RIPARIAN ZONE CONSERVATION IN A CHANGING URBAN LAND USE ENVIRONMENT: A CASE OF NAIROBI RIVER BASIN, KENYA

ABSTRACT

Riparian zones are vegetated strips of land located on each side of a watercourse or adjacent to a stationary water body. Ideally, the attributes of a riparian zone should include among others uninterrupted continuum of vegetation cover, appropriate vegetation structure and lateral width where ecological, social and economic functions should take place.

However, despite their significance as urban landscape elements, riparian zones are facing pollution, encroachment and degradation from urban land uses in Nairobi River Basin. This is a result of improper determination, use and management. The implications of this stated problem include failure to filter polluted surface run-off, riverbank erosion, increased incidences of flooding and soil erosion, and death of aquatic and terrestrial ecosystems that depend on riparian vegetation for survival. The cost of this problem to Kenya as a nation is monumental.

The main objective of this study was to assess factors that affect the determination, use and management of riparian zones in Nairobi River Basin. The study sought to answer the question of whether the policy and institutional factors, land use and biophysical factors, as well as, professional and land users’ factors influence conservation of riparian zones in the basin. This was with a view of developing an integrated model of conservation of riparian zones.

The study followed a descriptive research design which employed a mixed strategy involving quantitative and qualitative methods. Secondary data was collected using archival method. Primary data collection relied on questionnaires, observations and scheduled interviews as the main methods. The technique of content analysis assisted in grouping qualitative data thematically that was presented in a narrative form. Statistical data were mainly analyzed using Statistical Package for Social Scientists (SPSS), and summarized in percentages. The data was presented in tables and graphs to provide visual relationships between variables. However, geographical information systems (GIS) spatial techniques were used to examine the physical extent of the zones in relation to adjoining land uses.

The study established that weak policy and institutional framework have led to haphazard and incompatible multiple uses of the zones. In particular, planning and development control mechanisms are weak and there are unclear land administration guidelines and procedures to secure the riparian width and vegetation. Land use and biophysical factors are also not taken into account when formulating and implementing policies while professionals and land users have limited or no roles at all in securing riparian zones. As a result, these factors have played a major role in the continued indiscriminate invasion and ecological deterioration of riparian zones in the basin.

In conclusion, there is improper determination, use and management of riparian zones in Nairobi River Basin. Therefore, the areas that physically and ecologically fall in these riparian zones are encroached and degraded by urban land uses. The study recommends among others, an integrated model for effective determination, use and management of riparian zones.

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