115
© Springer Nature Switzerland AG 2020
B. R. Singh et al. (eds.), Climate Impacts on Agricultural and Natural Resource
Sustainability in Africa, https://doi.org/10.1007/978-3-030-37537-9_6
A Hydrological Assessment of Wetlands
in Lilongwe Peri-urban Areas: A Case
of Njewa Catchment, Lilongwe, Malawi
Abel K. Mkulama, Austin Tibu, and Kenneth Wiyo
Abstract Assessment of wetlands and evaluation of related anthropic factors are
crucial to monitoring impacts of land use changes on hydrological processes. The
objective of this research was to assess the hydrological changes of Njewa wetland
as it transforms from virgin wetland to industrial settlement. ArcGIS 10.6 was used
to analyze the changes in land cover. Global positioning system (GPS) was used to
collect geospatial data. Geographic information system (GIS) technologies such as
digital elevation model (DEM) were used to delineate the wetland catchment area
and produce maps. Velocity-area method was used to monitor streamflow discharge
for 10 months, resulting in a seasonal hydrograph. Velocity was estimated using
flotation method. The hydrograph was used to estimate baseflow (BF) and surface
runoff volume, depth, and coefficient.
The land cover changes indicate that Njewa wetland has transformed from a
virgin vegetative cover and farm land into a peri-urban center with lots of industrial
buildings. Consequently, surface runoff coefficient has increased from 0.24 to 0.65,
and the river flow was characterized with a low baseflow (close to zero). These
results underscore that land use changes lead to changes in hydrology of rivers in
Njewa wetland, leading to flooding in urban areas.
A. K. Mkulama (*) · A. Tibu
Environmental Science and Management Department, Lilongwe University of Agriculture
and Natural Resources (LUANAR), Lilongwe, Malawi
e-mail: abel.mkulama@bunda.luanar.mw; atibu@bunda.luanar.mw
K. Wiyo
Agricultural Engineering Department, Lilongwe University of Agriculture and Natural
Resources (LUANAR), Lilongwe, Malawi
e-mail: kwiyo@bunda.luanar.mw
© Springer Nature Switzerland AG 2020
B. R. Singh et al. (eds.), Climate Impacts on Agricultural and Natural Resource
Sustainability in Africa, https://doi.org/10.1007/978-3-030-37537-9_6
A Hydrological Assessment of Wetlands
in Lilongwe Peri-urban Areas: A Case
of Njewa Catchment, Lilongwe, Malawi
Abel K. Mkulama, Austin Tibu, and Kenneth Wiyo
Abstract Assessment of wetlands and evaluation of related anthropic factors are
crucial to monitoring impacts of land use changes on hydrological processes. The
objective of this research was to assess the hydrological changes of Njewa wetland
as it transforms from virgin wetland to industrial settlement. ArcGIS 10.6 was used
to analyze the changes in land cover. Global positioning system (GPS) was used to
collect geospatial data. Geographic information system (GIS) technologies such as
digital elevation model (DEM) were used to delineate the wetland catchment area
and produce maps. Velocity-area method was used to monitor streamflow discharge
for 10 months, resulting in a seasonal hydrograph. Velocity was estimated using
flotation method. The hydrograph was used to estimate baseflow (BF) and surface
runoff volume, depth, and coefficient.
The land cover changes indicate that Njewa wetland has transformed from a
virgin vegetative cover and farm land into a peri-urban center with lots of industrial
buildings. Consequently, surface runoff coefficient has increased from 0.24 to 0.65,
and the river flow was characterized with a low baseflow (close to zero). These
results underscore that land use changes lead to changes in hydrology of rivers in
Njewa wetland, leading to flooding in urban areas.
A. K. Mkulama (*) · A. Tibu
Environmental Science and Management Department, Lilongwe University of Agriculture
and Natural Resources (LUANAR), Lilongwe, Malawi
e-mail: abel.mkulama@bunda.luanar.mw; atibu@bunda.luanar.mw
K. Wiyo
Agricultural Engineering Department, Lilongwe University of Agriculture and Natural
Resources (LUANAR), Lilongwe, Malawi
e-mail: kwiyo@bunda.luanar.mw