تغییرپذیری اثرات متقابل برخی از صفات خاک بر زمان شروع رواناب (مطالعه موردی: حوزه آبخیز کجور)

The present research was conducted with the purpose of assessing the interaction between some soil properties and runoff generation time in the downstream of Educational and Research Forest Watershed of Tarbiat Modares University (Kojoor Watershed) located at Southeastern of Nowshahr. Rainfall simulation was done through applying a pumping rain simulator generating rain intensity of some 1.6 mm min-1. Accordingly, runoff generation time was determined from starting time of the simulation until runoff generation. In this research, some soil characteristics such as percentages of organic matter, clay, Silt, sand, antecedent soil moisture contents and soil bulk density were analyzed at two topography characteristics of slope steepness and aspect. For statistical analysis, a normality and variance homogeneity test was firstly carried out and variance analysis was then adopted. The significant relationships were ultimately evaluated using the Pearson correlation test. Results showed that the soil properties were strongly correlated to each others. Amongst them, there were just a positive correlation between the percentage of organic matter and topography properties with runoff generation time in the significant level of 5 %. Most of the runoff generation time were measured from plots of 44% and located at the western aspect that had the highest percentage of organic matter of 5.9%. It could be inferred from the results that the runoff generation time was significantly sensitive to environmental variables.