Investigation on morpho - climatic characteristics of gullies in order to classify gully affected regions in Zanjan province Iran.

In this research at first، gully erosion sites were studied in Zanjan province and their boundary drawn. Climates map by modified Demarton''s method prepared and two gullied regions with more than 500 ha area were selected from each climate. In each region one representative gully & 2 replications were chosen for measuring physical and morpho_metetric characteristics، gully initiation and development causes، land use & soil sampling region. Results revealed that there are 57 gully affected regions (552. 7 km2) and 9 climates by modified Demarton''s method in Zanjan province. Gullies are distributed in three of climates such as cold semi- arid، very cold semi- arid and moderate semi- arid climates. Cold semi- arid climate contains most of gullies (64. 91%) in Zanjan province. Gullies have clay، clay loam and loam clay soil texture dominantly and are lateral and formed along drainage ways. Most of the gullies are located on hills and some on plains. The view plan of gullies is dendritic and linear. The headcuts of gullies are digitated and pointed and the vertical plans of headcuts are generally vertical and inclined. Their cross section are V and U shaped. In viewpoint of their depth، they are in the intermediate class (1-10m). Dominant causes of gully formation include degradation of vegetation cover، land use change، soil erodibility and improper irrigation management. The gullies damages to rangelands، cultivate lands and roads and total damages were estimated about 2226. 9 billion Rials in Zanjan province.