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abstract 317

Construction of a Water Management Support System for the Chekka Bay area (Lebanon)

Author(s): Michel Bakalowicz, Ahmad El-Hajj, Nathalie Dörfliger
Lanini and Dörfliger : BRGM, Water Department, Montpellier, France Bakalowicz and El-Hajj: CREEN-ESIB, Beirut, Lebanon

Keyword(s): Lebanon, Chekka, WEAP, water demand, water supply

Article:

Poster:

Session: Poster session 1

AbstractChekka karst submarine springs in Lebanon are

considered as the most productive ones in the Mediterranean Sea. This fresh water could represent an interesting

water resource in a region that has to face both water scarcity and an increasing demand. But their potential

exploitation is only an option among others to fill the current or future gap between water supply and demand. In

order to support Lebanese water authorities in their way toward sustainable water management of the Chekka Bay

area, tools and guidelines are being elaborated within the MEDITATE European project. The project has adopted

an integrated approach relying on a hydrogeological study of the submarine spring catchment, a social and

economical survey at a larger scale and the integration of all these information and knowledge in a numerical

model.
The study area covers 1200 km2 of the North Lebanon district. It includes three rivers (Abou Ali, Asfour

and Jawz) and their watershed. Jurassic and cenomanian limestones form the two main aquifers of the area. The

most important water consumption is for irrigation then for domestic use with a population of nearly 1 million persons

in the study area.
A model has been developed with the WEAP software to simulate the dynamical links of water

resource and water demand in this case study, and to explore the system behaviour according to different

management options and evolution scenarios. After calibration, the model was run for a reference year. Effective

rainfall is estimated to almost 500 million cubic meters/year on the three watersheds, and 750 million cubic

meters/year on the overall study area. It appears that almost 80% of this water are infiltrated. But this amount of

water input is clearly underestimated in the Abou Ali watershed as shown by the comparison of simulated and

observed river flowrates. The discrepancies can be explained both by the inaccuracy of available time series data

(especially an under-evaluation of snowy precipitations) and by the poor knowledge of aquifer recharge areas.

Actually, the hydrogeological catchment from which recharge should be calculated is probably much wider than the

topographic one used in the model. This water resource has to be compared to the total water demand estimated

around 215 million cubic meters in 2005, and which could increase up to 70 % by the year 2030 in a “business as

usual” scenario.
The significant contribution of the WEAP model to this study is that it can evaluate at the same

time water resource and water demand at a monthly time step. It will be shortly applied to simulate the different

scenarios of water management that were defined after two Water Vision Workshops that have been organised with

the local stakeholders. At the same time, a cost-effectiveness analysis (CEA) of different measures that could bring

new resources to the area or could allow decreasing or stabilising the water demand has been performed. The

combined results of the WEAP model and of the CEA will allow providing informed guidelines to Lebanese water

authorities.

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Construction of a Water Management Support System for the Chekka Bay area (Lebanon)