The methodology described in this paper was developed to provide technical support to the field team of WRISS/GWU and facilitate their groundwater search in Northern Iraq.
However, it can be applied worldwide, in all kinds of terrains, and for this reason it has been reported in detail in this paper.
Landsat Enhanced Thematic Mapper (ETM) data in digital format were preferred over other satellite data due to the availability of three near- to mid-infrared bands, extremely useful for terrain and lineaments analyses. Moreover, the availability of a co-registered thermal band permitted further investigations on lineaments.
The approach used in the study was a development of the traditional standard sequence of drainage, landforms, cover and lineaments analyses, to which several improvements and additions were made, such as:
1. all data were in digital format and stored in a geo-database as GIS layers;
2. all analyses and interpretations were performed directly from the computer screen;
3. on the basis of a previous positive experience, thermal lineaments analysis was performed;
4. a comprehensive geo-database was created including all GIS layers which were considered of interest for the study;
5. by using the potentiality of GIS software, which allows stacking of georeferenced data for comparison and integration and data query for subsetting the needed information, selected layers of the database were superimposed on the Landsat image kept as background and a logical series of observations was made, leading to a well-substantiated set of interpretation assumptions.
The creation of a GIS database, including the data format and entry, is a time-consuming and laborious exercise, as high accuracy is definitely mandatory. However, once the database is complete, interpretation of features leading to selection of promising sites for groundwater search is carried out easily and quickly. This as a result of data availability of all information needed in a GIS environment.
The methodology can be further improved by adding other GIS layers, such as a Digital Elevation Model (DEM), road network, land cover and any other relevant information. The most important factor is the full integration of remote sensing and GIS techniques.
In the 30 priority areas selected by WRISS/GWU, 198 potential groundwater sites were identified, but many more could have been indicated.
Field checking of every site after identification by GPS, followed by geo-resistivity survey and, if positive, by drilling was foreseen. However, the political situation in the region forced the evacuation of the field team in February 2003 and, consequently, the ground verification was not carried out. However, the field team was able to check some of the potential sites indicated in the first maps provided to them and estimated the accuracy of the information at 90 percent, or in other words, that around 90 percent of the potential sites indicated would result in positive groundwater exploitation (oral communication of Prof. Markovic).
The authors sincerely hope that the present difficult situation in the region will give way to a more stable and peaceful outcome in the near future and that the technical assistance be resumed. In this new framework, it would be possible to make full use of the results of this study to provide groundwater sources for safe drinking water and for irrigation for the welfare of the local inhabitants.