Estimation of soil losses by USLE model using GIS at Mashhad plain, Northeast of Iran

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ORIGINAL PAPER

Estimation of soil losses by USLE model using GIS at Mashhad plain, Northeast of Iran Ali Bagherzadeh

Received: 4 April 2012 / Accepted: 29 October 2012 # Saudi Society for Geosciences 2012

Abstract The Universal Soil Loss Equation (USLE) is an erosion estimation model to assess the soil losses that would generally result from splash, sheet, and rill erosion. At the present study, spatial distribution of different erosion prone areas were identified by USLE model to determine the average annual soil losses at Mashhad plain, northeast of Iran. Soil losses were estimated on a 100×100 m cell basis resolution by overlaying the five digital parameter layers (R, K, LS, C, P). To determine the critical soil loss regions at the plain, cell-based USLE parameters were multiplied by ArcGIS ver.9.3. The estimated annual soil losses values were subsequently grouped into five classes ranging from 0 to 0.25 t/h/year around the trough line of the plain at Kashafrud River to 2–10 t/ha/year at the hills and pediment plains. Our results indicated a good correlation between land units of hills and pediment plains with the values of soil losses at the study area (R2 00.72), also the statistical analysis exhibited a high correlation between land use/cover of dry farming and soil losses (R2 00.78). Keywords Erosion . GIS . USLE model . Soil losses . Mashhad plain

Introduction Soil loss is one of the most serious environmental problems as it removes soil rich in nutrients and increases natural level of sedimentation in the rivers and reservoirs, reducing their storage capacity as well as life span. The land degradation results from a combination of changes in land use, A. Bagherzadeh (*) Department of Agriculture, Mashhad Branch, Islamic Azad University, Mashhad, Iran e-mail: [email protected]

agricultural intensification, and intense rainstorms. In recent years, erosion is increasingly being recognized as a hazard. Erosion not only causes damage to cultivated soils, it also affects water quality and is responsible for sediment transport, causing many remote problems such as mud floods. To restore the productivity of the soil and to prevent further damage from taking place, planning, conservation, and management of treated lands are vital. Therefore, an attempt to assess the erosion hazard and prioritization of watersheds for treatment would aid in better planning to combat this menace (Pandey et al. 2007). The prioritization and formulation of proper land management programs for sustainable development require information on soil losses and sediment production. Due to the complexity of the variables involved in erosion, it becomes difficult to measure or predict the erosion in a precise manner. The geographic information system (GIS) technology has provided very useful method of surveying, identifying, classifying, and monitoring several forms of earth resources. GIS-based data provide accurate information on various aspects of lands such as soil, topography and land use/cover, etc. It also assists in identificatio