The aim of this project was to prepare thematic maps of the Nairobi River Basin as well as a database for strategy framework. The thematic maps are aimed at demonstrating the findings in areas of point source pollution, land use, population density and industrial activity. The mapping exercise was to provide factual information on the status and distribution of pollution in the Nairobi river basin. The maps are also to provide users with baseline data to support effective policy and management decisions. The other objective of the study was to use Geographic Information Systems (GIS) to study the relationships between pollution, land use, drainage patterns and socio-economic parameters.
This would involve the integration of data of various themes to derive desired analyses and conclusions. Other use of spatial digital data would be for scientific modeling and knowledge dissemination. The final output would be the creation and production of maps with variable information themes for use in decision-making, planning and management of the river basin.
The specific objectives were to:
- Prepare a thematic base map of the Nairobi River Basin and database for strategy framework;
- Provide a well-documented, systematic and factual assessment of available information on pollution. Reliable identification of the location and situations in which pollution takes place is essential if viable remedies to the problem are to be addressed;
- Create and enhance awareness on the state of pollution in the rivers through the publication of maps;
- Integrate available data onto the map and develop maps to identify "hotspots" at which the rivers are most affected by pollutants.
The mapping exercise produced twelve maps altogether showing:
- The entire Nairobi River Basin and its surroundings;
- Roads, railway and tracks in Nairobi province;
- The 24 sampled points for pollutants;
- Land use distribution of residential areas, industrial area, national parks, forests and the central business district;
- The major polluting parameters in the rivers;
- The relative fertilizer contents in the sampled points;
- The total dissolved and suspended solids at the sampled points;
- Two pH categories for the sampled points;
- Relative heavy metal contents of the river water at the sampled points;
- The biological oxygen demand (BOD5) at the sampled points;
- The relative conductivities at the sampled points;
- The relative Chloride (Cl) and Fluoride (F) contents at the sampled points.
Though twelve maps were produced there is still a need to produce other maps depicting other themes for the river basin.
A GIS database designed for the Nairobi River Basin with appropriate logical structuring can facilitate modeling and provide cartographic ability to address questions on the interrelationships between pollution and drainage characteristics in the basin. The database can develop capability for querying the different layers of data.
The project database was established as a hub for all the stakeholders in the project. The main objective was to avail and store data for any interested individual or groups of individuals on the situation of the Nairobi River Basin on selected topics. The database system contains data on all topics related to the conditions and nature of the river basin. The database presents an opportunity for an automated, interactive and structured information system that is easily manipulated and accessed for information extraction or knowledge generation.
The information in the database includes both physical and socio-economic data. The physical data carries data of the Nairobi rivers including flow data, environmental data, physical contaminants, micro-biological contaminants and chemical contaminants. The socio-economic data includes data on settlements, water and sanitation, health and disease, pollution, legislation, flooding, solid waste and land use. The data sets are hierarchically organized under two broad classes: physical data and social data. The rest of the data sets are systematically placed beneath these two sub-classes.
At this stage of the project, the database was construed to contain both tabular datasets and descriptive information related or complimentary to the tabular datasets. Other additional datasets to the database include maps, photographs and analytical charts. The database will continuously be updated.
|
