Environmental Management in Developing Countries: Remote Sensing Case Studies

Abstract

One of the most serious threats to sustainable economic growth in developing nations is the increasing degradation of their natural ecosystems and the concurrent deterioration in the quality of life for their people. This paper presents two case studies on the utility of remote sensing as an environmental assessment and protection tool in two developing countries. These case studies were selected to represent the two major climatic regions where the majority of the world’s poor live. Guyana is a small tropical country on the northern coast of South America where 80 percent of the country’s revenues are used to service its debt. Jordan is a small arid to semi-arid country in the Middle East where the search for drinking water is directly linked to its development. In both these countries, as in many other developing countries, earth observation data are necessary for sustainable development.

In Guyana, all of the productive agricultural lands and 90% of the population of Guyana live in the narrow and fertile coastal plain (500 x 20 km) which is below sea level. Recently, the coastal dikes constructed for sea defence and improving irrigation of agricultural areas have been eroded and broken in various areas, resulting in severe flooding. Large sections of the sea wall are collapsing and approximately 2/3 of the coastline needs permanent structures or replacement. It is estimated that future large scale flooding could destroy almost U.S. $1 billion of economic activity in the coastal areas. The failure of the coastal defences is the result of a combination of factors. These include the depletion of the mangrove forest buffer caused by wood cutting for fuel and choking by sling mud; the increase of wave activities possibly due to a gradual rise in the mean sea level; and the lack of maintenance of the engineering structures (dikes and earth dams).

This case study discusses the use of combined synthetic aperture radar (SAR) and TM images for coastal zone mapping, for determining the priority areas of coastal repair and for the assessment of flood damage of the agricultural areas. The study has shown that parts of the Guyana coastline have changed by from a few meters to half of a kilometre over the past twenty years. This has serious implications for sea defence and commercial agriculture. Areas of erosion and accretion, mangrove forest depletion and agricultural land uses were identified.

In Jordan, there is an urgent need to manage and utilise the water resources in order to comply with the immediate and projected water demand in the country. All the known aquifers have been explored. Water harvesting is a national priority as water supplies are being depleted by intensive pumping. The main concern is to optimise the utilisation of the ground water resources and to protect them against depletion and pollution. For this reason, it is necessary to map in detail the hydrogeology of the aquifers. This second case study reports on the use of C-HH SAR and SAR/TM integration for providing information on the surface hydrogeological characteristics and land use practices of these sensitive watershed areas. The SAR image was used to map wadis (their surface distribution, channel morphology, and surface roughness of the wadi sediments); hydrogeological characteristics of rock units — limestone, basalts and alluvium; fractures (used to target exploratory wells); and land practices necessary for environmental protection of the aquifers. Although the SAR image itself provided very useful information, a combination of SAR and TM provides a more suitable image to map the surface characteristics of the aquifers.

These two case studies demonstrate the need to use appropriate remote sensing techniques to assist in environmental protection programmes in the developing world.