نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه جنگل، مرتع و آبخیزداری، واحد علوم و تحقیقات، دانشگاه آزاد اسلامی، تهران، ایران
2 گروه احیای مناطق خشک و کوهستانی، دانشکده منابع طبیعی، دانشگاه تهران، کرج، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Extended abstract
Introduction
Awareness of the soil erosion risk in watersheds makes it possible to identify critical areas and prioritize management and conservation programs. Due to the lack of accurate and acceptable information about the small amount of soil erosion in watersheds, it is often necessary to estimate the sensitivity or potential of different areas of the watershed in terms of the severity of soil erosion. The use of new RS/GIS techniques along with modeling processes such as soil erosion accelerates the recognition, control and management of natural resources. Among the many methods for predicting erosion using RS/GIS, the ICONA model simulation results are widely accepted. The ICONA model is one of the simplest and most flexible qualitative methods for assessing erosion risk map. This model is an erosion risk assessment method that uses qualitative decision rules and hierarchical organization of the four main inputs. The erosion risk map prepared with the ICONA model can be used as a reliable framework for erosion risk assessment. This model with its flexibility can be used in decision making to solve the problems of soil erosion and degradation in specific conditions of each country or study area. The purpose of this study is to apply the ICONA qualitative model and the use of RS/GIS techniques to assess the potential for erosion risk in the Kasilian watershed (representing large areas of mountainous and forested parts of northern Alborz in Iran).
Materials and methods
In this study, with the aim of investigating the risk of erosion and identifying areas sensitive to water erosion in the Kasilian watershed, remote sensing and GIS techniques were used in the framework of the ICONA model. The ICONA model consists of seven stages. This model starts with 4 layers of slope, geology, vegetation and land use and by preparing two layers of soil erodibility and soil protection maps, has identified and evaluated the potential for erosion risk in different land uses.
Study area
Kasilian watershed with an area of 6750 hectares in the geographical range of Alborz. It lies within the latitudes of 35° 58′ 45′′ to 36° 07′ 45′′ north, and longitudes of 53° 01′ 30′′ to 53° 17′ 30′ east and south of Savadkooh city. It is located in Mazandaran province. This area represents large areas of mountainous and forested parts of northern Alborz in Iran. Land use of Kasilian watershed mainly includes forests, pastures, agriculture, residential and rock outcrops.
Results and discussion
Due to its morphological and topographic characteristics, Kasilian watershed is an area with high density and elongation with a large area of very high slope class (20-35%), formations sensitive to water erosion (Shemshak formation), soil with heavy to semi texture heavy and hydrological group of soil is C. Therefore, erosion is predicted and observed in sensitive areas of the study area. Findings of the study in the area show that high vegetation has moderated the slope effect, in general, the highest level of erosion risk class is in the middle class. At the same time, the southern and higher parts of the forest lands of Kasilian watershed are in high risk of erosion due to reduced vegetation and slope. The findings also showed that the risk of erosion is very high in rangelands with high slope and low protection. The rock outcrop lands that exist in the upper elevations of the study area have a slope of more than 35%. These lands are in a very low erosion risk class. In fact, higher slopes can also provide a natural protection against soil erosion.
Conclusion
In total, 26.26% is in the medium erosion risk class, 25.44% in the low erosion risk class, 18.83% in the very low erosion risk class, 18.55% in the high erosion risk class and 10.92% is of very high erosion risk class. Rangelands and parts of agricultural lands rank first in the extent of the erosion risk class. The southern parts of the forest lands (with reduced vegetation cover) are in the high erosion risk class. This model can be used as a reliable framework for erosion risk assessment and can identify areas prone to erosion with a minimum parameter, cost and time reduction, accuracy and good flexibility.
کلیدواژه‌ها [English]
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