|
|
:
|
Optimal use of rainfalls, especially snow and rain in arid and semi-arid regions, can play an important role in providing water requirement for the green space in the dry seasons. On the other hand, poor vegetation can cause erosion and destruction in Sloping lands that can be partially resolved if water and soil resources are properly managed. Rainfall is one of the most important sources of water supply for various uses that can be collected prior to dealing with soil surface and contaminated, and in times of drought, the water requirement of plants and trees can be met. One way to collect rainwater is too impermeable the surface of the earth and to maximize runoff from rainfall. Impermeable surfaces can be naturally occurring like rock surfaces or can be artificially covered with materials such as asphalt, concrete, insulating sheets such as plastic, geomembranes and decamond. In this research project, four types of treatments, each with three replications of 4 m2 (2m×2m), were considered, including geomembrane cover area, plastic cover with sand protection, natural surface and natural surface with sand mulch. Results of 78 rainfall events over two years showed that in intermediate slopes of 30-44%, runoff from rainfall for geomembrane, plastic cover with sand protection, natural surface and natural surface with sand mulch were 84, 67, 3 and 2% of rainfall respectively and rainfall threshold for runoff at mentioned surfaces was 0.28, 2.56, 9.95 and 11.12 mm, respectively. Therefore, with respect to annual normal rainfall (245.7 mm), the volume of runoff accumulated for geomembrane, plastic cover with sand protection, natural surface and natural surface with sand mulch will be 206, 164, 7 and 5 liters / m2, respectively. Results of analysis of variance between treatments showed that the cumulative runoff from precipitation in different treatments was less than 1%. Comparing the means, the geomembrane cover treatment was identified as a suitable option for runoff production. In order to study soil erosion, sediment from runoff of natural surface and natural surface with sand mulch was measured. The results showed that sand mulch on natural surface reduced soil erosion tenfold and reduced soil erosion from 97 gr/m2 to 9.5 gr/m2 in two years.Keywords: Erosion, Geomembrane, Insulation surface, Rainwater, Runoff, Sand mulch, Sloping lands
|