Simulation of Evapotranspiration and Drainage from Potash Tailings Covers using Hydrus-1D

Abstract

Evapotranspiration is the sum of evaporation of water from soils and transpiration from plants. It is a crucial part of the water cycle and can be measured using lysimeters. However, lysimeters require high maintenance and operation costs; as such, evapotranspiration models are used for making predictions. Thus, the aim of the present study was to calibrate the Hydrus-1D to predict the water balance components of an evapotranspiration cover (in this case, a thin covering layer) for potash tailings piles. Further simulations were performed using different fine fraction proportions, soil textures and crop parameters. A high association between the calibrated and observed drainage of substrates was found, with a variation of 2.9% (approximately 13.6 mm). Drainage estimates were lower with increasing root depth, crop height and proportion of fine particles (< 2 mm diameter) in the substrates. Fine fractions in the substrates increased the water storage and the evapotranspiration capacity of the substrates and therefore contribute to improving the efficiency of evapotranspiration covers and can facilitate reducing brine drainage from potash tailings piles.