2006年特大干旱条件下森林植被对水资源的影响

2006年四川发生了百年一遇的特大干旱。按照自然地理条件相近、森林覆盖率有较大差异的原则,采用对比分析方法,于干旱末期,调查了四川盆地丘陵区13对乡镇(森林覆盖率高的乡镇森林覆盖率为28.26%～56.23%,平均为38.22%,相对应的低的乡镇森林覆盖率为5.65%～27.10%,平均为16.41%)内的溪河流量、堰塘和水井干枯情况以及人畜饮水现状。结果表明,在干旱季节,森林覆盖率低的乡镇溪河断流率平均为69.1%,断流天数平均为52 d;而覆盖率高的乡镇溪河断流率平均为25.5%,比前者少43.6%,断流天数平均为35.3 d,比前者少16.7 d,溪河平均断流起始时间比前者推迟17.3 d。森林覆盖率低的乡镇堰塘、水井平均干枯率分别为62.5%、70.0%,新打水井中,出水井率为48.2%;而覆盖率高的乡镇堰塘、水井平均干枯率分别为40.9%、43.7%,比前者分别低21.6%、26.4%,新打水井中,出水井率为57.7%,比前者高出9.5%。人畜饮水困难数占总人畜比例,覆盖率高的乡镇比覆盖率低的乡镇分别少24.0%、23.2%。

The Working of Forests on Water Resources of the Hilly Areas in the Sichuan Basin in the unusual drought in 2006

A centennial drought event happened to Sichuan province in 2006.In this paper,by the principle of similarity in the physical geography and biggish dissimilarity in the forest coverage among the investigated areas,investigations were made on some indexes such as the amount of river turnoff,the dry condition of ponds and wells,and the present condition of drinking water of people and livestock in the 13-couple towns in the Sichuan Basin at the end of arid period.Among 13-couple towns,the mean forest coverage in towns with higher forest coverage(town A) was 38.22%,ranging from 28.26% to 56.23%,and that in towns with lower forest coverage(town B) was 16.41%,ranging from 5.65% to 27.10%.Using the method of comparison and analysis,statistical data showed that the average ratio of river runoff was 69.1%,and the average days of river runoff were 52 days in town B in the drought season.The average ratio and days of river runoff were respectively 25.5% and 35.3 days in town A.Moreover,as compared with town B,the mean starting drying-up time among the drying-up rivers in town A was suspended for 17.3 days.In other aspects,the average ratios of dry ponds and wells were 62.5%,70.0%,respectively,and the average percentage of the well with water among the newly-dug wells in 2006 was 48.2% in town B.In town A the average ratios of dry ponds,and wells were 40.9% and 43.7% and the wells with water anorg the newly-dug wells were 57.7%,respectively.As for the average percentage of people and livestock lacking drinking water,town A was lower by 24.0% and 23.2% than town B,respectively.