Application of Remote Sensing Technologies and Geographical Information Systems in Monitoring Environmental Degradation in the Lake Victoria Watershed, East Africa

Introduction

The riparian countries of the Lake Victoria Region have in recent years seen the Lake as a resource that requires rational management to protect it from pollution and degradation (Klohn and Andjelic, 2001). For this reason the countries have formed research teams to assess the resources and the problems of the Lake, to develop management tools and to establish adequate institutional capacity in research. With the growing population and urbanization the multiple activities in the lake basin have increasingly come into conflict with ecological principles. This has contributed to rendering the lake environmentally unstable. The problems have arisen in the surrounding basins due to population pressure on environmental resources and associated human activities. The overall objective of this chapter is to present new emerging challenges of pollution and possible solutions. The on-going research on which this chapter is based is to examine current trends in environmental degradation and design interventions based on democratic community participation in the implementation of sustainable and environmentally sound land use and cultural practices that control soil erosion, water pollution, maximize biological diversity, sustain stream-flow as well as promote community livelihoods.

Visual interpretation of satellite data products coupled with field checking is a very useful technique of finding out the physical growth of urban centres. The expansion of urban centres is very fast and conventional ground methods are slow and in-accurate because by these methods, delineation of built-up area is difficult. Mapping and monitoring the urban sprawl, as a result of urban decay of city centre, at regular intervals is very essential for urban planners to understand the trend of development on the urban periphery and subsequently to regulate it. In this chapter various data products like Landsat MSS, TM, Topo sheets are used to find out the growth of built environment over a given period of time. Thematic Mapper imagery are used to prepare broad landuse/land cover maps. These technologies are very useful in finding out the potential, as well as shortcomings of satellite data products in various urban aspects such as water management models.

In related studies, Landsat Mult-Spectral Scanner (MSS) and Landsat Enhance Thematic Mapper (ETM) data have been used to analyze different habitats which are under different forms of land use (Harris 2003). Analysis of environmental and agricultural change can be used to further understand the implications of change at river basin levels.

Remote Sensing (RS) and GIS can also be used in the development of groundwater resources. However, one aspect of the limitations of applying GIS and RS to groundwater exploration and development is a current incompatibility between hydrological and hydrogeological models (Hawari et al 2007). There is need for a common platform that is compatible with both GIS and hydrological/hydrogeological models. Other issues of concern are in the areas of land surface temperature from thermal infrared data, surface soil moisture from passive microwave data, selecting groundwater recharge sites, simulation of groundwater systems, water quality using visible and near-infrared data, and estimating landscape surface roughness using radar and assessment of natural resources of mountain oases as well as water storage systems which determine the hydrological sustainability of watersheds (Luedeling 2007). The topographic, hydrologic and geologic characteristics as well as the locations of watersheds can be determined through use of remote sensing and image processing techniques.

Monitoring Urban Growth using satellite images and GIS (Al-Awadhi & Azaz 2005) and creating a database of historical land use information for the understanding and prediction of urban growth throughout the Lake Victoria Basin is critical for the management of natural resources in the region. For this case study, Aerial Photos and satellite images were used to map urban growth. The data presented in this chapter shows that the total built-up area has expanded at a very fast rate since 1986. More than just describing the incredible increase in urban areas, these results show the possibilities for future application of GIS in measuring growth in other areas. Maps showed an increase of about 50% in already urbanized areas. Residential land, itself, had the largest share of build-up in the case of Kampala City (Figure 1)