南亚热带鹤山5种生态系统的地表径流

SURFACE RUNOFF IN FIVE ECOSYSTEMS OF HESHAN SUBTROPICAL HILLY LAND

运用“小集水区径流场”技术对鹤山丘陵试验站５种生态系统地表径流进行了连续５年的观测与实验。结果表明：ａ．５种系统的地表径流系数马占相思林＜果园＜豆科混交林＜草坡＜林果苗系统，分别为２．３％、６．９７％、１３．３０％、１７．９０％、２２．１６％；径流模数变率差马占相思林＜豆科混交林＜林果苗系统＜草坡＜果园，分别为０．４６、０．５７、０．６３、０．６５、１．６８，可见两种人工林生态系统在蓄留水分、调节水量上均优于草坡，而两种农林复合生态系统有所欠缺；各系统的地表径流系数均有明显的干、湿季差异，表现为湿季＞全年＞干季，径流模数变率差的季节变化则恰好与此相反。ｂ．５种系统每场降水的地表径流量与降水量间存在着二次抛物线型回归关系，地表径流量随降水量的增加是非匀速的，年地表径流量主要由几场大的降水所决定；地表径流量与降水强度的关系不大。ｃ．５种系统发生产流的最小降水量马占相思林＞果园＞豆科混交林＞林果苗系统＞草坡，分别为１５．９、１３．２８、８．１、６．７１、５．２１ｍｍ；各系统对产流和洪峰的滞后约为１０—３０ｍｉｎ，马占相思林滞后时间最长，其含蓄水分、削减洪峰和调节地表径流的作用最为明显。文中讨论了造成林果苗和果园系?

The effects of five different ecosystems on surface runoff were studied through'watershed experiments' during 1993 to 1997 in Heshan Hilly Land Experiment Station.The results showed that the surface runoff coefficients of five ecosystems, viz. Acaciamangium forest, orchard, leguminous mixed forest, grassland, and forest-orchard-nurserysystem, were 2.3%, 6.97%, 13.30%, 17.90% and 22.16%, respectively, while thevariation rate difference of runoff modulus were in the order of A. mangium forest < leguminous mixed forest <forest-orchard-nursery system < grassland < orchard, being 0.46, 0.57, 0.63, 0.65and 1.68, respectively. The results showed that A. mangium forest and leguminous mixedforest have better hydrological function on water conservation and adjustment than theothers. Surface runoff coefficients were different among the seasons, showing that wetseason>annual>dry season, but the seasonal change in variation rate difference of runoffmodulus was in the order of dry season >annual >wet season. Between surface runoff (R) andprecipitation (P), there was a regressive relation equation, R =aP2+bP +c, and surfacerunoff had no significant relationship with the rainfall intensity, and the surface runoff wasoften provided by some heavy rains. The rainfall causing surface runoff in A. mangiumforest, orchard, leguminous mixed forest, forest-orchard-nursery system and grassland were15.9, 13.28. 8.1, 6.71 and 5.21 mm, respectively. The runoff occurence and the flood peakwas delayed by the five ecosystems for 10 to 30 minutes, and the maximum appeared in A.mangium forest. Some flows in hydrological function of orchard and forest-orchard-nurserysystem are discussed.