黄土丘陵区降雨后鱼鳞坑土壤水分动态模拟研究

为了明确鱼鳞坑措施下降雨后土壤水分再分布过程及范围的变化,以汇流面积2 m²,径流系数0.3为试验条件,选取规格为60 cm×40 cm×10 cm(长×宽×深)的鱼鳞坑,通过灌水试验研究了降雨强度分别为60,30 mm/h、历时1 h后连续7 d的土壤水分动态。结果表明:(1)降雨强度60,30 mm/h时灌水后第1天水分入渗深度为60,50 cm,第2天达到最大值,分别为80,60 cm,水分最大入渗深度随降雨强度增加而增大; 灌水后第1天水分水平入渗距离达到最大值40 cm,水分水平入渗距离随土层深度增加而降低。(2)灌水后7 d内,降雨强度60 mm/h时水分主要储存在深度10—80 cm距离鱼鳞坑中心0—40 cm的区域内; 降雨强度30 mm/h时,水分主要储存在深度10—50 cm距离鱼鳞坑中心0—40 cm的区域内。(3)深度10—30 cm处土壤水分在灌水后第1天达到最大值,30—50 cm处土壤水分在灌水后第3天达到最大值; 距离鱼鳞坑中心0—20 cm处土壤水分在灌水后第1天达到最大值,距离20—40 cm处在灌水后2～3 d水分达到最大值; 达到最大值后土壤水分逐渐降低至稳定。鱼鳞坑措施下降雨水分入渗深度可达80 cm,且随降雨强度增加而增大,水分水平入渗距离与降雨强度无明显关系。

Study on Simulation of Soil Water Dynamics in Fish-Scale Pit After Rainfall in Loess Hilly Region

In order to understand the effects of fish-scale pit on soil water dynamics after rainfall,the irrigation experiment was carried out.The size of fish-scale pit was 60 cm×40 cm×10 cm(length×wide×depth),the rainfall intensity was 60 mm/h and 30 mm/h and it lasted for 1 h.The runoff collection area was 2 m²,and the runoff coefficient was 0.3.The results showed that:(1)the vertical infiltration depth was 60 cm and 50 cm,repecttively,on the first day after irrigation that the rainfall intensity was 60,30 mm/h,the maximum vertical infiltration depth was 80 cm and 60 cm on the second day after irrigation;the maximum vertical infiltration depth increased with the increase of rainfall intensity;the maximum horizontal infiltration distance was 40 cm on the first day after irrigation;the horizontal infiltration distance decreased with the increases of soil depth;(2)the water was mainly stored at the depth of 10—80 cm and 0—40 cm from the center of the fish-scale pit within 7 days after irrigation that the rainfall intensity was 60 mm/h;the water was mainly stored at the depth of 10—50 cm and 0—40 cm from the center of the fish-scale pit within 7 days after irrigation that the rainfall intensity was 30 mm/h;(3)the soil moisture reached the maximum at depths of 10—30 cm and 30—50 cm on the first and the third day after irrigation,respectively;the soil moisture at a distance of 0—20 cm from the center of fish-scale pit reached the maximum on the first day after irrigation;the soil moisture at a distance of 20—40 cm reached the maximum on the second day or the third day after irrigation.The soil water content gradually decreased and reached to the stable level after reaching the maximum.The water infiltration depth in the fish-scale pit could be 80 cm,and increases with the increase of rainfall intensity.There is no obvious relationship between the horizontal infiltration range and rainfall intensity.