مجله ترویج و توسعه آبخیزداری
پیاپی 39 (زمستان 1401)

Soil is less exposed to erosion when is covered by vegetation. Vegetation is considered as one of the main factors preventing water erosion. The Revised Universal Soil Loss Equation (RUSLE) estimates soil loss as a combination of six factors including rainfall erosivity, soil erodibility, slope length and degree, vegetation and management factors.  Vegetation is one of the most effective factors in the mentioned equation. In the present study, the effect of vegetation on water erosion using Revised Universal Soil Loss Equation has been investigated in Madyanrood watershed. The results of this research showed that the minimum, maximum and average values of erosion risk are zero, 5202 and 69.14 tons per year per hectare, respectively, which becomes zero, 7631 and 108 tons per hectare per year, respectively by removing the effect of vegetation. Investigating the extracted maps, showed that the central areas of the basin and some southwest and northwest parts of the basin have a lower average annual erosion, which corresponds to the areas with more vegetation.

Landslides are one of the most important factors in the destruction of watersheds. The frequency of landslides is higher in sloping and wet slopes consisting of sensitive formations or due to human activities. Taleghan watershed is known as one of the most prone landslides in the southern slopes of Alborz mountain range, despite the significant area of Miocene marls and high natural humidity due to high density of drainage network and construction of Taleghan dam. A review of the records of studies related to the Taleghan watershed shows that older studies have been done with simple and qualitative tools and based on the experiences of experts, while today these methods have given way to quantitative statistical studies and methods based on machine learning. The evolution of landslide risk zoning tools in Taleghan also demonstrates this importance. In this study, while reviewing the research objectives, we have reviewed the application of methods over the past two decades and after reviewing 15 separate research articles, the evolution of landslide risk zoning tools in the Taleghan watershed has been investigated. The results showed that statistical models were better and more applicable than innovative models and qualitative and semi-quantitative methods, but it is noteworthy that the speed of using methods based on machine training and fuzzy logic was higher and This result is clearly seen in studies conducted in this basin (especially during the last five years).

Ever-increasing of population, global warming, and other natural disasters such as droughts and floods have led to a significant decline in health and ecosystem services. It further improves the necessity of planning and providing management measures for the tendency of watersheds towards optimal health, providing sustainable services, and avoiding critical conditions. However, due to the different conditions of the watersheds resulting from the prevailing conditions and their different resilience levels against the pressures, the elasticity of the watersheds to tend towards a relatively stable state is different. It accordingly is necessary to know the elasticity of watersheds to prioritize actions aimed at increasing the watershed health and ecosystem services. However, it was determined by reviewing the studies, until now, the conceptualization and modeling of the watersheds elasticity range in terms of watershed health and cultural, regulatory, provisioning, and supportive services have not been addressed yet. Therefore, in the present study, the management approach of the watershed elasticity domain and its importance and benefits in integrated watershed management are presented. Based on this, a framework for estimating the elasticity of watershed can be determined and a suitable model for explaining appropriate management practices to achieve sustainable development can be provided to local, regional, and national managers.