一、地表径流的利用 1.利用地表径流的必要性和可能性一、水文气象方面在天然情况下,供水量与农作物的需水量往往不相适应,这是灌溉设计中必须解决的一个课题。解决这个课题的办法不外两个方面,就是在一定的程度上改变灌溉制度,或是利用径流调节来改变当地供水的情况,我们采取的办法,目前是以后者为主。湖南雨量虽然丰沛,但季节上分布不匀,月变率也很大。在旱年情况下,不仅旱季(7～9月)雨量稀少,在季节的分布上又很悬殊,即使在湿年,由于雨量大量集中在雨季(4～6月),夏秋雨量仍可能稀 First, the use of surface runoff 1. The necessity and possibility of using surface runoff First, the hydrological and meteorological aspects Under natural conditions, the amount of water supply and crop water demand often do not adapt, which is irrigation design must be addressed in a subject. The solution to this issue is no more than two aspects: changing the irrigation system to a certain extent or using the runoff adjustment to change the situation of local water supply. The approach we have taken now is mainly the latter. Although abundant rainfall in Hunan, but uneven distribution in the season, the monthly rate is also great. In the dry years, not only the rainfall is scarce in the dry season (July-September), but also the distribution of the seasons is very poor. Even in the wet years, due to the large amount of rainfall concentrated in the rainy season (April to June), the summer and autumn rainfall may still be thin