『Abstract
　This research was conducted in the Afzar sub-catchment area of Ghara-Aghaj River, a semi-arid region in SW Iran, using a Geographic Information System (GIS) to compare the Erosion Potential Method (EPM) and Pacific Southwest Inter agency Committee (PSIAC) models in erosion-potential mapping and sediment-yield assessment. Data layers used in this study were generated from topographic maps, Landsat ETM⁺ imagery, aerial photographs, field surveys and barometric and pluviometric data; factor-class evaluation was used to determine EPM and PSIAC parameters. A raster-based Geographic Information System (GIS) was applied to generate the erosion-severity and sediment-yield maps. Output data was verified by field observation and by comparison with a Global Assessment of Soil Degradation (GLASOD) map. Comparison of the EPM and PSIAC results with field observations and the GLASOD map showed that although the results of the two erosion potential maps correspond in most areas, the results of EPM model were not as reliable as the PSIAC in identifying areas with very high erosion potential. It is suggested the EPM model should be used for rapid mapping of erosion-potential in regions with limited data layers, but field verifications indicated that PSIAC results were the more reliable.

Keywords: Iran; Arid region; GLASOD map; Potential mapping; Ghara-Aghaj river』

1. Introduction
2. Study area
3. Spatial data generation
　3.1. Surface geology and soil type
　3.2. Slope
　3.3. Land use and land cover
　3.4. Erosion processes
　3.5. Climate
　3.6. Channel erosion
　3.7. Runoff
4. EPM and PSIAC models
5. Results and discussion
6. Conclusions
Acknowledgements
References