Simulation Study On The Rainfall-runoff Regulation And Soil Water Redistribution Of Infiltration Hole On Loess Region

The frequent rainstorm and water consumption of vegetation still hindered the work of soil and water conservation and vegetation restoration in this area.Therefore,how to quickly reduce the runoff caused by rainstorms,improving the utilization of limited rainfall resources,and promoting the sustainable growth of vegetation had become an important scientific problem.The infiltration hole with depth and volume,it can be combined with the existing slope engineering measures to enhance the interception and infiltration of rainfall runoff.The infiltration hole can also increase the soil water storage in the deep soil and increase the degree of rainfall as a resource.In this paper,irrigation test and HYDRUS model simulation were used.The confluence area was 2 m² and the runoff coefficient was 0.3 as the simulation test conditions.We quantified and evaluated the interception and infiltration of rainfall runoff by infiltration holes with a diameter of 10 cm and different depths（h=60,80,100 cm）under different rainfall intensities(i=60,90,120 mm h^-1).We studied the water redistribution under the infiltration holes（h=60,100 cm）and fish-scale pits（60×40×10）under different rainfall intensities(i=30,60 mm h^-1).We also studied the dynamic changes of soil moisture over a period of one year under different measures.The main results were as follows:（1）The average time that infiltration hole was filled up with runoff in three rainfall intensity was 12.01,13.47,21.00 min under infiltration holes with 60,80,100 cm in depth,respectively.When the infiltration hole was full,the intercepted rainfall runoff converted into rainfall was 17.72,18.78 and 37.08 mm,respectively.The infiltration hole could completely prevent the runoff before it was full.The infiltration holes with60,80,100 cm in depth can reduce runoff by 34.46,40.48,45.67%under steady infiltration conditions,respectively.The 24-hour cumulative infiltration runoff of infiltration holes with depth of 60,80 and 100 cm was converted into rainfall of 400.76,469.73 and 512.73 mm,respectively.（2）The vertical and horizontal distances of soil moisture infiltration increased with time.On the 7th day after rainfall,the infiltration depths of H1(h=60 cm,i=60 mm h^-1),H2(h=60 cm,i=30 mm h^-1),H3(h=100 cm,i=60 mm h^-1)and H4(h=100cm,i=30 mm h^-1)treatments were 80,70,110 and 110 cm,respectively,and the horizontal infiltration ranges were 40,30,30 and 20 cm,respectively.The infiltration depths of F1(i=60 mm h^-1)and F2(i=30 mm h^-1)were 60 and 40 cm,and the horizontal infiltration ranges were 50 and 20 cm.On the 7th day after irrigation,the increase of soil water storage under the treatments of H1,H2,H3,H4,F1 and F2accounted for 23.83%,23.53%,56.95%,64.01%,25.87%and 26.45%of the simulated runoff,respectively.It was obvious that the infiltration hole with larger depth could store more soil water.（3）The hydrous-2D model was used to simulate the soil moisture dynamics under different measures for one year.The results showed that the soil moisture distribution was uniform at 0-80 cm from the center of the measure in the horizontal direction under different measures.Compared with natural slope（BL）and fish-scale pits（F）,infiltration holes（60 cm in depth,H60;100 cm in depth,H100）increased the infiltration depth of rainfall water in soil,and also changed the soil water distribution.Under H100 treatment,soil water infiltrated into the soil layer below 150 cm,and the infiltration amount was 0.19 mm.After one year,the order of rainfall water stored by soil under different treatments was H100（148.07 mm）>H60（143.12 mm）>F（121.68mm）>BL（115.73 mm）.The results of this paper showed that the infiltration hole could effectively intercept and infiltrate the rainfall runoff on the slope surface.Compared with the fish-scale pits,the infiltration hole could increase the depth of rainfall water infiltration,but the water level diffusion range was reduced.Infiltration holes can effectively increase the total soil water storage and deep soil water storage.The depth and density of infiltration holes should be selected according to the intensity and duration of extreme rainfall to adapt the complex environment.These results provided a theoretical basis and basis for using infiltration hole technology to control runoff,reduce natural disasters,and promote vegetation restoration and sustainable development in the loess area.