Simulating Water Flow and Salt Leaching Under Sequential Flooding Between Subsurface Drains

Abstract

Streamline behaviour and solute transport were investigated under sequential flooding situations using a HYDRUS‐2D/3D model. HYDRUS‐simulated solute breakthrough curves exhibit a similar shape as measured curves but breakthrough is slightly delayed. This might be caused by slightly different properties (particularly particle size distribution) of silica sand used to determine solute transport and van Genuchten parameters. The breakthrough curves for comparable flooding scenarios under both lower and upper drains suggest that uniform leaching is evident through sequential increase from ¼, ½, ¾, and complete flooding. This suggests that higher leaching efficiency under sequential flooding strategy is possible when compared to complete flooding. Visual and quantitative comparison of model simulations shows a very close match to Hele‐Shaw cell experiments. Based on simulation results of this study, it is evident that the HYDRUS 2D/3D model is a powerful tool for efficient use of scarce water resources and could successfully be used for leaching excess salts in arid and semi‐arid regions. Results by Skaggs et al. (2004) supported the use of HYDRUS‐2D and they recommended it as a tool for designing and management of drip irrigation systems. Copyright © 2013 John Wiley & Sons, Ltd.

Effects of macro-pores on water flow in coastal subsurface drainage systems

“…Progressive ponding enhances the local hydraulic head gradient in the interior. The leaching efficiency can be thus improved by up to 4 times with respect to the amount of water needed to drain the soil to the required soil depth [16,17]. While salt transport in the soil is affected by both advection and diffusion/dispersion processes, all these studies suggested that increasing the hydraulic head gradient between the drain and interior is the key to improving the efficiency of salt leaching.…”

“…The salt leaching method has been studied extensively via analytical solutions [7][8][9][10], laboratory experiments [11,12], field investigations [13][14][15] and numerical simulations [16][17][18][19].…”

The soil–water flow system beneath a cotton field in arid north-west China, serviced by mulched drip irrigation using brackish water

“…Arid regions are susceptible to high risk of salinization, which is mainly caused by the high evaporation rates as well as the retarded leaching characteristics of the soils in these areas. Irrigation is a major factor affecting soil salinity, and salts enter into the soil through applied water and accumulate in the root zone because of inadequate leaching (Mirjat et al 2014). In addition, excessive irrigation can lead to a rise in the water table.…”

Evaluation of evapotranspiration and deep percolation under mulched drip irrigation in an oasis of Tarim basin, China

“…During irrigating, solute salt in irrigation water accumulates in soils and gradually stores at the root zone by root water uptake. Besides, soil evaporation mainly occurs between mulches, and salts usually accumulate along the wetting fronts and the bare soil belts, which always lead to soil salinization (Mirjat et al, 2014) and affects the sustainable utilization of brackish water (Aragüés et al, 2015). With the years of increasing mulched drip irrigation with brackish water, the depth of 30 ~ 60 cm is the main 4 / 46 part of salt accumulation (Wang, 2013).…”