The topographic threshold of gully erosion and contributing factors

Maryam Zare,Masoud Nejabat,Hamid Reza Pourghasemi,Majid Soufi

doi:10.1007/s11069-022-05254-6

Abstract

The topographic threshold is based on the power relationship between area and slope and is widely applied in gully-erosion research; however, this relationship requires further testing. Accordingly, the Alamarvdasht Lamerd and Fadagh Larestan regions in Fars Province, Iran, were selected as case studies to explore the topographic threshold for gullies. Thirty active gullies were identified in each study area during field surveys, and data describing land use and land cover, drainage areas, slope, and the physical and chemical properties of the soils were assembled. Multivariate analysis was conducted using SPSS to determine the effects of these factors. Using the power relationship between the catchment area and slope for each gully, the analyses explored critical controls for gully development. The results showed that surface runoff was the most significant effective factor for gullies in the study areas. Sparse ground cover, fine-textured soils, and inappropriate land use contribute to gully development. The results suggest that the relationship between slope and drainage area in the Fadagh Larestan case study is S = 0.0192 A−0.159 for gully headcut areas and S = 0.0181 A−0.258 at gully outlets. The corresponding values of the exponent β at the gully headcuts and outlets at Fadagh were − 0.15, and −0.25, respectively. The corresponding relationships for gullies in the Alamarvdasht Lamerd area for the gully headcuts and outlets were S = 0.0143 A− 0.061 and S = 0.0073 A−0. 18, respectively, with β values of − 0.06 and − 0.18. This study provides a basis for determining the thresholds for initiating gully development. Analyses of the effective factors provide clues to improve the management of bare lands to prevent the initiation of gully erosion.

Highlights

Soil erosion remains a major problem in many regions of the world, and in many cases, the dominant source of sediment is gullies
This study determined that the power of the topographic threshold in the two study areas in Iran is negative, which indicates the dominant role of runoff in the formation of gullies
Topographic form properties exerted the strongest control on the topographic threshold for gullies in the study areas, followed by chemical and physical soil characteristics

Summary

Introduction

Soil erosion remains a major problem in many regions of the world, and in many cases, the dominant source of sediment is gullies. Erosion is one of the most productive drivers of runoff and sediment delivery from upland areas to valley floors and permanent channels, where the consequences of erosion are manifest. Initiation and development is a natural process that greatly impacts natural resources, agriculture, and environmental quality by degrading land and water, disrupting ecosystems, and enhancing hazards (Gayen et al, 2019). A common way to quantify the susceptibility of a landscape to a gully incision is to use topographical thresholds associated with specific land uses. The impacts of land management on these thresholds in agricultural settings have not been studied, land management may significantly affect the rates of runoff and erosion (Monsieurs et al, 2016)

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Conclusion