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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 December 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.

This research project aimed to estimate real evapotranspiration and recharge on karst aquifers and validate it using numerical simulation using physical data, with experimental sites set up in Lebanon for water quantity and quality monitoring and used as pilot areas for further studies.   This study set the ground for delineating recharge areas and identifying zones of high vulnerability to contamination, and consequently, enabling establishment of adequate measures for water protection and management.  
3-26 Doummar_ Flow measurement in a river during sampling for micropollutants
Flow measurement in a river during sampling for micro-pollutants

3-26 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 accomplished activities

The objective of the project has been to set up two pilot areas and conduct a high-resolution long term monitoring for research and water supply purposes.  The data collected over the four years throughout the project on two pilot areas was used to simulate flow in an integrated numerical distributed and semi- distributed models and to understand flow mechanisms in the system and predict future flow at the spring under varying climatic scenarios. The final objective has been to conduct detailed sensitivity analysis on key-vulnerability parameters and refine the weights attributed to them in qualitative vulnerability mapping methods.

Educational impacts

The PEER project provided the opportunity to set up a hydrogeological division at AUB and students benefited greatly from this experience. Students who have graduated while being involved in this project have succeeded in landing jobs in engineering or hydrological studies firms.  Applied materials from two courses GEOL318, and GEOL330K (hydrogeology and Hydrology of fractured and karst rocks) taught in several semesters at AUB were based on this research project. The applications included in a new graduate course (Applied methods in hydrogeology: GEOL 330I) were mainly related to the pilot sites of this project as well.

3-26 Doummar Geology invitation

Potential development impacts

In terms of potential development impacts, the developed integrated hydrological model could be presented to decision makers as a tool to forecast needs for alternative water supply resources for the future, in the face of climate change conditions and increasing urbanization. The project also correlates between wastewater indicators and easily monitored parameters at the spring to allow public entities responsible for water supply and water quality to predict arrival of water at the spring under transient conditions. This could count as a first step to initiate a platform for early warning system and the understanding of data collected at the spring. At the conclusion of the project, the team will share the results with the appropriate end-users and stakeholders to increase their awareness in these topics.  The ultimate intent is to translate the assessment of quantitative vulnerability into guidelines for groundwater protection on catchment areas.  Connections have been established with government agencies  such as water establishments and Water authorities, and data collected was has been so far provided at  monthly intervals to the water supply establishment.

To ensure implementation of this project and its continuity, during the last months of the project, the PEER team: (1) Finalized and validated vulnerability assessment;  (2) collected and processed data from the monitoring network,, as well updated the models with new data; (3) Refined catchment characterization, especially the parameters playing a role in model output and vulnerability. (4) in efforts to establish a link between science and policy;  used the results of the vulnerability study to tailor guidelines for groundwater catchment protection in karst system for Lebanon. (5)  dissemination workshop upon complete finalization of data results was  conducted with municipalities of Bikfaya and Kfarzebbiane and water establishment stakeholders to increase awareness in terms of water quality and quantities.  

Peer reviewed publications in international journals

  • Doummar J. Kassem A., Gurdak J., 2018 Impact of historic and future climate on spring recharge and discharge based on an integrated numerical modelling approach: Application on a snow-governed semi-arid karst catchment area.) 
  • Doummar, J., and Aoun, M. 2018. Assessment of the origin and transport of four selected emerging micropollutants sucralose, Acesulfame-K, gemfibrozil, and iohexol in a karst spring during a multi-event spring response Journal of contaminant hydrology. 
  • Doummar, J., and Aoun, M. 2018. Occurrence of selected domestic and hospital emerging micropollutants on a rural surface water basin linked to a groundwater karst catchment. Journal of Environmental Sciences. pp. 77: 351. h7ttps://
  • Doummar J. Kassem A., and Gurdak, J. Quantitative assessment of the Key-Parameters of vulnerability in karst systems based on a numerical integrated hydrogeological model.  
  • Dubois E, Doummar J., Pistre S, Larocque M. Calibration of a semi-distributed lumped model of a karst system using time series data analysis: the example of the Qachqouch karst spring (Lebanon)
  • Dubois E,  Doummar J.,  Pistre S,  Larocque M, 2020. Calibration of a lumped karst system model and application to the Qachqouch karst spring (Lebanon) under climate change conditions