黄土丘陵区不同降雨条件下聚水沟土壤水分研究

Soil Moisture of Rainwater Harvesting Ditches Under Different Rainfall Conditions in the Hilly Loess Region

为提高陕北黄土丘陵区林地降水的有效利用率,以水平阶地为对照,进行了填充石子、秸秆、树枝、基质等不同材料的聚水沟保墒试验研究。结果表明：天然降雨量小于6mm时,聚水沟内土壤含水量未增加;降雨量在6~10mm时,聚水沟沟底约10cm土层土壤含水量与对照出现差异（p〈0.05）;25~40mm降雨条件下,聚水沟两侧垂直40cm以上土层平均储水量较对照差异显著高16.14%,其土壤含水增量表现为：秸秆（4.8%）〉树枝（3.5%）〉石子（3.1%）〉对照（2.4%）〉基质（2.3%）;日降雨量大于40mm时,聚水沟30—190cm土层的拦蓄储水量较对照提高了12.6%~17.5%,此后无降雨时,聚水沟两侧30cm×30cm×70cm体积内大于13%的高水分含量可以维持近一个月;典型136.8mm的月累积降雨对石子、秸秆、树枝、基质覆盖聚水沟内水分扩散影响深度分别为120,160,160,130cm。综合分析,聚水沟内填充秸秆和树枝在增加水分入渗的同时对周边土壤水分的分配及存储效果好于石子和基质。

To improve the effective utilization rate of rainfall in the loess hilly region of north Shaanxi Province, this paper examined the conservation effect of rainwater harvesting ditchs （RHD） filled with gravel, straw, branch or matrix compared with level terrace. The results showed that soil moisture presents no increase in the RHDs under the rainfall lesss than 6 mm. When the rainfall ranged from 6 to 10 mm, soil moisture content exhibited significant differences in 10 cm soil layer of RHD（p〈0.05）. Under the condition of 25~40 mm rainfall, the average water content is 16.14% higher than the control in the vertical 0~40 cm soil layer on both sides of RHDs, the amounts of increment soil moisture by RHDs were in the order of straw （4.8%）〉branch（3. 5%）〉stone（3. 1%） 〉reference（2. 4%）〉matrix（2. 3%）. According to the data of disposable dammed-up, the water storage increased by 12.6~17. 5~ in the 30--190 cm soil layer after daily above 40 mm rainfall compared to the control, more than 13% of water moisture can be maintained for nearly a month in 30 cm× 30 cm× 70 cm distance on both sides of RHD when there is no rain in the later period. The water influence depths of gravel, straw, branch, matrix ditches are 120, 160, 160, 130 cm, respectively, under the condition of 36. 8 mm of typical month accumulative rainfall. In summary, RHDs filled with straw or branch not only improve water infiltration, at the same time, but also promote surrounding water distribution and storage, which shows better effects than the filled gravel or matrix.