黄龙山区不同类型小流域的产流过程及其特征

 在黄龙山区选择自然条件基本相似的森林小流域、森林采伐小流域和荒坡草灌小流域,利用量水堰,于1999—2003年对流域的产流及其过程进行了系统的研究。结果表明:不同类型小流域径流的年际和年内变化不同。森林小流域全年产流,产流量主要与降水量有关;荒坡草灌小流域则仅在暴雨季节产流,产流量主要与雨强有关。除发生特大暴雨年份外,森林小流域的产流量均超过荒坡草灌小流域,5年内平均前者比后者多3倍。不同类型小流域对降水的调节作用不同,5年平均森林小流域比荒坡草灌小流域减少洪水径流94.9%,达5.2mm,增加枯水期径流0.5mm,占年径流量的8.7%,从而使流域径流保持相对均匀和稳定。采伐森林可以改变小流域的径流分布,常年径流被暴雨径流所代替,但其量比荒坡草灌小流域少。不同类型小流域产流过程不同,森林小流域产流过程平缓,洪水起伏程度小;而荒坡草灌小流域产流曲线陡峭,洪峰形成迅速,回落也较快。

Yield process and its characteristics in different kind of small watersheds in Huanglong mountainous area

Using the method of measuring weir, the runoff yield and its process are studied in forested watershed, cutting watershed and rangeland watershed during the period from 1999 to 2003 in Huanglong mountainous area. The results show that the runoff variations of interannual and seasonal are various. The runoff in forested watershed is yielded during a whole year and its amount is mainly connected with precipitation. The runoff in rangeland watershed is yielded only in storm season and its amount is mainly connected with storm intensity. Except the rare storm year, the annual runoff yield amount in forested watershed is more than that in rangeland watershed and the former tops the latter by 3 times on an average of 5 years. The different kind of small watersheds have also different functions on the regulation of the precipitation. The annual flood runoff amount in forested watershed has decreased by 94.9% over the rangeland watershed, up to 5.2 mm on an overage, and the runoff in dry season in the former has increased 0.5 mm over the latter, amounting to 8.7 percent of annual runoff amount, which results in the runoff yield in the watershed relatively well-distributed. Cutting forest can change the runoff distribution in watersheds. The runoff yield during a whole year by that only formed in storm season, but its amount is less than that in rangeland watershed. The runoff yield in different kind of small watershed is various. In forested watershed it is comparatively is replaced process of gentle and its fluctuating range is comparatively smooth, while the curve of runoff yield in rangeland watershed is steep, the flood peak is formed rapidly, and it falls after a rise more quickly .