Unraveling the Spatial Signature of Gully Erosion in the Arid and Semi-Arid Regions of the Northeast of Iran: Every Single Factor Matters!

The present study is aimed to model the spatial pattern of gully distribution across the silt-rich soils of the northeastern loess of Golestan province, Iran. To this end, multiple data-involvement scenarios were designed, and their further contributions to the performance of a presence-only probabilistic model (Maximum Entropy) were assessed. The results revealed that the interconnection of topological and hydrological factors mainly corresponds to the spatial signature of gully distributions across the study area. In particular, valley depth, height above the nearest drainage, and drainage networks contributed the most to the model's performance. Based on the area under the receiver operating characteristic curve (AUROC) index, engaging factors collectively result in the highest goodness-of-fit and prediction power with the respective values of 0.889 and 0.867. The areal extent of the susceptibility classes indicates that approximately 15% (~ 121 km 2 ) of the region is highly susceptible to gully occurrence, which entails further pragmatic actions and mitigation measures.