海滦河流域的地形与暴雨

TOPOGRAPHY AND RAINSTORM IN WATERSHED OF HAIHE AND LUANHE RIVERS

海滦河流域由于燕山、太行山成弧形,东北——西南穿越全流域,与夏半年东南气流乎几成直角,致使东南迎风坡成为多暴雨区,暴雨不仅量大,频次高,持续时间长:西北背风坡则反之,不论暴雨量,还是暴雨雨日都很少,持续时间不过几小时。而且由于造山运动留下多级夷平面和河流切割的喇叭口地形,在中部太行山区出现两个降水最大高度带。

Yanshan Mountain and Taihang Mountain stretch from northeast to southwest across the whole watershed, forming an arc and meeting the southeast summer air stream almost at a right angle. In the windward slopes on the southeast side of the mountains there is abundant rainstorm with large amount of precipitation, high frequency and long duration. In the leeward slopes on the northwest side, on the contrary, both the amount of precipitation isless and rainstorm days are fewer, and the duration of storm is no more than a few hours. Owing to the multistage levelled surfaces formed by mountain making and the negative delta topography dissectcd by rivers, there are two altitudinal belts with relatively abundant precipitation in the central section of the Taihang Mountains area.