Modeling of Indigenous Marab Water Harvesting Technique in the Jordanian Badia

<p>In drylands, agriculture is mainly rainfed due to the absence of water resources for irrigation. In such contexts, water harvesting interventions have been part of the knowledge and legacy of the local communities for centuries. In the Jordanian Badia, research centres like ICARDA (the International Centre for Agriculture Research in Dry Area) have tried to improve this knowledge and have developed several experiments to increase local communities&#8217; livelihood by introducing up-to-date water management practices.</p><p>This study focused on the modeling one of these interventions, the Marab Water Harvesting technology (WHT), a macro-catchment water harvesting system that gets flooded by the run-off of the upstream watershed, increasing the water infiltrated and stored in the soil. This water buffer enhances barley production, hence more fodder is available for the local livestock, allowing the communities to reduce the grazing pressure on their lands.</p><p>AquaCrop by FAO was used to simulate the crop cycle. The data needed to run the simulations were collected in fieldwork in the Jordanian Badia during the cropping season 2021/2022. Satellite images were also used to improve the calibration and validation process, together with yield data. Different scenarios were run to assess the performance of the Marab WHT, considering: comparison with the traditional cropping technique, flooding events reduction, different soil textures, and different climatic conditions.</p><p>The results of the simulations were: i) barley produced more in the Marab WHT (8.13 t/ha) rather than with the traditional cropping technique (between 0.00 - 1.00 t/ha; &#160;ii) silty soils were the most productive with 9.25 t/ha of biomass production, while the least productive had been the clay soils with 6.60 t/ha; iii) with a changing climate, the Marab WHT started to reduce its production by 4-8 % with a +0.5&#176;C temperature increase. In contrast, the reduction of precipitation didn&#8217;t impact significantly the crop, decreasing the yield by only 4 &#8211; 10%. In fact, the main cause of the high crop yield reduction was the timing and numbers of the flood events, causing barley failure if both the first and last flood events are removed. Without the first flood, the yield decreases by up to 80%, while removing the last flood event the reduction in biomass is 50%.</p><p>&#160;</p>