CHAPTER ONE INTRODUCTION 1.1 Background to the Study
This study focuses on the environmental impacts of flooding on agricultural activities in Kwale and its environs. Flooding has been a long-term issue which affects the inhabitants of Kwale. In many natural systems, floods play an important role in maintaining key ecosystem functions and biodiversity. They link the river with the land surrounding it, recharge groundwater systems, fill wetlands, increase the connectivity between aquatic habitats, and move both sediment and nutrients around the landscape, and into the marine environment (Apan, et al., 2010). For many species, floods trigger breeding events, migration, and dispersal. These natural systems are resilient to the effects of all but the largest floods. The environmental benefits of flooding can also help the economy through things such as increased fish production, recharge of groundwater resources, and maintenance of recreational environments (Bunn and Arthington, 2002).
The environmental resources in Kwale most especially the land and soil resources are greatly threaten by flooding. The Kwale and its environ is covered by beautiful vegetation naturally checking the menace. This flooding menace has destroyed arable land for agricultural purposes which are the major socio-economic activities of the Kwale people. The government in his attempt to curb the situation has constructed a drainage system some meters away from the major road to redirect and channel all the water flowing to the erosion sites into the drainage system which is emptied into the river. Despite all this effort, the situation still remains the same.
Areas that have been highly modified by human activity tend to suffer more deleterious effects from flooding. Floods tend to further degrade already degraded systems. Removal of vegetation in and around rivers, increased channel size, dams, levee bank and catchment clearing all work to degrade the hill-slopes, rivers and floodplains, and increase the erosion and transfer of both sediment and nutrients (Douglas, et al., 2005). While cycling of sediments and nutrients is essential to a healthy system, too much sediment and nutrient entering a waterway has negative impacts on downstream water quality. Other negative effects include loss of habitat, dispersal of weed species, the release of pollutants, lower fish production, loss of wetlands function, and loss of recreational areas (Kingsford, 2000).
Flooding is one of the environmental problems that have confronted man since immemorial. Flooding is a widespread and age long phenomenon. In Kwale, flooding has created and causes untold hardship such as destruction of building and properties, interruption of socio-economic development of the area. Jon (2011), defined flooding as a condition, which exist when any overland flow over an urban or rural area, that is sufficient to cause property damage, health hazard, nuisance and the obstruction of the socio-economic activities in the area. He went further the types of flooding to include rivers flood, flash flood, splash flood and flood bondages.
Agriculture has changed significantly in terms of the production patterns and structure and a significant trend has been the development towards fewer and larger holdings with more intensified and specialized production. This development has included an increased mechanization and use of fertilizers and pesticides. Biodiversity has been affected negatively both by the physical changes in the landscape and by the changes in the production methods. As the agricultural production has intensified, all levels of biological diversity (genetic, species, and habitats) have declined in farming environments. The more intensive land use corresponds for example to the decrease in the populations of farmland birds.
Many of our coastal resources, including fish and other forms of marine production, are dependent on the nutrients supplied from the land during floods. The negative effects of floodwaters on coastal marine environments are mainly due to the introduction of excess sediment and nutrients, and pollutants such as chemicals, heavy metals and debris. These can degrade aquatic habitats, lower water quality, reduce coastal production, and contaminate coastal food resources (Poff, et al., 2003). It is against this background that this study is carried out to examine the environmental impacts of flooding on agricultural activities in Kwale and its environs.