Watershed Resilience - Soil and Water Management in Arid Regions to Prevent Desertification

Abstract

 Jordan faces a critical challenge of land degradation and water scarcity, primarily affecting the extensive natural rangeland (Badia), which covers over 80% of the country's area. The degradation of natural vegetation, adversely affects local agropastoral communities that are depending on livestock farming and triggeing downstream issues such as flash floods and sedimentation in dams. Water harvesting and increasing vegetation cover are promising technologies to adapt and reduce the impact.   The Badia Research Site (BRS), a confined watershed of approximately 1000 hectares, rainwater harvesting (RWH) and plantation techniques have shown promise in reducing soil erosion and runoff rates and enhancing various ecosystem services. The BRS research is mainly led by the International Center for Agricultural Research in the Dry Areas (ICARDA) and the Jordan National Agriculture Research Center (NARC), supported by the United States Forestry Service (USFS).   This study involves (1) scaling out two RWH techniques, namely the Vallerani and the Marab, on a larger basin. The scaling out utilises local and international datasets, incorporating biophysical parameters such as land use, digital elevation models, slope, topographic wetness index, soil texture, and climate data. Optimal ecological conditions for plants, including temperature and soil pH, are considered. (2) The Soil and Water Assessment Tool (SWAT) is employed to analyse and assess the impact on surface hydrological processes.   The focus is on the Wadi Al Mujib basin, covering 6584.37 km2 in the central part of Jordan. The semi-arid to arid environment comprises two principal wadies, Wadi Al Walah and Wadi Mujib, with distinct catchment surfaces. The basin's predominantly desert land, receiving varying levels of rainfall, poses challenges to 80% of its area, while the remaining 20% is dedicated to agricultural and residential use.   The study further employs the model to evaluate global climate change scenarios, assessing the impact and quantifying changes in ecosystem services with and without restoration efforts. These findings contribute to supporting the Jordanian government's restoration endeavours, offering a holistic approach to addressing land degradation and water scarcity challenges in the region.   Keywords: Watershed assessment, Degraded land restoration, Suitability mapping, Water harvesting techniques, Sustainable land management, and Ecosystem Services