# Spatial hotspot analysis of soil erosion rate and classification of homogeneous zones using GIS in a mountainous contrasting land-use watershed

## TL;DR

This study uses GIS to analyze soil erosion in a mountainous watershed in Iran, identifying hotspots and suggesting targeted land management strategies.

## Contribution

The study introduces a spatial hotspot analysis approach for classifying erosion-prone zones in a contrasting land-use watershed.

## Key findings

- Over 65% of the watershed has moderate to very high erosion rates, averaging 7-ton ha⁻¹ year⁻¹.
- High erosion hotspots (HH clusters) are located in the southwest, while low erosion coldspots (LL clusters) are in the north and northeast.
- Erosion is most severe in areas with heavy rainfall, steep slopes, fine soils, and sparse vegetation.

## Abstract

Soil erosion poses a significant challenge to environmental sustainability, especially in regions with varying land-use patterns and topography. Soil erosion is a major environmental threat affecting soil quality, reservoir sedimentation, agricultural land, and watershed hydrology. This study aims to identify and classify homogeneous sub-watersheds in a mountainous watershed in Iran using GIS. Forty years of climate data, a high-resolution DEM, land-use maps, soil texture, and NDVI were applied to derive the main factors, while the P factor was determined based on slope classes and land-use types. The RUSLE results showed that annual soil erosion in the watershed had an average of about 7-ton ha⁻¹ year⁻¹, with more than 65% of the watershed area falling into the moderate to very high erosion classes. Average key factors were R = 78.08 MJ·mm/ha·hr·year, K = 0.28 t·ha·h/MJ·mm·ha, LS = 1.62, and C = 0.39. The highest erosion occurred in areas with heavy rainfall, steep and long slopes, fine-textured soils, and sparse vegetation. Spatial autocorrelation analysis using Moran’s I and the Getis–Ord Gi* statistic showed a clustered spatial pattern of erosion. High–high (HH) clusters, indicating severe erosion hotspots, were found in the southwest, while low–low (LL) clusters, representing minimal erosion coldspots, occurred in the north and northeast. These results support sub-watershed prioritization and indicate the need for targeted erosion control in high-rate zones. These results contribute to the development of more targeted and sustainable land management practices to mitigate soil erosion rates and improve watershed conservation efforts.