Modelling

Groundwater and Solute Transport
in the Beka’a

As part of a joint German-Arab technical cooperation between BGR, ACSAD and NCRS, a groundwater model was prepared for the shallow aquifer in the Zahle area (Beka'a Valley, Lebanon) in close cooperation with Arab scientists. The pilot area is a typical example for a region where intensive farming and urban activities put increasing pressure on the environment.

A data collection campaign supplemented an existing data base for the Beka’a Valley that had been established in a previous project phase. The field campaign for the initial setup of the model ran from spring to autumn 2002 and involved the monitoring of hydraulic heads and certain parameters of water quality. Monitoring has been continued up to date on a monthly basis.

Model construction is based on the GMS 3.1 software (Groundwater modelling system - a groundwater model developed by the U.S Department of Defence). Model development involved the reconstruction of aquifer geology as well as the derivation of boundary and initial conditions - a task during which local expertise on geology and groundwater in the Beka’a was combined with modelling expertise from the German side.

After modelling water transport, the working group focussed on the leaching of pollutants from three waste dumps in the pilot area. A prognosis of contaminant leaching from these dumps to the aquifer up to the year 2010 was calculated and the contaminant plumes emitted from the waste dumps were visualized in 3D using GMS tools.

Preliminary Model Results results indicate

• areas particularly affected by pollution from the waste dumps, i.e. where a threat to farming activities and other forms of land use are likely to occur.

• Better suitable locations for waste dumps.

A brief evaluation of the results with regard to decision making and land-use planning has been made so far. Further modelling work, however, still has to be done in order to consolidate the obtained results and integrate other pollution aspects (i.e. non-point source pollution from agricultural activities).