Groundwater risk intensity mapping in semi-arid regions using optical remote sensing data as an additional tool

Due to semi-arid to arid climatic conditions, Jordan has limited groundwater resources. As a result of agricultural activities and untreated wastewater, most of the groundwater in the karstic areas is microbiologically contaminated. Groundwater vulnerability, hazards, and risk intensity were mapped (scale 1:50,000) at a test site near the Jordan Rift Valley. The mapping included the use of optical remote sensing to complement conventional data in areas with poor data. LANDSAT ETM+ data, and colour and panchromatic aerial photographs at different scales were incorporated using visual image interpretation and digital image processing. The applicability of the different remote sensing data sources is discussed and recommendations for their usage are given. Information derived from digital images offers new opportunities for vulnerability and hazard assessment, particularly when related to land use, vegetation cover, urbanisation and infrastructure. The resulting maps indicate clearly the vulnerable areas and the "hot spots" of potential contamination in the test site and form an important basis for integrated groundwater management studies and the long-term planning of protective measures. The application and transferability of the European vulnerability approach (COST Action 620) to the test site in Jordan proved to be good, in general, although modifications were necessary to suit local conditions.