Afforestation plays a crucial role in the remission of water and soil erosion, adsorption of heavy metals, and protection of soil microbial community structure for mining areas. However, soil drought, the variability of precipitation, and low rainwater use efficiency severely limit the early survival rate of trees. A new small-scale system of rainwater harvesting combined with irrigation (RWHI) for afforestation in mining areas was established, which consisted of a rainwater catching board, storage tanks, and ceramic emitters. A daily water balance model under variable water supply was presented and experimentally verified to confirm the optimum catchment area, the storage capacity of tanks, and the rated discharge of ceramic emitters. Taking the Wuda mining area in Wuhai, China, as a case study, three representative years, including dry, normal, and wet years were selected by analysing local rainfall features. The results showed that the soil water content in the root zone maintained a suitable range (between field capacity and wilting coefficient) using the RWHI system. With the aim of the maximum system operating reliability for various weather conditions and tree species, it was recommended that the rated discharge of the ceramic emitter of 6 ml h-1, storage tanks of 25 L, the catchment area of 1 m2, and filling water schedule of twice a year were employed. A generalised equation for the estimation of the filling water amount was given. The vegetation coverage of the mine was significantly improved, and the survival rate of trees (Murraya paniculate) exceeded 90% using the RWHI system. It was indicated that the RWHI system has a broad application prospect in the afforestation of the mining areas.
Keywords: Afforestation; Mine area; Optimal design; Rainwater harvesting; Water balance model.
Copyright © 2022 Elsevier Ltd. All rights reserved.