| Because of the population grows,increasing demands,water requirements have increased but water supplies are getting harder and harder.New techniques must be used in irrigated agriculture in order to produce more food using less water and to do so without degrading water resources.Cavity-making technology in loess soil can help meet this challenge by giving growers greater control over the application of rainfall water.It can increase rainfall infiltration saving,thus to solve the problem of water resources shortage in northwest loess area of China.Therefore,the purpose of this study is to advance our current understanding of soil moisture storage in subsurface and water infiltration rate in loess soil.Therefore,two sets of experiments,namely dripping infiltration,and ponded infiltration were conducted on two soil columns filled with loam and silty clay loam,respectively,with and without applying cavity technical method.For the soil column applied with loess cavity,both experiments were simulated using HYDRUS-2D/3D,version 2.x and the simulated results were verified by those of observations.The results that two experiments shared the findings.The dripping infiltration experiment shows that?1?the wetting fronts of soil column with loess cavity when the water reached the cavity were 35,36,39,41,45,46,49,50,54,55,58,59,63,64,68,and 69 cm deep lower than those of no cavity soil column of 37,38,42,44,47,48,52,53,56,58,62,63,66,67,70,and 71 cm,respectively.Conversely,the wetting in 45degrees of soil column with loess cavity was found to be higher;?2?The infiltration rate of soil column with cavity was reduced from 3.25 to 0.309 cm.h-1,while those of soil column without loess cavity slightly reduced from 3.25 to 0.318 cm.h-1.?3?The water contents of cavity column at 14 and 30 cm were found to be higher than those beneath the cavity,and soil column without cavity;?4?The RMSE and EF values for water content at 14,30,46,and 62cm were 8.186,8.696,6.19,and 2.7 cm3.cm-3 and-1.69,-0.21,0.41,and-0.06,respectively.The analysis of RMSE and EF for wetting front was 3.42 cm and 0.95,respectively,which were shown a better agreement between the observed and simulated data by Hydrus 2D/3D.This means that the model's performance on simulating wetting patterns in soil column with loess cavity was acceptable.The RMSE and EF values of infiltration rate were 0.18 cm.h-1 and0.94,respectively.The ponded infiltration experiment shows that?1?the loess cavity significantly decreased the infiltration rates when the flux permeated through it(varying from 0.358 to0.208 cm.min-1)as compared with no cavity soil column(varying from 0.408 to 0.241 cm min-1);?2?similarly,the total cumulative infiltration and at the termination of wetting front advancement of soil column with cavity were 66 cm and 69 cm lower than that of no cavity soil column?76 and 78 cm?,respectively.Consequently,the soil moisture at the subsurface and surrounding the loess cavity was effectively ameliorated and less water could infiltrate deeper;?3?the model was capable of predicting water infiltration processes in the soil column with loess cavity,and the root mean square error of simulated water contents,wetting front advancements,cumulative infiltrations,and infiltration rates were from 0.22 to 3.63cm3.cm-3,1.6 to 3.63 cm,3.44 cm,and 0.026 cm.min-1,respectively.Overall,the findings in this study indicate that loess cavity can effectively increase soil moisture storage at the shallow surface.Moreover,the HYDRUS-2D/3D model is capable of simulating and predicting scenarios to help achieve stable shallow soil surface with loess cavity,even though it seems slightly underestimate the water distribution of dripping infiltration. |
PDF Full Text Request