Exploring the Potential of Treated Wastewater Reuse for Irrigation in the Beqaa under Current and Future Climate Scenarios

Abstract

The water resources in Lebanon are facing severe pressure due to the increase in the population, with the accompanying climatic changes that have exacerbated the water shortage problem. This study investigates the potential of treated wastewater reuse (TWWR) to supplement irrigation water needs to close the gap between supply and demand for crop production under climate change scenarios in the Beqaa Valley. A framework for the economic assessment of the (TWWR) for irrigation was provided as a solution for water shortages in the Beqaa. The Ablah region and its wastewater treatment plant (WWTP) in the Beqaa were identified as a case study because they have an operational and an irrigation network for local farmers that supplies TWW to their land. After calculating the water requirements of the Ablah crops under the business-as-usual conditions and under the two climate change scenarios, the results showed that continuing with the current scenario will lead to an increase in the water deficit in future years. As a solution, the study suggested an improved agricultural scenario (IAS) to reduce groundwater withdrawals and increase crop yields by increasing the proportion of TWW in the water balance and reallocating the land to different types of crops that are more suitable for the specific regional conditions. The results revealed that the (IAS) increased the TWW contribution to 28% instead of 12% in currunt scenario of irrigation water, compared to reducing the pressure the groundwater contribution to 72%. Also, IAS reduces the deficit in both climate scenarios, as SC.1 will remain positive after facing a deficit, while the deficit in SC.2 is reduced by 70%. Additionally, an economic assessment of the costs associated with (TWWR) to replace groundwater, including energy costs and crop yield profits, was conducted. The cost estimate showed that replacing some groundwater with TWW for irrigation is less expensive than full irrigation with groundwater, at prices of $0.18 and $0.48, respectively. Using TWW gave the farmer economic feasibility for supplementary wheat and grapes irrigation. In comparison, supplementary irrigation of wheat with groundwater was not economically feasible, and the study recommended that wheat remain rainfed. Therefore, the price of TWW can be considered the most important factor that affects users’ willingness to use TWW. Most significant TWWR is an opportunity that must be exploited and developed to meet the demand for water and address the water shortage in Beqaa. The framework of this study can be an important tool in facilitating the use of TWW and helping decision-makers and farmers manage and plan further.