Impacts of infiltration trenches on hydrological ecosystem services : a systematic review.

Abstract:

• There is a growing concern about interventions on natural infrastructure to deal with climate change impacts and water security. These interventions include forestation, terraces, small reservoirs and infiltration trenches, among others. Infiltration trenches are shallow trenches dig along contour line with soil accumulation above or below the trench. In mountainous region, such as the Peruvian Andes, the infiltration trenches have been promoted as a way to reduce soil erosion and surface runoff. However, the promotion of these trenches often lacked evidence about their expected results.
• It is important to consider sound knowledge available about the operation and maintenance of the trenches to maximize the hydrological services and reduce its negative impacts. As far as we know, there is no synthesis of the hydrological impacts of infiltration trenches. Therefore this study proposes to synthetize the available evidence of the impacts of infiltration trenches across mountainous regions of the world with systematic review and meta-analysis methods.
• 57 studies (80 different sites) from 12 countries have been synthetized. Most of the studies were at the plot level and a few studies have been carried at the watershed level (streamflow measured).
• There were not enough studies available to conclude whether infiltration trenches increased soil infiltration or not. However, infiltration trenches significantly reduced surface runoff and soil (laminar) erosion.
• To conserve and restore natural land cover may provide higher hydrological benefits than infiltration trenches with less disturbance for the ecosystems and lower long-term maintenance cost.