JPCE 1070 No. of Pages 7, Model 5+
ARTICLE IN PRESS
8 September 2005 Disk Used
Physics and Chemistry of the Earth xxx (2005) xxx–xxx
www.elsevier.com/locate/pce
2 Managing water under climate change for peace
3 and prosperity in Swaziland
F
a,*
4 Jonathan I. Matondo , Graciana Peter a, Kenneth M. Msibi b
OO
a
5 Department of Geography, Environmental Science and Planning, University of Swaziland, Private Bag 4, Kwaluseni, Swaziland
b
6 Water Resources Branch, Swaziland
Accepted 15 August 2005
PR
9 Abstract
10 The enhanced greenhouse gas effect is expected to cause high temperature increase globally (1.0–3.5 C) and this will lead to an
11 increase in precipitation in some regions while other regions will experience reduced precipitation (±20%). The impact of expected cli-
ED
12 mate change will affect almost all aspects of human endeavour. The major focus of this paper is management of water resources under
13 climate change for peace and prosperity in Swaziland. The impact of climate change on hydrology and water resources has been eval-
14 uated using general circulation model (GCM) results (rainfall, potential evapotranspiration, air temperature, etc.) as inputs to a rainfall
15 runoff model. The evaluation of the effect of climate change on hydrology and water resources in Swaziland has been carried out in three
16 catchments namely: Mbuluzi, Komati and Ngwavuma.
CT
17 MAGICC model was used to simulate the climate parameters for Swaziland given the baseline conditions. Eleven GCMs were used
18 and three of them were found to simulate very well the observed precipitation for Swaziland. These GCMs are: the Geophysical Fluid
19 Dynamics Laboratory (GFDL), the United Kingdom Transient Resalient (UKTR) and the Canadian Climate Change Equilibrium
20 (CCC-EQ). The three GCMs were used to project the temperature and precipitation changes for Swaziland for year 2075. This infor-
21 mation was used to generate the temperature, precipitation and potential evapotranspiration values for the three catchments for year
E
22 2075. This information was used as input data to a calibrated WatBall rainfall runoff model. Simulation results (after taking into con-
23 sideration water use projections) show a water deficit from June to September in both the Komati and Ngwavuma catchments and a
RR
24 water deficit from May to September in the Mbuluzi catchment. Efficient water utilization in the agricultural sector (i.e., using drip
25 irrigation) gives a water savings of 33.6 · 106 m3per year (1.065 m3/s), 47.6 · 106 m3per year (1.509 m3/s) and 16.8 · 106 m3 per year
26 (0.533 m3/s) in the Komati, Mbuluzi and Ngwavuma catchments, respectively. The saved water could be used for other economic activ-
27 ities and meeting SwazilandÕs water release obligations to downstream riparian states of South Africa and Mozambique.
28 2005 Published by Elsevier Ltd.
CO
29 Keywords: Greenhouse gases; Climate change; General circulation models; Watball model; Simulation results; Efficient water utilization
30
31 1. Introduction tain regions while drought related and competing water 37
UN
use issues will intensify in other regions (Miller, 1989; 38
32 The greenhouse gases effect is expected to cause global Shaakee, 1989; IPCC, 1990). Therefore, there is a need to 39
33 warming which in turn will cause changes in average pre- evaluate the impact of climate change on hydrology and 40
34 cipitation for any region in the order of ±20% (WMO/ water resources at the local level. The assessment of the im- 41
35 ICSU/UNEP, 1989). Generally it is expected that floods pact of expected climate change on water resources in- 42
36 now considered rare would occur more frequently in cer- volves the use of GCM models coupled with hydrologic 43
models (Kunz, 1993). This approach has been used in three 44
catchments. 45
*
Corresponding author. Tel.: +268 604 3070; fax: +268 518 5276.
E-mail address: (J.I. Matondo).
1474-7065/$ - see front matter 2005 Published by Elsevier Ltd.
doi:10.1016/j.pce.2005.08.041
, JPCE 1070 No. of Pages 7, Model 5+
ARTICLE IN PRESS
8 September 2005 Disk Used
2 J.I. Matondo et al. / Physics and Chemistry of the Earth xxx (2005) xxx–xxx
46 Simulation results in the three catchments for the con-
47 sidered climate change scenarios and for dry, wet and aver-
48 age year conditions without taking into consideration
49 water abstractions that are presented in Matondo et al.
50 (2004). The impact of expected climate change on hydrol-
51 ogy and water resources in Swaziland, while taking into
52 consideration the projected water demand in the three
53 catchments, are presented in this paper.
54 2. Background information
F
55 The Kingdom of Swaziland is situated in South Eastern
OO
56 Africa between the 25th and 28th parallels and longitudes
57 31 and 32 East. It lies some 48–225 km inland of the In-
58 dian Ocean littoral and hence physically landlocked, mean-
59 ing all traffic in and out of the country has to be routed via
60 one of its neighbours, South Africa or Mozambique. The
country has a total surface area of 17,360 km2 and as such
PR
61
62 is the smallest country in the southern hemisphere.
63 It is bounded by the Republic of South Africa in the Fig. 1. Drainage basin of Swaziland.
64 north, west and south, and by Mozambique on the east.
65 Although small in size, Swaziland is characterized by a
Komati and Usutu basins both originate in South Africa 101
66 great variation in landscape, geology and climate. It also
while the rest of the basins originate within Swaziland. It 102
ED
67 lies within the Maputoland Centre, an area reported to
should also be noted that all the rivers in Swaziland are 103
68 have the greatest biodiversity in southern Africa.
international rivers and therefore development of surface 104
69 There are four distinct physiographic regions within the
water resources must be undertaken in collaboration with 105
70 country namely: highveld, middleveld, lowveld and lubom-
the other riparian states namely, South Africa and 106
71 bo, which are clearly distinguished by elevation and relief
CT
Mozambique. 107
72 (Murdoch, 1970). SwazilandÕs climate is generally subtrop-
73 ical, with hot and wet summers and cold and dry winters.
3. Methodology 108
74 Further variations in climatic conditions occur within the
75 different physiographic regions giving rise to three clearly
The expected climatic changes due to anthropogenic 109
E
76 distinguishable climate types.
activities will cause global warming. The effects of global 110
77 The HighveldÕs temperate climate is characterized by
warming will bring changes in annual average precipitation 111
RR
78 wet summers and dry winters, and annual rainfall averag-
values in the order of ±20% (IPCC, 1990). Extreme events 112
79 ing 1500 mm. Temperatures vary between a maximum of
(droughts and floods) now considered rare will occur more 113
80 about 33 C in mid-summer and 0 C at night in mid-
frequently in certain regions. General circulation models 114
81 winter. At the other extreme, is the Lowveld which experi-
(GCMs) provide physically based predictions of the way 115
82 ences a sub-tropical climate. This region receives the lowest
climate might change as a result of increasing concentra- 116
CO
83 annual rainfall of about 450 mm. There is also a large diur-
tions of atmospheric carbon dioxide and other trace gases. 117
84 nal temperature range experienced here with maximum
The GCMs are mathematically representative of the earthÕs 118
85 temperatures often reaching the upper 30 C. Semi-arid
climate system and they simulate atmospheric processes at 119
86 pockets of areas are found in this region, which is also
a field of grid points that cover the surface of the earth 120
87 liable to desertification. The frequency of heavy downpours
(IPCC, 1996). 121
UN
88 is more uniform across Swaziland than the total rainfall.
Census records of 1997 were used in determining the 122
89 Between 75% and 83% of precipitation (summed mean
population in each of the three catchments. The catchment 123
90 monthly amounts) comes in summer months (October–
area was superimposed to the census remuneration maps 124
91 March).
and thus determining the population within the catchment. 125
92 The water sources in Swaziland are mainly surface
The population was divided into two groups (rural and ur- 126
93 waters (rivers, reservoirs), ground water and atmospheric
ban), based on differences in water consumption. Livestock 127
94 moisture. There are seven drainage basins in Swaziland
population (cattle) was determined using information from 128
95 and these are: Lomati, Komati, Mbuluzi, Usutu, Ngwavuma,
dipping tanks located within the catchment. Table 1 shows 129
96 Pongola and Lubombo (see Fig. 1). The latter two basins
the demographic information in the three catchments. 130
97 (Pongola and Lubombo) are smaller and under utilised
The impact of expected climate change on hydrology 131
98 and their water allocation has not yet been gazetted to be
and water resources is evaluated at year 2075 while taking 132
99 apportioned by the Water Apportionment Board, hence,
into consideration of the expected water abstractions. 133
100 there are no gauging stations in these two basins. The
ARTICLE IN PRESS
8 September 2005 Disk Used
Physics and Chemistry of the Earth xxx (2005) xxx–xxx
www.elsevier.com/locate/pce
2 Managing water under climate change for peace
3 and prosperity in Swaziland
F
a,*
4 Jonathan I. Matondo , Graciana Peter a, Kenneth M. Msibi b
OO
a
5 Department of Geography, Environmental Science and Planning, University of Swaziland, Private Bag 4, Kwaluseni, Swaziland
b
6 Water Resources Branch, Swaziland
Accepted 15 August 2005
PR
9 Abstract
10 The enhanced greenhouse gas effect is expected to cause high temperature increase globally (1.0–3.5 C) and this will lead to an
11 increase in precipitation in some regions while other regions will experience reduced precipitation (±20%). The impact of expected cli-
ED
12 mate change will affect almost all aspects of human endeavour. The major focus of this paper is management of water resources under
13 climate change for peace and prosperity in Swaziland. The impact of climate change on hydrology and water resources has been eval-
14 uated using general circulation model (GCM) results (rainfall, potential evapotranspiration, air temperature, etc.) as inputs to a rainfall
15 runoff model. The evaluation of the effect of climate change on hydrology and water resources in Swaziland has been carried out in three
16 catchments namely: Mbuluzi, Komati and Ngwavuma.
CT
17 MAGICC model was used to simulate the climate parameters for Swaziland given the baseline conditions. Eleven GCMs were used
18 and three of them were found to simulate very well the observed precipitation for Swaziland. These GCMs are: the Geophysical Fluid
19 Dynamics Laboratory (GFDL), the United Kingdom Transient Resalient (UKTR) and the Canadian Climate Change Equilibrium
20 (CCC-EQ). The three GCMs were used to project the temperature and precipitation changes for Swaziland for year 2075. This infor-
21 mation was used to generate the temperature, precipitation and potential evapotranspiration values for the three catchments for year
E
22 2075. This information was used as input data to a calibrated WatBall rainfall runoff model. Simulation results (after taking into con-
23 sideration water use projections) show a water deficit from June to September in both the Komati and Ngwavuma catchments and a
RR
24 water deficit from May to September in the Mbuluzi catchment. Efficient water utilization in the agricultural sector (i.e., using drip
25 irrigation) gives a water savings of 33.6 · 106 m3per year (1.065 m3/s), 47.6 · 106 m3per year (1.509 m3/s) and 16.8 · 106 m3 per year
26 (0.533 m3/s) in the Komati, Mbuluzi and Ngwavuma catchments, respectively. The saved water could be used for other economic activ-
27 ities and meeting SwazilandÕs water release obligations to downstream riparian states of South Africa and Mozambique.
28 2005 Published by Elsevier Ltd.
CO
29 Keywords: Greenhouse gases; Climate change; General circulation models; Watball model; Simulation results; Efficient water utilization
30
31 1. Introduction tain regions while drought related and competing water 37
UN
use issues will intensify in other regions (Miller, 1989; 38
32 The greenhouse gases effect is expected to cause global Shaakee, 1989; IPCC, 1990). Therefore, there is a need to 39
33 warming which in turn will cause changes in average pre- evaluate the impact of climate change on hydrology and 40
34 cipitation for any region in the order of ±20% (WMO/ water resources at the local level. The assessment of the im- 41
35 ICSU/UNEP, 1989). Generally it is expected that floods pact of expected climate change on water resources in- 42
36 now considered rare would occur more frequently in cer- volves the use of GCM models coupled with hydrologic 43
models (Kunz, 1993). This approach has been used in three 44
catchments. 45
*
Corresponding author. Tel.: +268 604 3070; fax: +268 518 5276.
E-mail address: (J.I. Matondo).
1474-7065/$ - see front matter 2005 Published by Elsevier Ltd.
doi:10.1016/j.pce.2005.08.041
, JPCE 1070 No. of Pages 7, Model 5+
ARTICLE IN PRESS
8 September 2005 Disk Used
2 J.I. Matondo et al. / Physics and Chemistry of the Earth xxx (2005) xxx–xxx
46 Simulation results in the three catchments for the con-
47 sidered climate change scenarios and for dry, wet and aver-
48 age year conditions without taking into consideration
49 water abstractions that are presented in Matondo et al.
50 (2004). The impact of expected climate change on hydrol-
51 ogy and water resources in Swaziland, while taking into
52 consideration the projected water demand in the three
53 catchments, are presented in this paper.
54 2. Background information
F
55 The Kingdom of Swaziland is situated in South Eastern
OO
56 Africa between the 25th and 28th parallels and longitudes
57 31 and 32 East. It lies some 48–225 km inland of the In-
58 dian Ocean littoral and hence physically landlocked, mean-
59 ing all traffic in and out of the country has to be routed via
60 one of its neighbours, South Africa or Mozambique. The
country has a total surface area of 17,360 km2 and as such
PR
61
62 is the smallest country in the southern hemisphere.
63 It is bounded by the Republic of South Africa in the Fig. 1. Drainage basin of Swaziland.
64 north, west and south, and by Mozambique on the east.
65 Although small in size, Swaziland is characterized by a
Komati and Usutu basins both originate in South Africa 101
66 great variation in landscape, geology and climate. It also
while the rest of the basins originate within Swaziland. It 102
ED
67 lies within the Maputoland Centre, an area reported to
should also be noted that all the rivers in Swaziland are 103
68 have the greatest biodiversity in southern Africa.
international rivers and therefore development of surface 104
69 There are four distinct physiographic regions within the
water resources must be undertaken in collaboration with 105
70 country namely: highveld, middleveld, lowveld and lubom-
the other riparian states namely, South Africa and 106
71 bo, which are clearly distinguished by elevation and relief
CT
Mozambique. 107
72 (Murdoch, 1970). SwazilandÕs climate is generally subtrop-
73 ical, with hot and wet summers and cold and dry winters.
3. Methodology 108
74 Further variations in climatic conditions occur within the
75 different physiographic regions giving rise to three clearly
The expected climatic changes due to anthropogenic 109
E
76 distinguishable climate types.
activities will cause global warming. The effects of global 110
77 The HighveldÕs temperate climate is characterized by
warming will bring changes in annual average precipitation 111
RR
78 wet summers and dry winters, and annual rainfall averag-
values in the order of ±20% (IPCC, 1990). Extreme events 112
79 ing 1500 mm. Temperatures vary between a maximum of
(droughts and floods) now considered rare will occur more 113
80 about 33 C in mid-summer and 0 C at night in mid-
frequently in certain regions. General circulation models 114
81 winter. At the other extreme, is the Lowveld which experi-
(GCMs) provide physically based predictions of the way 115
82 ences a sub-tropical climate. This region receives the lowest
climate might change as a result of increasing concentra- 116
CO
83 annual rainfall of about 450 mm. There is also a large diur-
tions of atmospheric carbon dioxide and other trace gases. 117
84 nal temperature range experienced here with maximum
The GCMs are mathematically representative of the earthÕs 118
85 temperatures often reaching the upper 30 C. Semi-arid
climate system and they simulate atmospheric processes at 119
86 pockets of areas are found in this region, which is also
a field of grid points that cover the surface of the earth 120
87 liable to desertification. The frequency of heavy downpours
(IPCC, 1996). 121
UN
88 is more uniform across Swaziland than the total rainfall.
Census records of 1997 were used in determining the 122
89 Between 75% and 83% of precipitation (summed mean
population in each of the three catchments. The catchment 123
90 monthly amounts) comes in summer months (October–
area was superimposed to the census remuneration maps 124
91 March).
and thus determining the population within the catchment. 125
92 The water sources in Swaziland are mainly surface
The population was divided into two groups (rural and ur- 126
93 waters (rivers, reservoirs), ground water and atmospheric
ban), based on differences in water consumption. Livestock 127
94 moisture. There are seven drainage basins in Swaziland
population (cattle) was determined using information from 128
95 and these are: Lomati, Komati, Mbuluzi, Usutu, Ngwavuma,
dipping tanks located within the catchment. Table 1 shows 129
96 Pongola and Lubombo (see Fig. 1). The latter two basins
the demographic information in the three catchments. 130
97 (Pongola and Lubombo) are smaller and under utilised
The impact of expected climate change on hydrology 131
98 and their water allocation has not yet been gazetted to be
and water resources is evaluated at year 2075 while taking 132
99 apportioned by the Water Apportionment Board, hence,
into consideration of the expected water abstractions. 133
100 there are no gauging stations in these two basins. The
