黄土丘陵区竹节式聚水沟的蓄水特性

Water impounding characteristics of bamboo-shaped rainwater harvesting ditch in the hilly loess region

竹节式聚水沟是近年来陕北黄土丘陵区大力推广应用的一种雨水集蓄利用新技术．为了研究不同填充物（树枝、秸秆、石子）聚水沟的蓄水特性，在自然状态和模拟降雨条件下对各聚水沟土壤水分状况和拦蓄水能力进行测定，研究各种填充物的持蓄水特性．结果表明：自然状态下，5—10月各处理土壤储水量变化呈先降低后升高的趋势．5月，树枝沟、石子沟、秸秆沟和水平阶地30～200cm土壤储水量分别为186．76、177．23、169．26和185．76mm；与5月相比，10月树枝沟、石子沟和秸秆沟土壤储水量分别增加14．24、20．28和21．23mm，水平阶地降低6．52mm．10月各处理30～200cm垂直剖面上土壤水分恢复深度不同，秸秆沟和树枝沟恢复深度最大，达到140cm，石子沟次之，为110cm，水平阶地恢复深度最小，仅为80cm．模拟降雨条件下不同填充物聚水沟的拦蓄水总量为：秸秆沟（99．5L）〉石子沟（91L）〉树枝沟（71．5L）．浸水试验测得树枝和秸秆的持水率与浸水时间存在对数函数关系，而吸水速率与浸水时间存在幂函数关系，持水率与吸水速率之间呈负对数关系．秸秆的吸持水能力较树枝强；石子的吸持水能力很弱，随时间基本不发生变化，持水率与吸水速率之间呈线性负相关．3种聚水沟在黄土丘陵区均具有较好的推广应用价值，以秸秆沟的拦蓄水、持水效果最好．

Bamboo-shaped rainwater harvesting ditch （BRHD） is a new water harvesting and appli- cation technology being promoted in the hilly loess region of North Shannxi Province. This paper measured the soil moisture condition and water storage capacity of BRHDs filled with straw, branch or gravel through field and simulated rainfall experiments to evaluate the water holding and absorp- tion capacity of different BRHD fillers. From May to October, the water storage of BRHDs showed a decrease trend at first and then increased in field experiment. The water storage depths within 30- 200 em profile of branch ditch （ BD）, gravel ditch （GD） and straw ditch （SD） were 186.76, 177.23 and 169.26 mm in May, respectively, and increased by 14.24, 20. 28 and 21.23 mm in October, respectively. In contrast, the water storage depth of the level bench was reduced by 6.52 mm in October from 185.76 mm in May. The soil water restoration depth was different between BRHDs with different fillers and the level bench within 30-200 cm profile in October. The SD and BD had the deepest restoration depth （140 cm）, followed by GD （110 cm）, and the level bench was the minimum （80 cm）. Through rainfall simulation experiment, the amount of water intercepted by BRHD was in the order of SD （99.5 L） 〉GD （91 I,） 〉BD （71.5 L）. The water-holding rate of straw and branch showed logarithmic function with soaking time, while the water-absorption rate followed a power function. Moreover, there was a negative logarithm correlation between water-hold- ing rate anti water-absorption rate. Straw showed a better water holding and absorption capacity than branch. Gravel had a weak water holding and absorption capacity which was almost not changed during soaking, while it displayed a negative liner correlation between water holding rate and ab- sorption rate. The three kinds of BRItDs could be applied in the hilly loess region, and that filled with straw would exhibit the best capacity of water interception and holding.