鹤山丘陵草坡的水文特征及水量平衡

HYDROLOGICAL PROPERTIES AND WATER BALANCE OF GRASSLAND ECOSYSTEM IN HESHAN HILL REGION

在中国科学院鹤山丘陵综合开放实验站的草坡集水区对大气降水和径流进行了连续4年的观测，并于1994年对该集水区的蒸散进行了测定，结果表明：1）鹤山丘陵区年均降水量1761．37mm，大气降水有明显的干湿季之分，干季降水量占全年降水量的12．47％，湿李占87．53％。年均降水量中有62．24％可引起地表产流，即年均产流降水量1096．3mm。产流降水以中、小雨额度为大，但产流水量主要由大、暴雨供给。文中根据降雨量较大地区的降水、产流特征和规律，提出了产流降水和产流水量的概念。2）鹤山丘陵草坡集水区年总径流系数50.12％，地表径流系数17．33％。地表径流主要集中在湿季产生，与降水量呈二次抛物线型回归关系，与降水强度关系不大。3）1994年水量平衡各分量中，实际降水输入1841．55mm，年径流量970．28mm，径流系数52．69％，径流是系统的最大输出项；蒸散量851．56mm，意味着年降水收入中46．24％的水量以汽态形式返回了大气。蒸散的月变化呈双峰型，不同于降水的季节分配，径流的月变化则与降水同步。系统蓄水年变化量19．71mm，约占年降水量的1．07％，但其月变化却非常大，在-68～104mm之间。草坡集水区的水量平衡是一种收入对支出的补给和收支项目中可变性的动态平衡。4）鹤山丘陵草坡水热季?

Experiments were conducted on the grassland watershed at the Heshan Hill Region Experimental Station.Rainfall and runoff records were kept for four years,while evapotranspiration in the grassland watershed was studiedin just one year, 1994. These studies indicate: 1) average annual precipitation was 1761mm,and there is significant seasonal variation. Dry season rain accounted for 12 % of the annual precipitation,while wet season rain made up 88%.Moderate and light rain events were the most frequent though most precipitation was derived from by heavy rain anddownpours. 62% of rain fell in events sufficient to cause surface runoff. 2) The annual runoff and surface runoff coefficient were respectively 50% and 17%. Variation in surface runoff was closely related to variation in precipitation,though less with variation in rainfall intensity. 3) The water balance for 1994 included rainfall input of 1842mm andthe output via runoff and evapotranspiration were 970mm and 852mm respectively. Annual molsture variation for theentire system was just 19. 7mm, but monthly variation was significant, ranging from- 68mm to 104mm. This adjustedwater distribution over a single year,and between years so that the water balance of the grassland was in a form of dynamic balance. 4) Unbalanced seasonal distribution of both water availability and heat,large rainfall events causing surface runoff and the large proportion of surface runoff are three important factors restricting vegetation improvement.Managing change in the way the system losses and reserves its water is a key element in the restoration mechanisms ofdamaged ecosystem.