|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
U.S. Partner: Jason G. Gurdak, San Francisco State University
Project Dates: September 2014 to February 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.
|Flow measurement in a river during sampling for micro-pollutants||Installation of a multi parameter probe in a spring|
Summary of Recent Activities:
| || Tracer injection in a river to detect exchange between river and spring|
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 research team continues monthly collection, correction, and analysis of data each month and performed further sensitivity analysis on their numerical model. They also carried out a variety of field work, including a tracer experiment during the snow melt event on one of the pilot areas (March 2017), a tracer experiment in the river to validate the connection between the river and the major spring in one catchment area (Qachqouch Spring, February 2017), and a sampling campaign for micro-pollutants in the river to assess the transport of pollutants between surface and groundwater (Qachqouch Spring, March 2017).
Outreach and collaboration activities
have been ongoing:
1) The municipalities and public stakeholders are being informed about the study; data is being shared with the Water Establishment for water supply purposes.
2) Preparation of a local association (Lebanese Association of Underground Space) as a platform to start the local Chapter of Hydrogeologists (IAH);
3) Nominated a member of the Karst Commission (http://karst.iah.org/)
4) Preparation of a potential PhD topic to be co-advised in collaboration with the Karst Institute in Slovenia.
Potential developmental impacts: The project aims at developing a vulnerability method based on a numerical model, which is almost complete. Based on a robust sensitivity analysis, a weighing for parameters influencing recharge will allow to refine key vulnerability parameters. On a smaller scale, the project unraveled a connection between a highly polluted river and the Qachqouch spring. The delineation of the exact locations of point source river water infiltration will allow to mitigate groundwater contamination and outline its main sources and type. The model also aims at identifying potential impacts of climate change on the quantity of water available at the spring. This can only be achieved after the model is fully calibrated.
The municipalities and public stakeholders are being informed about the study; data is being shared with the Water Establishment for water supply purposes. The data collected by the project are submitted to the main governmental stakeholder to detect any potential impact that large scale pumping might incur on the studied catchment. This work might yield 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.
Future plans: (1) Ongoing fieldwork and modeling and submission of manuscripts by the end of January 2018; (2) Dissemination of results through a workshop (one dedicated day for hydro-geology in Lebanon) where graduate students and other researchers present recent research in this field- March 2018; (3) Creation of the International Association of Hydro-geologists Chapter in Lebanon
Manuscripts and conferences:
1) Doummar J. and Aoun M. 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. (Manuscript uploaded and scheduled for submission to Journal of contaminant hydrology on October 17th 2017.
2) Doummar J. Kassem A., Gurdak J., Prediction of future spring discharge under various scenarios of climate change using an integrated spatially distributed numerical model of a mountainous karst spring in Lebanon (MIKE-she) (In preparation, to be submitted mid November 2017 to Hydrogeology Journal or Environmental Earth Sciences).
3) Doummar J. Aoun M., Occurrence and detection frequency of selected micro-pollutants in groundwater and surface water on a rural semi-arid catchment area. (In preparation, to be submitted end of October to Environmental Earth Sciences)
4) Doummar J. Kassem A., Quantitative assessment of the Key-Parameters of vulnerability in karst systems based on a numerical integrated hydrogeological model. (In preparation, to be submitted end of November 2017 to hydrogeology Journal).
5) Doummar J. Kassem A., Gurdak J., Prediction of future spring discharge under various scenarios of climate change using an integrated spatially distributed numerical model of a mountainous karst spring in Lebanon (MIKE-she) to be presented at the American Geophysical Union Conference (AGU 2017) December 11-15 2017, New Orleans, USA.
| Extraction of data from a climatic station|| Snowmelt monitoring with tracer injection [Photos courtesy of Dr. Doummar]||Injection of a red dye in a snow to monitor snowmelt|| |
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