پژوهشنامه مدیریت حوزه آبخیز (Jul 2024)
Biological Control of Soil Erosion in the Kilanbar Watershed, Kermanshah Province, Iran
Abstract
Extended Abstract Background: Soil erosion, a significant form of land degradation, poses severe challenges to humanity in different ecosystems. It serves as a comprehensive index for evaluating the development and sustainability of land management programs. Assessing the status and spatial extent of soil erosion has become crucial in developing countries. Biological management, a recommended and effective means of controlling soil erosion in the early stages of all processes, offers a practical solution. Biological methods, such as minimum tillage operations and limited intervention in nature, prove to be more cost-effective and efficient than structural measures. Despite these advantages, biological measures have not received adequate attention in soil erosion control. This research addresses this gap by applying biological management in the Kilanbar Watershed (Kermanshah Province, Iran), demonstrating its effectiveness and cost-efficiency. Methods: The layers of elevation from sea level, aspect, and slope steepness were prepared and combined in the geographic information system (GIS) software to prepare 38 land units. In the Kilanbar Watershed, 14 land units with the ability to perform biological management measures were extracted based on the expert and technical opinions of the watershed manager and considering different bases to improve the performance and decision-making of the units with an area of less than 300 ha. The Kilanbar Watershed is located in Ravansar City, west of Kermanshah Province. The study area is approximately 10798 ha. The highest and lowest elevation points of the watershed are 2183 and 1388 m above mean sea level, respectively. The mean annual precipitation, temperature, and relative humidity are 533 mm, 11.4 °C, and 45.1%, respectively. The status of soil erosion in each land unit was completed based on the scoring of the BLM form based on the visual and expert opinions, and a map of the erosion pattern was prepared in the land units. Ambrotropic and hyetographs were drawn using the 30-year precipitation and temperature data of the Ravansar synoptic station to determine the periods of drought and wet conditions and to identify suitable plants with the characteristics of the region. A climatic–agricultural map was prepared and integrated into the GIS using meteorological station data (temperature, precipitation, evaporation, and transpiration), and plant species were selected according to ecological expectations for watershed biological measures. Results: According to the BLM form results, one and eight land units are in partial and low erosion conditions, respectively, and five other land units are in medium erosion conditions. According to the erosion pattern map, the majority of the studied area, about 70% of the watershed, is in a low and medium erosion state, which naturally confirms the high ability to use appropriate biological measures to control soil erosion. According to ambrothermic and hyetograph measurements, June to September were dry months, and precipitation changes were more significant than temperature changes from October to May. According to the climatic–agricultural map, the region is divided into five classes. Class 4 (4819.3 ha) and Class 1 (364.83 ha) had the largest and smallest areas, respectively. Finally, the zoning of suitable rangeland species in the watershed showed that rangeland species of Asteragalus ascendes, Avena fatua, Picnomon sp., Achillea millefolium, Bromus tomentellus, and Hordum blubosum dominantly covered the region. Based on the study results, appropriate plant species were introduced for the studied watershed. Accordingly, conservation and reclamation measures were recommended to improve land productivity and ecological conditions and avoid land use changes for the study area. The essential measures include vegetation in rangeland ecosystems aiming at preventing the role of the canopy cover from directly impacting raindrops on the soil surface, increasing water infiltration in the soil, stabilizing soil aggregates due to roots extension, increasing grazing capacity and livestock production, and increasing its efficiency and productivity with time. Conclusion: The findings of this study hold significant potential for the Kilanbar Watershed. The proposed biological erosion measures, tailored to the ecosystem's unique conditions, are effective, low-cost, and environmentally compatible. They offer a sustainable solution for managing soil and water resources in various ecosystems. Implementing these measures can significantly reduce soil erosion in the watershed, particularly in areas with low to moderate erosion status. This research is an essential initiative in applying biological erosion measures in the Kilanbar Watershed, demonstrating that soil erosion can be effectively and practically controlled in approximately 67% of the watershed through biological methods in the critical land-use areas of rangelands and agriculture. It is important to note that applying biological erosion measures requires comprehensive and integrated investigations, considering the different parts of the ecosystem. With these findings, the proposed approach in this research can be extended to other watersheds across the country, particularly those with slight to moderate erosion status, while maintaining the principle of comprehensiveness and respecting the unique conditions of each watershed.
