Streamflow and Soil Moisture of Agroforestry and Grass Watersheds in Hilly Area

LIU Gang-Cai; TIAN Guang-Long; SHU Dong-Cai; LIN San-Yi; LIU Shu-Zhen

摘要

A study was conducted in a hilly area of Sichuan Province,Southwestern China, to compare the streamflow and soil moisture in two upland watersheds with different land use patterns. One was an agroforestry watershed, which consisted mainly of trees with alder (Alnus cremastogyne Burkill) and cypress (Cupressus funebris Endl.) planted in belts or strips with a coverage of about 46%, and the other was a grassland primarily composed of lalang grass (Imperata cylindrica var. major (Nees) C. E. Hubb.), filamentary clematis (Clematis filamentosa Dunn) and common eulaliopsis (Eulaliopsis binata (Retz.) C. E. Hubb) with a coverage of about 44%. Streamflow measurement with a hydrograph established at the watershed outlet showed that the average annual streamflow per 100 mm rainfall from 1983 to 1992 was 0.36 and 1.08 L s-1 km-2 for the agroforestry watershed and the grass watershed, respectively. This showed that the streamflow of the agroforestry watershed was reduced by 67% when compared to that of the grass watershed. The peak average monthly streamflow in the agroforestry watershed was over 5 times lower than that of the grass watershed and lagged by one month. In addition, the peak streamflow during a typical rainfall event of 38.3 mm in August 1986 was 37% lower in the agroforestry watershed than in the grass watershed. Results of the moisture contents of the soil samples from 3 slope locations (upper, middle and lower slopes) indicated that the agroforestry watershed maintained generally higher soil moisture contents than the grass watershed within 0-20 and 20-80 cm soil depths for the upper slope, especially for the period from May through July. For the other (middle and lower) slopes, soil moisture contents within 20-80 cm depth in the agroforestry watershed was generally lower than those in the grass watershed, particularly in September, revealing that water consumption by trees took place mainly below the plow layer. Therefore, agroforestry land use types might offer a complimentary model for tree-annual crop water utilization.

机译：在中国西南部四川省的丘陵地区进行了一项研究，比较了两个具有不同土地利用方式的山地小流域的水流和土壤水分。一个是农林业分水岭，主要由al木（Alnus cremastogyne Burkill）和柏树（Cupressus funebris Endl。）种植在带状或条状中，覆盖率约为46％，另一种是主要由拉朗草组成的草地（Imperata cylindrica var。major（Nees）CE Hubb。），丝状铁线莲（Clematisfilosa Dunn）和常见的eulaliopsis（Eulaliopsis binata（Retz。）CE Hubb）覆盖率约为44％。利用在流域出口处建立的水文图进行的流量测量表明，农林流域和草地流域在1983年至1992年期间每100 mm降雨量的年平均流量分别为0.36和1.08 L s-1 km-2。这表明，与草类流域相比，农林业流域的流量减少了67％。农林分水岭的月平均峰值流量比草木分水岭的峰值平均流量低5倍以上，滞后一个月。此外，在1986年8月典型的38.3 mm降雨事件中，农林流域的水流峰值比草地流域的水流低37％。在三个坡度位置（上坡度，中坡度和下坡度）的土壤样品的水分含量结果表明，在上层土壤深度为0-20和20-80 cm处，农林流域的土壤水分含量总体上高于草类流域。坡度，尤其是从五月到七月的时期。对于其他（中下部）坡度，农林业流域内20-80厘米深度的土壤水分含量通常低于草木流域，特别是在9月，这表明树木的耗水量主要发生在耕层以下。因此，农林业用地类型可以为树木年生作物的水分利用提供一个补充模型。

Streamflow and Soil Moisture of Agroforestry and Grass Watersheds in Hilly Area

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