[Rainwater harvesting effect of biocrusted soil-surfaces and the key influencing factors in the hilly region of Chinese Loess Plateau].

Abstract

In the hilly region of Chinese Loess Plateau, rainwater harvesting is a common ecological engineering measure utilized to reduce soil erosion and amplify the efficiency of water resource utilization. However, the effects on rainwater harvesting and the chief influencing factors of biocrusts as a potential material are unclear. In this study, we conducted a field simulation experiment with intensities of 40, 60, 80, and 100 mm·h^-1 between bare soil and biocrusts developed in aeolian soils, with bare soil as a control to explore the differences of the initial abstraction time, cumulative rainfall amount, and rainfall harvesting efficiency. We further analyzed the influencing factors of the rainwater harvesting effect. The results showed that the biocrusted soil-surfaces significantly decreased the initial abstraction time. When compared with the cyano biocrusts and bare soil, the reduction of the initial abstraction time of moss biocrusts was decreased by 49.7%-77.5% and 89.7%-110.0% when the rainfall intensities ranged from 40 to 100 mm·h^-1 and the slope was 40°. In addition, biocrusted soil surfaces significantly increased the cumulative rainfall amount and rainfall harvesting efficiency. These differences were considerable amongst the dissimilar surface cover types. In comparison to bare soil, when the rainfall intensity was 100 mm·h^-1 and the slope was 40°, the cumulative rainfall harvesting efficiency of moss and cyano biocrusts was increased by 29.6% and 7.8%, respectively. Both moss and cyano biocrusts increased rainfall harvesting efficiency of 25.7% and 6.8%, respectively. Variance analysis demonstrated that the rainfall harvesting efficiency was appreciably affected by surface cover type, slope, and rainfall intensity. The interaction between these factors was considerable except for slope and rainfall intensity. Additionally, important considerations for the actual construction included slope length, slope, and biocrust cultivation. In conclusion, biocrusted soil-surfaces have a high rainfall harvesting efficiency, but moss biocrusts have a much greater rain-collecting effect that improves even more as the slope and intensity of the rain increases.