THE PROJECT FOR GROUNDWATER RESOURCES ASSESSMENT … · THE PROJECT FOR GROUNDWATER RESOURCES...

December 2015

Japan International Cooperation Agency

Kokusai Kogyo Co., Ltd.

THE PROJECT FOR GROUNDWATER RESOURCES ASSESSMENT IN THE

MIDDLE AWASH RIVER BASIN IN THE FEDERAL DEMOCRATIC REPUBLIC OF

ETHIOPIA

FINAL REPORTGEOLOGICAL AND HYDROGEOLOGICAL MAPS

The Federal Democratic Republic of EthiopiaMinistry of Water, Irrigation and Electricity

Composition of the Report

Executive Summary

Main Report

Supporting Report

Data Book

Geological and Hydrogeological Maps

This Report is prepared based on the price level and exchange rate of July 2015. The exchange rate is:

US$1.0 = ETB20.6298 = JPY123.80

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Lake Ziway

Lake Koka

Lake Yardi

Lake Ertele

Lake Abijata

Lake DendiLake Ala Semite

Lake Wenchi

Lake Dalay

Lake Goletsho

Awash Wenz

Abay

Ramis

J ema

Bilate Wabe Shebele Wenz

Wechti Wenz

MugerW

enz

Addis Abeba

Nazret

Yilu

Gola

Lemi

Mine

Guna

Meki

Dera

Kula

Rago

Bube

Robi

Hobe

Bu-i

Teji

Ambo

Doba

Erer

GotaBike

Hirna

Wanje

Akaki

Chole

Iteya

Arara

Suten

Ada-a

Kibet

Deder

Asela

Ramis

Ziway

Magna

ModjoHmero

Harew

Sheno

Fiche

Robit

Sagure

Diksis

Arerti

Agemti

Molale

Sodoma

Merewa

Woliso

Huruta

Hujufa

Tibila

Koshim

Ombole

Dilila

Bedesa

Godina

Ginchi

Asebot

Mesala

Chacha

Gewane

Dalocha

Chancho

Fulensa

Gelemso

Melkasa

Endibir

Roepeyh

Enewari

Meranga

Rukeyisa

Butajira

Gunchire

Dida Adi

Metehara

Aro Dimtu

Adis Amba

Tulu Bolo

Muke Ture

Haro Kile

Adis Alem

Harawacha

Tarma Ber

Welenchiti

Mucha Roba

Melka Jilo

Debre Sina

Goha Tsion

Debre Tsige

Arba Reketi

Midre Kebda

Bantu Liben

Addis Hiwot

Chefe Donsa

Debre Zeyit

Alem Ketema

Gojo (Jeldu)

Guba Koricha

Asebe Teferi

Shola Gebeya

Debre Birhan

Teferi Birhan

Anchar Bedeyi

Gebre Guracha

Ejere N Shewa

Sire W Hararghe

Arb Gebeya W Shewa

Abomsa (Tinsae Birhan)

Loko

Bofa

Arba

Muger

Eurdo

Koshe

Fetra

Duber

Beltu

Jihur

Sembo

Afdem

Dejen

Ejersa

Boreda

Segele

Kutara

Gebiba

Deneba

Fitale

Mezezo

Jebuha

Adulala

Ankober

Kechemo

Sululta

Ginager

Chifara

Mechara

Berehet

KurkuraDinkiti

Kachisi

Mendida

Tedo Ber

Delajebo

Jima Arsi

Alem Tena

Yemistina

Adami Tulu

Mama Midir

Sirtu Ager

Alem Gebeya

Melka Werer

Biyo Karaba

Tikur Chika

Hagere Sernay

Sheik Hussein

Melka Kunture

41°0'0"E

41°0'0"E

40°0'0"E

40°0'0"E

39°0'0"E

39°0'0"E

38°0'0"E

38°0'0"E

10°0

'0"N

10°0

'0"N

9°0'

0"N

9°0'

0"N

8°0'

0"N

8°0'

0"N

400000

400000

500000

500000

600000

600000

700000

700000

9000

00

9000

00

1000

000

1000

000

1100

000

1100

000

LegendStudy Area

Towns

\ Capital

!5 Regional Capital

!!! Major towns

!! Other towns

Major Rivers

Roads

Trunk

Link

Main Access

Feeder

Collector

New Proposed

Unclassified

0 5025km

´

LOCATION MAP

AbbayAwash

Wabi Shebele Aysha

Genale-Dawa

Tekeze

Omo-Gibe

Denakle

Baro-Akobo

Rift Valley

Mereb

Aysha

OROMIA

SOMALI REGION

AMHARA

AFAR

TIGRAY

SOUTHERN REGIO

50°0'0"E

45°0'0"E

45°0'0"E

40°0'0"E

40°0'0"E

35°0'0"E

35°0'0"E

15°0

'0"N

10°0

'0"N

10°0

'0"N

5°0'

0"N

5°0'

0"N

LegendStudy Area

Region

Major Basin 0 200 400100km

´

Addis Ababa

Project Area

Federal Democratic Republic of Ethiopia

Project Area

i

CONTENTS

Location Map Contents List of Tables List of Figures Abbreviations

Page:

1 Survey Summary ............................................................. 1-1

1.1 Objective and area of the project ................................................................ 1-1

1.2 Methodology of the Project ........................................................................ 1-2

2 Summary of Geography and Geology ............................. 2-1

2.1 Summary of geography .............................................................................. 2-1

2.2 Regional geological and tectonic setting .................................................... 2-4

3 Geology ........................................................................... 3-1

3.1 Adama town, Mt. Boseti and its surrounding areas .................................... 3-1 3.1.1 General ............................................................................................ 3-1 3.1.2 Geological unit ................................................................................ 3-4

3.2 Kone – Mt. Fentale and its surrounding areas .......................................... 3-24 3.2.1 General .......................................................................................... 3-24 3.2.2 Geological unit .............................................................................. 3-26

3.3 Mojo town – Arerti town – Debre Birhan town and its surrounding areas .......................................................................................................... 3-44 3.3.1 General .......................................................................................... 3-44 3.3.2 Geological unit .............................................................................. 3-46

3.4 Awash town – Asebe Teferi town and its surrounding areas ................... 3-61 3.4.1 General .......................................................................................... 3-61 3.4.2 Geological unit .............................................................................. 3-62

3.5 Correlation of stratigraphy of each part of the study area ........................ 3-81

3.6 Correlation of stratigraphy with previous studies ..................................... 3-85

3.7 Geological structure .................................................................................. 3-87 3.7.1 Fault system .................................................................................. 3-87 3.7.2 Active structures ........................................................................... 3-87

3.8 Volcanic activity ....................................................................................... 3-88 3.8.1 Characteristics of volcanic topography in the middle Awash

River basin .................................................................................... 3-88 3.8.2 Volcanic history in the middle Awash River Basin ...................... 3-91

4 Hydrogeology .................................................................. 4-1

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4.1 Data collection of hydrogeology ................................................................ 4-1 4.2 Groundwater potential .............................................................................. 4-24

4.2.2 Classification and characteristic of aquifers ................................. 4-29

4.3 Hydrogeological map and groundwater flow ........................................... 4-40

4.4 Water quality testing ................................................................................. 4-44 4.4.1 Results of water quality testing ..................................................... 4-44 4.4.2 Analysis items and methodology .................................................. 4-50 4.4.3 Results of water quality testing ..................................................... 4-51

5 Geology and Hydrogeology around Lake Beseka ........... 5-1

5.1 Topography, geology and geological structure .......................................... 5-1 5.1.1 Topography ..................................................................................... 5-1 5.1.2 Geology ........................................................................................... 5-7 5.1.3 Geological structure ...................................................................... 5-29

5.2 Hydrogeology ........................................................................................... 5-30 5.2.1 Aquifer classification and groundwater flow ................................ 5-30 5.2.2 Hydrogeological map and cross-sections ..................................... 5-38 5.2.3 Results of water quality testing ..................................................... 5-41

iii

List of Tables Page:

Table 1.2.1: Satellite Image for Interpretation .............................................................. 1-3 Table 3.1.1: Stratigraphy in Adama Town-Mt. Boseti .................................................. 3-2 Table 3.1.2: Geological Succession along Adama Town-Mt. Boseti ............................ 3-6 Table 3.1.3: Geological Succession along Lake Koka – Hurita Town – Sire

Town ......................................................................................................... 3-7 Table 3.2.1: Stratigraphy in Kone-Mt. Fentale and its Surrounding Areas ................. 3-25 Table 3.2.2: Geological Succession along Kone-Mt. Fentale ..................................... 3-27 Table 3.2.3: Geological Succession along Mt. Fentale – Awash Town ...................... 3-28 Table 3.3.1: Stratigraphy in Mojo Town-Arerti Town-Debre Birhan Town and

Surrounding Areas .................................................................................. 3-45 Table 3.3.2: Mojo Town-Arerti Town -Debre Birhan Town ...................................... 3-51 Table 3.3.3: Mojo Town – Chefe Donsa Town – Debre Birhan Town ....................... 3-52 Table 3.3.4: Arerti Town – Melka Jiro Town ............................................................. 3-56 Table 3.4.1: Stratigraphy in Awash Town-Asebe Teferi Town .................................. 3-62 Table 3.4.2: Geological Succession of Mieso Town-Asebe Teferi Town-Arba

Bekete Town .......................................................................................... 3-68 Table 3.4.3: Geological Succession of Bordede Town – Bube Town – Belo

Town ....................................................................................................... 3-69 Table 3.4.4: Geological Succession of Adami Hara –Kora Town -Debala Town ...... 3-72 Table 3.4.5: Geological Succession of Asebot Town – Beka Town. .......................... 3-73 Table 3.4.6: Geological Succession of Awash Town – Mieso Town ......................... 3-75 Table 3.5.1: Correlation of stratigraphy in the study area ........................................... 3-82 Table 3.6.1: Correlation of stratigraphy with existing documents and maps .............. 3-86 Table 4.1.1: List of References ...................................................................................... 4-1 Table 4.1.2: Number of Data by Parameter in Well Database (with coordinates) ........ 4-5 Table 4.1.3: Existing Well Data in West Hararge Zone ................................................ 4-8 Table 4.1.4: Existing Well Data Around Lake Beseka ............................................... 4-11 Table 4.1.5: Existing Well Data in Arsi Zone ............................................................. 4-13 Table 4.1.6: Existing Well Data in East Shewa Zone, Amhara Region and others .... 4-16 Table 4.2.1: Aquifer Unit Classification and Characteristics ...................................... 4-29 Table 4.2.2: Modified Hydrogeological Map - Aquifer Classifications and

Definitions .............................................................................................. 4-33 Table 4.2.3: Aquifer Parameters and Units of Existing Wells and JICA Wells .......... 4-34 Table 4.2.4: Aquifer Classification and Productivity .................................................. 4-35 Table 4.2.5: Result of Groundwater Recharge Estimation by Sub-basins .................. 4-36 Table 4.2.6: Ratio between Groundwater Recharge and Yield ................................... 4-39 Table 4.4.1: Sampling List .......................................................................................... 4-46 Table 4.4.2: Previous Water Quality Standard of Ethiopia ......................................... 4-50 Table 4.4.3: New Water Quality Standard of Ethiopia and WHO .............................. 4-51 Table 4.4.4: List of Sampling Points in Dry Season 2015 .......................................... 4-69 Table 5.1.1: Classification and Characteristics of Topography around Lake

Beseka ...................................................................................................... 5-1 Table 5.1.2: Geological stratigraphy around Lake Beseka and correlation with

other areas .............................................................................................. 5-29 Table 5.2.1: Existing Wells and JICA Wells with Columnar Section around Lake

Beseka .................................................................................................... 5-35 Table 5.2.2: Aquifer Unit Classification and Characteristics around Lake Beseka .... 5-37 Table 5.2.3: List of Sampling Points around Lake Beseka ......................................... 5-42

iv

Table 5.2.4: List of Existing Water Quality Data (around Lake Beseka) ................... 5-43 Table 5.2.5: Results and List of Isotope Analysis ....................................................... 5-51 Table 5.2.6: List of Points for Tritium Analysis ......................................................... 5-54

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List of Figures Page:

Figure 1.1.1: Area Covered by the Geological and Hydrogeological Maps ................. 1-1 Figure 1.2.1: The Project Flow ...................................................................................... 1-2 Figure 1.2.2: SPOT Satellite Image ............................................................................... 1-4 Figure 1.2.3: ALOS Satellite Image .............................................................................. 1-5 Figure 1.2.4: ASTER DEM ........................................................................................... 1-7 Figure 1.2.5: Topographical Information Map by Satellite Images .............................. 1-8 Figure 2.1.1: The Central Sector of the MER ............................................................... 2-1 Figure 2.1.2: Major Basins in Ethiopia ......................................................................... 2-2 Figure 2.1.3: Digital Elevation Model of the Middle Awash River Basin .................... 2-3 Figure 2.1.4: River System of the Middle Awash ......................................................... 2-3 Figure 2.2.1: Schematic Diagram for Development of Red Sea Rift and Aden

Sea Rift, and failed African Rift (MER), (Source: http://www3.interscience.wiley. ............................................................... 2-5

Figure 3.1.1: Location map of outcrops ........................................................................ 3-3 Figure 3.1.2: Kelefa River (L-AB21) ............................................................................ 3-4 Figure 3.1.3: Tulu (L-AB07) (top left), Chefeko (L-AB08)(top light), Mt.Debeso

(L-AB09)(bottom) .................................................................................... 3-5 Figure 3.1.4: Sire (L-AB35) (top), Boko (L-AB11) (bottom) ....................................... 3-8 Figure 3.1.5: Koka Dam (L-AB02) (top), Rukecha (L-MAD40) (bottom) ................... 3-9 Figure 3.1.6: River Robi L-AB28) ......................................................................... 3-10 Figure 3.1.7: Bofa (L-AB25) (top left), Holly Spring (L-AB39) (top right),

Weleso River (L-AB43) (bottom) .......................................................... 3-11 Figure 3.1.8: Photos of Thin Sections of Sample Number140419-1 .......................... 3-12 Figure 3.1.9: Jogo (L-AB06) (top), West of Bofa Town (L-AB22) (bottom) ............. 3-13 Figure 3.1.10: Photos of Thin Sections of Sample Number 140414-1 ....................... 3-14 Figure 3.1.11: Photos of Thin Sections of Sample Number 140414-2 ....................... 3-15 Figure 3.1.12: Photos of Thin Sections of Sample Number 140414-5 ....................... 3-16 Figure 3.1.13: Photos of Thin Sections of Sample Number 140414-6 ....................... 3-17 Figure 3.1.14: Photos of Thin Sections of Sample Number140419-3 ........................ 3-18 Figure 3.1.15: Photos of Thin Sections of Sample Number140419-5 ........................ 3-19 Figure 3.1.16: Northeastern Cliff of Gademsa Caldera (L-AB05) .............................. 3-19 Figure 3.1.17: Boru River (L-AB19) (top), Sire (L-AB37) (bottom) ......................... 3-20 Figure 3.1.18: Gambedra (L-AB38) ............................................................................ 3-21 Figure 3.1.19: Welensu (L-AB17) (left), Mt.Boseti (L-AB29) (right)........................ 3-21 Figure 3.1.20: Madiga, (L-MAD37) (top), Lake Koka (L-AB10) (bottom) ............... 3-22 Figure 3.1.21: Harorecha (L-AB32) (left), Haribona (L-AB42) (right) ...................... 3-23 Figure 3.1.22: Waka Bute (L-AB04) (top), Miesa (L-AB03) (bottom) ...................... 3-24 Figure 3.2.1: Bosena (L-KF02) Bokan ........................................................................ 3-26 Figure 3.2.2: Photos of Thin Sections of Sample Number 140415-4 ......................... 3-29 Figure 3.2.3: Southeastern Foot of Mt. Fentale (L-KF39) .......................................... 3-30 Figure 3.2.4: Sobebor (L-KF23) (top), Boru Alore (L-KF18) (middle) and

Dinbiba (L-KF30) (bottom) ................................................................... 3-31 Figure 3.2.5: Photos of Thin Sections of Sample Number140417-5 .......................... 3-32 Figure 3.2.6: Dodose Use (L-KF20) (top) and Bogda (L-KF25) (bottom) ................. 3-33 Figure 3.2.7: Kone (L-KF13) (top) and Ofe, Southwestern Foot of Kone Caldera

(L-KF03) (bottom) ................................................................................. 3-34 Figure 3.2.8: Photos of Thin Sections of Sample Number 140415-2 ......................... 3-35 Figure 3.2.9: Korke (L-KF10) ..................................................................................... 3-36

vi

Figure 3.2.10: Dinbiba (L-KF31) (top), Southern Foot of Mt. Fentale (L-KF30) (bottom left) and Southern Foot of Mt. Fentale (L-KF34) (bottom right) ....................................................................................................... 3-37

Figure 3.2.11: Photos of Thin Sections of Sample Number 140415-3 ....................... 3-38 Figure 3.2.12: Photos of Thin Sections of Sample Number140417-1 ........................ 3-39 Figure 3.2.13: Photos of Thin Sections of Sample Number140417-2 ........................ 3-40 Figure 3.2.14: Photos of Thin Sections of Sample Number140417-4 ........................ 3-41 Figure 3.2.15: Boru Alore (L-KF21) ........................................................................... 3-42 Figure 3.2.16: Photos of Thin Sections of Sample Number 140415-1 ....................... 3-43 Figure 3.2.17: Dinbiba (L-KF29) ................................................................................ 3-43 Figure 3.3.1: Balchi (L-MAD14) (top), Balchi (L-MAD15) (bottom) ....................... 3-46 Figure 3.3.2: Aroge Minjar (L-MAD29) (top and middle), Chifey (L-MAD12)

(bottom left), Gina Ager (L-MAD30) (bottom right) ............................ 3-48 Figure 3.3.3: Aroge Minjar (L-MAD29) (top), Balchi (L-MAD14) (middle left),

Zengo (L-MAD10) (middle right), Gobemsa (L-MAD25) (bottom) ..... 3-49 Figure 3.3.4: Gidm Asfa (L-MAD21) (top), Zongo (L-MAD10) (bottom left),

Megezeze (L-MAD24) (bottom right) ................................................... 3-50 Figure 3.3.5: Mt. Bokan (L-MAD09) .......................................................................... 3-53 Figure 3.3.6: Samasembet (L-MAD11) ....................................................................... 3-54 Figure 3.3.7: Aroge Minjar (L-MAD29) ..................................................................... 3-54 Figure 3.3.8: Kunche (L-MAD06) .............................................................................. 3-55 Figure 3.3.9: Jolo (L-MAD41) .................................................................................... 3-57 Figure 3.3.10: Chefe Donsa (L-MAD02) .................................................................... 3-58 Figure 3.3.11: Mt. Zikwala (L-MAD41) ..................................................................... 3-58 Figure 3.3.12: Argoba (L-MAD04) (top), Lake Haro Meja (L-MAD01) (bottom

left), Lake Haro Kilole (L-MAD39) (bottom right) ............................... 3-59 Figure 3.3.13: Wubit Ager, Kersa River (L-MAD19) ................................................. 3-60 Figure 3.3.14: Borchota (L-MAD23) .......................................................................... 3-60 Figure 3.3.15: Borchota (L-MAD23) .......................................................................... 3-61 Figure 3.4.1: Arba Rekete (L-AA59) (top), Komena (L-AA35) (bottom left) and

Cheleleka (L-AA09) (bottom right) ....................................................... 3-63 Figure 3.4.2: Huse Ridge (L-AA53) ............................................................................ 3-64 Figure 3.4.3: Photos of Thin Sections of Sample Number140416-1 .......................... 3-65 Figure 3.4.4: Photos of Thin Sections of Sample Number140416-2 .......................... 3-66 Figure 3.4.5: Asebe Teferi (L-AA57) (top), Agemti (L-AA20) (bottom) ................... 3-67 Figure 3.4.6: Gara Gumbi (L-AA06) (top) and Dalecha (L-AA46) (bottom) ............. 3-70 Figure 3.4.7: Type Locality (L-AA30) (top) and its Vicinity (L-AA29) (bottom) ..... 3-71 Figure 3.4.8: Type Locality (L-KF43) (top) and Gara Gumbi Rasa (L-AA10)

(bottom) .................................................................................................. 3-74 Figure 3.4.9: Type Locality, Awash River (L-KF42) (top) and Komena

(L-AA40) (bottom) ................................................................................. 3-76 Figure 3.4.10: Photos of Thin Sections of Sample Number 140416-4 ....................... 3-77 Figure 3.4.11: Type Locality, Riv. Jejeba (L-AA03) .................................................. 3-78 Figure 3.4.12: Type Locality, Adami Hara (L-AA33) (top), Buri Korkoda Ridge

(L-AA22) (bottom left) and Awash Arba (L-KF40) (bottom right) ...... 3-79 Figure 3.4.13: Type Locality, Mt. Asebot (L-AA44) (top), Kulbas (L-AA38)

(bottom left) and Aneno (L-AA21) (bottom right) ................................ 3-80 Figure 3.4.14: Awash River (L-KF41) ........................................................................ 3-81 Figure 3.5.1: Geological Map of Study Area .............................................................. 3-83 Figure 3.5.2: Geological Cross-Section of Study Area ............................................... 3-84

vii

Figure 3.7.1: “En Echelon” arrangement of the active volcano-tectonic axis within the northern part of the Ethiopian rift (after Elc Electroconsult and Geotermica Italiana, 1987) ...................................... 3-88

Figure 3.8.1: Elevation Map of the Study Area ........................................................... 3-90 Figure 3.8.2: Stages in the Development of the Ethiopian Rift (after Kazmin and

Berhe, 1978) ........................................................................................... 3-91 Figure 4.1.1: Location Map of Existing Wells .............................................................. 4-6 Figure 4.1.2: Yield of Existing Wells ............................................................................ 4-7 Figure 4.1.3: Yield and Drilling Depth in West Hararge Zone ................................... 4-10 Figure 4.1.4: Yield and Drilling Depth in Arsi Zone .................................................. 4-15 Figure 4.1.5: Yield and Drilling Depth in East Shewa Zone, Amhara Region and

others ...................................................................................................... 4-21 Figure 4.1.6: Location Map of Spring and Hand Dug Wells ...................................... 4-23 Figure 4.2.1: Relation between Yield and Depth of the Existing Wells ..................... 4-25 Figure 4.2.2: Groundwater Level Contour Map in West Hararge Area ...................... 4-26 Figure 4.2.3: Groundwater Level Contour Map in Amhara Area ............................... 4-27 Figure 4.2.4: Groundwater Level Contour Map in East of Lake Koka to Dera

Town ....................................................................................................... 4-28 Figure 4.2.5: Groundwater Level Contour Map in North to East of Lake Koka ......... 4-28 Figure 4.2.6: Groundwater Level Contour Map around Lake Beseka ........................ 4-29 Figure 4.2.7: Location Map of Sub-Basin, Small Towns and Model Existing

Wells ....................................................................................................... 4-38 Figure 4.3.1: Hydrogeological Map in the Middle Awash River Basin ...................... 4-41 Figure 4.3.2: Hydrogeological Cross Sections ............................................................ 4-42 Figure 4.3.3: Groundwater Table Contour Map .......................................................... 4-43 Figure 4.4.1: Location Map of Sampling Points for Water Quality Testing ............... 4-45 Figure 4.4.2: Trilinear diagram ................................................................................... 4-53 Figure 4.4.3: Trilinear Diagram (All Data) ................................................................. 4-55 Figure 4.4.4: Trilinear Diagram (River Water) ........................................................... 4-56 Figure 4.4.5: Trilinear Diagram (Wells) ...................................................................... 4-57 Figure 4.4.6: Trilinear Diagram (Spring) .................................................................... 4-58 Figure 4.4.7: Trilinear Diagram (Lake Water) ............................................................ 4-59 Figure 4.4.8: Trilinear Diagram (Others) .................................................................... 4-60 Figure 4.4.9: Hexadiagram .......................................................................................... 4-61 Figure 4.4.10: Distribution Map of Hexadiagram (All data: Data around Lake

Beseka at upper left) ............................................................................... 4-63 Figure 4.4.11: Distribution Map of Hexadiagram (River water) ................................. 4-64 Figure 4.4.12: Distribution Map of Hexadiagram (Wells) .......................................... 4-65 Figure 4.4.13: Distribution Map of Hexadiagram (Spring) ......................................... 4-66 Figure 4.4.14: Distribution Map of Hexadiagram (Lake Water) ................................. 4-67 Figure 4.4.15: Distribution Map of Hexadiagram (Others) ......................................... 4-68 Figure 4.4.16: Location Map of Sampling Points along Awash River (Short

Rainy and Dry Seasons) ......................................................................... 4-70 Figure 4.4.17: The Hexa diagram of Short Rainy and Dry Season along Awash

River ....................................................................................................... 4-70 Figure 4.4.18: Trilinear diagram of Short Rainy and Dry Season along Awash

River ....................................................................................................... 4-71 Figure 5.1.1: Elevation Map around Lake Beseka ........................................................ 5-3 Figure 5.1.2: Topographic Classification Map around Lake Beseka (background:

shaded relief map created from ASTER DEM data) ................................ 5-4

viii

Figure 5.1.3: NW-SE Topographic Section around Lake Beseka (A-A’) ..................... 5-5 Figure 5.1.4: E-W Topographic Section around Lake Beseka (B-B’) .......................... 5-5 Figure 5.1.5: N-S Topographic Section around Lake Beseka (C-C’) ........................... 5-6 Figure 5.1.6: Index map of aerial photos used for the topographical analysis .............. 5-6 Figure 5.1.7: Paleo-channel flowing into the southern part of Lake Beseka................. 5-7 Figure 5.1.8: Geological Map around Lake Beseka ...................................................... 5-8 Figure 5.1.9: Geological section around Lake Beseka .................................................. 5-9 Figure 5.1.10: Outcrop photos of Birenti-Hada rhyolites ............................................ 5-10 Figure 5.1.11: Outcrop photos of the older ignimbrite ................................................ 5-11 Figure 5.1.12: Outcrop photos of the Nura Hira basalts .............................................. 5-12 Figure 5.1.13: Outcrop photo of Dino ignimbrite ....................................................... 5-12 Figure 5.1.14: Outcrop photos of Sobebor volcanic sand beds ................................... 5-13 Figure 5.1.15: Outcrop photos of the Pleistocene basalts............................................ 5-15 Figure 5.1.16: Outcrop photo of Kone ignimbrite ....................................................... 5-16 Figure 5.1.17: Outcrop photos of the Fentale volcanic rocks ...................................... 5-17 Figure 5.1.18: Outcrop photos of the Fentale ignimbrite ............................................ 5-18 Figure 5.1.19: Outcrop photos of the blisters of the Fentale ignimbrite ..................... 5-19 Figure 5.1.20: Outcrop photos of the recent basalts .................................................... 5-20 Figure 5.1.21: Photos of alluvial plains and deposits .................................................. 5-20 Figure 5.1.22: Location of existing wells and observation wells constructed by

this project and profile lines around Lake Beseka ................................. 5-22 Figure 5.1.23: Borehole log profile A-A’ section ....................................................... 5-23 Figure 5.1.24: Borehole log profile B-B’ section ........................................................ 5-24 Figure 5.1.25: Borehole log profile C-C’ section ........................................................ 5-25 Figure 5.1.26: Borehole log profile D-D’ section ....................................................... 5-26 Figure 5.1.27: Borehole log profile E-E’ section ........................................................ 5-27 Figure 5.1.28: Borehole log profile F-F’ section ......................................................... 5-28 Figure 5.1.29: Outcrop photos of faults distributed in the detailed study area ........... 5-30 Figure 5.2.1: Geological Map, Existing Wells and JICA Wells around Lake

Beseka .................................................................................................... 5-32 Figure 5.2.2: Columnar Section of JICA Well (AW BH-3) and Geological

Correlation .............................................................................................. 5-33 Figure 5.2.3: Columnar Section of JICA Well (AW BH-4N) and Geological

Correlation .............................................................................................. 5-33 Figure 5.2.4: Columnar Section of JICA Well (AW BH-5) and Geological

Correlation .............................................................................................. 5-34 Figure 5.2.5: Groundwater Level Contour Map around Lake Beseka (Less than

100 m depth of Existing Wells) .............................................................. 5-36 Figure 5.2.6: Groundwater Level Contour Map around Lake Beseka (More than

100 m depth of Existing Wells) .............................................................. 5-36 Figure 5.2.7: Well Depth and Fluoride Concentration around Lake Beseka .............. 5-38 Figure 5.2.8: Hydrogeological Map around Lake Beseka ........................................... 5-39 Figure 5.2.9: Hydrogeological Section around Lake Beseka ...................................... 5-40 Figure 5.2.10: Location Map of Water Quality Testing Points around Lake

Beseka .................................................................................................... 5-43 Figure 5.2.11: Trilinear Diagram around Lake Beseka ............................................... 5-45 Figure 5.2.12: Hexadiagram at Sampling Points around Lake Beseka ....................... 5-46 Figure 5.2.13: Hexadiagram of Main Sampling Points at West of Lake Beseka ........ 5-47 Figure 5.2.14: Hexadiagram of Main Sampling Points at South West of Lake

Beseka .................................................................................................... 5-48

ix

Figure 5.2.15: Hexadiagram of Main Sampling Points at South of Lake Beseka ....... 5-49 Figure 5.2.16: Delta Diagram of Stable Isotope around Lake Beseka ........................ 5-53

x

Abbreviations

AAU Addis Ababa University AGRAP Alidge Groundwater Resources Assessment Project AIDS Acquired Immune Deficiency Syndrome ALOS Advanced Land Observing Satellite ASTER Advanced Spaceborne Thermal Emission and Reflection Radiometer ASTER-GDEM ASTER-Global Digital Elevation Model BFI Base Flow Index CAD Computer Aided Design (System) CDE Center for Development and Environment, Ministry of Agriculture CFC Chloride Fluoride Carbon CREC China Railway Engineering Corporation CSA Central Statistical Agency CSE The Conservation Strategy of Ethiopia C/P Counterpart (organization or personnel) DB Datebase DCI Ductile Cast Iron DEM Digital Elevation Model DF/R Draft Final Report DTH Down-the-hole Hammer DWL Dynamic Water Level EA Environmental Assessment EC Electric Conductivity EEPCO Ethiopia Electric Power Corporation EGRAP Ethiopian Groundwater Resources Assessment Program EIA Environmental Impact Assessment EIGS Ethiopian Institute of Geological Survey, now renamed as Geological Survey of

Ethiopia (GSE) EL Elevation ELC Elc electroconsult milano and Geotermica italiana pisa, Italia (an Italian

Consultant) ELSA Equilibrium Lake Surface Area EMA Ethiopia Mapping Agency ENGDA Ethiopian National Groundwater Database ENGWIS Ethiopian National Groundwater Information System EPA Environmental Protection Agency, now renamed as Ministry of Environment

and Forest (MEF) EPC Environmental Protection Council ERA Ethiopian Road Authority ERC Ethiopian Railway Corporation ESA Ethiopian Standard Agency ESIA Environmental and Social Impact Assessment ET Evapotranspiration EWCA Ethiopian Wildlife Conservation Authority EWTEC Ethiopia Water Technology Center, now renamed as Ethiopia Water

Technology Institute (EWTI) EWTI Ethiopia Water Technology Institute, formerly known as Ethiopia Water

Technology Center (EWTEC) F/R Final Report FAO Food and Agriculture Organization of the United Nations FAO-AGLW FAO Water Resource, Development and Management Services

xi

FDM Finite Difference Method FEM Finite Element Method GD Groundwater Directorate (of MoWIE) GDP Gross Domestic Product GHB General Head Boundary GIS Geographical Information System GL Ground Level GNI Gross National Income GPS Global Positioning System GSE Geological Survey of Ethiopia GSP Galvanized Steel Pipe GTP Growth and Transformation Plan GWR Groundwater Recharge HIV Human Immunodeficiency Virus IAEA International Atomic Energy Agency IC/R Inception Report IEE Initial Environmental Examination IMF International Monetary Fund INGEIS Instituto de Geocronología y Geología Isotópica (Institute of Geochronology

and Geology, Argentine) ISO International Standard Organization ISODATA The Iterative Self-Organizing Data Analysis Technique IT/R Interim Report ITCZ Inter-tropical Convergence Zone JICA Japan International Cooperation Agency LEL Local Evaporation Line LMWL Local Meteoric Water Line M&E Monitoring and Evaluation M/M Minutes of Meeting MCM Million Cubic Meter MDGs Millennium Development Goals MEF Ministry of Environment and Forest, formerly known as Environmental

Protection Agency (EPA) MER Main Ethiopian Rift MOA Ministry of Agriculture MoWR Ministry of Water Resources, now renamed as Ministry of Water, Irrigation and

Electricity (MoWIE) MoWE Ministry of Water and Energy, now renamed as Ministry of Water, Irrigation

and Electricity (MoWIE) MoWIE Ministry of Water, Irrigation and Electricity, formerly known as Ministry of

Water, Irrigation and Energy(MoWIE), Ministry of Water and Energy (MoWE) or Ministry of Water Resources (MoWR)

MSE Metehara Sugar Estate MWL Meteoric Water Line NASA National Aeronautics and Space Administration, USA NGI National Groundwater Institute NGO Non-Governmental Organization NMA National Meteorology Agency OLEPB Oromia Land and Environmental Protection Bureau ORP Oxidation and Reduction Potential O(R)WMEB Oromia (Regional) Water, Material and Energy Development Bureau OWNP One WASH National Program OWWDSE Oromia Water Works Design and Supervision Enterprise

xii

P/R Progress Report PA Preliminary (Environmental) Assessment PASDEP Plan for Accelerated and Sustained Development to End Poverty PC Personal Computer PPP Purchasing Power Parity PRSP Poverty Reduction Strategy Paper PVC Polyvinyl Chloride R/D Record of Discussions REA Regional Environmental Agencies RESTEC Remote Sensing Technology Center of Japan RVLB Rift Valley Lakes Basin SC Steering Committee SCM Steering Committee Member or Steering Committee Meeting SDPRP Sustainable Development and Poverty Reduction Program SEA Strategic Environmental Assessment SFGS Streamflow Gauging Station SP Spontaneous potential SPOT Satellite Pour l'Observation de la Terre (French Satellite for Earth Observation) SRTM Shuttle Radar Topography Mission SS Suspended Solids TDS Total Dissolved Solids TEM Transient (or Time-domain) Electromagnetic Method TIR Thermal Infrared TM Thematic Mapper TOR Terms of Reference TU Tritium Unit TWSSO Town Water Supply Service Office TWSSSE Town Water Supply and Sewerage Service Enterprise UAP Universal Access Program UNEP United Nations Environment Programme UNESCO United Nations Educational, Scientific and Cultural Organization UNICEF United Nations Children’s Fund uPVC Unplasticized Polyvinyl Chloride USBR United States Bureau of Reclamation USGS United States Geological Survey UTM Universal Transversal Mercator VES Vertical Electrical Sounding VIP Ventilation Improved Pit WASH Water Supply, Sanitation and Hygiene Program WB World Bank WC Water Committee WFB Wonji Fault Belt WHO World Health Organization WSDP Water Sector Development Program WSSM Water Supply and Sanitation Master Plan WWDSE Water Works Design and Supervision Enterprise WWMEO Woreda Water, Mineral and Energy Office ZWMEO Zonal Water, Mineral and Energy Office

Chapter 1

Survey Summary

The Project for Groundwater Resources Assessment JICA in the Middle Awash River Basin, Final Report (Geological/Hydrogeological Maps) KOKUSAI KOGYO CO., LTD.

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1 Survey Summary

1.1 Objective and area of the project a. Objective of the project

The geological and hydrogeological study was executed as a part of the Project of “Groundwater Resources Assessment in the Middle Awash River Basin in the Federal Democratic Republic of Ethiopia (hereafter, the Project)” based on the results of the record of discussions (R/D) agreed and signed by the Federal Democratic Republic of Ethiopia and Japan International Cooperation Agency (JICA) on 27 May 2013. The objective of this geological and hydrogeological study is to create the geological map and hydrogeological map in the Middle Awash River Basin based on the results of the analysis of geology, hydrogeology, and water quality and to discuss the groundwater potential through the use of the geological and hydrogeological map.

b. The Project schedule

The Project started in May 2013 and was confirmed to end in December 2015.

c. Area of the Project

The area of approximately 20,000km2 in the Middle Awash River Basin covered by the geological and hydrogeological maps is shown in Figure 1.1.1 below;

Figure 1.1.1: Area Covered by the Geological and Hydrogeological Maps

Source: the Project Team, Data: Production by Project member


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1.2 Methodology of the Project a. The Project flow

The Project flow was shown in the following Figure 1.2.1; The geological and hydrogeological maps were created mainly by five works, namely satellite image analysis (for example land classification, lineament analysis), classification of geological units based on the existing geological maps and reports, geological field survey, arrangement of existing well data, and evaluation of hydrogeological units.

Figure 1.2.1: The Project Flow

Source: the Project Team, Data: Production by Project member


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b. Satellite image analysis

b.1 Satellite image

The interpretation of surface information on satellite imagery to grasp the volcanic geographical condition and geological structure for the basic data of hydrogeological condition was conducted using the following satellite imagery (refer to Table 1.2.1).

Table 1.2.1: Satellite Image for Interpretation

Satellites Shooting data and information Main purpose

1994-, resolution, 30m Extract DEM to create contours

2006-2007, Pacromatic, 0.5m resolution

high accuracy , Lineament, Geological structure, Topography, Vegetation, Collection of land use information

2006, 3 bands, ortho-rectified Extract DEM, Interpretation on 3D model

2008-2011,resolution, 10m Elevation map, Hydrology information map, Wide-area topography, vegetation, Collection of land use information

ALOS: Purchasing area for the shooting and shooting data

The SOPT and ALOS satellite imagery have been shown in Figure 1.2.2 and Figure 1.2.3.


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Figure 1.2.2: SPOT Satellite Image

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MelkaWerer

SirtuAger

Delajebo

MelkaKunture

DinkitiSheikHussein

AlemGebeya

HagereSernay

Sembo

Deneba

Berehet

Gebiba

AlemTena

Mechara

Chifara

Ginager

Duber

Sululta Arba

Bofa

Koshe

Segele

KechemoJimaArsi

Ankober

Eurdo

Adulala

Bulbula

AdamiTulu

Wilbarey

Muger

DebreZeyit

DebreBirhan

FicheGebreGuracha

Chacha

Asebot

Sheno

SholaGebeya

Ambo

Ginchi

TejiGodina

ChefeDonsa

MelkaJilo Metehara Bedesa

Sire WHararghe

AncharBedeyi

AddisHiwot

Abomsa(TinsaeBirhan)

ModjoBantuLibenDilila

Bu-i MidreKebda

Ombole

Koshim

TibilaTeferiBirhan

Magna

Hujufa

BeleArsi

HobeRobi

Roepeyh

Ziway

HurutaEndibir

Bube

Woliso

AdisAlem

AsebeTeferi

Asela

HaroKile

Kula

Dera

Kibet

Meki

MukeTure

Dida Adi

Merewa

Sodoma

TuluBolo

Arb GebeyaW Shewa

Guna

Gunchire

GubaKoricha

Melkasa

Mine

Suten

Arara

AgemtiIteya

Gelemso

Chole

Butajira

Chancho

Akaki

Lemi

Gojo(Jeldu)

Gola

Welenchiti

Rukeyisa

Arerti

Diksis

SagureDalocha

Wanje

DebreTsige

Nazret

AddisAbeba

Omo-Gibe

Awash

Abbay

RiftValley

WabiShebele

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Figure 1.2.3: ALOS Satellite Image

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AlemTena

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Godina

ChefeDonsa

MelkaJilo

Metehara

AncharBedeyi

AddisHiwot Abomsa

(TinsaeBirhan)

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Koshim

Tibila

TeferiBirhan

Magna

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GubaKoricha

Melkasa

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Iteya

Welenchiti

Arerti

Nazret

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MelkaKunture

DinkitiSheikHussein

AlemGebeya

HagereSernay

Sembo

Deneba

Berehet

Gebiba

AlemTena

Mechara

Chifara

Ginager

Duber

Sululta Arba

Bofa

Koshe

Segele

KechemoJimaArsi

Ankober

Eurdo

Adulala

Bulbula

AdamiTulu

Wilbarey

Muger

DebreZeyit

DebreBirhan

FicheGebreGuracha

Chacha

Asebot

Sheno

SholaGebeya

Ambo

Ginchi

TejiGodina

ChefeDonsa


Sire WHararghe

AncharBedeyi

AddisHiwot



Bu-i MidreKebda

Ombole

Koshim

TibilaTeferiBirhan

Magna

Hujufa

BeleArsi

HobeRobi

Roepeyh

Ziway

HurutaEndibir

Bube

Woliso

AdisAlem

AsebeTeferi

Asela

HaroKile

Kula

Dera

Kibet

Meki

MukeTure

Dida Adi

Merewa

Sodoma

TuluBolo

Arb GebeyaW Shewa

Guna

Gunchire

GubaKoricha

Melkasa

Mine

Suten

Arara

AgemtiIteya

Gelemso

Chole

Butajira

Chancho

Akaki

Lemi

Gojo(Jeldu)

Gola

Welenchiti

Rukeyisa

Arerti

Diksis

SagureDalocha

Wanje

DebreTsige

Nazret

AddisAbeba

Omo-Gibe

Awash

Abbay

RiftValley

WabiShebele

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c. Surface interpretation

The Digital Elevation Model (DEM) has been generated from the SRTM for shaded relief model and Aster Satellite imagery (refer to Figure 1.2.4). The data has been applied to create contours and shaded relief model to understand the surface characteristics of the Study area. The shaded relief model has been utilized to assess the lineaments and other geomorphological marks (such as volcanic craters and bodies) to support the structural evidence in relation to its geological setting and history. The major faults, lineaments and volcanic topographic aspects are presented in Figure 1.2.5 for using the shaded relief model, SPOT and ALOS imageries.

The geological structures in this area are characterized by the MER distributed from Rift Valley Lakes Basin (hereafter refer to as “RVLB”) and the Southern Afar Rift lied next to the northeast of the MER. The MER extends from the southern Afar margin to the Lake Chamo area in RVLB, whereas the South-western Ethiopian Rift (hereafter refer to as “SWR”) is located to the west and represents roughly N-S trending basins related to the Kenya Rift. The Gregory rift of Kenya links to the north with Chew Bahir rift. In accordance with Halcrow 2008, the character of the faults in the two rifts is explained

In a large sense, the central MER direction has been changed from NNE-SSW in the southwest Study area to NE-SW in the main Study area, and the western and eastern rift escarpment run in NE-SW direction (refer to Figure 1.2.5).

This area is called as northern MER, and the northern MER continues to run to the south Afar Rift in NE-NNE direction. The east rift escarpment come to the rift floor as the step faults in the east rift of the Study area, but the west escarpment is unclear. The rift floors, plain area bounded by the both side escarpment, lie in the grabens from the northern part of RVLB to the northeast of the Study area. The scablands have distributed continuously in the rift floor, and runs to the south Afar Rift. These volcanic bodies have lined from the Corbetti, Aluto volcanos (the Aluto is active volcano) in the central MER of RVLB to the Tullu Move, Gedemsa, Boset, Kone and Fantale volcanoes in NE-SW direction in the eastern MER, and have accompanied with caldera and rhyolitic pyroclastic flows largely. There are lots of scoria pyroclastic cones in surrounding volcanic lines. The floor of northern MER is dissected by clear, fresh NE-SW to NNE-SSE trending faults known as the WFB, and WFB can be traced to the southern Afar Rift.


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Figure 1.2.4: ASTER DEM

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SirtuAger

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DelajeboMelka

Kunture

Alga

Sedika

Dinkiti SheikHussein

HaderoTunto

BurkaJere

Kobo(Harar)

MamaMidir

AlemGebeya

Kurkura

HagereSernay

SemboHareto

Deneba

Jihur

Siba

Yemistina

Yeweynit

SireGino

Beltu

Berehet

GulaBedesa

Gebiba

Nada

Saja

AlemTena

Mechara

Chifara

Dodi

Dole

Ginager

Kutara

Duber

Fetra

Sululta

Delo

Arba

Kulubi

Bofa

Koshe

Gena

Segele

Boreda

Nefera

Taza

Kechemo

Gamoji

JimaArsi

GoroBale

Loko

Ejersa

Ankober

Eurdo

Adulala

Banta

Bulbula

AdamiTulu

Wilbarey

Deneba

Baso

Kose

Omonada

Dinkore

Muger

AlemKetema

DebreZeyit

GohaTsion Robit

TarmaBer

DebreSina

DebreBirhan

EnewariEjere NShewa

FicheGebre

Guracha

Fincha-aChacha Bike

GotaErer

BedenoHarawacha

Doba

Mesala

Asebot

Sheno

SholaGebeyaGoben

Sheboka

HamusGebeya WShewa

Guder AmboGinchi

Teji Godina

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Sire WHararghe

Harew

MuchaRoba

Tirtira

HmeroAncharBedeyi

AddisHiwot



SilkAmba

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BotorKetar

ToleJima Abelti

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MidreKebda

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Koshim

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Magna

Hujufa

BeleArsi

Hobe

Gobesa

Robi

Meliyu

HisuSinana

Goba

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Mio

KoreArsi

Kofele

Shashemene

ArekaWaka

LomaBale Zima

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AlidiAdejijo

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Robe

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Asasa

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Asela

HaroKile

Haydro

Kula

Shambu

Dera

Deder

Burka

ArsiNegele

KersaChilalo

Kibet

Meki

MukeTure

Shone

Dida Adi

Yejube

Merewa

Sodoma

TuluBolo

Arb GebeyaW Shewa

Farichu

Guna

Gunchire

MumichaGubaKoricha

Miaw

Mazorya

Dodola

Abebe

Hosaina

AlemGena EShewa

Melkasa

Mine

Molale

Morocho

Morsito

Mana

Ada-a

Niso

Obo

Sura

Suten

GurandaArsi

Gurlero

Arara

ArbaReketi

Guracha

AgemtiIteya

Boko

Gelemso

Chofira

Chole

Fonko

FulensaTawla

Butajira

Chancho

Akaki

Lemi

WeyabetaWeyge

AbdelaBale

AdisAmba

Durame

Edeneba

Gojo(Jeldu)

Gola

Welenchiti

Rukeyisa

Yilu

Arerti

AroDimtu

Bele

Giyorgis

Aje

Diksis

Sagure

Sirba

Dalocha WanjeFofa

Gibe Asendabo

GimbichuDoyoGena Alaba

Kulito

Aweli

Gedeb

GunaArsi

Jara

Ginir

Hirna

Adaba

DebreTsige

Nazret

Awasa

AddisAbeba

Omo-Gibe

Awash

Abbay

Genale-Dawa

RiftValley

WabiShebele

LakeErtele

LakeDendi Lake Ala

Semite

LakeAbijata

LakeShalla

Lake AwassaLake O'ACheleleku

LakeGoletsho

LakeChomen

LakeKoka

LakeLangano

LakeZiway

Lake Dalay

LakeWenchi

LakeBeseka

41°0'0"E

41°0'0"E

40°0'0"E

40°0'0"E

39°0'0"E

39°0'0"E

38°0'0"E

38°0'0"E

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10°0

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0"N

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0"N

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0"N

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1100

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550m amsl Blue to 4200m amsl Reddish brown

Source: the Project Team, Data: ASTER


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Figure 1.2.5: Topographical Information Map by Satellite Images

(m)

(m)

Source: the Project Team, Data: SRTM+ Result of survey in this project


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d. Creating of the geological map

The main existing geological maps in the Project area and its surrounding areas are as follows;

Geological map of Nazret, Ethiopian Institute of Geological Surveys (EIGS), 1978 Geology and Developing of the Nazret area, northern Ethiopia rift, Kazmin etc. EIGS

1978 Geological map of Dire Dawa, EIGS, 1985 Geological map of Debre Birhan, Geological Survey of Ethiopia (GSE), 1993 Geology of Debre Birhan area, Daniel Mesheha etc. compiled, GSE, 2010 Geological map of Akaki Beseka area, GSE, 1997 Geology of Akaki Beseka, Efrem Beshawered compiled, GSE, 2010 Geology of Addis Ababa map sheet, GSE, 1997 Geology of Addis Ababa city, Getahun assigned, GSE, 2007

A reliable hydrogeological map was created based on a detailed geological map. Therefore, in the preliminary survey of geology in the field, the middle Awash River Basin was divided into four areas in accordance with the aspects of geology and distribution. The strata of each area were correlated based on the specific geology (a key bed), and the correlation chart was described. Finally, the stratigraphy in the entire area was created and the geological map was completed in the middle Awash River Basin (Map scale of 1:250,000 in the entire area and 1:100,000 in Lake Beseka area).

Chapter 2

Summary of Geography and Geology


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2 Summary of Geography and Geology

2.1 Summary of geography a. Landform

The Study area is located in the northern sector of the Main Ethiopian Rift (hereafter referred to as “MER”), and the Study area of the northeast broadens northward into the Afar Rift (refer to Figure 2.1.1: : Northern; : Central and : Southern of MER respectively). The geological tectonic direction in the rift escarpment of MER has been changed from NE-SW to ENE-WSW between and (refer to Figure 2.1.1), and it made an aperture at the Aden junction in the Afar Rift.

The Study area is bounded by the western rift escarpment along the northwest highlands heading towards Addis Ababa, and the altitude of the highlands ranges from 1500m to 2600m above mean sea level (hereafter refer to as “amsl”). The graben in MER runs in NE-SW direction. The altitude of the lowlands in the Study area changes from 1750m amsl of Tuluri Mountain in the southeast, to 1000m amsl at Awash area in the east. The rift floors are subjected to recent volcanic activities from Moye volcano (altitude 2349m amsl) in the southwest, to Fantale volcano (altitude 2007m amsl) in the east. In between of the two volcanoes, several volcanoes and pyroclastic cones are distributed continuously. In Arsi zone, located in south and southwest in the Study area, the rift escarpment is located between the central rift of MER to the west and the Arsi plateau to the east. The altitude of this escarpment ranges from 1500m amsl to 2500m amsl. The Arsi plateau bounded by the lowland in the east and the altitude of the lowland changes from 1000m to 1900m amsl. The Arsi plateau elevation ranges from 2000m amsl at Sire to 3625m amsl at Arba Gugu Mountain.

Figure 2.1.1: The Central Sector of the MER

b. Watershed classification

In Ethiopia, there are 12 major basins and each is subdivided into minor sub-basins (divided by the Ministry of Water Resources (hereafter refer to as “MoWR”) (old name) refer to Figure 2.1.2). The Study area lies next to the northeast of Rift Valley Lakes Basin and the topographical elevation decreases toward the northeast in general. The Awash River flows

Source: G. Woldegabriel, 1990


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toward the northeast, in which direction the elevation of topography also decreases, and its flow direction changes to the north in its middle area.

Source: Ministry of Water, Irrigation and Electricity: MoWIE

Figure 2.1.2: Major Basins in Ethiopia

c. Hydrographic system

The Awash River source is Mt. Warque in the west of Addis Ababa. The river runs toward south-eastern direction for around 130 km and then changes its direction to the northeast at around Mt. Zuqualla. After passing through the Awash National Park, the Awash River is being joined by the Kesem River, the biggest tributary, from its left bank side. The river finally flows into Lake Abbe located on the national boundary with Djibouti. Since Lake Abbe has no water outfall, the Awash River Basin forms a closed water area. The total length of the Awash River is 1,200 km and the total catchment area is 112,700 km2.

The Middle Awash River Basin is defined by the Ministry of Water, Irrigation and Energy (MoWIE) as the watershed area upstream Melka Werer town in Afar Region. Total catchment area of the Middle Awash is 29,280 km2 according to the measurement by the JICA Study Team with available Digital Elevation Models (DEMs). The length of the Middle Awash reaches around 380 km.

General topographic view and river system of the Middle Awash River Basin are shown in Figure 2.1.3 and Figure 2.1.4, respectively.

MEREB GASH

TEKEZE

ABBAY

AWASH

DENAKIL

BARO AKOBO

OMO GIBE

AYSH

WABI SHEBELE

OGADEN

GENALE DAWA

RIFT VALLY

Ministry of Water Recourses Water Recourses information,

Natural Recourses & Environmental Meta data Center

GIS & Remote Sensing Group

Major River Other Rivers

Fresh Water Safety Lakes Sandy Salt Plain

International Border

River Basins Border


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Figure 2.1.3: Digital Elevation Model of the Middle Awash River Basin

Figure 2.1.4: River System of the Middle Awash

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Addis Abeba

Adama (Nazret)

Gola

Mine

Guna

Meki

Dera

Kula

Bube

RobiHobe

Bu-i

Teji

Wanje

Akaki

Chole

Iteya

Suten

Kibet

AselaZiway

Magna

Modjo

Sheno

Diksis

Arerti

Agemti

Sodoma

Merewa

Woliso

Huruta

HujufaTibila

Koshim

Dilila

BedesaGodina

Ginchi

Asebot

Chacha

Chancho

Gelemso

Melkasa

Endibir

RoepeyhHombole

Butajira Dida Adi

Metehara

Tulu Bolo

Muke Ture

Haro Kile

Adis Alem

Welenchiti

Melka Jilo

Debre Tsige

Midre Kebda

Bantu Liben

Addis Hiwot

Chefe Donsa

Gojo (Jeldu)

Guba Koricha

Shola Gebeya

Debre Birhan

Teferi Birhan

Anchar Bedeyi

Arb Gebeya W Shewa

Abomsa (Tinsae Birhan)

Bishoftu (Debre Zeyit)

Bofa

Arba

Muger

Koshe

Duber Sembo Segele

Deneba

Fitale

Adulala

Ankober

Kechemo

Sululta

Ginager

Chifara

Mechara

Berehet

Mendida

Delajebo

Jima Arsi

Alem Tena

Adami Tulu

Sirtu Ager

Alem Gebeya

Melka Werer

Hagere Sernay

Melka Kunture

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40°0'0"E

39°0'0"E

39°0'0"E

38°0'0"E

38°0'0"E

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9°0'

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8°0'

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8°0'

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Elevation (m. amsl)

Source: the Project Team, Data: Result of survey in this Project

Source: the Project Team, Data: Result of survey in this Project


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2.2 Regional geological and tectonic setting a. Regional geological setting

The study area belongs to northern part of the Main Ethiopian Rift (MER). MER developed over a span from the Oligocene to the Quaternary. During that period, major volcanic episodes are recognized in Oligocene, middle Miocene, late Miocene, early-middle Pleistocene and Holocene (WoldeGabriel et al. 1990). An overview of the history of MER development is as follows;

The oldest volcanic activities are basalt and rhyolite flows in Oligocene, exposed in and around the rift margins (e.g. Blue Nile gorge), which formed lava plateau in the surrounding area. By middle Miocene, the rift was formed in some parts with containment basaltic flows. In Pliocene, a huge pyroclastic flow covered the northern part of study area. This characteristic pyroclastic flow deposit is currently observed at the depth of around 2100m in the basin floor by geothermal well, indicates a minimum of 2km of downthrown in the rift basin since its eruption (WoldeGabriel et al. 1990, WoldeGabriel et al, 2000).

In Pleistocene, Wonji Fault Belt (WFB), which is the main spreading axis of MER, is formed at the rift floor, and floor basalt and rhyolite are erupted along WFB. The volcanic activities are characterized by peralkaline fissure basaltic eruptions and rhyolitic eruptions which make volcanoes and calderas. MER was formed as symmetrical depression zone in this period and many lakes appeared and disappeared by obstruction of volcanic deposit and/or climate change.

b. Regional tectonic setting

The initial stage of MER formation is closely related to that of the Red Sea and Aden Sea. In Mesozoic time, north – central MER was bulged. That is deduced by the existence of thick Mesozoic sediments in Kella horst (North of Butajira) and the Blue Nile gorge.

In Oligocene, large and huge volcanic activity created a lava plateau. In early Miocene, three radial rifts might have been formed in the plateau. After that, two rifts spread open and were downthrown to the sea, which became the Red Sea and Aden Sea. The other rift, which was not spread well, became the MER.

Such kind of tectonic activity is considered to have occurred in the initial stage when the continent started splitting, and caused by rising of hot plumes from the mantle (refer to Figure 2.2.1).

Structural and stratigraphic relations of volcanic rocks along both rift escarpments of MER indicate a two-stage rift development. The early phase started during late Oligocene – early Miocene and was characterized by a series of alternating and opposed half grabens. The half-grabens evolved into a symmetrical rift during the late Miocene. The area also was characterized by active rifting during Plio-Pleistocene, around 2000m of subsidence was estimated (WoldeGabriel et al, 1990).

The rift floor is nowadays covered by lakes, lacustrine sediments, basalts from fissure eruptions, and silicic tephra from the nearby Quaternary volcanoes.


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Figure 2.2.1: Schematic Diagram for Development of Red Sea Rift and Aden Sea Rift, and failed African Rift (MER), (Source: http://www3.interscience.wiley.

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