St project final

Lake level change in the main Ethiopian rift valley using multi-temporal imageries
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ADDIS ABABA UNIVERSITY
COLLAGE OF NATURAL SCIENCE
GRADUATE STUDIES UNDER SCHOOL OF EARTH SCIENS
Stream: Remote sensing and Geoinformatics
Lake level change in the main Ethiopian rift valley using multi-temporal
satellite imageries
By: Tewabe Melka
ID:GSR/ 6217/10
SUBMITED TO: Dr.Bekele Abebe

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Abstract
The Main Ethiopian Rift Valley lakes suffer from water level change due to several natural and
anthropogenic factors. These fluctuations are disturbing the stability of the ecosystems, putting very
serious impacts on the lives of many animals and plants around the lakes. Hence, studying the
hydrodynamics of the lakes was found to be very essential. The main purpose of this study is to
know which lakes show significant water level change and quantify tha amount of surface area change
fom year to year.The research methodology is based on multi-temporal satellite image analysis using
15 year interval .The data taken at dray season to avoide the effect of high recharge efect.The results of
the study revealed that much of the rift valley lakes show decreasing water level. especially lakes
in the Central Ethiopian Rift, Lake Ziway , Abiyata, Langano and shalla are declining . Among them
Abiyata is drastically reduced in size (about 120 km 2
from 1973-2017). In the southern Rift ,lake
Abaya and Hawassa are rising ,while lake chamo is declining .However lake hawasa show increasing
trend from 1973-1989 but now it become decreasing.Lakes in awash river basin , lake Beseka ,which is
under concideration in this study showes significant water level change in an increasing trend .It increase
a size of 37km2
from 1973-2017.

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Table of Contents
Introduction .................................................................................................................Error! Bookmark not defined.
1.1 Background..................................................................................................................................................1
1.2 Importance of the study..............................................................................................................................1
1.3 Objectives..........................................................................................................................................................2
1.3.1 Main objective…………………………………………………………………………………………………………… 2
1.3.2 Specific objective …………………………………………………………………………………………………………2
2. Approach and Methodology ...................................................................................................................................2
2.1. Data Collection.................................................................................................................................................2
2.2. Preprocessing...................................................................................................................................................3
3. General overview of the study area........................................................................................................................3
3.1 General..............................................................................................................................................................3
3.2 Geological and geomorphological characterizations........................................................................................5
3.3 Climate of the rift valley basin ..........................................................................................................................6
3.4 General hydrology of the lakes under consideration........................................................................................7
4. Data analysis and presentation...............................................................................................................................8
4.1 Northern rift valley lake ...................................................................................................................................8
4.1.1 Lake Beseka………………………………………………………………………………………………………………….8
4.2 Central rift valley lakes....................................................................................................................................10
4.2.1 Lake Ziway…………………………………………………..……………………………………………………………..10
4.2 .2 Lake Abiyata……………………………………………………………………………………………………………… 11
4.2. 3 Lake Langno……………………………………………………………………………………………………………….. 11
4.2. 4 Lake Shala…………………………………………………………………………………………………………………..11
4.3 Southern rift valley lakes.................................................................................................................................16
4.3.1 Lake Hawassa……………………………………………………………………………………………………………….16

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-
4.3.2 Lake Abaya…………………………………………………………………………………………………………………. 17
4.3.3 Lake Chamo………………………………………………………………………………………………………………….17
5.Counclusion and Recommendation .......................................................................................................................24
5.1 Conclusions......................................................................................................................................................24
5.2 Recommendations ..........................................................................................................................................24
Reference ..............................................................................................................................................................25
List of Tables
Table 1. Specifications of the data used for analysis…………………………………………………………..2
Table 2. Lake lavel changes for Lakes Beseka in square kilometers (km2
……………………………..10
Table 3. Lake lavel changes for Lakes Ziway ,Abjata, Langano and Shala in square kilometers ..15
Table 4. Lake lavel changes for Lakes Hawasa, Abaya and Chamo in square kilometers (km2
)…22
List of Figures
Figure 1 :location map of the study area..............................................................................................4
Figure 2 :Tmporal image of lake Beseka ................................................Error! Bookmark not defined.
Figure 3: Map shows lake lavel change on lake Beseka........................................................................9
Figure 4. Graph Lake Beseka water level changes in square kilometers..........................................10
Figure 5 :Tmporal image of lake Ziway ...............................................................................................12
Figure 6: Map shows lake lavel change on Ziway Lake.......................................................................13
Figure 7 :Temporal image of lake Abijata,Langano and Shala...........................................................14
Figure 8 :map shows lake level change on lake Abijata,Langano and Shala....................................14
Figure 9 : Graph shows Lake Ziway water level changes in square kilometers.................................15
Figure 10: Graph shows Lake Abijata, Langano and Shala water level changes in square kilometers
.............................................................................................................................................................16
Figure 11:Temporal image of lake Hwasa..........................................................................................18
Figure 12: Map shows lake lavel change on lake Hwasa ....................................................................18

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-
Figure 13 :Temporal image of lake Abaya...........................................................................................19
Figure 14: Map shows lake lavel change on lake Abaya.....................................................................20
Figure 15:Temporal image of lake Chamo..........................................................................................21
Figure 16: Map shows lake lavel change on lake Chamo ...................................................................21
Figure 17. Graph shows Lake Hawasa water level changes in square kilometers............................22
Figure 18. Graph shows Lake Abaya water level changes in square kilometers ..............................23
Figure 17:Graph shows Lake chamo water level change in square kilometers.................................23
Figure19: Graph shows the total water level change in square kilometers from 1973-2017............23

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INTRODUCTION
1.1 Background
A lake is a large, in land body of standing water that occupies a depression in the land surface. Lakes and
lake shores are attractive places to live and play. Clean, sparkling water, abundant wildlife, beautiful
scenery, aquatic recreation and fresh breezes all come to our mind when we think of going to the lake.
Despite their great value, lakes are fragile and ephemeral (Thompson et al., 2005)
The water-level of a lake changes seasonally and fluctuates annually due to the difference of seasonal or
yearly precipitation and evaporation (Kinshiro, 1974). The levels and sizes of lakes are governed by
many natural and anthropogenic factors. Climatic, hydrological and man induced factors control lake
levels change in many ways. Changes in lake levels result from a shift in the water balance or the net
steady-state removal of water via various surface and subsurface processes. In particular, closed terminal
lakes fluctuate significantly in response to climatic changes but tend to maintain equilibrium between
input and output (Tenalem Ayenew, 2002)
Remote sensing imageries have been widely used to detect changes occurred on water-level of a lakes or
any other feature ,that is caused by either due to natural factors or anthropic factors. Change detection,
defined by as “the process of identifying differences in the state of an object or phenomenon by
observing it at different times”, essentially comprises the quantification of temporal phenomena from
multi-date imagery acquired by satellite based multi-spectral sensors. It identified by as the process
involving the application of multi-temporal datasets to quantitatively analyze the temporal change of the
phenomenon. Hence, change detection can be generalized as a means of identification, recognition and
quantification of temporal differences of the same features or phenomenon occupying a well-defined
spatial extent.
1.2 Importance of the study
The size and level of lakes are changing due to the influence of many natural and anthropogenic factors.
Climatic changes such as decreasing trend of precipitation in the highlands and increasing of temperature
(and hence increasing of rate of evaporation) are the most important factors that cause a decline in the
size and level of the Ethiopian Rift Valley Lakes (Tenalem Ayenew, 2002).These anthropogenic and
hydro-climatic changes cause a grave consequence on the easily fragile ecosystem and affect the lives of
many animals and plants in the area. This in turn hinders the tourism of the country. Therefore, it is
extremely essential to identify the most important factors that cause the decline in the level and size of

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lakes so as to propose some appropriate water resource management measures and practice them towards
the protection of the lakes.
1.3 Objectives
1.3.1 Main objective
The main objective of this research project is to assesses and detect temporal lake level changes in the
most common Ethiopian rift valley lakes using multi-temporal satellite imageries
1.3.2 Specific objective
 Digitize and determine the areal extent of selected lakes using satellite images, acquired at
different time interval
 Compare and contrast the variation of its area from time to time on each lake
 Identify which lake show significant level change and its trend
2. APPROACH AND METHODOLOGY
2.1. Data Collection
In order to reach at the final aim of the study, I used four Landsat image with fifty (15) year interval
starting from 1973 up 2017 . The data is obtained from US Geological survey (USGS). All the data is
taken at dray season to reduce the effect of recharge. The table bellow tells clear information about the
data of acquisition.
Table 1. Specifications of the data used for analysis
Year Satellite Sensor Date of acquisitionPath Row
1973
Landsat 1-3 MSS
168 54 Mrch-03
168 55 Jounary-12
168 56 Faubrary-17
1989 Land sat(4&5) TM
168 54 Jounary-01
168 55 Faubrary-14
168 56 Jounary-17
2003
Land sat( 4,5 and 7) TM &
ETM+
168 54 January -12
168 55 January -12
168 56 Faburary-04
169 55 Jounary-17

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169 56 March-02
2017 Land sat 8
OLI – TRIS
168 54 January -01
168 55 January -10
168 56 Faubrary-11
169 55 Faubrary-17
169 56 January -01
2.2. Preprocessing
The collected image data then geometrically corrected and referenced to UTM 37N coordinate system
(WGS 84 datum and Spheroid). Furthermore the band combination is adjusted in such a way the feature
/water/is clearly extracted. By zooming in the images and then digitizing their boundaries (perimeters),
shape files for each lake corresponding to each year were created. . The areas of the lakes for each year
were then obtained by calculating the areas of the corresponding shape files using the ArcGIS and
ERDAS IMAGINE software
3. GENERAL OVERVIEW OF THE STUDY AREA
3.1 General
The study area covers a total area of 35857.139719 km2
and lies between 05°30Ń and 09°45Ń latitude
and 37°00É and 40°00É longitude (Figure1).
The Ethiopian Rift Valley is part of the Great East African Rift which is the largest, longest and most
conspicuous feature of its kind on earth, stretching for nearly 5,600km from the Red Sea into the mouth
of the Zambezi River in Mozambique. The elevation, width and tectonic setting of the Ethiopian Rift
Valley are extremely variable. The interesting feature of the northern and central sectors is the existence
of open and closed lakes situated within large depressions. The major lakes are located within the central
Main Ethiopian Rift with relatively higher elevations as compared to Afar and Chew Bahir Rift
bordering Kenya. These lakes occupy an enclave of internal drainage basins separating the tributaries of
the Nile and Wabishebele River Basins (Tenalem Ayenew, 2009).

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Figure1: location of the study area
The Rift Valley of Southern Ethiopia runs NNE from the Kenya frontier of 600Km to the Koka Dam on
the Awash River where the rift begins to open out into the Afar and Danakil depressions (Grove et al.,
1975). The most important rift valley lakes is located on the floor of the Rift valley and encompasses
three major water basins from NE to SW (Tamiru Alemayehu et al., 2004 cited in Huib et al., 2006):
 Northern rift basin /the Awash basin/ Koka, Beseka, Gemari, and Abe are most important one.
 Central Ethiopian Rift (CER) valley Ziway, Langano, Abyata and Shala lakes are the most
important ones.
 Southern rift basin Hawassa, Abaya, Chamo and Chew-Bahir are the third most important
lakes.

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These three basins are not connected by surface water, but it is suggested that they may be connected by
underground faults running in NE-SW direction (Tenalem Ayenew, 2004). However, the hydrogeology
of the three main water basins in the Rift valley is highly complex and the spatial dynamics of
groundwater resources are poorly understood.
3.2 Geological and geomorphologic characterizations
During the beginning of the Cenozoic Era, Eastern Africa was deluged under molten lava and thick beds
of explosive rocks with intense tectonic activity that initiated the formation of the rift valley. The
Ethiopian Rift is created by volcanic and faulting activity that formed various volcano-tectonic
depressions in the floor of the rift, which later became lakes. The Ethiopian Rift is part of the Great East
African Rift Valley, also called the Afro-Arabian rift, which extends from Jordan in the Middle East,
through Eastern Africa to Mozambique in Southern Africa. It also extends from the Kenyan border up to
the Red Sea and divides the Ethiopian highlands into a western and eastern halve. The wide areas buried
under volcanic materials, the thickness and variety of the rock sequences and the prolonged duration of
the eruptions make East Africa one of the world most remarkable volcanic regions. Without composite
volcanic centers made largely of lava, there would have been no mountains and crater lakes and without
faulting, there would have been no imposing escarpment gorges, canyons and extended rift valley floor
occupied by a series of lakes (Tenalem Ayenew, 2009).
The lakes occupy the rift floor, and are bounded to the east and west by escarpments and high elevation
plateau formed by Cenozoic volcanotectonic processes. Most of the flat rift plains around the lakes are
covered with thick lacustrine sediments and volcanoclastic Quaternary deposits with scattered volcanic
centers (Barbieri et al., 1975; Zanettin et al., 1980 cited Tenalem Ayenew, 2004).
The Rift Valley floor is covered by Quaternary sediments and volcanics, the slopes and the highlands are
predominantly composed of Tertiary basalts, locally subordinated by Precambrian basement (Mohr, 1961
cited in Susanne, 2004). Most of the flat rift plains around the lakes are covered with thick lacustrine
sediments and volcanoclastic Quaternary deposits with scattered volcanic centers (Barbieri et al., 1975;
Zanettin et al., 1980 cited in Tenalem Ayenew, 2004).
The rift is distinctly separated from the plateau by a series of normal step faults oriented parallel to the
north north-eastern and south south-eastern trending rift axis. A persistent belt of intense and fresh
faulting marks the floor of the Main Ethiopian Rift (MER). Numerous geothermal manifestations and

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caldera volcanoes characterize this active region. Volcanism has persisted up to the present day in the
Afar within small eruptive centers (Baker and Wohlenberg, 1971 cited in Tenalem Ayenew, 2004).
There are also frequent earthquakes all over the Ethiopian Rift; the epicenters are almost exclusively
related to the major rift structures.
The Ethiopian Rift valley has highly variable elevation, width and tectonic setting. Very interesting
feature of the northern and central sectors is the existence of open and closed lakes situated within the
large depressions. We find the major lakes in the central Main Ethiopian Rift with relatively higher
elevations as compared to the Afar and Chew Bahir Rift bordering Kenya.
3.3 Climate of the rift valley basin
Lakes in the Ethiopian Rift are sensitive indicators of Late Quaternaryclimates (Grove et al.,
1975). The strong topographic characteristics control the expected tropical climate, soil, natural
vegetation and as a result the population distribution. The lakes of the Ethiopian Rift experience a
wide range of climate, stressed by the annual north-south movements of inter- and sub-tropical
frontal zones across the country.The climate is humid to subhumid in the highlands and semiarid in
the rift valley with distinct wet and dry seasons (Daniel Gemechu, 1977 cited in Tenalem
Ayenew, 2009).
Rainfall in Ethiopia is erratic and subject to large spatial variability, which is largely determined
by altitude. Areas above 2500 m may receive 1400-1800 mm y-1, mid-altitude regions (600-2500 m)
may receive 1000-1400 mm per year, and coastal lowlands generally receive less than 200 mm per
year (Huib and Herco, 2006). The rainfall pattern is largely influenced by the annual oscillation of
the inter-tropical convergence zone, which results in warm, wet summers and dry, cold and windy
winters (Huib and Herco, 2006). The average annual rainfall ranges from 1150 mm in the
highlands to 650 mm in the rift floor (Tenalem Ayenew, 1998). There is no clear trend (increase or
decrease) in rainfall characteristics in the rift valley region during the last 40 years (Tamiru
Alemayehu et al., 2006 cited in Huib and Herco, 2006).
The main rainy season is between June and September and the dryseason lasts from October
to February. The main rainy season accountsfor 70-90% of the total annual rainfall in the
basin. Minor rain events,originating from moist south-easterly winds, occur between March
and May. Due to their nature, these rainfall events are more pronounced in the highlands (Huib and
Herco, 2006) .The adjacent highlands experience higher rainfall and lower evaporation. During
the wet season between June and September, north-westerly monsoon wind bring dry air from
Arabia which results in limited rainfall in few areas near the Red Sea coast and Danakil

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depression (Tenalem Ayenew, 2009). The highland rainfall is the ultimate source of
replenishment of the rift lakes in the form of groundwater, river discharge and overland flow
(Tenalem Ayenew, 2009). The prevailing temperatures largely depend on altitude. The mean
annual temperature is around 15°C in the highlands and 20°C in the rift valley (Huib and
Herco, 2006).
Most of the rainfall in the CER is intercepted by the highlands. Open water evaporation (lake
evaporation) is in the order of 1800-2000 mm per year (Dagnachew Legesse, 2004; Tenalem
Ayenew, 2003 cited in Huib and Herco, 2006). Actual evapotranspiration depends on the
landuse and availability of water and varies between 700 and 900 mm per year (Tenalem
Ayenew, 2003 cited in Huib and Herco, 2006).
3.4 General hydrology of the lakes under consideration
The East African Rift lakes are bordered to the east and west by large altitude highlands
where the major tributary feeder rivers originate. The rift consisting of large lakes starts in
the neighborhood of Lake Abhe and extends some 1000km to the south into northern Kenya
(Mohr, 1962 cited in Tenalem Ayenew, 2009)
Many of the studied lakes are located within a closed basin fed by perennial rivers. The
major rivers are Meki-Katar and Bilate, which feed Lakes Ziway and Abaya respectively. The
Meki River discharges the runoff from the plateau west of Lake Ziway and the Ketar River
discharges the water from the eastern and south-eastern plateaus. The catchments of these two
rivers cover 5610 km2 (Dagnachew Legesse et al., 2004 cited in Huib and Herco, 2006). Lakes
Abaya and Chamo are seasonally connected by an overflow channel, Langano and Abiyata by
the Horakelo River, Ziway and Abiyata by the Bulbula River. Lake Chamo is fed by Sille
and Kulfo Rivers. It outflows to the Chew Bahir during extreme wet seasons via Metenfesha
(Tenalem Ayenew, 2009). Abiyata and Hawassa are terminal lakes without surface water
outlets.Lake Hawassa is connected to a wide swampy area and the small lake Cheleleka
through the Tikur Wuha River. A major part of the water inflow of Lake Abyata originates
from Lake Ziway through the Bulbula River,Hence both lakes are hydrologically connected.
Considerably less water is discharged from Lake Langano to Lake Abiyata through the
Horakelo River. Lake Abyata is the terminal lake of the catchment (CER), from where the
water evaporates.

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4. DATA ANALYSIS AND PRESENTATION
4.1 Northern Rift valley lakes
4.1.1 Lake Beseka
Lake Beseka, which is located in the northern main Ethiopian rift valley region near to Methara
Town, is one of drastically rising or expanding lake in Ethiopia. In 1960’s and around the lake
level was insignificant compared to current status. Now the lake level covers an area above 50 km2
.
During the 1973’s the lake level is estimated to be 14 km and then with the next five ten year the level
of the lake is increase by 37km2.
More over maps, tables and figures below, present the overall
conditions about the given lake.
Figure 2: Temporal image of Lake Beseka

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Figure 3: Map shows lake lavel change on lake Beseka

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Table 2. Lake lavel changes for Lakes Beseka in square kilometers (km2)
Lake
name
Estimated area in km2
at the
time of data aqcuation
Lake lavel change in km2
b/n
sucssive years
Total
change
1973 1989 2003 2017 1973-1989 1989-2003 2003-2017 1973-2017
Beseka 14 33 49 51 +14 +16 +2 +37
Figure 4. Graph Lake Beseka water level changes in square kilometers
4.2 Central Rift valley Lakes
4.2.1 Lake Ziway
Lake ziway, which is located in the central part of main Ethiopian rift valley region, this lake is
actually shows decreasing water level , Even though the amount of change is not a very drastically.
During the 1973’s the lake level is estimated to be 431 km2
and then within five ten year interval the
level of the lake is decreased by 6 km2
and now the surface area of this lake calculated as 425 km2
.
0
10
20
30
40
50
60
Areakm2
Year

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4.2 .2 Lake Abiyata
Lake Abijata, which is located in the central part of main Ethiopian rift valley region, this lake is
one of drastically shrinking or decreasing lake of the rift valley lakes and also Oromia region lakes
compared to its initial state .
During the 1973’s the lake level is estimated above 200 km2
and then with the next five ten year the
level of the lake is decreased by 120 km2
.With this trend this lake will not be there after three and four decades.
4.2. 3 Lake Langno
This lake is also located in the central part of main Ethiopian rift valley region, this lake is actually
shows decreasing water level, Even though the amount of change is not that mach considerable. This
lake can be taken as the stable relative to his friend.
and then with the next five decades the level
of the lake is decreased by 4 km2
.
4.2. 4 Lake Shala
Lake Shala ,which is also located in the central part of main Ethiopian rift valley region, this lake is
actually shows decreasing water level , relative to Langano this lake shows some change ,even if that is
not very high.
and then with the next five decades the level
of the lake is decreased by 9 km2
.

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Figure 5 : Tmporal image of Lake Ziway

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Figure 6: Map shows lake lavel change on Ziway Lake.

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Figure 7 :Temporal image of Lake Abijata,Langano and Shala
Figure 8: Map shows lake level change on Lake Abijata,Langano and Shala

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Table 3. Lake lavel changes for Lakes Ziway ,Abjata, Langano and Shala in square kilometers (km2)
Figure 9 : Graph shows Lake Ziway water level changes in square kilometers
422
423
424
425
426
427
428
429
430
431
432
1973 1989 2003 2017
Areakm2
Year
Lake name
at the
time of data acqusition
b/n
sucssive year
Total
change
1973 1989 2003 2017 1973-1989 1989-2003 2003-2017 1973-2017
Ziway 431 426 426 425 -5 0 -1 -6
Abijata 200 154 107 80 -46 -47 -27 -120
Langano 233 232 229 229 -1 -3 0 -4
Shala 311 308 303 302 -3 -5 -1 -9

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Figure 10: Graph shows Lake Abijata, Langano and Shala water level changes in square kilometers
4.3 Southern Rift valley Lakes
4.3.1 Lake Hawassa
Lake Hawasa , this is located in the southern part of main Ethiopian rift valley region, near
a town called Hawassa , it shares the name of this town. This lake shows an increasing in water
level between the first fifty year (i.e1973-1989) and it become more or less constant between
(1989 -2003) and with the recent year it becomes decrease.
,then with the next fifity (15) year the
level of the lake increase by 5 km2
and now it decrease by 2 km2
and covers 93 km2
.This lake
also taken as a stable lake similar to lake Langano , relative to the other drastically changed lakes
.
0
50
100
150
200
250
300
350
1973 1989 2003 2017
Areakm2
Year
abijata
langano
shalla

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4.3.2 Lake Abaya
Lake Abaya , which is located in the southern part of main Ethiopian rift valley region.
This Lake is the largest lake in the Ethiopian Rift valley lakes. The water level of this lake shows
an increase trend with the study time interval .
, and then with the next five
decades the level of the lake is increased by 9 km2
and now the surface area of this lake
calculated as 1155 km2
.
4.3.3 Lake Chamo
Lake Chomo ,which located in the southern part of main Ethiopian rift valley region, it is
found at the southern end of the other lakes . This lake is shows significance decreasing water
level, basically at the western side of the lake portion.
and then with the next five decades
the level of the lake is decreased by 28 km2
and now the surface area of this lake calculated as
311 km2
.

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Figure 11:Temporal image of lake Hwasa
Figure 12: Map shows lake lavel change on lake Hwasa

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Figure 13 :Temporal image of lake Abaya

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Figure 14: Map shows lake lavel change on Lake Abaya

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Figure 15:Temporal image of Lake Chamo
Figure 16: Map shows lake lavel change on Lake Chamo

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Table 4. Lake lavel changes for Lakes Hawasa, Abaya and Chamo in square kilometers (km2)
Lake
name
at the
time of data acqusition
b/n
sucssive years
Total
change
1973 1989 2003 2017 1973-1989 1989-2003 2003-2017 1973-2017
Hawasa 90 95 95 93 +5 0 -2 +3
Abaya 1115 1118 1121 1155 +3 +3 +34 +40
Chamo 339 324 306 311 -15 -18 +5 -28
Figure 17. Graph shows Lake Hawasa water level changes in square kilometers
87
88
89
90
91
92
93
94
95
96
1973 1989 2003 2017
Areakm2
year
1090
1100
1110
1120
1130
1140
1150
1160
1973 1989 2003 2017
Areakm2
year

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Figure 18. Graph shows Lake Abaya water level changes in square kilometers
Figure 17:Graph shows Lake chamo water level change in square kilometers
Figure19: Graph shows the total water level change in square kilometers from 1973-2017
280
290
300
310
320
330
340
350
1973 1989 2003 2017
Areakm2
year
-140
-120
-100
-80
-60
-40
-20
0
20
40
60
Beseka Ziway Abijata Langano Shalla Hawassa Abaya chamo
Areakm2
Lakes
1973-2017

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5. Conclusion and Recommendation
5.1 Conclusions
The result of the study reveald that Lakes Abiyata, Chamo, Ziway , shalla and Langano are
declining while Beseka ,Abaya and Hawassa are rising. With in the increasing trend lake
hawass is not constant,it increase and then decrease.
Among the studied lakes, Abiyata is drastically reduced in size (about 120 km2
from
1973-2017).The other seriously affected lake is Chamo with about 28 km2
reduction in its
area between 1973-2017.
Lake Abaya was found to be relatively stable and increase during the indicated period (34
km2
increase in its area) . However lake hawassa is not more stable ,it was increase from
1973-1989 and then decline from 2003-2017.
The other increasing lake is Beseka,it increase a total area of 37km2
from 1973-2017.
5.2 Recommendations
 A great deal should be done two know the major reason,about the significant water
level change in rift valley lakes,because most of them shows a decreasing trend.
 Researchers should be aware the flactuation of water levels behind ,antropogenic
factor (i.e with respect to structures) and come with a revalent decision to know the
major reason about there decling trend.
 Concerned bodies need to work in harmony to manage water use in the Ethiopian
Rift Valley lakes.
 Since Lake Abiyata is seriously affected, special attention is needed to replenish the
water in the lake by controlling the use of water and save the lives of many endemic
animals including the flora and fauna.

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 Further studies need to be made on the Ethiopian Rift Lakes to accurately identify
the prevailing factors that are causing lake water level fluctuations, especially in the
Lake Abaya-Chamo Basin.
 Educations on the consequences of excess water use and on how to protect the water
resources need to be given to some representatives of the community living around
the lakes
Reference
Azeb Belete (2009). Climate Change Impact on Lake Abaya Water Level.
Unpublished MSc. Thesis, Addis Ababa University, Addis Ababa.
Berihu Abadi (2007) .Brittle Fractureand Lake Level Change at Beseka: Main Ethiopian Rift,
Metehara Area. MSc. Thesis, Addis Ababa University, Addis Ababa
Dagnachew Melaku and Abate Shiferaw (2014). GIS and REMOTE Sensing Based
Water Change Detection of Lake Hayq, North Central Ethiopia. Journal of
Environment and Earth Science Online 4(5): 70–88.
Grove, A.T., Alayne, F.S. and Goudie, A.S.(1975). Former Lake levels and climatic
changes in the rift valley of Southern Ethiopia. The Geographical Journal, 141:177-194.
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