Hydrological effects of forest surface disturbance, a case study

Forests have had a vital role in survival, growth and development of human communities in various epochs of history. Overexploitation of the forest resources induced environmental disturbance leading to desertification and disappearance of civilizations. Deforestation has detrimental effects on the watershed environment which resulted in increasing flooding and sediment yield. Since long time ago, many studies have been conducted to evaluate the effects of managerial and engineering treatments on forest ecosystems characteristics. Since the hydrologic response of forest disturbance has been rarely considered, the present study has been conducted to investigate the effect of forest disturbance on hydrological components in sample plot scale with three replicates in the northern forests of Iran during seventeen storm events occurred from October 2009 to April 2010. The rain depth was measured by using a rain gauge installed in the study area. The runoff volume and sediment yield were also measured through field data collection and lab analyses by weighting and decantation methods. The results of the study showed significant effects of forest degradation (P <0.001) on hydrological components of runoff volume and coefficient, sediment yield and concentration. So that, the amount of runoff, runoff coefficient, sediment concentration and yield in disturbed area was found 5, 10, 18 and 6 times of those recorded for the undisturbed forest area, respectively.