A Ab bs st tr ra ac ct t. . This paper reviews applications of remote sensing and geographic information systems (GIS) techniques to the assessment of tropical waters. These applications are discussed in the context of specific management objectives and sensors used. The need to monitor the spreading patterns of weeds in the tropical waters, land-use changes in the areas surrounding them, change detection, disappearance of wetlands, productivity and nutrient status, in order to establish trends and subsequently develop predictive models to facilitate effective management, is highlighted. GIS capability can be used to link ecological information with the management decisions of these waters. Remote sensing provides useful information in the form of satellite images and aerial photographs that can be integrated and analyzed in a GIS to provide useful spatial information and temporal changes over large geographic areas affecting the structure and function of tropical waters. K Ke ey yw wo or rd ds s: : GIS, remote sensing, sustainable management I In nt tr ro od du uc ct ti io on n Shallow tropical waters play a vital role in many people's lives and contain remarkable communities of plants and animals. Shallow tropical waters are profoundly affected by their locality and by changes taking place on land, even at great distances from them. They are often faced with a number of threats as a result of socio-economic activities, taking place within them and their catchments. Rapid population growth in catchment zones has resulted in intensive use of land for farming, deforestation and growth of urban centers. Consequently, there is accelerated runoff leading to increased silt and nutrients discharge into the shallow tropical waters.Currently most tropical lakes are being choked by water hyacinth (Eichhornia crassipes), which continues to cause severe hardship and immense economic difficulties to most countries. The pressure on tropical waters from the weed requires intensive research in order to come up with useful suggestions towards their management. It is at this level that availability of automated, real time data becomes imperative. Remote sensing has developed rapidly to address these needs. The advantage of remote sensing as documented by Richards [64] and Sabins [69] is its ability to capture and record land details instantaneously. Its spatial resolution and aerial coverage provide the researcher with a synoptic view of a land surface. Such data derived from remotely sensed images may be stored efficiently and analysed effectively in a GIS (Risser and Treworgy,[67]).

Abstract. Effect of farming practices on wetlands in Kisii District was determined through assessment of farmers' environmental awareness. Effective conservation of wetlands in the district cannot depend on prohibitions but should be based on users' knowledge and attitudes of wetlands. The present study examined farmers' knowledge of the environmental effect of agricultural expansion to wetlands; absence of knowledge of characteristics of farming activities and the attitudes of farmers with respect to planning mechanisms that might be used to support wetland protection in the area. The majority of farmers ignored the effect of agriculture on wetlands. Those who occupied wetland areas practiced intensive agriculture and were ignorant of the effect of this on water quality, soil and landscape. The government should implement training programmes for all wetland users in Kisii District to make them more environmentally aware of the impacts of farming practices on wetlands. This is meant to make them become more environmentally aware of the effects of farming practices on these ecosystems and eventually change their behavior. There is a need to build a conservation ethic among wetland users by educating them to sustainably utilize wetland resources and training them to practise sustainable agriculture.

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In many African savanna landscapes, domestic and wild herbivores cooccur across different land-use systems, but the role of land-use in shaping their spatial relationship is poorly understood. We evaluated the spatial relationship between cattle and wild herbivores categorized by body sizes and feeding habits across different land-use types, namely, private ranches (PR), transitional lands (TRL), and pastoral grazing areas (PGA), in Laikipia County, Kenya. Cattle and wild herbivores spatial distribution data were obtained from Kenya's Department of Resources Survey and Remote Sensing (DRSRS). Spatial relationships between cattle and different wild herbivore guilds were analyzed using Ripley's bivariate 12 function. In PR, wild herbivore guilds showed significant attraction to cattle at short distances. In TRL, wild grazers, mixed feeders, megaherbivores, and medium-sized ungulates exhibited significant attraction to cattle. Additionally, repulsion was observed between cattle and browsers at short distances under this land-use system. In PGA, wild grazers, mixed feeders, and megaherbivores repelled strongly with cattle at short distances while browsers and medium-sized ungulates were significantly attracted to cattle. Cattle and wild herbivores were more randomly and independently distributed in PR than in TRL and PGA. These spatial relationships imply better coexistence between cattle and wild herbivores in PR than in TRL and PGA.

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Brick making is one of the major small-scale industries in Sironga which has been expanding due to the growing demand for urban expansion. Due to the increasing population pressure, brick-making is competing for the wetland resources. Sironga wetland is threatened with serious degradation and probable loss of plant diversity. Conversion of this wetland for economic uses such as brick making has resulted in its loss. The objective of the study was to assess the effects of brick making on plant diversity in Sironga wetland. Nyamira County, Kenya. A one metre by one metre quadrat frame was laid down and perpendicularly recorded the percent cover for each species found inside the quadrant plus the percentage area covered by the bare ground litter. From each transect lines "diagonally" detailed vegetation under study was then done. The plant species were recorded and classified into three life-forms; herbs, sedges and grasses. The study revealed that grasses had the highest diversity H = 1.144. Diversity for herbs was H = 0.987 and H = 0.899 for reeds respectively. The study concluded that brick-making activities affected the plant diversity in Sironga wetland. This may be attributed partly to the limited information and awareness campaigns to the surrounding communities on the values and benefits of wetland ecosystem services and the lack of alternative livelihood sources. The study recommends that alternative livelihoods are provided and awareness campaigns on the values and benefits of wetlands to the residents are done by the relevant agencies.