MANAGING WATER UNDER CLIMATE CHANGE FOR PEACE AND PROSPERITY
IN SWAZILAND
Jonathan I. Matondo, Member IWRA, IAHS, IET, University of Swaziland; Graciana Peter
University of Swaziland and Kenneth M. Msibi, Water Resources Branch, Swaziland
Abstract
The enhanced greenhouse gas effect is expected to cause high temperature increase globally (1.0
to 3.5 degrees Celsius) and this will lead to an increase in precipitation in some regions while
other regions will experience reduced precipitation (±20%). The impact of expected climate
change will affect almost all the sectors of the human endeavor. However, the major purpose of
this paper is the management of water resources under climate change for peace and prosperity
in Swaziland. The impact of climate change on hydrology and water resources has been
evaluated using General Circulation Model results (rainfall, potential evapotranspiration, air
temperature etc.) as inputs to a rainfall runoff model. The evaluation of the effect of climate
change on hydrology and water resources in Swaziland has been carried out in three catchments
namely: Mbuluzi, Komati and Ngwavuma.
MAGICC - Model was used to simulate the climate parameters for Swaziland given the baseline
conditions. Eleven GCMs were used and three of them were found to simulate very well the
observed precipitation for Swaziland. These GCMs are: the Geophysical Fluid Dynamics
Laboratory (GFDL), the United Kingdom Transient Resalient (UKTR), and the Canadian
Climate Change Equilibrium (CCC-EQ). The three GCMs were used to project the temperature
and precipitation changes for Swaziland for year 2075. This information was used to generate the
temperature, precipitation and potential evapotranspiration values for the three catchments for
year 2075. This information was used as input data to a calibrated WatBall rainfall runoff model.
Simulation results (after taking into consideration of water use projections) show a water deficit
from June to September in both the Komati and Ngwavuma catchments and a water deficit from
May to September in the Mbuluzi catchment. Efficient water utilization in the agricultural sector
(i.e. using drip irrigation) gives a water savings of 33.6x10 6 m3 per year ( 1.065 m3/s), 47.6x106
m3 per year (1.509 m3/s) and 16.8x106 m3 per year (0.533 m3/s) in the Komati, Mbuluzi and
,Ngwavuma catchments respectively. The saved water could be used for economic activities and
meeting Swaziland’s obligation to the down steam riparian states of South Africa and
Mozambique and therefore alleviating conflict between the riparian states.
Introduction
The greenhouse gases effect is expected to cause global warming which in turn will cause
changes in average precipitation for any region in the order of plus or minus 20%
(WMO/ICSU/UNEP, 1989). Generally it is expected that floods now considerd rare would occur
more frequently in certain regions while drought related and competing water use issues will
intensify in other regions (Miller, 1989; Shaakee, 1989; 1PCC 1990).Therefore, there is a need to
evaluate the impact of climate change on hydrology and water resources at the local level. The
assessment of the impact of expected climate change on water resources involves the use of
GCM models coupled with hydrologic models (Kunz, 1993). This approach has been used in
three catchments.
Simulation results in the three catchments for the considered climate change scenarios and for
dry, wet and average year conditions without taking into consideration of the water abstractions
are presented in Matondo et al 2003. The impact of expected climate change on hydrology and
water resources in Swaziland, while taking into consideration of the projected water demand in
the three catchments are presented in this paper.
Background information
The Kingdom of Swaziland, is situated in South Eastern Africa between the 25 th and 28th
parallels and longitudes 31o and 32o East. It lies some 48 to 225 kilometres inland of the Indian
Ocean littoral and hence physically landlocked, meaning all traffic in and out of the country has
to be routed via one of its neighbours, South Africa or Mozambique. The country has a total
surface area of 17,360 km2 and as such, the smallest country in the southern hemisphere. It is
bounded by the Republic of South Africa in the north, west and south, and by Mozambique on
the east. Although small in size, Swaziland is characterized by a great variation in landscape,
, geology and climate. It also lies within the Maputoland Centre, an area reported to have the
greatest biodiversity in Southern Africa.
There are four distinct physiographic regions within the country namely: highveld, middleveld,
lowveld and lubombo, which are clearly distinguished by elevation and relief (Murdoch, 1970).
Swaziland enjoys a climate which is generally subtropical, with hot and wet summers and cold
and dry winters. Further variations in climatic conditions occur within the different
physiographic regions giving rise to three clearly distirnguishable climate types.
The highveld and upper middleveld are characterized by a Cwb climate. The lower middleveld
and lubombo range have a Cwa climate whilst the western and eastern lowveld have a Bsh
climate (Murdoch, 1970). Mean annual rainfall ranges from about 1500 millimetres in the
highveld to a little less than 500 millimetres in the southern lowveld.
The Highveld’s temperate climate is characterized by wet summers and dry winters, and annual
rainfall averaging 1500 millimetres. Temperatures vary between a maximum of about 33 oC in
mid-summer and 0oC at night in mid-winter. On the other extreme end is the Lowveld which
experiences a sub-tropical climate. This region receives the lowest annual rainfall of about 450
mm. There is also a large diurnal temperature range experienced here with maximum
temperatures reaching the upper 30os are not uncommon. Semi-arid pockets of areas are found in
this region, which is also liable to desertification. The frequency of heavy downpours is more
uniform across Swaziland than the total rainfall. Between 75% and 83% of precipitation
(summed mean monthly amounts) comes in summer months (October – March).
The water sources in Swaziland are mainly surface waters (rivers, reservoirs), ground water and
atmospheric moisture. There are seven drainage basins in Swaziland and these are: Lomati, Komati,
Mbuluzi, Usutu, Ngwavuma, Pongola and Lubombo (see Figure 1). The latter two basins (Pongola
and Lubombo) are smaller and under utilised and their water allocation has not yet been gazatted to
be apportioned by the Water Apportionment Board, hence, there are no gauging stations in these
two basins. The Komati and Usutu basins both originate in South Africa while the rest of the basins
originate within Swaziland. It should also be noted that all the rivers in Swaziland are international
IN SWAZILAND
Jonathan I. Matondo, Member IWRA, IAHS, IET, University of Swaziland; Graciana Peter
University of Swaziland and Kenneth M. Msibi, Water Resources Branch, Swaziland
Abstract
The enhanced greenhouse gas effect is expected to cause high temperature increase globally (1.0
to 3.5 degrees Celsius) and this will lead to an increase in precipitation in some regions while
other regions will experience reduced precipitation (±20%). The impact of expected climate
change will affect almost all the sectors of the human endeavor. However, the major purpose of
this paper is the management of water resources under climate change for peace and prosperity
in Swaziland. The impact of climate change on hydrology and water resources has been
evaluated using General Circulation Model results (rainfall, potential evapotranspiration, air
temperature etc.) as inputs to a rainfall runoff model. The evaluation of the effect of climate
change on hydrology and water resources in Swaziland has been carried out in three catchments
namely: Mbuluzi, Komati and Ngwavuma.
MAGICC - Model was used to simulate the climate parameters for Swaziland given the baseline
conditions. Eleven GCMs were used and three of them were found to simulate very well the
observed precipitation for Swaziland. These GCMs are: the Geophysical Fluid Dynamics
Laboratory (GFDL), the United Kingdom Transient Resalient (UKTR), and the Canadian
Climate Change Equilibrium (CCC-EQ). The three GCMs were used to project the temperature
and precipitation changes for Swaziland for year 2075. This information was used to generate the
temperature, precipitation and potential evapotranspiration values for the three catchments for
year 2075. This information was used as input data to a calibrated WatBall rainfall runoff model.
Simulation results (after taking into consideration of water use projections) show a water deficit
from June to September in both the Komati and Ngwavuma catchments and a water deficit from
May to September in the Mbuluzi catchment. Efficient water utilization in the agricultural sector
(i.e. using drip irrigation) gives a water savings of 33.6x10 6 m3 per year ( 1.065 m3/s), 47.6x106
m3 per year (1.509 m3/s) and 16.8x106 m3 per year (0.533 m3/s) in the Komati, Mbuluzi and
,Ngwavuma catchments respectively. The saved water could be used for economic activities and
meeting Swaziland’s obligation to the down steam riparian states of South Africa and
Mozambique and therefore alleviating conflict between the riparian states.
Introduction
The greenhouse gases effect is expected to cause global warming which in turn will cause
changes in average precipitation for any region in the order of plus or minus 20%
(WMO/ICSU/UNEP, 1989). Generally it is expected that floods now considerd rare would occur
more frequently in certain regions while drought related and competing water use issues will
intensify in other regions (Miller, 1989; Shaakee, 1989; 1PCC 1990).Therefore, there is a need to
evaluate the impact of climate change on hydrology and water resources at the local level. The
assessment of the impact of expected climate change on water resources involves the use of
GCM models coupled with hydrologic models (Kunz, 1993). This approach has been used in
three catchments.
Simulation results in the three catchments for the considered climate change scenarios and for
dry, wet and average year conditions without taking into consideration of the water abstractions
are presented in Matondo et al 2003. The impact of expected climate change on hydrology and
water resources in Swaziland, while taking into consideration of the projected water demand in
the three catchments are presented in this paper.
Background information
The Kingdom of Swaziland, is situated in South Eastern Africa between the 25 th and 28th
parallels and longitudes 31o and 32o East. It lies some 48 to 225 kilometres inland of the Indian
Ocean littoral and hence physically landlocked, meaning all traffic in and out of the country has
to be routed via one of its neighbours, South Africa or Mozambique. The country has a total
surface area of 17,360 km2 and as such, the smallest country in the southern hemisphere. It is
bounded by the Republic of South Africa in the north, west and south, and by Mozambique on
the east. Although small in size, Swaziland is characterized by a great variation in landscape,
, geology and climate. It also lies within the Maputoland Centre, an area reported to have the
greatest biodiversity in Southern Africa.
There are four distinct physiographic regions within the country namely: highveld, middleveld,
lowveld and lubombo, which are clearly distinguished by elevation and relief (Murdoch, 1970).
Swaziland enjoys a climate which is generally subtropical, with hot and wet summers and cold
and dry winters. Further variations in climatic conditions occur within the different
physiographic regions giving rise to three clearly distirnguishable climate types.
The highveld and upper middleveld are characterized by a Cwb climate. The lower middleveld
and lubombo range have a Cwa climate whilst the western and eastern lowveld have a Bsh
climate (Murdoch, 1970). Mean annual rainfall ranges from about 1500 millimetres in the
highveld to a little less than 500 millimetres in the southern lowveld.
The Highveld’s temperate climate is characterized by wet summers and dry winters, and annual
rainfall averaging 1500 millimetres. Temperatures vary between a maximum of about 33 oC in
mid-summer and 0oC at night in mid-winter. On the other extreme end is the Lowveld which
experiences a sub-tropical climate. This region receives the lowest annual rainfall of about 450
mm. There is also a large diurnal temperature range experienced here with maximum
temperatures reaching the upper 30os are not uncommon. Semi-arid pockets of areas are found in
this region, which is also liable to desertification. The frequency of heavy downpours is more
uniform across Swaziland than the total rainfall. Between 75% and 83% of precipitation
(summed mean monthly amounts) comes in summer months (October – March).
The water sources in Swaziland are mainly surface waters (rivers, reservoirs), ground water and
atmospheric moisture. There are seven drainage basins in Swaziland and these are: Lomati, Komati,
Mbuluzi, Usutu, Ngwavuma, Pongola and Lubombo (see Figure 1). The latter two basins (Pongola
and Lubombo) are smaller and under utilised and their water allocation has not yet been gazatted to
be apportioned by the Water Apportionment Board, hence, there are no gauging stations in these
two basins. The Komati and Usutu basins both originate in South Africa while the rest of the basins
originate within Swaziland. It should also be noted that all the rivers in Swaziland are international
