两个高发期 ,且发生概率和危害程度均是 2 0世纪 90年代 >80年代 >70年代 >6 0年代 ,但只要高标准、规范化地采取水土保持措施 ,恢复植被覆盖 ,完善现有水利设施 ,充分发挥“土壤水库”、“生物水库”和现有工程水库的蓄水抗旱潜力 ,以集水区或小流域为基本地理单元再适当兴建小型水利工程 ,确保占土地总面积 10 %左右的塘堰等蓄水面积 ,将 70 %～ 80 %的自然降水通过陆面拦截 (含蒸散 )方式截留并蓄存下来 ,使排出集水区或小流域的水量控制在年降水量的 10 %～ 2 0 % ,并积极推广应用农业节水技术 ,红壤丘陵区的季节性干旱问题就可以基本解决更多还原

【Abstract】 Based on the long-term meteorologic data from 1960 to 2001 and our relevant researches from 1990 to 2001 in Taoyuan County(28°24′～29°24′N,110°51′～111°36′E,4458.4 km~2)of Hunan,the seasonal drought problems in the red soil hilly region of the middle subtropical zone of China were studied. The primary reasons for seasonal drought are as follows:(1)The distribution of precipitation is uneven though the amount of it exceeded 1400 mm per year,of which (45.9%) occurred from March to June and (27.4%) from July to September,meanwhile,low-precipitation and high evaporation coincided with high evaporation and temperature in the period of from July to September;(2)water-holding capacity of red soil is only about 334 mm in the 1 m depth soil layer,and available soil water reservoir is also very low,which covers only (34.1%) of soil water reservoir;(3)the distribution of farmland water conservancy construction is unbalanced and the function of drainage and irrigation systems have degenerated. According to the drought criteria of soil-plant system,annual occurring frequency of seasonal drought is above 85%,and the frequency of moderate and severe drought is about 50%,which often occurs from July to next February and results from high temperature and low precipitation in this period. However,annual occurring frequency of climatic drought is 59.5%,and the frequency of moderate and severe drought is 31.0% by using the assessing standards of Z index. Obviously,the drought seemed to be more severe with the former method,and the frequency and damage increased from 1960s to 1990s,which indicated that the capacity of resisting seasonal drought decreased gradually in red soil hilly region. According to the research results and practices,in order to keep the rational water circle in agro-ecological system and sustainable development in the red soil hilly region,the sufficient rainfall resources must be considered to enhance the water-holding capacity and drought-resisting potential of soil reservoirs,biology reservoirs and engineering reservoirs. Agricultural water-saving construction must be utilized,and water conservancy equipment should be improved,and water resources management mode must be set up to primarily intercept and store water by taking the small watershed or catchment area as a basic unit. To achieve these aims,main measures may be as follows:by using high standard soil-water conservation measures and raising surface vegetation coverage,water abundant layer would be formed at 40～80 cm layer on hill-slope,where soil water content is higher by 30%～50% than that at 0～40 cm and 80～100 cm soil layers and by 30%～75% than stable wilting water content even during drought season;at the same time,soil and water conservation measures would increase rainfall interception ratio in land and water flow rate in soil,resulting in harvesting 500～700 mm rainwater per year. In addition,it would increase 30%～50% of irrigation capacity to renew existing water conservancy engineering,and it would intercept 70%～80% of rainwater in land surface and subsurface. To construct small-scale water conservancy engineering in which the area of reservoir and pond would cover about 10% of the total land area of the small watershed or catchment. As a result,the above measures combined with agricultural water-saving techniques would relieve seasonal drought in red soil hilly region.更多还原