Salinity sources of Kefar Uria wells in the Judea Group aquifer of Israel. Part 2 - Quantitative identification model

The Kefar Uria group of wells have experienced an increase of salinity of the pumped water in the last two decades. The source of salinity is not known. Geohydrological and geochemical considerations of Part 1 (Avissar et al., in press) suggest two possible mechanisms and sources. The first source is infiltrating at the top of the aquifer, in contact with the overlaying formation and is close to the wells. The second source is deep and more distant and is attributed to salt leaching. In the present study, a methodology is developed in order to select the most probable source by quantitative modeling of flow and transport. The problem is more difficult than similar ones investigated in the literature, because of the complex three-dimensional flow pattern. However, simplified models can be used for the limited scope of source identification. The aquifer is modeled as a semi-infinite confined one under steady state conditions. The saline water input area and the 13 wells are represented by source distributions and an analytical solution is obtained for the flow field. A best fit between computed and measured well pressure heads leads to reasonable value of the identified permeability. Advective solute transport from salinity sources to wells is modeled numerically by particle tracking and leads to partition of solute flux among wells. Comparison of calculated wells salinity and the measured ones leads to the conclusive selection of one of the sources as the most probable one.