漓江上游典型森林群落内外降雨特征研究

Research on Rainfall Characteristics Through Typical Forest Community in Upper Reaches of Lijiang River

2009—2011年,对漓江上游典型森林群落木荷(Schima superba)林内和林外降雨进行了观测,结果表明:试验区降水年内分配极不均匀,干旱与暴雨频发,雨季降水占全年降水的82.39%,旱季降水仅占全年江水的17.61%。2011年生长季节总体表现为极其干旱,但降水总量却高于前几年的平均值,5—6月降水总量占观测期间降水总量的63.59%。单次最大降雨16h达319.8mm,降雨强度达20.0mm/h;超过50mm的日降雨量占观测日降雨总量的65.25%。木荷林内外降雨联系紧密,林内穿透降雨量与林外降雨量存在显著线性相关,但降雨穿透率与林外降雨量及强度之间的关系复杂。在高雨量级或强降雨情况下,林内降雨穿透率大,变异小,小于2.5mm/h的降雨穿透率为60.96%,变异系数为39.81%;大于8.0mm/h的降雨穿透率为72.40%,变异系数为5.64%。本研究为正确认识流域森林生态水文功能,制定有效的水资源调配和水源涵养林管理措施提供科学依据。

From 2009 to 2011,a typical forest community of Schima superba was monitored and the interception effect of tree canopy on precipitation was analyzed in upper reaches of Lijiang River.The results showed that the precipitation distribution of the year was irregular and the rainfall mainly happened in rainy season,which accounted for 82.39% of the total,while only 17.61% was distributed in dry season.It seemed that 2011 was a dry year,but the precipitation with an average annual value was higher than the last few years,and the precipitation mostly occurred from May to June（63.59%）.The largest rainfall was 319.8 mm in 16 hours and rainfall intensity was 20.0 mm/h.Furthermore,the single rainfall（50 mm） during the study period which accounted for 65.25% of total precipitation.The throughfall was positively correlated with precipitation outside,but the relationship between canopy interception rate and precipitation outside was complex.The coefficient of variation（CV） was 39.81%,when rainfall was less than 2.50 mm/h,while the CV was 5.64% when rainfall was more than 8.00 mm/h.This research has provided the scientific basis for understanding forest hydrological functions and developing water resources allocation strategy as well as improving water conservation forest management practice in this area.