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Partnerships for enhanced engagement in research (PEER) SCIENCE
Cycle 3 (2014 Deadline)

Assessment of real evapotranspiration and recharge processes on two karst pilot groundwater catchments (Lebanon) using an integrated spatially distributed numerical model: applications for water resources management purposes

PI:  Joanna Doummar (, American University of Beirut
U.S. Partner: Jason G. Gurdak, San Francisco State University
Project Dates: September 2014 to September 2018

About 25% of the freshwater worldwide originate from karst aquifers. These aquifers are a source of a very important supply, but are also highly heterogeneous. They are characterized by a duality of recharge and flow which directly influences the groundwater flow and spring responses. Given this heterogeneity in flow and infiltration, karst aquifers are very difficult to conceptualize, as they do not always obey standard hydraulic laws. Estimates of real evapotranspiration and recharge to aquifers are needed in the computation of the water balance of an aquifer catchment area. Karst aquifers are the predominant type of aquifer in Lebanon, and an accurate estimation of input parameters (recharge, real evapotranspiration) in catchment areas is not available for the appropriate assessment of groundwater resources at a national level. To date, only a few groundwater-distributed/lumped numerical models have been done on selected catchments in Lebanon due to the scarcity of data and the difficulty in simulating highly heterogeneous karst aquifers.

The objective of this research project is to estimate real evapotranspiration and recharge on karst aquifers and validate it using numerical simulation using physical data. The project will help set up experimental sites in Lebanon for water quantity and quality monitoring that can be used as pilot areas for further studies. The correct estimation of the water balance and its seasonal variation allows indirectly understanding aquifer systems in Lebanon. Once validated, the results of the investigations can be extrapolated  in different catchment areas in the country at a later stage. This study sets the ground for delineating recharge areas and identifying zones of high vulnerability to contamination, and consequently, enables establishing adequate measures for water protection and management. Finally, predictions concerning water availability for the future will be better assessed through a well-distributed numerical conceptual model given the climate change scenarios for the area and the increase in water consumption.
3-26 Doummar_ Flow measurement in a river during sampling for micropollutants3-26 Doummar_ Installation of a multi parameter probe in a spring.jpeg
Flow measurement in a river during sampling for micro-pollutantsInstallation of a multi parameter probe in a spring

3-26 Doummar_ Tracer injection in a river to detect exchange between river3-26 Doummar_ Tracer injection in a river to detect exchange between river and s
  Tracer injection in a river to detect exchange between river and spring
Summary of Recent Activities:
Year 3 of the project has been dedicated to completion (calibration and validation) of the numerical models while refining field parameters for the conceptual model and development of a vulnerability method based on the numerical model. During the past year the team has been conducting fieldwork, data analysis, numerical modeling, participation in conferences and dissemination of results, work on manuscripts.

Impacts and successful results: (1) The set up of a monitoring network on two pilot catchment areas for the collection of high resolution data for the characterization of spring flow and input data on the two pilot areas has been completed. Collection of data will continue to establish a long-term series of records for further validation

(2) Collection of data and extensive field work for the catchment characterization has been completed. Further small scale mapping will be undertaken in certain areas to validate catchment delineation including one tracer test on the Qachqouch catchment which entails: (a) monthly collection of data from the installed equipment and annual maintenance of probes/cleaning of sensors; (b) tracer experiments.

The months of January-March 2018 were dedicated mostly to the preparation and finalization of pending manuscripts
for submission to international journals in addition to ongoing data collection and analysis.
Outreach and collaboration activities have been ongoing. The municipalities and public stakeholders are being informed about the study; data is being shared with
the Water Establishment for water supply purposes.
Potential developmental impacts:  The municipalities and public stakeholders are being informed about the study; data is being shared with the Water Establishment for water supply purposes. Upon completion of the objectives of this project, results will be shared with main stakeholders to initiate the development of guidelines for protection zones on karst catchment in Lebanon based on a quantitative approach. Contacts will be made with policy makers once the scientific aspect of the project is complete to look into this alternative from a policy enforcement angle.

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