Environmental Engineering Reference
In-Depth Information
the vicinity of rivers and streams, which serve as sources for a potable water supply of
urban population centers. In other cases, the downstream users of polluted rivers and
streams, flowing through urban population centers are rural communities, who use the
polluted waters directly, without any treatment. Thus, the uncontrolled urban
development has negative impacts, not only in terms of social and economic conditions,
but in terms of environmental and public health protection as well.
This chapter presents two specific case studies of spatial variation of river water
quality and the impact of land use patterns in urban environments, typical for the region.
The first case study investigates the water quality variation of Lilongwe River, which
passes through the city of Lilongwe, the capital city of Malawi. The River serves as the
main source of potable water supply to the city. The impact of different land use patterns
along the upper reaches of the river has been investigated up to the abstraction point for
the water treatment plant.
The second case study focuses on the spatial water quality variation of the Mbabane
River, passing through the city of Mbabane, the capital city of the kingdom of Swaziland.
The water quality of the river, passing throughout the city has been investigated at several
locations, reflecting specific land use patterns, and a point downstream the city, where the
river water is used for direct domestic and agricultural use.
Both studies have been conducted in an environment where no regular water quality
monitoring of the river water quality has been performed previously. Also, in general, the
existing water quality monitoring laboratories deal with selected parameters only and are
orientated mainly to the control of potable water quality. Any other related data,
concerning natural or effluents' water quality and quantity, is missing as well.
Considering these conditions, and the fact that the studies have been performed within a
limited time frame, they could be viewed as a preliminary investigation for the
development of a more substantial monitoring program, and a water quality management
policy for both cases.
2 LILONGWE RIVER, MALAWI
2.1
About the country and the catchment area
Malawi is a republic in Southern Africa, formerly the British protectorate of Nyasaland,
bounded on the North by Tanzania, on the east by Lake Malawi (formerly Lake Nyasa).
Malawi extends about 835 km to south and varies in width from about 80 km to 160 km.
The total area of the country is 118,484 km
2
; nearly one fourth of it is water surface,
mainly Lake Malawi and three smaller lakes. Malawi is a land locked country located
between 16
o
S, and 9
o
N and between 36
o
W and 32
o
E. A schematic map is shown in
Figure 11.1.
Lilongwe is the capital city located in the central part of Malawi. Lilongwe district is
located between longitudes 14.5
o
and 13.5
o
, and latitudes 33.5
o
and 34.5
o
. The district has
the altitude ranging from 1000 m to 1500 m above sea level.
The Dzalanyama catchment is located on the south-west of Lilongwe district. The
rivers of Lilongwe, Lisungwi and Likuni originate from this catchment. The catchment
area for Lilongwe River is about 1800 km
2
.
