Environmental Engineering Reference
In-Depth Information
generates the runoff. This chapter focuses on high-density areas, which are
predominantly populated by the low-income part of the city's population. This type of
land use pattern consists of a residential development scheme, with corresponding basic
infrastructure (road, electricity, water reticulation and sewerage). However, the
accelerated pattern of urban growth has led to a considerable overpopulation of the
existing housing developments together with the construction of illegal buildings, which
resulted in a significant overload of the existing urban infrastructure. It is most
pronounced in the following directions:
• The maintenance of road surfaces is unsatisfactory, with numerous potholes, which
increases the erosivecapacity of runoff and the transport of suspended material into the
drainage system;
• Blockages and overflow of the sewer system are common practice, as reported in
Chapter 4;
• Poor solid waste management practice, resulting in the spreading of litter over public
places and de-positing it into drainage channels, thus enhancing the risk of diffuse
pollutants transport;
The drainage system consists of open ditches along the roads, usually with grass cover,
which discharge at convenient locations to existing streams and natural depressions.
There are no large drainage channels to collect and accumulate the runoff;
correspondingly, the pollution generated is of diffuse pattern in terms of both-spatial and
temporal variation.
The study focuses on the evaluation of stream water quality, which receives the runoff
from low-cost and high-density urban residential areas. For this purpose, a study area in
Kuwadzana, Harare, has been investigated. An attempt has been made to evaluate the
influence of different types of land use patterns, within the study area, including
residential housing, plots designated for home industries (as a representative example of
IS economic activities), open spaces, informal agriculture plots. Specific attention is
given to the management approaches and corresponding abatement measures that could
be applied to control and reduce diffuse pollution in such types of urban developments,
which could be regarded as typical for many developing countries.
2 REGULATION AND ASSESSMENT
2.1
The informal sector of the economy
The emergence of the home industries activities which forms part of the IS was among
other factors caused by the location of about 20 ha of land, designated for low-income
housing development, established abut 2.5 km southwest of the urban center. However,
the development of municipal housing in the designated areas did not keep pace with the
population growth within the municipality as a whole. Major low income housing
schemes include Glen View (the development started shortly before independence),
Warren Park and Kuwadzana located at 8 and 12 km respectively in the direction to the
west of the city center. Others include Budiriro to the southwest between Glen Norah and
Hatcliffe, about 15 km to the North of the city center. The expansion of this type of urban
