Conceptualization of flow in a snow-governed groundwater catchment in Lebanon: A science- based approach for future guidelines for sustainable water management.
Project by UNICEF in collaboration with University Saint Joseph (USJ)
Objectives and work plan
The main objective of the proposed study lies in the conceptualization of flow in a complex karst catchment feeding two major springs (a yearly discharge of 30 Mm3) governed mainly by snowmelt. In order to achieve this goal, the proposed methodology aims at first at the delineation of the zone of contribution i.e., the catchment area of two springs: Laban and Assal spring by conducting two tracer experiments in dolines. The tracer will be monitored at both springs to highlight a hydrogeological connection with the injection point, to estimate transport velocities and other transport characteristics highly reflective of the dynamics in the aquifer. In parallel, a pressure transducer will be installed at the Laban spring (currently lacking measurements) to measure water level at intervals of 30 min (to be calibrated with discharge) to obtain a high resolution monitoring of the flow rate at the spring. Assal spring is monitored since 2014 through an AUB- USAID funded project, thus data is collected continuously. Intensive field work is planned for monthly data collection, tracer experiments implementation and monitoring, as well as geological mapping and identification of existing dolines over an area of at least 25 km2. In a second phase, the collected data over the first 6 months will be analyzed and processed using two different approaches: 1) a correlative analysis between the input (provided by a team from USJ about the snow cover and equivalent water) and the spring flow rate variation. Additionally, a preliminary water balance can be estimated after a collection of data over 10 months (including the already available data from previous ongoing projects). This study highlights the importance of the conceptualization of hydrological systems and high resolution monitoring of a pilot area before any intervention measure regarding water quality and quantity and associated policies can be drafted. The study provides the evidence for 1) the zone of contribution to the springs, which highly influences risks for contamination or aquifer vulnerability, 2) the expected flowrates and a continuous measurement of future volumes of water for supply, 3) the influence of climatic parameters on the water volumes, and finally 4) insights into the impact of anticipated climate change in terms of increase of temperature and decrease of precipitation (translated indirectly into an increase of the recession period at the spring).
Two public dissemination half-day events will be planned to launch the project to stakeholders and disseminate final and progress results at the end of the project. These two participatory events help increase the awareness of stakeholders about groundwater issues and management.