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Title: A 3D CONCEPTUAL HYDROGEOLOGICAL MODEL FOR THE LOWER JORDAN RIFT VALLEY

Author: J. Bensabat, A. Flexer, J. Guttman, N. Inbar and A. Yellin-Dror

Year: 2009

Publisher: European Water Resources Association (EWRA)

Description:

In the frame of the Integrated Water Resources Management (IWRM) SMART project, funded by the German Ministry of Science (BMBF) a trans-boundary model (Jordan, Palestine and Israel) was constructed for the simulation of groundwater flow in major water bearing layers, in order to provide rational estimation of the water resources, their availability, to design groundwater exploitation schemes and to quantify the expected changes subsequent to the global climate change. The study area is the Lower Jordan Rift Valley (LJRV). Its geology and topography is rather complex and displays notable differences between the eastern part (Jordan) and the western one (Palestinian Authority and Israel). Uplifted rift shoulders bordering deep depressions filled with young sediments are common along the area. On the Highlands west of the basin floor, Middle Cretaceous carbonates and Upper Cretaceous clays, marls, chalks and cherts are exposed. The eastern highlands are composed mostly of Paleozoic, Lower Cretaceous Nubian sandstone and Middle-Upper Cretaceous carbonates. The different rock units on the two opposite sides of the basin reflect both relative motion and differential uplift. The basin-fill holds within it a few km thick succession of Neogene to Holocene marls, clays and conglomerates as well as salt bodies and layers. The main aquifers that supply most of the water demand are the deep water bearing layers of the Judea Group mainly the Cenomanian-Turonian carbonates in the west and the Lower Cretaceous Kurnub Group and the Cenomanian-Turonian Ajlun Group in the east. As first step a conceptual model of the LJRV geology and hydrogeology was constructed. It included the definition of the model borders, of the major geological layers to be taken into account for the purpose of water resources evaluations and the major faults (those capable of having an impact on the groundwater flow and transport processes). To this end
a digital elevation model (DEM) with a resolution of 1X1 km was constructed for the elevation of the Top Turonian layer. Then a similar DEM was constructed for the thicknesses of the relevant layers above and below the Top Turonian. Additionally the major faults were mapped, together with their dip. All this information was organized within the frame of a GIS based application. The second step was to create a model made of triangles in plan view and of triangular prisms in 3D. The model was created by spreading point following a predefined density distribution, suited to match the geological characteristics of the subsurface. Fault paths were included as constraints. The resulting set of points was triangulated using a constrained Delaunay triangulation (Vigo). The
vertical topography was constructed by applying an interpolation procedure based on Compact Support Radial Basis Functions. Regular geological cross-sections and outcrop maps were constructed from previous studies, borehole data, geological maps and seismic data and then compared to the Geological cross-sections and exposed layers created from the resulting model. The output show good agreement with the existing cross-sections and outcrops map. The model will further be used to the evaluation of the groundwater resources in the LJRV.