Ecosystem services provision by gully control. A review

Gully erosion causes severe damage to crops and infrastructures and affects the provision of ecosystem services worldwide. To assess the potential of gully control measures to protect ecosystem services and assess the conditions required for their large-scale implementation, this paper critically evaluates a range of gully control measures documented in the World Overview of Conservation Approaches and Technologies (WOCAT). Environmental and socio-economic impacts of technologies are assessed, as well as the implications for ecosystem services, costs and benefits of implementation, and stakeholder’s perception. It is demonstrated how gully control measures provide notable on-site and off-site benefits for socio-economic, cultural, ecological, and production goals, and to protect crucial ecosystem services. Control measures particularly contribute to soil and water conservation and to regulating ecosystem services by controlling soil erosion, water cycling, and natural hazards. Most effective control measures consist of combined vegetative and structural measures and of catchment wide interventions. While implementation of gully control can initially be expensive, on the long term, the cost-benefit ratio is usually positive. Moreover, the results emphasize the importance of evaluating control measures considering monetary aspects and all ecosystem services they provide. Nevertheless, individual farmers can often not afford the implementation and maintenance costs due to barriers for implementation and therefore require sustained institutional support.

Gully Morphology and Rehabilitation Measures in Different Agroecological Environments of Northwestern Ethiopia

Gully erosion is a serious threat to the society and environment of the study, primarily caused by surface runoff and dramatically accelerated due to rugged topography and human induced factors. Intensive measurements of gully characteristics were undertaken to investigate the morphologies of gully, while aiming for sustainable gully rehabilitation; therefore, a total of 63 gully samples from three different agroecologies were randomly observed. The morphological variability of measured gullies was evaluated and the resulting CVs had been between 0.27 and 0.39 except for gully length, which had highest variability (CV = 1.10). The highest gully length (2,400 m) and highest lower width (6 m) were observed on Dembia district, which might be due to the loose and pulverized condition of the soil. The correlation matrices for many parameters of gully morphology in different districts of Semien Gondar showed several sets of significant relationships. Some of the assessed gullies showed that appropriate physical gully control structures integrated with vegetative measures have resulted in a significant reduction of soil loss and stabilized the gully from further enlargement. There could be various justifications for the success of these structures; however, the most important measures were vegetative management and exclusion of cattle.