Restoring Degraded Rangeland Ecosystem In Jordan: Optimizing Mechanized Micro-Water Harvesting Using Rangeland Hydrology And Erosion Model (RHEM)

Abstract

Jordan’s rangelands, the so called Badia, home of the Bedouins, are threatened through a combination of over-exploitation of its ecosystem services and a changing climate towards drier seasons coupled with erratic rainfalls. In recent decades once fertile grazing lands transformed into sparsely vegetated and crusted dessert grounds unable to retain the sporadic rainfalls within the landscape and quickly draining the surface runoff inevitably connected with soil erosion and gully development. To counter-measure imminent land degradation the International Center for Agricultural Research in the Dry Areas (ICARDA) pushes mechanized micro-Water Harvesting (WH) based rangeland restoration using the Vallerani plow system, intermediately breaking up crusted soil layers and hard pans to approximately 50cm soil depth and creating dispersed micro-catchments – well protected and surface runoff accumulating pits suitable for the re-seedling of different shrubs, boosting their initial growth and root development, and leading to shrub island evolvement eventually spreading out over the landscape. However, optimum design – particularly the spacing between these micro-harvesting pits mechanically aligned – depend on various environmental conditions of the Badia. In this study, Rangeland Hydrology and Erosion Model (RHEM) was used to assess degraded rangeland hydrology – thus to transparently suggest on Vallerani WH layout tailored for the magnitudes and occurrence probabilities of the rainfalls, consequential soil erosion and sediment accumulation affecting the storage capacity of the WH pits. The study combined physical based process modeling and ground truthing through different runoff and sediment related experiments. Preliminary results demonstrate a great potential of RHEM-based assessment of surface runoff related WH design; according case study results will be first-time presented at the conference. Eventually, full-developed system might support a transparent implementation area selection and sound WH design interlinked with success and failure risks representing the highly variably environmental pattern of the Badia.