Intrinsic Vulnerability Assessment for the Alluvial Aquifer in the Northern Part of Jordan Valley

The Northern Jordan Valley (NJV) is an important and significant water basin in Jordan where most of Jordan's agricultural crops are produced. Knowing that the aquifer system is mainly composed of alluvial deposits, it is important to assess the potential of ground water for pollution. For this purpose intrinsic vulnerability was assessed using SINTACS model with the aid of geographic information system (GIS) techniques. The final results show that about 40% of the investigated area has been classified as high to very high vulnerable to groundwater pollution. These results were correlated with measured concentration of nitrate (NO3-1) at different locations. A high correlation was found between areas of high nitrate concentrations and those of high vulnerability category. To validate the model results, a sensitivity analysis has been carried out to assess the influence of each of SINTACS parameters on the obtained vulnerability values. It was found that the soil overburden attenuation capacity parameter (T) and the depth to the groundwater parameter (S) are the most sensitive parameters to SINTACS vulnerability model. The effective-weights analysis was also performed in this study to revise the weights in the computed vulnerability index. It was noticed that the effective weights for each parameter were sometimes varies from the theoretical weights assigned by the SINTACS method.