Prioritising interventions for the reduction of erosion in classical gullies: a modelling study

Context

Gully erosion is a significant socioeconomic and environmental issue that affects agricultural productivity, infrastructure, and water quality of receiving waters. Despite a variety of interventions to prevent gully formation and rehabilitate existing gullies, cost-effective interventions are specific to individual gullies.

Aims

The aim of this study was to assess the performance of a suite of gully management interventions across three different classical gullies.

Methods

A one-dimensional process-based model, MERGE (modelling erosion resistance for gully erosion), was used to quantify the sediment yield exiting the gullies, in response to various management interventions.

Key results

The net decrease in sediment yield was 2.5–57.4% for each of four interventions applied in isolation and 51.2–78.7% in combination. Reductions in sediment yield for each intervention varied markedly among sites, by a factor of 2.6–78.3 in absolute terms. This resulted in a unique ranking of the interventions by their effectiveness for a given site. Overall, interventions applied in combination were most effective, outperforming those applied in isolation by a factor of 1.24–1.37, but the effect of applying interventions in combination was not additive.

Conclusions

This study demonstrates the ability of the gully erosion model MERGE to be a useful tool to identify and tailor effective intervention strategies for individual gullies, and be a useful guide for decision making for erosion management.

Implications

Analysis of expected benefits of gully remediation using tools such as MERGE is important for assessing options at gully sites due to their widely varying response.