Factors Controlling the Morphology and Volume - Length Relations of Ephemeral Gullies in the Western Arid Regions of Iran

Understanding the development of gully volumes requires the empirical relations between gully volume (V) and length (L) to be established in the field. So far, such V–L relations have been proposed for a limited number of gullies/environments and were especially developed for ephemeral gullies.In this study, V–L relations were established for ephemeral gullies in southern Ilam. In order to take the regional variability in environmental characteristics into account, controlling factors of gully cross-sectional morphology were studied for 90 cross-sections. The results indicated that the soil properties were the most important controls of gully cross-sectional shape and size. Cross-sectional size could be fairly well predicted by their drainage area. The V–L relationship for the complete dataset was V=15.45 L 0.12 (n = 90, R2=0.06). In addition, gully volume was also related to its catchments area (A) and catchment slope gradient (Sc). This study demonstrated that the V–L and V–A×Sc relations were not suitable to assess ephemeral gully volume.