Groundwater modelling is hindered by the lack of adequateinformation about the groundwater system and hence theneed for an interactive and efficient system for datapreparation and results analysis. Such a lack ofinformation usually necessitates the use of tediousiterative methodology within a sensitivity analysisscheme. The heterogeneous aquifer systems complicate theissue since more data is required to simulate the system.This study demonstrates the integrated approach to bridgethe gap between data handling and modelling. The karstcretaceous aquifer system (complex aquifer system) of theEastern Basin in the West Bank is used to illustrate thisapproach. The groundwater modelling approach integrates the outputsfrom different programs for data preparation andanalysis. These include (1) Groundwater Database (GWW)(2) Geographic Information System (GIS) (3) GroundwaterModelling System (GMS). In addition, the paper will summarize the data collectionefforts, problems faced and experience gained workingwith heterogeneous media. This involves linking theresults from various field investigations for groundwaterdevelopment programs in the West Bank.