Comparison of intra and inter variations of runoff and sediment in plots installed in range and reclaimed forest land uses

Studying intra and inter variations of runoff and sediment on storm basis facilitates understanding problems in a watershed. However, such studies have been fortuitously conducted. Accordingly, this study was planned to evaluate intra and inter variations in runoff and sediment on storm event basis in plot scale with dimension of 50×50 cm in rangeland and reclaimed forest treatments with three replications at Kodir village in Alborz Central mountain range. For this study, a pumped rainfall simulator with 5 liters volume capacity, intensity of about 1 mm/min and drops diameter of 1 mm and similar to prevailing precipitation conditions in the study area for a period of about 22 min was used. The amount of runoff and sediment at the onset of starting runoff generation were collected at every 2 min from April 2009 to May 2010. The results of the study showed that the trend of runoff within events in both range and revived forest use was initially increasing and then decreasing. Sediment variation with further fluctuations was found similar to that of runoff. The amount of runoff and sediment in the rangeland use was 3.8 and 7.7 times more than those recorded for reclaimed forest use. Also, the highest and the least amount of runoff in both uses occurred in April 2010 and September 2009, respectively, while the highest and the least amount of sediment occurred in February and September 2009.