Mesoclimate regulation induced by landscape restoration and water harvesting in agroecosystems of the horn of Africa

When changes are made in a landscape, these changes may impact on the local climate. In arid and semi-arid agroecosystems, measures such as Landscape Restoration and Water Harvesting (LRWH) are implemented in order to revert land degradation and increase agricultural yields, by means of reducing runoff losses and increasing soil moisture. The present work analyses to what extent storing soil moisture, with adequate land and water management practices, can reduce temperatures in the hot months after the rainy season in a semi-arid climate. Since it is reported that Soil Moisture (SM) deficit can enhance heatwaves in diverse regions of the world because of Soil Moisture-Temperature Coupling (SMTC), it is hypothesized that increasing soil water availability, during the dry and hot periods, can mitigate hot temperatures. The analysis was carried for Enabered catchment, in Tigray Region, Ethiopia, where the rainy season runs from June to September. Here, large scale LRWH implementation ended in 2008. Using remote sensing data, the present study evaluates (1) to what extent LRWH implementation can enhance SM conservation at agroecosystem scale; (2) to what extent LRWH implementation can mitigate temperatures in the dry season at agroecosystem scale; and (3) the evidence of SMTC effects. Results show an increased capacity of the catchment to maintain SM accumulated in the rainy season and consequent reduced temperatures. Increase of SM was especially significant for September (P < 0.01), while temperature decrease was evident in October (P < 0.01) and November (P < 0.05), with decreases of Land Surface Temperatures (LST) up to 1.74 °C A simple, parsimonious linear regression model demonstrates that SMTC is evident at catchment scale and that the implementation of LRWH measures provides a climate regulation effect in the watershed. The present work can reinforce the call for an increased adoption of water harvesting, land restoration and green water management, in order to increase the resilience of agricultural ecosystem and food security in arid and semi-arid areas.