Evidences of climate mitigation from Landscape Restoration and Water Harvesting: A Remote Sensing Approach

When changes are made in a landscape, changes are made to the microclimate. When farmers plant trees in or around their field, and when communities dig bunds to improve water retention, they change the local climate around them. In the current global climate debate, adaptation and mitigation are dominant concepts, while no attention has been paid to local solutions that can enhance local climatic resilience of landscapes. In arid to semi-arid areas of the world, measures such as Landscape Restoration and Water Harvesting (LRWH) are implemented to revert land degradation and increase soil moisture, reducing runoff losses. The present work aims to analyse to what extent storing soil moisture, with adequate land and water management practices, can reduce temperatures in the hot months after the rainy season, as a consequence of Soil Moisture-Temperature Coupling. Since it is demonstrated how soil moisture deficit can enhance heatwaves in diverse regions of the world, it is hypothesized that increasing soil moisture availability, during the dry and hot periods, can mitigate hot temperatures. The analysis has been carried out for Enabered catchment, in Tigray Region, Ethiopia, where the rainy season runs from June to August. Here, large scale LRWH implementation ended in 2008. An analysis based on remote sensing data has been carried out to evaluate (1) to what extent LRWH implementation can enhance soil moisture conservation at catchment scale; (2) to what extent LRWH implementation can mitigate temperatures in the dry season at catchment scale; and (3) if SMTC were evident. Results showed an increased capacity of the catchment to retain soil moisture produced in the rainy season until September (P < 0.01) and October (P < 0.1) and reduced temperatures for September (P < 0.1), October (P < 0.01) and November (P < 0.05), with decreases of Land Surface Temperatures up to 1.74 °C. A simple, parsimonious linear regression model demonstrated that SMTC is evident at catchment scale and that the implementation of LRWH measures provided a climate mitigation effect in the watershed. The present work can reinforce the call for an increased adoption of water harvesting, land restoration and green water management, to increase the resilience of agricultural ecosystem located in arid and semi-arid areas, that represent a key element to achieve global food security.