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Machar Marshes: Nile Basin (South Sudan)
Chapter · January 2016
DOI: 10.1007/978-94-007-6173-5_220-1
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Machar Marshes: Nile Basin (South Sudan)
Yasir A. Mohamed
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The Natural Resources of the Machar Marshes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cross-References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Abstract
The Machar marshes are the major wetland in the Sobat basin, in South Sudan.
The Sobat is a tributary of the White Nile originates from the Ethiopian highlands.
The wetland formed by the spill from the Baro River and the inflows from the
eastern torrents (Yabus and Daga). The Machar marshes is an important ecosystem, supports rich flora and fauna in the area, as well as a grazing land for the
Nilotic tribes of South Sudan. Unlike other wetlands in Southern (e.g., Sudd), the
Machar marshes is the least monitored and understood. The literature shows
different estimates of the flooded area, varies between 3350 and 20,000 km2.
This chapter provides a description of the Machar marshes, its biodiversity and
the water resources system, as well the key challenges for conservation and/or
development of the marshes.
Y.A. Mohamed (*)
Hydraulic Research Center, MoWRIE, Wad Medani,, Sudan
Department of Integrated Water Systems and Governance, UNESCO-IHE, DA, Delft, The
Netherlands
Faculty of Civil Engineering and Applied Geosciences, Water Resources section, Delft University
of Technology, GA, Delft, The Netherlands
e-mail: y.mohamed@hrc-sudan.sd
# Springer Science+Business Media Dordrecht 2016
C.M. Finlayson et al. (eds.), The Wetland Book,
DOI 10.1007/978-94-007-6173-5_220-1
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Y.A. Mohamed
Keywords
Machar marshes • Nile • Wetland • Biodiversity • South Sudan
Introduction
The Machar wetland known as the “Machar marshes” is the largest wetland in the
Baro-Akobo-Sobat subbasin (BAS), one of the major subbasins of the Nile (Fig. 1).
The wetland is located in South Sudan, to the east of the famous Sudd wetland. The
Fig. 1 Location map, showing the position of the Machar marshes (inset) in the Nile River Basin.
(Nile River Basin map: Map Design Unit of the World Bank; inset map by the author)
Machar Marshes: Nile Basin (South Sudan)
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literature shows different wetland size varying between 3,500 and 6,500 km2. Large
spills of water from the Baro River, which originates from the Ethiopian highlands,
find their way to the Machar marshes during the flood season from July to
September. In addition, significant inflows from torrential tributaries, namely the
Yabus and Dagga, end up in the marshes. Only a small percentage of the water drains
downstream to the White Nile through Khor Adar. The topography of the Machar
marshes is characterized by very flat slopes, of less than 1 %.
The climate and vegetation cover of the Machar marshes are dominated by the
seasonal flooding of the swampy plains. The temperature ranges from 20 C to
35 C, with extremes of 11–43 C. The annual rainfall over the marshes is about
800 mm/year, while the actual evapotranspiration over the wider catchment around
the Machar marshes is 1,300 mm/year (Mohamed et al. 2004). However, the
potential evapotranspiration is much higher than actual.
The hydrology of the BAS basin is very complex and the least understood among
the other subbasins of the Nile. Numerous rivers join and bifurcate along the flat
slopes of the basin, in particular over the plains of South Sudan. There are very
limited ground measurements of river levels and discharges. The literature shows
few studies on the Machar marshes, mainly investigating the water balance of the
marshes, and potential water savings (JIT 1954; El-Hemry and Eagelson 1980;
Sutcliffe 1993; WaterWatch 2006). Those studies show no consensus regarding the
derived estimates of wetland area, water volume, or evaporation losses.
The area of the Machar marshes is a home to hundreds of thousands of people
from the Nilotic tribes – the Dinka, Nuer and Shuluk, as well as other tribes – the
Morlei and Anjwak. These are nomadic tribes that migrate with their cattle to and
from the “toich,” the local word for grazing land. It is also a home of the unique
Mangala Ghazals (ancient poetic form), named after the town of Mangala in South of
Sudan. The Machar marshes have a very rich biodiversity, and the region of the
marshes, as well as the larger BAS, is characterized by very limited or no infrastructural development. Accessibility to the marshes during the rainy season is only
possible by air. Tall grasses and shallow water depth allow no navigation during
the rainy season.
The Natural Resources of the Machar Marshes
Biodiversity
The BAS basin includes numerous wetlands, of which the Machar marshes are the
largest. The Machar marshes provide habitats supporting a very rich flora and fauna.
The seasonal climatic variation from the wet rainy season (June to October), to a
long dry season (November to May), plus seasonal river spills into the marshes
provides the marshes with their unique alternating wet/dry habitat characteristics.
Three zones of land cover exist in the Machar area: permanent wetlands only in the
deepest parts of the water bodies, seasonal flood plains inundated due to river spills
and rainfall, and the dry areas at the fringes. While Acacia trees and scattered shrubs
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Y.A. Mohamed
Fig. 2 Land and water use types in the Baro-Akobo-Sobat basin around Machar marshes (map by
the author)
exist in the fringes of the marshes, papyrus and tall grass dominate the permanent
water bodies. The main land use types in the Machar area are shown in Fig. 2,
including grassland, savannah, open shrub land, and limited permanent wetlands.
The Machar marshes provide rich habitats supporting a very wide range of
wildlife species, in particular on the seasonally flooded grasslands, including
Tiang Damaliscus lunatus; White-Eared Kob Kobus kob ssp. leucotis, Hartebeest
Alcelaphus buselaphus, and Oribi Ourebia ourebi are found in large numbers.
The ecosystem of the marshes provides essential services to the rural communities living in the area. The seasonal flood plains of the marshes are the main grazing
lands for the local Nilotic Nuer, Morle, and Dinka tribes. The forest is the main
source of building materials and energy for the rural communities. The livelihoods of
tens of thousands of the people living alongside the marshes depend on fish
resources as an important source of protein. However, available information about
the natural resources, including water, land, biodiversity, and ecosystem services,
remains very scarce.
Water Resources
The drainage network of the Machar marshes and BAS in general is very complex,
see Fig. 3. Although clear river channels drain the high mountains of the Ethiopian
Machar Marshes: Nile Basin (South Sudan)
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Fig. 3 The drainage system of the Baro-Akobo-Sobat basin and the Machar marshes (map by the
author)
Plateau flowing from east to west, the river courses become indistinct and spill at a
number of places in the plains of South Sudan.
The Machar marshes are formed because of the excessive spills from the Baro
River, inflows from Eastern Torrents (Yabus, Daga), and rainfall over the wetland
itself. Sutcliffe and Parks (1999) indicated the occurrence of spills from the Baro
River if the flow at the upstream gauging station of Gambela exceeds 1.5 km3/
month. This threshold of 1.5 km3/month was estimated by comparing the measured
river flows at the upstream and downstream stations of Gambela and the Baro River
mouth, respectively. Depending on the Baro River flows at Gambela, the spill to
Machar marshes varies considerably between a minimum of 1 km3/year up to 7 km3/
year for years with high floods. Average inflow to the Machar marshes from Yabus,
Daga and other streams was estimated as 1.7 km3/year (JIT 1954).
The computation of the water balance of the Machar marshes may give a fair idea
about the water resources potential of the wetland. The main components of the
water balance are: (i) spills from the Baro river, (ii) inflow from the eastern torrents,
Yabus and Daga, (iii) rainfall over the marshes (Fig. 4a), (iv) evapotranspiration (ET)
(Fig. 4b), and (v) outflows through Khor Adar and other streams to the White Nile,
or to the lower Sobat. However, little is known about the areal extent of the Machar
marshes. Consequently, quantifying the water balance has been difficult. It is not
uncommon to see different definitions or delineations of the Machar wetlands and
hence different results of water balance computations (see Table 1).
The large variation in the estimate of the water gain from the Machar marshes,
from 1 to 8 km3/year, indicates the high uncertainty of the available results.
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Y.A. Mohamed
Fig. 4 Annual rainfall and actual evapotranspiration (ETa) over the Machar area in mm/year for
2007 (graphics by the author)
However, most literature agrees on 4 km3/year as an average potential water saving
from the Machar marshes.
Various studies estimated an annually flooded area (swamp and grassland)
between 3,350 and 20,000 km2. Using Landsat imagery, El-Hemry and Eagleson
(1980) estimated the area of the swamps as 8,700 km2, while FAO Africover gives
only 2,913 km2 of permanently and seasonal swamps. Hurst (1950) estimated the
area of swamp as 6,500 km2. Sutcliffe and Parks (1999) estimated the area of
inundated land using a water balance model to vary between 1,500 and 6,000 km2.
Recent analysis of satellite images to assess wetland area in South Sudan showed
that the Machar marshes are mostly seasonal and not permanent swamps (Mohamed
et al. 2004). In fact the (actual) evaporation from the Machar marshes significantly
drops during the dry season, resulting in smaller annual ETa compared to the
neighboring Sudd wetlands. The study by Water Watch (2006) indicated a wetland
area of up to 12,346.7 km2. The disagreements regarding the area of the Machar
marshland reflect the current limited level of understanding.
Future Challenges
The Machar marshes are a very important seasonal wetland in South Sudan, fed by
rivers originating from the Ethiopian highlands. The Machar area has not seen
development in recent history, because of its harsh environment and also instability
in the area. The people living in the Machar area are among the poorest in the Nile
Basin. Competition for grazing land and water sources is not uncommon in the area.
Regional plans for water resources development have been started by the Eastern
Nile Technical Regional Office (ENTRO). This includes storage dams upstream on
the Ethiopian side of the Baro River. The strong dependency of communities on the
El-Hemry and
Eagelson 1980
Sutcliffe 1993
WaterWatch 2006
Investigator
JIT 1954
Measurements, water balance
ET from Satellite images,
Methodology
Measurements, water balance,
aerial surveys, site visits
Water balance, landsat images
2.3
3.5
Spills
from
Baro
km3/yr
2.8
1.7
5.6
Inflow
from East
km3/yr
1.7
Table 1 Water balance results of the Machar marshes according to different researchers
0.12
0.1
Outflow to
W. Nile
km3/yr
0.1
~4
Gain from
Machar = 1
~8
Water saving
potential
km3/yr
~4
3350
?
3500
Machar
marshes area
km2
?
Area could not be
delineated
Remarks
No evidence for
area
Over-estimated
Machar Marshes: Nile Basin (South Sudan)
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Y.A. Mohamed
area’s natural resources requires critical assessment of the impacts of future interventions in the BAS basin.
The natural resources system of the Machar marshes, and the hydrology in
particular, is not clearly understood. The literature has shown different results of
water resources potential in the Machar area. The major part of the river system is not
gauged, and even the installed gauges at key locations have not been operational
most of the time. Therefore, it is strongly recommended to create a knowledge base
of the natural resources of the Machar area, to inform wetland conservation and
future development planning. Because of the very difficult accessibility to the
Machar marshes, remote sensing techniques can be a useful source of information.
Cross-References
▶ Bahr el Ghazal: Nile River Basin (Sudan and South Sudan)
▶ Baro-Akobo River Basin Wetlands: Livelihoods and Sustainable Regional Land
Management (Ethiopia)
▶ Nile Delta (Egypt)
▶ The Mayas Wetlands of the Dinder and Rahad: Tributaries of the Blue Nile Basin
(Sudan)
▶ The Nile River Basin
▶ The Rugezi Marsh: A High Altitude Tropical Peatland in Rwanda
▶ The Sudd (South Sudan)
References
Africover http://www.glcn.org/activities/africover_en.jsp
El-Hemry II, Eagleson PS. Water balance estimates of the Machar Marshes. Cambridge, MA:
Department of Civil Engineering, Massachusetts Institute of Technology; 1980. Report no. 260.
Jonglei Investigation Team. The Equatorial Nile project and its effects in the Anglo-Egyptian
Sudan: Being the report of the Jonglei Investigation Team. Khartoum; 1954.
Mohamed YA, Bastiaanssen WGM, Savenije HHG. Spatial variability of evaporation and moisture
storage in the swamps of the upper Nile studied by remote sensing techniques. J Hydrol.
2004;289:145–64.
Sutcliffe JV. Hydrological regimes and vegetation of Nile basin wetlands. In: Regional Conf. on
Environmentally Sound Management of the Upper Nile Watershed (Khartoum); 1993.
Sutcliffe JV, Parks YP. The hydrology of the Nile, IAHS Special Publication No. 5. Wallingford/
Oxfordshire: IAHS Press/Institute of Hydrology; 1999. http://iahs.info/bluebooks/SP005.htm
WaterWatch. Wetland evaporation in the Baro-Akobo Basin. Technical report prepared for ENSAP;
2006.
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