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Water footprint assessment of the Litani River Basin, Lebanon

Stokvis, Brian (2017) Water footprint assessment of the Litani River Basin, Lebanon.

Abstract:Water scarcity is a major global risk that is threatening food security of many countries in arid and semi-arid regions. To improve the performance on water use, the Food and Agriculture Organization (FAO) is working on a remote sensing tool (WaPOR) to monitor agricultural water productivity in three levels of continental, national and local scales. Part of the programme is to assess water productivity of selected irrigation schemes in Africa and Middle East. This study assessed the water productivity of major crops in the Upper Litani Basin (ULB) in Lebanon and will be modified and employed for the validation of Remote Sensing data in the WaPOR project. The ULB is the main river basin in Lebanon and hosts half of the agricultural lands. Previous studies in the ULB reported significant increases in groundwater abstraction resulting in decreasing surface flows over the last 50 years. The water footprint (WF) concept was followed to execute a water footprint assessment (WFA) of all internal processes in the ULB. This WFA consists of four phases which are described below. (1) Goal and scope: Goal: This study aims to assess the efficiency and sustainability of the green and blue water consumption in the ULB besides suggesting some adoptive scenarios and evaluating the improvements to formulate a water-sustainable scenario that achieve food security of the region. Scope: The daily green and blue WF of human processes inside the ULB including households, industries, trees and major crops were accounted from 2011 to 2016. The blue water scarcity was assessed in a monthly basis by comparing total blue WF and sustainable water availability. Three scenarios were formulated to improve the situation, taking into consideration the Sustainable Development Goals of the UN. (2) WF Accounting: The blue WF of crops was estimated using the AquaCrop-OS model which is able to simulate water use and yield of crops based on the environmental and management conditions. A list of 225 similar zones was derived from maps containing 10 major crop types, 4 soil types and 6 weather zones. Management settings in producing crops were based on literature and our own field surveys. The model was parameterized by adjusting sensitive parameters after comparing the simulated and observed yields. The blue WF of domestic, industries and trees were derived from previous studies. (3) Sustainability assessment: The sustainability of crop production was assessed from three perspectives including process, product and geographic perspective. Main findings from all perspectives were as follow: • Process: Drip irrigation and mulches were found water saving techniques compared to no mulching and sprinkler or surface irrigation practices. No optimal spatial zones were identified. • Product: Wheat, barley and potato had a high nutritional blue water productivity. Tobacco and favabeans represented a high economic blue water productivity. It means that relatively low amount of blue water can be used to produce kcals or US$ for these crops. • Geographic: Severe water scarcity happened to five months of the year, resulting in an overexploitation of 37 million m3 per year. (4) Response formulation: Three scenarios were formulated to improve water use performance • Scenario 1: Mulching for all crops • Scenario 2: Scenario 1 + drip irrigation for all summer crops • Scenario 3: Scenario 2 + relocation of crops Scenarios 1 and 2 had positive but limited effects on the water saving. These scenarios can reduce blue WF by respectively 16.9 and 22.4 percent per year. In scenario 3, a revised cropping pattern was suggested by focusing on high value crops and more efficient use of rainfall. Here, the blue WF savings was estimated 97 percent per year while nutritional and economic production had increased. Scenario 3 fulfilled the sustainable requirements and achieved the food security plan. Several assumptions had to be made because of limitation in local data. However, this is the most comprehensive study so far compared to available studies and reports to focus on the high-resolution assessment of WF of the ULB region underlying the variations during 6 years of the study and it was calibrated and validated using in-situ data in the ULB. This study introduces many opportunities for future researchers to improve and expand this approach in the whole Lebanon and in other countries
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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