Steady-State Subsurface Drainage of Ponded Fields by Rectangular Ditch Drains

Abstract

A comprehensive analytical solution is presented for the steady‐state two‐dimensional drainage problem of the water flow from a horizontal ponded surface into rectangular cross‐section array ditches. The ditches partially penetrate into a homogeneous and isotropic porous medium of finite depth over an impervious layer. The solution includes the equations for drainage discharge into ditches, the drainage discharge through the seepage face and the water depth portion of a ditch, and seepage velocities along the ponded surface. The equations are obtained using the Schwarz–Christoffel transformation in the conformal mappings of the physical and hodograph planes on to an auxiliary plane. The proposed analytical solution is validated by comparing the results with the known experimental data and the other analytical works. The results of the analyses show that seepage velocity along the ponded surface water decreases with distance from the ditch and accordingly leaching of salts is non‐uniform. Closer spacing between two adjacent ditches, shallower water depth in the ditches, and deeper depth of the ditches are advantageous in removing salts from fields. Copyright © 2014 John Wiley & Sons, Ltd.

Experimental Study on the Potential Use of Bundled Crop Straws as Subsurface Drainage Material in the Newly Reclaimed Coastal Land in Eastern China

“…Salt leaching in humid area can be accomplished by rainfall when proper drainage system is in place. In the initial stage of reclaiming the saline soils, however, higher drainage intensity, or closely spaced drainage pipes is often required to speed up the salt leaching, or the soil remediation process [11][12][13][14]. However, as the soil salinity decreases with the cultivation and the drainage leaching processes, drainage intensity should be lowered to encourage more rainfall storage in soil for improved water use efficiency [15] and prevent losses of soil nutrients from excessive leaching [16,17].…”

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

“…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].…”

An analytical solution for predicting the transient seepage from a subsurface drainage system

“…While various analytical solutions [6][7][8][9][10], laboratory experiments [11,12], field investigations [13][14][15] and numerical simulations [16][17][18][19][20] have been conducted to examine the flow and salt transport behavior within drainage systems, most of these studies focused on steady-state conditions [6,21]. For salt leaching, flushing is mainly examined with consideration of continuous surface ponding.…”