A Closer Look at the Hydrologic Inputs
By, Tekleab Shibru Associate Professor of Geomatics, Chicago State University
Abstract
Abstract Egypt has registered an impressive diplomatic success in convincing that Ethiopia has ample alternative freshwater to Nile river water. International communities and financial institutions are effectively persuaded and built a perception, which condemns Ethiopia’s moral virtues of using Nile water, the allegedly, only source of water for 95 million Egypt’s population as well as its entire agriculture. Such perception emanates from sole Ethiopia’s highlands rainfalls pattern, sources of various transboundary rivers, supporting the livelihoods of people in neighboring downstream countries. A rather credible water resources of the two countries or sub-basins can only be assessed and compared by analyzing and accounting all relevant components of the sub-basins’ water budget. Rainfall, as side, Nile river sub-basin of these countries receives water through stream inflow, extraction of groundwater, and desalinization of seawater. While Ethiopia’s Nile river sub-basin obtains 456 BCM water per annum from rainfall, Egypt’s Nile river sub-basin receives 202 BCM of water from combined stream inflow, extraction of groundwater, and desalinization. Accordingly, although, Ethiopia edges Egypt in the amount of water received, this has evidently exposed flawedness of diplomatically pushed perception against Ethiopia’s right to use Nile water. Further inventory of other components of the sub-basin’s water budget shall only legitimize and re-enforce this right. Keywords: Nile River, Hydrologic Inputs, Sub-basin water budget, Ethiopia, Egypt.
A model showing hydrologic water budget of a watershed (Source: Gala and Young, 2015
Climate graphs of various places in the Nile sub-basins of Ethiopia (Source: climatedata
Summary
Egypt has registered an impressive diplomatic success in convincing that Ethiopia has
ample alternative freshwater to Nile river water. International communities and financial
institutions are effectively persuaded and built a perception, which condemns Ethiopia’smoral
virtues of using Nile water, the allegedly, only source of water for 95 million Egypt’s population
as well as its entire agriculture. Such perception emanates from sole Ethiopia’s highlands rainfalls
pattern, sources of various transboundary rivers, supporting the livelihoods of people in
neighboring downstream countries. A rather credible water resources of the two countries or sub-
basins can only be assessed and compared by analyzing and accounting all relevant components
of the sub-basins’ water budget. Rainfall, as side, Nile river sub-basin of these countries receives
water through stream inflow, extraction of groundwater, and desalinization of seawater. While
Ethiopia’s Nile river sub-basin obtains 456 BCM water per annum from rainfall, Egypt’s Nile river
sub-basin receives 202 BCM of water from combined stream inflow, extraction of groundwater,
and desalinization. Accordingly, although, Ethiopia edges Egypt in the amount of water received,
this has evidently exposed flawedness of diplomatically pushed perception against Ethiopia’s right
to use Nile water. Further inventory of other components of the sub-basin’swater budget shall
only legitimize and re-enforce this right.
Keywords: Nile River, Hydrologic Inputs, Sub-basin water budget, Ethiopia, Egypt.
Introduction
Egypt has gotten an impressive diplomatic upper hand with regards to Nile water resources.
The diplomacy that has created a global perception that Ethiopia has ample alternative water
resources, to need the Nile water for its development successfully. Additionally, it has skillfully
engraved, in the minds of international communities and financial institutions, that the Nile water
is the only blood line for Egypt’s social as well as economic lives. Ninety five percent of Egypt’s
100 million population depends on Nile river for drinking water and additionally, almost all
cultivated agriculture relay on irrigation from Nile water.
This perception is founded on the fact that Ethiopian highland, the source of the Nile river,
is receiving a large amount of rainfalls as compared to Egypt. Ethiopian highlands obtain rainfall
as high as 2000 mm per annum, in comparison to Egypt annual average rainfall, which in the order
200mm. This discrepancy in rainfall data is the basis for the diplomatic propaganda. It is framing
the perception that Ethiopia doesn’t need to share the Nile water resources or risk destabilizing
Egypt’s socio-economics. This emanate from a simplistic and reductionistic view, since, rainfall
data is only a part of the story of the overall water resources in both countries. The overall water
resource assessment is best accounted by the concept of hydrologic water budget (Fig. 1).
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Fig. 1: A model showing hydrologic water budget of a watershed (Source: Gala and Young,
2015)
Hydrologic water budget is an effective scientific tool for understanding water resources.
It is also a means of evaluating availability of water for a particular countryor watershed. It
provides a bases for assessing components of water regimes ofa hydrologic cycle. Generally,
water resources exist on the earth surface as ocean, lakes, wetlands and streams. It also occurs
subsurface as soil water in unsaturated zones, shallow (perched) and deep groundwater in saturated
zones. Finally, water resources also exist above the surface of the earth in the atmosphere as vapor,
cloud, fog and droplets. Generally, water is stored on the land surface, subsurface in the earth crust
and on atmosphere, as three distinct regimes of water reservoirs.
Water is in a constant movement between these regimes, through a process also known as
hydrologic cycle. Therefore, the overall water resources of a country or watershed is better
assessed when resources in these hydrologic regimes are inventoried or accounted in detail.
Hydrologic water budget facilitates the accounting of water resources as changes of water held or
stored by a watershed. It is a difference of the amount of water coming and leaving the watershed
and is represented by an equation, expressed as:
∆???? = (???? + ????????)− (???????? + ????????)
Where:
∆???? = Net in watershed’s water regime (storage)
???? = Precipitation (i.e., Rainfalls)
???????? = Inflow
???????? = Evapotranspiration
???????? = Outflow
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While rainfalls and water inflows are considered as hydrologic inputs i.e., pathways of
water gains by a watershed; the evapotranspiration and water outflow are regarded as hydrologic
outputs i.e., pathways of water loss out of a watershed. Net watershed’s water regime (storage) is,
hence, referring to the amount of water resources of the landscape, which is the function of
watershed’s hydrologic input and output. Net storage is positive when hydrologic input is higher
than the output and negative, where hydrologic input is lower than the output. Such accounting is
the only credible mechanism to assess water resources of the two countries or sub-basins and
compare. Its credibility is drawn from the assessment that integrates all relevant hydrologic
components.
Therefore, the objective of this article is to conduct detailed inventory of each hydrologic
component for Blue Nile watershed in Egypt as well as Ethiopia. First, this is to help the
understanding of dynamic water resources in two countries. Additionally, it is to ensure an
objective and credible comparison of integrated itemized hydrologic resources of each component.
The ultimate objective is to attempt to debunk the perception that Ethiopia has higher water
resources vis-à-vis Egypt.
Hydrologic Inputs
Several hydrologic input pathways are available for a watershed or country to gain water
resource. These are:
1. Precipitation (Rainfalls),
2. Extraction of Groundwater
3. Stream Inflow, and
4. Desalinization
1. Precipitation (Rainfalls)
Atmospheric air circulations are a great distributors of water vapor and other aerosols.
Water vapor is collected from areas where moisture is plentiful, carried it around for a deposition
in areas where the moisture is less plentiful. Such distribution is possible due to water-vapor’s
concentration such that water vapor moves from areas of high vapor concentration (pressure) to
areas where it is low. Precipitation (Rainfall) is a process by which water vapor held in the
atmosphere precipitate. Water vapor rises in altitude, cools adiabatically, coalesces, and condenses
into tiny droplets that the air can’t hold against earth’s gravity. Precipitation occur when these
droplets precipitate onto the earth’s surface in the form of liquid or solid.
Four major air mass systems are responsible for rainfalls formation on Ethiopia’s Nile river
sub-basin (Berhanu et al., 2014). These are Intertropical Convergence Zone (ITCZ), Tropical
Easterly Jet (TEJ), Subtropical Jet (STJ), Somali Jet (SJ) and Red Sea Convergence Zone (RSCZ).
The amount and distribution of the rainfalls the country obtained, however, depends on the
intensity of these weather systems, as conditioned by seasons, altitude and geographical location.
The average annual rainfalls vary from as low as 200 mm in the southeast, east and northeast of
the county to 1,200 mm in the central and western highlands. According to FAO land and water
bulletins (1997), the average annual rainfalls on Ethiopia’s Nile river sub basin is in the order of
~1125mm. For Ethiopia’s Nile river sub basin, with a geographical area of 405,110 km square, the
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mean annual rainfalls give the water resource equivalent to 456 billion cubic meters (BCM) per
year.
Fig. 2. Climate graphs of various places in the Nile sub-basins of Ethiopia (Source: climate-
data.org)
On the other hand, Egypt’s rain forming processes and distribution are different from the
abovementioned processes of Ethiopia’s Nile river sub basin. For Egypt’s sub-basin, the weather
system responsible for rainfall formation is the prevailing northwesterly wind during
autumn/winter and a process aided by convective system in the aftermath of storm events. The
weather system produces heavy rainfall specially in the northern coast and northeastern part of the
country. The mean annual rainfall Egypt’s Nile river sub-basin receives ranges from 100 mm and
200 mm in the Mediterranean coast; to 50 mm and 100 mm in the Nile Delta.
According to FAO report 1997, out of the total inhabited area of 77,041 km; cultivated area
of Egypt constitute 11 million feddans (i.e., where 1 feddan = 0.42 ha) of lands; which is equitant
to 46200 km2. Almost all cultivated lands are confined to Nile valley and Delta irrigated with
water. Therefore, only considering cultivable and inhabited areas, where the overall mean annual
rainfall is estimated to average at 150 mm (Ibrahim, and Afandi, 2014), the total amount of water
resources of Egypt’s Nile river sub-basin receives from rainfall is in the order of 12 BCM of water
per year.
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Fig. 2. Climate graphs of various places in the Nile Delta of Egypt (Source: climate-data.org)
2. Stream inflow
The inflow is sheet or channelized water movement on the surface as streams, rivers and
other forms of topographies. The movement on the landscape isin response to gravitational force
and topographic gradient. It is water resources gained of a watershed and the rate is a function of
an ambient weather condition. Inflows are the main source of Egypt sub-basin’s irrigation as well
as drinking water is an inflow. According to Water Systems Analysis Research Group of the
university of New Hampshire, Egypt receives the net inflow of Nile water at rate up to 12229 m3/s
and on average 2622 m3/s. These are equivalent to 386 BCM and 84.6 BCM per year of water;
respectively. Even after the Nile river flows for more than 900 km in Egyptian desert, still
discharge gauge at Ekhsase, north of Cairo, records flow rates as much as 59 BCM and on average
39 BCM per year of water.
3. Extraction of Groundwater
Apart from the Nile river inflow and precipitation, Egypt also explores alternative sources
of water. These are extraction of groundwater resources and desalinization of seawater.
Groundwater is the water found in saturated zones beneath the surface of the earth. Hence,
groundwater extraction is the process of mining this water from the saturated zone. The process
brings water up to the surface for domestic consumption. This can happen naturally in areas where
the water-table and landscape intersect. It is also harvested through a well installed to pump
groundwater from saturated zones. No literature is available on groundwater use of Ethiopia.
However, according to Mohie and Moussa (2016), Egypt is annually extracting 2.5 BCM and 6.5
BCM from non-renewable deep as well as shallow groundwater, respectively.
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4. Desalinization
Desalinazation is the process of removing excess salts and other minerals from seawater in order to produce a usable for drinking and irrigation water. Seawater is boiled to turn into steam
so that salt and other mineral are filtered for table salt production. Once the salt is separated, the steam is condensed back into liquid water and harvested for domestic water supply. Using several desalination plants, Egypt is currently recovering water resource that, approximately, amounted to one BCM of water per year (Desalination.biz, 2019). Ethiopia’s lack of access to seawater will permanently bares the country from having any chance of current and future exploitation of desalinzation.
Conclusion
This article has conducted detailed inventory of the hydrologic inputs of Egypt’s as well as Ethiopia’s Nileriver basin. Accordingly, Ethiopia’s Nile river sub-basin receive an overall
hydrologic input in the order of 456 BCM water per annum, mainly from rainfalls. On the other hand, the overall hydrologic input to the water budget Egypt’s Nile river sub-basin is 12 BCM of water from rainfalls, 84 BCM of water from Nile river inflow, 9 BCM of water from groundwater extraction and 1 BCM of water from desalinization. This is equivalent to 202 BCM of water per year. This is 234 BCM lower than Ethiopia’s and is almost 1/2 of the amount Ethiopia’s Nile river sub-basin receives. However, though the discrepancy is there, it is abundantly clear that the validity of the global perception of Ethiopia’s water plentiful is exposed. The perception is based on simplistic overview and an overwhelmingly exaggeration of precipitation component of hydrologic water budget. A more inconvenient truths shall be revealed with further inventory of
the other components of the water budget. Therefore, it is critical for the international communities and financial institutions to scientifically fact-check, before condemning the moral virtue of Ethiopia’s use of Nile river resources.
References:
Berhanu, B., Seleshi, Y., & Melesse, A. M. (2014). Surface water and groundwater resources of Ethiopia: potentials and challenges of water resources development. In Nile River Basin (pp. 97-117). Desalination.biz (20 February 2019), Egypt expedites 16 desalination projects, Water desalinization and reuse accessed on May 2020 from Gala, T. S., & Young, D. (2015). Geographically isolated depressional wetlands– hydrodynamics, ecosystem functions and conditions. Science and Education, 3(4), 108-116. Ibrahim, S., & Afandi, G. (2014). Short-range rainfall prediction over Egypt using the weather research and forecasting model. Open Journal of Renewable Energy and Sustainable Development, 1(2). Land, F. A. O. (1997). Irrigation potential in Africa; A basin approach. 4. Mohie El Din, M. O., & Moussa, A. M. (2016). Water management in Egypt for facing the future challenges. Journal of advanced research, 7(3), 403-41