The 250 million people who live in the Afro-Asian dryland belt face water shortage for their entire lives. Hundreds of millions more in less drought-prone regions have to cope repeatedly with reduced supplies. Resolving the shortage of domestic water supplies in arid and semi-arid lands largely focuses on groundwater resources and efficient capture of available surface water, preferably by recharging underground resources. The key lies in accurate and informative geological maps. Yet most areas of need have never been geologically mapped at scales better than 1:250,000. The area is enormous and the number of trained Earth scientists who serve it falls far short of requirements for adequate, conventional field mapping. A significant increase in the number of geoscientists able to interpret cheap and universally available remotely sensed data in a water-supply context is needed to close that knowledge gap fast enough to prevent yet more disasters and to relieve those that are unavoidable.
Water Exploration: Remote Sensing Approaches is an introductory but intensely practical learning resource centred on the use of remote sensing technologies to address geology, terrain and hydrology. It is based on the author’s widely used book Image Interpretation in Geology (Drury, 2001), together with a free version of professional image processing and desktop mapping software (MicroImages’ TNTmips). Geoscientists with access to a computer and the internet can independently study the standalone course in office, at home or in the field using a wide selection of exemplary image and map data. Background theory is taught in six richly illustrated chapters:
- Chapter 1 covers the basics of hydrogeology;
- Chapter 2 is an introduction to remote sensing in the visible, reflected and emitted infrared, showing how the spectral properties of different surface materials can be used to design image processing and analysis strategies;
- Chapter 3 reviews the ‘traditional’ yet still highly effective use of stereoscopic aerial photography in terrain mapping and photogeology, using easily viewed stereo anaglyphs;
- Chapter 4 upgrades this approach to the wide-area stereo coverage available from ASTER data for several geologically well studied areas to demonstrate the relationships between terrain, rock types and structures in several study areas covered by detailed geological maps, and less well-known areas from NE Africa;
- Chapter 5 shows how the spectral approach introduced in Chapter 2 can be applied to multispectral Landsat and ASTER data, using various image processing strategies. It centres on a structurally complex area in central Eritrea that shows a wide variety of lithologies to demonstrate the mapping power of free Landsat and ASTER data;
- Chapter 6 covers digital analysis of topographic elevation data to extract accurate drainage networks useful in assessing surface water harvesting and aquifer recharge opportunities.
A series of practical exercises teach the use of the free TNTmips software package to interpret data sets from a wide variety of study areas that illustrate many aspects of geology related to groundwater resources. They are intended to encourage users to develop skills and experience in water-resource reconnaissance. The exercises cover the basic tools used in image interpretation:
- Displaying and enhancing image data;
- Detecting different minerals;
- Terrain and hydrological analysis;
- Making digital geological maps.
An Appendix guides users in acquiring and preparing globally available, free image data to use in the free software package, at a limited but still useful image size (1000 x 1000 pixels or 30 x 30 km using Landsat ETM+ and OLI, or ASTER data).
The learning resource is aimed at geoscience professionals in national surveys; independent consultants; senior geology undergraduates and engineers working in the WASH or WatHab sections of NGOs and international agencies. Successful completion should confer the ability to undertake water related mapping projects to a professional standard anywhere in the Afro-Asian dryland belt.
Water Exploration: Remote Sensing Approaches is delivered online at https://h2oexplore.wordpress.com/. For users who have poor Internet connection the entire resource can be delivered on DVD at cost of delivery and materials.
Drury SA (2001) Image Interpretation in Geology, (3rd edition): Nelson Thorne/Blackwell Science: London.