Artificial biological soil crust property and potential for rainwater harvest

It is important to collect limited rainwater for agricultural and domestic use in arid and semiarid areas. Rainwater harvesting systems used for collection, storage and purification of rainwater are critical for rainwater utilization. Materials used in building the surfaces of rainwater harvesting plots determine the efficiency of rainwater harvesting system as they affect the hydrological characteristics of the plot surfaces. This paper discussed the potential and feasibility of artificially cultivated biological soil crusts (BSCs) as surface materials of rainwater harvesting plots. It investigated the effects of artificial BSCs on soil physical properties and infiltration and also on the efficiency of rainwater harvest. The results showed that the surface soil (0~1 cm) with artificial BSCs contained more tiny particles and less coarse particles than natural soil. However, no significant difference was noted in bulk density of 0~5 cm soil between artificial BSCs and natural soil. Infiltration rate decreased under artificial BSCs. Initial and stable infiltration rates as well as stable infiltration water volume of BSCs decreased by 59.1%, 44.4% and 50.0%, respectively. The investigation based on rainwater harvesting plots established on 30° slope loamy soil mountain showed that BSCs rainwater runoff efficiency increased. The average runoff efficiency of BSCs rainwater harvesting plot was 60.86% during six runoff events in May to August 2005. BSCs rainwater harvesting plot increased runoff efficiency over that of natural soil by 23.0%. Benefit analysis showed that BSCs not only increased runoff efficiency, but also longer-lasting with significantly less runoff sediment. BSCs were therefore recommended as potential green materials for rainwater harvest.