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Description
BY. G ti.IICIIAEL G IKIRSTOS
DECC~IUhR. ~!EKELLE.
2013
E II 1101'11\
1. Introduction . .. .......... .
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1.1. Loc:=ation and accessibility ................................................................................ ............ . 1 1.2. Objective of the study ............................................................ ...................................... . 3 1.3. Methods and materials used 3 1.4. Climate and topography ...........................................................................: .................... 3 •• •• •• ••• ••• 0 ••••• ••• •
••••• • 0 •••• ••••• •
•
•
••• •
••• •
•
• •••••
••• • •• •
• •
0 0 •••• 0 •
0 ••••••• •
•• • 0 •
0 0 0
1.5. Existing water source ................................. .... ............................................................... 3
2. Geology and hydro geology ... ......... ...................... .... ..................... .4
2.1 Geology ...... .. ...................... . 4 2.2 Hydrogeology ............................................................................................................... . 4 •
0 •••••••••••• • •
•
•• •
•• 0 •••••••••••••• •
•
• •••••••••••••••• • ••••••••••••••••• •
•••• •• •
•
••• •
•
• •
3. Geophysical survey . . . . . . . . . . . . .. . . .. .. . . . . . .. . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
3. 1 VESO 1 (Tyrabora) ................. ........................................................................................ 7 3.2 VES02 (Kartato) .................................................................................................. .......... 9 3.3 VES03 (Bahl) ............................................................................................................... 10 3.4 VES04 (Baht existing wereda we ll) .............................................................................. 1 J 3.5 VES05 (Bah I) .......... .... ................... ..... .......................... ... ......... ................ ............ ...... . 13 3.6 VES06 (Kartato) ........... ........................................................................... ........... ... ....... 14 3. 7 VES07 (Berahle) ....................................................... ................................................... 16 3.8 VES08 (Folho) ............................................................................................................. 18 3.9 VES09 (Berahle) ........................................ .................................................................. 19 3. 10 VES I 0 (Tyrabora) ................................................ .................................. ....................2 1 3.11 VES 11 (Asekah) .........................................................................................................23 3.12 VES 12 (Asekah) .........................................................................................................25 3.13 YES 13 (fyrabora) ......................................................................................................27
4. Discussion, Conclusion and Recommendations ... .. .......... .. ... ......... ... ....28
4. 1 Discussion and Conclusion ..................... .......................................................... ............28 4.1 I Nearby option ........................................................................................................28 4.1.2 Far option ..............................................................................................................29 4.2 Recommendations ........................................................................................................29
5. TECHNICAL SPECIFICATION ... ... ............ ............... .. ............ .... .32
Scope ......... ..................... ........... :.................................................................................32
. . In vesttgat1on ................................................................................. ..........32 5.6. Material Supply ........................................................................................................... 33 5.6.1 Screen, Blind Casing and Observation Pipes ..........................................................33 5.6.2 Gravel Pack ...........................................................................................................33 5.7. Well Flushing and Deve1opment ..................................................................................34 5.8. Well Head Construction ................................... .... ........................ ................................34 5.9. Well Testing (Pumping Test) .................. .................. ................... ................................34 5.9. J Step draw-do\vn Test ............................................................................................. 34 5.9.2 Constant Discharge Test ................................................................. .......................35
5.9.3 Recovery Test ... ..... .................................. ....................... .... .................. .................36 5.9.4 Pumping Test Requirements ...................................................................... ............ 37 5.10. Water Sampling and Quality Analysis ..................................... ..... ..... .................. .......37 5. 11. Technical Report................ ..
. .................... .............................................. .....38
II
Groundwater
refugee Camp ( AAAA)
List of figures Figure I Location map of the area and site options .................................................................. 2 Figure 2 Curve matching and interpreted layer parameters of VESO I ...................................... 7 Figure 3 Curve matching and interpreted layer parameters ofVES02 ...................................... 9 Figure 4 Curve matching and interpreted layer parameters of VES03 ................................... .. 10 Figure 5 Curve match ing and interpreted layer parameters ofVES04 ..................................... !! Figure 6 Curve matching and interpreted layer parameters of VES05 .. ........... .. ..................... . 13 Figure 7 Curve matching and interpreted layer parameters of VES06 ... ........ ... ... .................... I 4 Figure 8 Curve matching and interpreted layer parameters of VES07 .......... ........................... 16 Figure 9 Curve matc hing and interpreted layer parameters of VESOS ......................... .......... . 18 Figure I 0 Curve matching and interpreted layer parameters o f VES09 ................................... 19 Figure II Cur\e matching and interpreted laye r parameters of VES I 0 ...................................21 Figure 12 Curve matching and interpreted la)'er parameters of VES II ................... ................ 23 Figure 13 C urve matching and interpreted layer parameters of VES 12 ........... ... ... ... .. ........ .... .25 Figure 14 Curve matching and interpreted layer parameters of V ~S I 3 ... ...... .................. ........27
List of tables fable I VES sites and their location ..... ... .......... ........ ................................. ......... .................... 6 Table 2 Layer parameters and possible lithology at VES 0 I (Tyrabora) ............................. ...... 8 Table 3 Layer parameters and possible lithology at VES 04 (Bah I existing we ll) ................... . I 2 Table 4 Layer parameters and possible Iithology at VES 06 (Kartato) ................ .................... I 5 Table 5 Layer parameters and possible lithology at VES 07 (Berahle) .... ................................ 17 Table 6 Layer parameters and possible lithology at VES 09 (Berahle) ...... ....... ... ............. .......20 Table 7 Layer parameters and possible lithology at VES I 0 (Tyrabora) .. ......................... ....... 22 Table 8 Layer parameters and possible litho logy at VES II (Asekah) ....................................24 Table 9 Layer parameters and possible lithology at VES 12 (Asekah) ..... .... ... ................. .......26
C05000
li08000
0 0
~
N .,., .,..
------ll.:-========:=:1
0
1; 1-1000
li08000
005000
1,000
2,000
4,000 MehlrS
Location map of the area and site options
1. Introduction
Shortage of safe drinking water is one of the major problems in Ethiopia. As a manifestation, most towns, semi-towns and rural societies of the country have no sustainable source of water supply. The Afar regional state is one of the regions in Ethiopia with less access to adequate water supply sources. So far the main source of water for domestic use is mainly obtained from groundwater. The reason for the dependence on the groundwater is because the development of surface water is by far expensive as compared to the development of groundwater. But groundwater exists in economic quantities in virtually most parts of the region. Furthermore it is not evenly distributed with respect to its quantity and quality. Thus there is a need for site specific study to assess the localized groundwater occurrence in the region. Among the areas in the region characterized by uneven distribution of groundwater is Village Tyrabora found in Berahle wereda, in response to variation in type of rocks, degree of secondary structures, grain size and sorting of the sediments with in the area and also shortage/no rainfall. In other words, the uneven distribution is resulted from the difference in the amount of recharge; lithology and topography prevailed in the area. Administration for refugee and Return Affairs (ARRA) has planned to supplement the existing in adequate safe supply of drinking water in Berahle refugee camp through the construction of deep boreholes. Hence as the request made by ARRA for hydrogeo logist from Tigray Water Resource Bureau to locate possible groundwater site for deep well drilling, two borehole sites with additional two options were proposed.
1.1. Location and accessibility The study area is located in zone two, Wereda Berahle of Afar region at about 120 kms away from Mekelle town, the capital city ofTigray region (Fig.l ). It is found at about 1 to 5kms from Berahle to the right of the all weather road of Mekelle -Berahle. The specific site selected for drilling is accessible by track (needs only minor maintenance).
•
1.2. Objective of the atudy The main objective of the present study is to select borehole sites mainly for the Benhle refugee camp of ARRA supported by UNHCR and UNICEF. 1.3. Methods and materials used Important materials and equipments were collected and previous works conducted in the area were reviewed prior to fieldwork to have an idea about the area in relation to geology, topography and hydrogeologic condition. Geophysical survey specifically vertical electrical sounding was applied to under:.tand the geological variation with depth at d ifferent options/ selected target areas. T he material U'>ed during the stud> include topographic map, J land held Garmin GPS, SAS 4000 Geoph) k s instrument and "iatcllitc image of the area. fP2 ~oftwnre was used for the intcrprctatton oft he rco;i'>tl\ tl\ '> urvc>. 1.4. Climate and topography l he t.1rgct area i-; generally charactcri1ed by arid climate with little or/and no rainfall.
I'L•pvgraphicall>t. Berahle is charactenzed by flat plain surrounded by a rugged chain of ridges anJ nwunt::~i m.. I he area is sttuated
,\l ,t l oc <~l
valley :.urrounded by an undulating morphology
comp a a H - of Basement comple\. dtlls and recent dykes. The htllside of Berahle is highly rugged and dis:.ccted in nature.
1.5. Existing water source
,\ ccording to the infom1ation obtained from the wereda and ARRA representatives, the current population (refuges) in the village is increasing. The water source currently they are using is from
t\\0
''ells located at nearby the target beneficiaries. One of the two wells drilled is
hallo"..· depth and with low yield. fn addition, one deep borehole O\\ned by the wereda is en ing for Berahle and nearby local people. As it was observed duri ng the fie ld work and information obtained from the two representatives, water from the existing wells is not sufftcicnt to satisfy water demand for the people and the animals of the nearby local people. In addition to the quantity, quality of the water obtained from the existing and feature dr illing \\ells should be taken into consideration. As it was observed during the field work more residence homes for the local people and refuges are being constructed around the existing wells and also common toilets arc being implemented within and around the compound of the residents. This all activities in conjunction with the fracture properties of the surrounding geological material can facilitate the time and speed of contamination of the wells, which will
be difficult to have enough water fi1r the locul peoplt as W a H a Q G Z D W F U resource of the area is ' j\l" ' ' found to be limited. , · "' • ' 11 ) • 3
'Ria..,.. Ia order 10 prevent any damap to the drilled well and avoid any water conr.minltioa. any residence expansion and construction of toilets around the upstream nearby of the well must be avoided. In order to control1mpact of the existing activities over time. it is important to establish a long tenn :t) tematic una lysis of , .. uler sumpies from the \'tells supplying the local people
2. Geology and hydro geology 2.1 Geology Ba Jon S U H a L R X V W X - L H a regional geology and field observations, the gcolog•c lormnrions tdtn11ticd in d)k
o.. mhlc and its surrounding) are Basement complex, Andes1te and Gmnodiorite
nd thick Allu\ial Jepo!;its transported from the surrounding rugged ba ement
compte cs. The \llu\ial deposit ofthe area L a limited to the river banks and beds. This deposit i:. nlso
ob cncu at local plains just nt the foot mountainous terrain. The grain size of" the allu\i31 depo it varie:. from big boulders at the foot of the mountains to silt} material at tar urea-. from
the c:hff!
l1le 8 ement complex mainly consists of metavolacanics and mcta..cdunent-.. I he dcgrc.:e (.\f \\ealhering and degree <.lf fracturing is highly variable from place to place Torx,graphicnlly d11s fonnation i5 characteri1ed by a highly rugged and dissccteJ C\'mple\. terrain . Antidine ami
ync:hne fe ture In
re common phenomenon which U H V X O W a m unJul.tti 1g tl'J'('gr.tphk kature .
me nrca of the c tchments, the
W Z a P W Q O rPd.. ,.,
sec:ondat) m tenal fill In areas tlte ha nn dtonte dyke
nd
1!50 out
(:flll!lll
htghh Q O O a ā G a ā G tn altcrat11.m und •
um1plc' '' P W W X G a G o\• an umksih: nntl
At u number ol pl,tu:s, the d) kc" X a tllttudcd tnt\\ the ha'>cmcnt a O W Q S O F
cro1pped nt url.lce with de lined urtcnt.ltion
2.2 Hydrogeology
Jr Wld" teroccurrenc:e i greatly 111t1uenced by the gcoiOS), IOJI gr phy und cJun ltc luctor<; th 1 prev tied rn gt\ien ren By U1<: nt nly c ntrolleu by the
me I tthe h)dro cc.lo , conuttinn <'I the tully tea is
eulogy nd colo
1
I truClure Them 110 source ot groundwater is
rcc:hnr e from mull II r n lhe other h nd rate ofrech r e
1
mf1uenocd b'- tt • J
1e
.
mtenstty lll
rainfull. t po mphy nd h,>Lirnuhc p pertte ofthe rock format 1on out c d h roprc Ill I C C:At(hmenl
• f: 1 ' nn raJO a I. Accordmg to the local people of the t •r&ct urea, only two or 1hrec times of rainf.lll · • per }car IS the conHnl1n cond1tton ofthe area J hus the S R a V L E K ! of ild..1t! • · ,.. • rrre; arge IS Irom F·lood., Rivcr' and Unlnrtun.ttel) . the r.ain tall L Q W a Q V W W \ tn the t r ct area i \<:ry lu v/
·
( AAA.A )
4
streamS dud drained fi'om the adjacent highlands. Penneability, storativity and a Q V P L V V L Y L W \ of rock is either due to inter-granular or fracture pore spaces in the rocks. Penneabtllty of the rock around the project area is also expected to have both granular and fractured properties. In this area the rocks found exposed is the basement, intrusive and alluvial deposit. Crystalline rocks( basement and intrusive) are generally impermeable, because they don't have primary porosity and permeability, hence ground water occurrence is localized and structurally controlled, which is dependent on fracture systems and weathered zones. The basement rocks in the area are found on the upstream part of the area as topographic high, steep slop less accessible rugged escarpment which drain towards the target area. The rocks are surfacially weathered and affected by different direction of fracturing system. Streams flow from the escarpment easily eroded the top part of the rock and deposit it on the flat area as thick alluvial sediments. Alluvial deposits with boulder to gravel size are common at the foot of the ridges. And thick soil underline by coarser gravel is also common on the flat area and valley topographies. Therefore although this rock is rugged and less accessible, it serves as important source of recharge to the target area through the base flows. In addition to the nature of fracturing, orientation and the dip direction are also by far positively correlated with the recharge capability of the rocks. The weathered granodiorite rocks become loose, porous and permeable. Based on the recharge condition and the previous borehole history of the area, the possible site for borehole site location is at/nearby the river bed or at the alluvial deposit of the river bank. Thus as the target of the study was to explore sites characterized by a geologic formations possessing either primary or secondary permeability in combination with favorable recharge conditions, sites were located near to the river beds of the area.
3. Geophysical survey Considering different options, geophysical survey was conducted at different areas. The geophysical method applied was electrical method, particularly vertical electrical sounding (YES). Schlumberger array was applied to collect the required electrical response of the geological materials. The main objective of the geophysical survey is to determine the · an thickness /geological variation, depth to· water table and to identify wl1eth er tl1ere IS embedded impervious layer of tillite. The geophysical data collected d · h fi . ' unng t e 1eld survey · • was interpreted with the help of IP2 software. Accordingly each YES 1 . . resu t IS descnbed below The geographic locatiOn of the spots at which geophysical .su1vey . . earned · out .IS was summarized in table below.
Groundwater resource as
fugee camp
(ARRA)
5
Table I VIS • • ud •••lr loeatlon
Site aame Rqion Tyrabora
Afar
Tabla
Kushet
Berahle
Tyr abora
VESao X(east) Y(aortb) Remark a
Kartato
Afar
Berahle
BahI
Afar
Berahle
BahI
Afar
Berahle
Bah I
Afar
Kartato
Tyrabora
-Tyrabora -- f-
01
03 02
•
-
609419
1530497
609480
1530551
609739
1530667
609726
1530678
.
. .
-
-
Tyrabora
04
Berahle
Tyrabora
OS
609750
1530550
Afar
Berahle
Tyrabora
06
609433
1530501
Berahle
Afar
Berahle
Berahle
07
610028
1532146
folho
Afar
Berahte
Berahle
08
609739
1531299
Berahle
Afar
Berahle
Berahle
09
609919
1531901_
Tyrabora
Af ar
Berahle
Tyrabora
10
609409
1530181
Asekah
Afar
Berahle
Aseka h
11
611742
1525211
Option
Selected
-
I.
-
Asekah
Afar
Berahle
Aseka h
12
611264
1525764
Ber ahle
Afar
Berahle
Tyrabora
13
609428
1530213
Option
selected
-
-
I ht.: curve matching and the interpreted layer parnmeters (Rcs1sti\ 1t). W K N N Q F a V and depth the selected YES points} are indicated in the figures below.
!'-
3. 1 VESD1 {Tynlbora)
'
••• •
•• ••
••• •• •
.• •
• : : '
.
.• •
•••
•• ••
. : : . ------------·-···-········ ········,·········...
•••
!
... ..
āāāāāāāāāāāāāaāāāāāāāāāāāāaāāāāāā
..
•
..: .:.•
..• .
•• •
F
..•• ..•
--- - -- ------·~·-····· ··- ·· · -·····;··············
•
..••:•
:. ••
.: .• •• ...• :: . . .. . . . ----r.:-7:':~~C::::::~s.:.::.;; : ; ············-~---·· · ·····-·······:· ······ ······· ... ..... ·····.. ......................... .. ··············:-········ . . .. . . . . . : . : : ..• :. . :. .• .• .. • •• •• lCXI : ,· ---1r-r-----~--~~--t-----~ ··~---~~----~--~~\r-i------~·4---~--+ • • .• •. •' ...• .. ..• .• : .:: . .: . . : : . . ......... .... . ................. .:. ········ ·······:······· . ..... .........-........ ........... --····················· ······.... -------.... . .•• . .•. • ..• .. ..• • . .... . ······ ........ .. .. ·············\··················· i·············· .. . . . ..• .:• .• .• • • .. .: :. ••. .. . ..•• •• 1>8 :
:
: : :
0
•
: : :
·········---- -~--
~
···-~--
~'
''~,------l----~~_L·~~~~r----~----~~---~~~----~--~~~--~~
N 1 2 3 4 5 6 7
p
214 307 6.71 14.5 174 29.9 34120
I
h 1 .81 1.29 3.18 16.1 12.7 45.2
I
d
1.81 3.1 6.28 22.4 35.1 80.2
Figure 2 Curve matching and interpreted layer parameters of VESOl
As it is indicated in the curve matching, different layers with inter-layering of high and low resistivity are identified. The layer parameters as identified from the interpretation result and the possible lithology of each layer is summarized below.
' Groundwater re5ource
a~s.es~~~
'
refugee Camp
(ARRA,)
7
3.2 VES02 (Kartato)
liD
..• .. ..•
.:••
.:••• . . . : ..I• ..•' ··············~········ ··· · ··· · ··\··· ···· · ······ ········ ······:·· ..' ' .'' · '' ..' .' .' . '' ... .. O
O
O
••
••• •• ••
, , , ,
.
:
:
..:•
..:•
. .• .. ..: ..• . : ...:
:
..• .. .• .•• .• . . .••.. . .. .. .. •• .• ..•• .. •'• .. .• ...---.,\ . ...i;. .... ..... ... .. ..
1--- ------
::
• •
••• •
:' • :
!
:
•
:'
:
:
. ~-----)l
. ...: .
o o o o o o o o o o o ,;. o 0 o o o I o o o o o oO
. . . . ;. . . . . . . . . r. . . . . .................!'............ :
: : :
•• • • 0 •
• 0 •••• •••
•
. /:
•
:
:
......t ............ .
.:.•
. . •• .• ...• ..• : : ..:
· ·· · ··· · ···· · · ··~ ·· ·· · ·········
........... .L/......... . .
... .
p
••
•
.-.-...
l ;· _...... ...-........
. •
ABf.
'~,----t::':t----t:':::::J~,o~~o--~·~----~~·----~ ,0 N
1 2 3 4 5 6 7
D
605 105 3.85 24 5.16 134 14
I
h 1 0.468 1.18 0.888 1 .67 5.03 8.42
d
0.468 1.65 2.53 4.2 9.24 17.7
figure 3 Curve matching and interpreted lnycr parAmeters of VES02
As it is indicated in the curve matching, different layers with inter-layering of high and low rcsisti vity are identified.
Groundwater resource
~ses6JIIent ~o.r. Be,~a , a re£ugee Camp
.' '
'
~---
./
.·
(AAAA)
9
•
. 3.3 VES03 (Bah/) p
. .... . •
'
···-~--
. ····· ... ··- ... ... . ... .................... .•
·· ·· ·······- ······-~---· ·· ·-·····
I ................... ····· •...• ·--- ··------······-· •
.•• .•
. ········ ····· ·· ····~---· ·········
.......-- .... ... ..• ..• .••. .. .. . ..• .. .. .. .: . ..............:: ... -.-.....-.--... ·:.--. ... ···············-··········· . .: . . . • .. .. ..:.• ..•• ..• . . .: . ·············-~----····· ····· ·· .,:•....... . .. .• ..• ..
·~·· ······-- -~--········ ··
-~---··
·········· ···· ··~---- ··· ······
I
:
J
·····-····-···l···-·····-···· ..:
. .. ..•
..: ...•.......•.. ....
·············· ..:" "'' ..
.
··········:········· ····-·· :
.........
.
.
-- ~- ---···· ·-----···· -; ....•••..... ••
11~.--~·--~~~~~--~~~~~~--~~~~~~ N 1 2 3 4 5 6 7 8
p
1
103-1 711 60.7 4.19 63.9 1382 64.4 3157
h I 1.1 4 0.113 3.27 4.26 1.26 9.45 227
d 1.1 4 1.25 4.52
8.78 10 19.5 247
t I
I
Figu re 4 C urve
matching and interpreted layer par am eter s of VES03 •
As itts indicated in the curve matching, difTcrcnt layers with inter-layering of high and low )
resistivity are identified. This site is not recommended for any groundwater well drilling.
I I I
I
Gr o undwater resource
Camp ( ARRAJ
10
le J
Tab
Layer
uyer parameten and poss ible lithology a t VES 04 ( Bah I n isting we red a well)
Resistivity
Thickness
Depth
(ohm meter)
(m)
(m)
Possible lithology
I
81.9
0.397
0.397
2
856
0.853
1.25
Dry coarse top soil
3
3.02
1.78
3.03
Fine grained alluvial deposit
4
135
4.85
7.88
Coarse grained dominating alluvial deposit
5
17.9
13.7
21.6
Fine grained dominating
6
821
40.8
62.3
Coarse grained +slightly fractured BS
7
16.8
49.8
112
Highly fractured metavolcanic, saturated
8
2005
-----........._ --------
Dry top soil
Slightly fractured to massive metavolcanic
'-
\
12
3.5 VES05 (Bah/)
p
.. •. .. I . . • .. . ..• .•••. .. .. ..• .• . . ......... . . . . ..................;. ··········· . ·· ······· ······-~· ·················-; ·············· .... .. ... ·····-·········· •• : . . . . .• .•• . • .. . ~ • : .. .. ""-.. ; ..• : .. : .: . . ....... :' ............... •. .' ............t. -· .. ···········•*"'''"-...·- ·············· ················.. ············-· .: --··············:············ . .......: ··········· . .... ····---~- - - --· · ···· · ···· ·· ···:·····
:/
_,
0
~
••
•
·.
0
:
;
•
•
•
0
•
•
•
•
•
:
:
:
0
~ •
:
•
; l
;
~ :
:
: '
ASr.
1~______j:__~~~-4 ' r-~-h,~______L:t-_.--~J'~~~J,~o-----~·~--~~~~~~,w ~
1
N 1 2 3 4
5
6 7
P
I
h
289 0.521 2.98 33 6.44 ' 1.89 3.63 152 13.2 7.11 1763 30.5 4.12
I
0
d
0.521 3.5 5.39 9.01 22.2 52.7
.
.Figure 6 Curve matching and interpreted layer pnrameters of VESOS As it is indicated in the curve matching, differc ntlaycrs with inter- layering of high and low resistivity are identified.
'
\
' Groundwater resource
' assess~nt
'
Camp (ARRA)
13
. 3. 1
VESOf (Kartato)
..• •• ..••
•• •• ••
...........:,............. .... .. ...:..............................;... •• • ••
.. .• ..•
•
• ••• •
•• •••
.:
..........-.. 0.,!' . . . . ......... :•
..• .• .••• .•
.. ...•••
.. •• . •• ·········-~--···· ········ ·· ~·········· · ··· ··············:·· . .: .: •
:?1
:.
········ · ·- --- · ~· -········· -
.
·········-···~-
.. .
·· ··· ··-· ····~·-·····-·
• •••• -
• •
•••• :.
1
i\ • . .. . .T... ~"<::::::::""!j,:
ll-L ' ~
:
0 0
: :
::
+
..
..
.:
::
•
~
•
•
• -. . ... .
.. .
... ..... ·-· ~·. - -~ ---- · · · · . ...• :; ............. . :
.. •
• •
• •
•
•
........ •
.....
J-........-=="'V..,. i
r.. ........ .
.• ..•.• .•
i i . . : ~-~-4 : ~.-*~ ' ~[1
:
I
•
.• .•
••
l- ·
p • . ...• .•..• • :. .'t ' ...; .............. •' ·······--···· ···
..• •
:
..................;. ..... .
. .;.. ......
0
•
;
:
..-· ............,;...... . ........ ::.
..
·····
. .. .. . . . . . J l=d-~,•~~~,:~~~~~ 'r-t •: ~~~~r. IWJ N 1 2 3 4 5 6 7 8
p
l
•
• •
h
60.1 0.39 723 0.793 2.-i 0.884 82 4.15 9.24 16.5 26956 1.65 60.7 65.7 4098
•
• •
•
•
•
• •
•
•
...
0 • .. •
• •
•
• •
•
•
•
•
•
'
I
d
0.39 1.18 2.07 6.22 22.7 24.3 90. 1
f•gure 7 Curve matching and interpreted layer parameters of VES06 As tt1s indu.:nted in the cul'\e match1ng dim·r~nt layers \\ith •nll'r-la)ering ot high and low
resbti\ily urc id.::ntificd I he layer p.1rameter\ nsldc.:n!lficd from the interpretatiOn result and the possible lithology of each layer is summarized he low
.
~
\ '
Camp
•
(ARR,A)
14
•
...
_
~ .....
. •
•
N
1 2 3 4
5 6 7 8
P
I
h
1502 0.237 231 2.26 14.1 1.78 3.26 99 10.2 7.41 14.2 333 38.3 50.2 5323
I
d
0.237 2.5 4.27 7.54 14.9 29.1 79.3
I
Figure 8 Curve matching and inter p reted layer parameters of VES07 As it is indicated in the curve matching, different layers \\ith inter-layering of high and low
l I I
resistivity are identified. The layer parameters as identified from the interpre tation result and the possible lithology of each layer is summarized below
I~ Groundwater resource
e Curp (ARAAJ
16
r-1"' Ll)'tr parameters and possible lithology at YES 07 (Berahle)
JfR'Jf Resistivity
(ohm meter)
Thickness
Depth
(m)
(m)
Possible lithology
I
1502
0.237
0.237
2
231
2.26
2.5
Coarse sand to gravel size dominating, dry
3
14.1
1.78
4.27
Fine grained dominating river deposit, dry
4
99
3.26
7.54
Coarse sand to gravel dominating river deposit
5
10.2
7.41
14.9
Fine grained dominating river deposit, dry
6
333
14.2
29. 1
Gravel to cobble size dominating deposit, dry
7
38.3
50.2
79.3
Sand to gravel size dominati ng, saturated
8
5323
---------
--------
Coarse river deposit, dry
Massive metasediment, dry
Con clusion nnd recommendations of VES07 (Berahle) proposed borehole site. As indicated in the geophysical interpretation result, layer 7 is characterized by relatively low resistivity value. From previous experience and field observation of the area, such a low resistivity values are expected be a characteristics of saturated Sand to gravel size dominating alluvial deposit. ln addition, small deposit of cobbles/boulder is also expected within the expected water bearing zone of layer seven. Thus layer seven is considered as a main aquifer zones. Based on the geophysical interpretation result, the recommended depth of drilling is 100 meters but the actual depth of drilling should be detcnnined during supervision based on the actual geological findings. The drilling diameter in the upper soft fonnation is 143/4" and the rest should be 12 ".The well should be packed by appropriate selected gravel and should be well developed. The specific geographic loctltion of the proposed site is 6 10028m east and 1532146m north and the relative location map of the proposed site is indicated in Fig. I.
Groundwater resource
ugee Camp (ARRA)
17
..... ..·~• .................. ~..
.. .. .. .. ..... ............... .. .. .. '
·-~
. .. . ..: .
j .... ~ .....
I
" " ;.. " " .. ~
...
--·l·.............................
.. .
...""" ...... <•.."""" •" ... " I .. ... "
"
...
.. ;.................. ·············
j .... . ........ , ............
•loo "" (.. •+""•":·"" . "" '" •• I•"'0""'""" ·•
.. ..
~-- ... "" ....; ..... """...
N 1 2 3 4 5 6 7 8
h 1 0.365 28 226 0.501 13.2 3.46 4.98 2.71 5.77 833 25.5 17 2185 59.3 15.9 p
."i......
I.....;............ -I-.............!.. .......... ...... . ...........··
d 0.365 0.866 4.33 7.04 12.8 38.3 97.6
Figure 9 Curve matching and interpreted layer par ameters of VESOS
Groundwater resource
..
••• •••
.:.•
l • •
•
0
••
..
.
·············-~·-·······
•
....
....... -.
:
' ······· ·········· ··:······ ···· ...0.. ••. i.0.. ••. .••• 0..... -~• ....0.....•.• ············ •
..
···········• •••........... ••
.•••
····-···.... i·· · ···········~·• . ............. ············
.• •• ........ ... ..• ······················· . ··-···· .. . .. .. • . ..• ...........,•... .. . ....... .............. . .. .: ..•• . N
I
1 2 3 4 5 6 7 8
p
376 378 99.8 120 16.8 174 23.4 164
I
h
1.85 0.151 5.12 1.64 9.26 31 .5 33.4
I
. ............ •
•
•• 0 .........
........••• . ..
..
• o
o
•
. .···--·--------1 .-• .• ..••. . ... .. '...• . • •• •
• • • r •
• •
d
1.85 2 7.12 8.76 18 49.5 82.9
f igu re 10 Curve matc hing and interp reted layer pa ra m eters of VF.S09
I I
As it i indicated in the curve mutchin~t~. diflercnt ln)crs \\i th inter-In' crin£
or high and low
resistivity nre Identified. The laye r pur.Hne tl'rs as identified from the interpretation result and the po :;ible hlhology of each la)cr is summari1cd below
t
Gr o un dwater re5our ce
•••••ament
19 (AARAJ ... .t '•
......_ tl..-.
.....
.. .•
Con clusion and recommendations of VES09 (Berahle) proposed borehole site. As indicated in the geophysical interpretation result, layer 7 is characterized by relatively low resistivity value. From previous experience and field observation of the site, such a lo\\ resisllvity values are expected be a characteristics of saturated and to gravel size dominating alluvial deposit. In addition, some portion of the 8th layer is asstu11ed to be saturated coarse grained dominating alluvial deposit to fractured metasediment. Small ueposit of cobbles SiLe is also expected within the expected water hea1 i ng zone of both layl'rs. 'l hus layer seven and l>Otnc
portion of layer eight are considered as a main aquifer .zones. Based on the geoph) sical interpretation result, the recommended depth of drilling is I 'iO meter!> but the actunl depth <>f dnlll ng should be dctemlincd uurm.: supcr\iiSIOil based on the actual geological tindings. I he drilling di.uneter in the upper soh fbrmation 1s 143/4" and the rest sh11uld be 12 ". f he w~:ll :;houh.l be p.u:kcJ by appropriate se leetcu wra\el anJ should he \\t..:ll d~\l'iopcd The spccilic geographic lm:ataon ol thl! propu~l!d sik i~ 6()«)C) J9m ca-.t and 15'\ 190im n•lrtll a d th location map of the proposed s1tc 1s inJ1catcd 1n Fig. I.
-
..
n
· c re1attvc
Ca~~~,p ( AARAJ
20
(Tytllbora)
•
t I
'
I
h
N
410 650
'2
8.87
:l 4
l I I I I I I
-4 7.1 5.74 58.4 11 .7 4064
5 6 1
'
0 72<4 1.08 1.6 4 3.99 7.11 l1 48.5
...
'
.
II
o.n • t .8 1
3.45
1.44 U .6
31.6 80.2
, ur~ 11 ( un ~ matC"hinf! and inttrpffttd Ia) cr p11ramr-trn or\ f \ 1
1
\s
t
1
1 ~ 10J 1.:atcJ m lht' .:unc mat.:h•nJ;. u.m:rcntla~e-" "tt.h mter-1
~cnng oflugh :md ll1,,
tt\'· arc •Jcntltlcd The l:~~cr parameters ns •Jc:nufi~J from the tntcrnr ,.. "'•t" l 10n re u11 Md thl' I"•~ 11:-h: hthology of each Ia~ cr •~ summ.trizc:d belo"
rc i
tl\
(ohm meter)
tmJ Top
10
all
I 81
164
~s
Fme
47. 1 5.74
71
A
17
11 .7
Uuvtal
lO gnl\~l
4
14
dcpoStt
Fme
s
lO
--·---
metaSCchmenl,
I
I
I : - - - - - - - 22
Qrt:JVDdrMt•r .,.._.._ • • • • - -
Ot I' (A.lJL}
•
(bekah)
•• •• •
• • • ..
••• •
: ••
•
.... . • . ...
t'.. •• •• •
~
..
•
••
•
••• •• •
··~1~·
• •••
..... .
•
•
• •• •
.... ·--·.....
- ·-········
h 0 '121
"z 1
• '., I
I
l
l l .l
lUI
u•
2 I 117 t 4
IZ S 41
10
.u ..
•n 12 ( un nd
nll
.
•
•
'I 1. 175
ahh In
• •• •• •• •
... ... .
tnt
tl ...
.. 85
•
d
I 55 '11 IJl
I I
.•••. ...•.
na
ntt
che ur.
I fJltYifd I
r
ed fhe I h
t
r
ff fllr8
t
ttn
en" th
t\ ' I
I Sit
du
and possible lithology at YES 11 (Asekah) (ohm meter)
Thickness
Depth
(m)
(m)
Possible lithology
]
1801
0.221
0.221
2
322
1.73
1.95
Sand to gravel
3
28. 1
4.85
6.81
Fine grained dominating, dry
4
107
6.44
13.2
Fine sand to gravel dominating, ry
5
22.4
12.9
26.2
Sand to gravel dominating alluvial deposit, mo
6
231
54.8
8
Slightly to moderately fractured granodiorite , !
7
71.7
44.4
125
Highly
8
194
---------
--------
Dry top soil inating, dry
granodiorite, saturated
Slightly fractured granodiorite, moist
Conclusion and r ecommendations of VESl l (Asekah) proposed boreh ole site. As indicated in the geophysical interpretation result, layers 7 and 6 are characterized by relatively low resistivity value. From previous experience and field observation, such a low resistivity values are expected be a characteristics of saturated and fractured granodiorite rock .
•
addition, some portion of the 8th layer is assumed to be moist slightly fractured granodiorite. Thus layers seven and six are considered as a main aquifer zones. 13ased on the geophysical interpretation result, the recommended depth of drilling is 200 meters but the actual depth of
I
drilling should be determined during supervision based on the actual geological findings. The
l
drilling diameter in the upper soft formation is 141/4" and the rest should be 12 ". fhc wdl should be packed by appropriate selected gravel and should be well developed. The specific
'I
geographic location of the proposed site is oll742rn cast nnd 1525211 m north and the relative location map of the proposed site is indicntcd in Fig. I.
I I I Ic:~~ ~ I l
c..., (AARA.)
and possible lith olo~ey at Vf:S J 1 (Asekah)
(ohm meter) 1801
1 hid,ncss
D~:pth
(m)
( Ill)
-Possibll." lllholugy
0.22 I
22 1
IJcy top sot
2
322
1.73
I. 5
Sa
3
28. 1
4.85
6.8 I
hne grained domin.lllng, clry
4
107
5
22.4
6
to gra\cl
13.2
- to l-ine sa11d
12.9
26 2
Sand to gm\~:
231
54.8
80 y
Slightly to moderately lr c1ured
7
71.7
44.4
125
llighly fractured granooionte,
8
194
---------
--·-----
-6.44
~ru\cl
I
dornin tlllg, dry
•
1 I, I
od10nt turnted
SlightJy fractured gr nooaonte, moist
Co ndu ion and recommendations of VESll (A ekah) propo,ed hon:hoJ '!lite.
As inJtcated in the geophysical interpretation result,
la)cr~
7 and o nrc ch r tenzcd by
relathcly low resisti\ity value. From previous expenence and field
h
n tton.
\1h
I \\
re i ttVJty value are expected be a characteristJcs of ~aturatcd nd fru lured mnodt rat nx ddit10n. ome portJOn of th 8th layer is assum~:J 1\l lX' mot t It htb fi J'hu 1 "iers 111 tcrpr
ven anti 51){ are considered ns ll nwn a~utlcr :zone B
tnt•on re ult, the recornrnt!IHk·d dl·pth of
dnllm~ 1 ~t)(l
dulling houhl he detc1111111ed dunng upcn 1 tnn h tq>d on th
drtllin
1hruueter 10
the upper ott
toull be pocket.l hy ppropn te plu loc u n of lhc propo
h11111 '''"" 1
14~ 4" And th
m t
1
tured g•rruto
d ( n the geop~ 1 .....Ql l:lut the
111 I 1
hnuld be 1.... Th \\ U
le I d r \ I nd hould he \\ II d , ]
d 111
tt I 61 I 742m e t nd I S2 211m nonh
......... e.r ...................
tJ
(Asekah)
1
0 0 0 0
0 0
••• •••
•• I
0
•
0 0 0
•
•
0
--~--~-- -~- - - -···········~-----··· 0
•
• •• •• • • •
0
0
• •• •
•
••
••
0
•
0
•
1
••
0
0 0 0
0
• • •
0 0 0
'' • •'
• • '• •
0
•••
...
... ... -- ... '' 0 0 0 0
-...
•'
z ')
4
I
29.4 99.9 20
5 6 I II
f&
2 0 06 122
• 0 0
•'
'
10
h
227 4 77
0 0 0
0 0
l
N 1
0
'
•
0 34 7 1.1 4 1 J ,l
12.3
l':i 2 51 8 91 . 6
: ;
•0
:
0 0
• ..
.
."' •
0 0 0 0 0
••'
•
•
0 0 0 0
....
_..,
..
• ••
••
0
'
0
--·····
' •••
•••
~
... 0 0
•
••
0
••
••
••
'•
:
l ll
;;; - :I l
d 0 3 41 I 49 14 8 27. 1 42 J !14. 1
186
'
f'laurct I J ( un t m!ltdun g nlllnttr pr t hiJ
',
,,
11 1
--
--····· · ··-~--·0
0 0 0 0
0 0
............ . •
'' '
••
•
0 0 0
''
. ....... . ......• ..................
••
0
.•
0
0
0
••• ••• •
0
•
0 0 0 0
~ -- · · -- · • • 4 ••
0
............
._:•
•
•
0
•••
0
0 0 0
0
•• ,•' .... . .... . ......,.' .... 0
1(
• •••
•
0
•••
••• ••
'
••
0
••• ••
0
0
0 0 0
········J····-······ •
............ ,• ... • •• • •
0
•
0
0 0
0 0 0 •
0
•
----- ....
0 0
0 0 0 0 0 0 0 0
' •
••
• ••• •• ••• ••
0
0 0
0 0
0 0 0
0
............. , ....................... , .....•..•.
-- - ... ----- ··· .. ....,.• ....... .. ..... ••
0
• • •
0 0
0 0 0
0
••••• ••• •• ••• • • •
•
0 0
0
•
• •••
0
••
0
0
0
••
••• •
p
0 0 0
0 0 0
•• ...... . ........ -·········~·-·· · ··· •
0
• • ••
0
1- .•.•
0 0 0
••
•• • ••
•
0 0 0 0 0
0
0
••
•
0
I~H'I Jl ra mr lt r
nf \
t S l .2
mda~.:ateJ 10 th cum~ m h.:htn , c1tfT'crcnt layc:n \\ith illler·l ) cnn of htr,h milo"
rc • u v•tY lfC Jdentaficd 1llC l yer panuncters 5 ldc:nt•flcd from the Hltl."tpret tlon fC!>uh und th\!
po tblc lttholo
of
h l cr IS
n d bel
(Asekah)
1
'' '''
'
'' ' •' •'
'
••' •
''
... -·. --~---····-··· ···-~---···---
••• .' • ' ••• •'
.'' . ••
'
'
'
. . ····'···
· ·- ········~·· · ··········· · ·····
••
• •'
•
,. ........ -· -''
'
' ' ·······-~·-····-·------; '
'' ' '' ''
.....
:
' •••
••••
..........
••' • ' '(• .......... . ' •
.. . ..
•• •'
' •' ,''
••'
p
•' '
.....
'
••
•
.....
'
•
. ' '
1~-f-7----~~~~~~': -.--~:---+---+·----~~~ •• •'
..
'
•
.....,.''' .................. ,...... '
'
' ''
·--~------·········r-······
•' '' ''
'
•
.••• .•
• •• •
..•
5 6 1
.,
'l'll 411 29 4 !)9.9 ?0
0.347 1.14 13.3 12.3 15 ?. 5 1.8
?0 6
91 6
16
•' •
••'
.
' '
1
h
' '
•
'
?. :1 4
.... ...
• •
•
.. ·······--·--··············-······-- .............. ....
N I
' ' ' •'
10
1.--~
····-···· •
_
..,......... _, ;
'
••
..• • '
.
••
'
•• •• ' '• ••
I
d 0 14/ I 49 I 4 II ?1 1 4?' J
'I4. 1 186
122
ftau r t'l ( 'un e mlh;hlng tnt! tnh:rprtl t tlllnu Jlllnl m C' Itr f•f \ t ~ 1 2
5 11 15
I I
11 JA1 1~,;ated 111 th
cur~c mntchtn
daiTer nt I er!l "nh mtcJ·I )enn o f Ju •h
d lo"
11
rc 1 ta\ tl'i re aUcnuhe I lltc I )'Cr p1mmc 1dcnttfaed from the tnt rpret.lltlon r~ uh on!! the po 5 able hthology of e h I )Cf I ri ed bel
Ca ,. (NfltAJ
25
Conclusion and r ecommendations of VES12 (Asekah) proposed bor eh ole site. I
As indicated in the geophysical interpretation result, layers 7 and 6 are characterized by
I
relatively low resistivity value. From previous experience and field observation, such a low
I
resistivity values are expected be a characteristics of saturated and fractured granodiorite rock. In
I
addition, some portion of the 8th layer is assumed to be moist slightly fractured granodiorite.
f
Relatively low water is also expected from the moist sand to gravel dominating alluvial deposit of layer five . Thus layers seven and six arc considered as a main aquifer zones. Based on the geophysical interpretation result, the recommended depth of drilling is 200 meters but the actual depth of drilling should be determined during supervision based on the actual geological findings. The drilling diameter in the upper soft formation is 143/4" and the rest should be 12 ".
I I I
The well should be packed by appropriate selected gravel and should be well developed. The specific geographic location of the proposed site is 611264m east and 1525764m north and the relative location map of the proposed site is indicated in Fig. I.
Groundwater r e s ou rce .ass es
26
• t
•
•
•
•
I
N 1
2 3 4
5 6
7 8
h
490 1327 3.37 <43.1 3.29 75.9 10 3607
Flgu~ ,_.
d
0.394 0.982 0.257 4.47 6 ... 1 10.6 30.7
0.394 1.38 1.63 6.1 12.5 23.1 53.8
Cun e matching and interpreted Ia) er pa..-meten of\'"[ 13
i\s it i tndt~uteJ
10
the curve m.J.tching. diffaent la)ers '' ith inter-In) cring of high and lo\\
rc astr ..,t) 1rc identt tied. I his lie j., not recommended for an~ ~round\\atcr"' II drilling.
C•np (~J
27
Conclusion and Recommendations Discussion and Conclusion The electrical resistivity (VES) investigation conducted at the surveyed area was able to delineate the water bearing layers and has determined the thickness of the expected aquifer. Even though minor inaccuracies may normally be anticipated the main results of the VES survey can be described as follow.
•!• On the VES curves only the major and dominant resistivity layers were presented and lithologically described
•!• Dt~e to the limitation of the me~hod in detecting thin layers especially at greater depth, there could be thin layer of metasediments with granodiorite that assumed as one lithology.
•!• Sites with maximum thickness of Saturated alluvial deposit and fractured granodiorite were considered as the most prospective and favorable sites for locating the borehole. Based on the VES geophysical interpretation and actual field observation, different option sites as indicated in the location map are identified as promising sites for deep borehole site drilling. The option sites are based on the groundwater availability. The option sites are classified as nearby and far option to the center of beneficiaries village. The sites mentioned as far option are expected to give better yield than the nearby options.
4.1.1 Nea rby option This option consists of assessing water source nearby to the village of main target beneficiaries. The advantage of this option is it is very near to the target beneficiaries and easy to connect to
I I
I I I
I I I
the already implemented infrastructures. Under this option two possible sites are identified during the field site investigation.
./ Option one: VES09 with coordinates of 609919 UTME an d 1531901 UTMN
'
elevation of 672m. Tabia: Bcrnhlc, K ushct: 8 (\l'ahlc and Site n ame: Bcr a hle ./ O ption two: VES07 with coordinates of 610028 UTME and I 532146UTMN elevation of 667m. Tabia: Bcr ahle, Kushet: Bcrahle and Site name: Bcrahlc' For both option sites, the recommended depth of~!} lling ranges between 100- 150 meters (ISOm depth for VES09 and lOOm depth for
VE~P-7? 1 bntt ,the actual depth of drilling should be
. d during drilling supervision bast!d on the act~al drilling findings S k' determme · · ee mg good Groundwate r ' resour ce assessment
fAAA.A;
28
~,po:sed
sites are located near to river bed so about a meter of well head
.,-,- _, to prevent the flood s coming from the high land areas. Water samples ect~~d
at intervals after water strike depth and it should be tested for its quality at
using a field kit. In both options a drilling rig which combined MUD drilling and WJ,i'/air rotary method of drilling with a well trained drilling crew is recommended.
4.1 .2 Far option The water source from this option is expected to have relatively better yield than the sites of nearby option. But the disadvantage with this option is its distance from the target beneficiaries (4 to 5 kilometer of air distance). The root to convey from this source is also relatively rugged
and dissected topography. Hence the cost of system construction will be relatively higher. Under this option two possible sites are identified during field site investigation. -/ Option one: VE S12 with coordinates of 611264 UTME and 1525764UTMN, elevation of711m. Tabia: Berahle, Kush et: Asekah and Site name: Asekah -/ Option two: VESll with coordinates of611742 UTME and 1532511UTMN, elevation of 667m. Tabia: Bcrahle, Kush et: Asekah and Site name: Asekah
For both option sites, the recommended depth of drilling is 200meters but the actual depth of drilling should be determined during drilling supervision based on the actual drilling findings_ Seeking good recharge condition, the proposed sites are located near to the river bed of the area so about a meter of well head should be constructed to prevent the floods coming from the high land areas. Water samples should be collected at intervals after water strike depth and it should be tested for its quality at site level using a fie ld kit In both options a dr 'll' I
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combined MUD drilling and DTI Yair rotary method of drilling with a well t · d d 'll' rame n mg crew is recommended.
4.2 Recommendations Based on the observation of the existing water supply of the a e d th . . . r a an e new Site mvestigation the followmg recommendations are forwarded. ' •
Groundwater systems are dynamic and adjust continually to 1 rt h . . s 10 term and long term c anges m cltmate, groundwater withdrawal and 1 d • an use. Water level me from observation wells are the principal source f. nti . asurements ::-:~~ , ""'· so I ormatiOn about the hydro geolog· · v 'l'. n 11 1
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29
on aquifers and how these stresses affect groundwater recharge, discharge. Hence it is important to establish a long term systematic ure!me:nts of water levels from observation wells that will provide essential data needed to evaluate chang~ll in the resource over time. Moreover in predicting the longterm yield of the existing wells, it is also necessary to consider changes in static water level (SWL) resulting from seasonal and long term variations in recharge and declines due to other withdrawals from the aquifer. Hence it is necessary to estimate how much the SWL and thus the available draw down may decline from the position that is occupied during the well acceptance test. Thus records of water level fluctuations in longterm observation wells in the area will also be useful in this effort. These records should be analyzed in order to see if changes within the well are occurring and hence suggested causes and corrective actions can be made. •
As it was observed during the field work more residence homes for the local people and refuges are being constructed around the existing wells and also common toilets are being implemented within and around the compound of the residents. This all activities in conjunction with the fracture properties of the surrounding geological material can facilitate the time and speed of contamination of the wells, which will be difficult to have enough water for the local people as the groundwater resource of the area is found to be limited.
•
Therefore in order to prevent any damage to the drilled well and avoid any water contamination, any residence expansion and construction of toilets around th e upstream · t.mg acuv · ·· nearby of the wells must be avoided. In order to control impact of th e ex1s 1tJes over time, it is important to establish a long term systematic an a 1ysts · f o water samples from the wells supplying the local people.
llded. In addition, about a meter of well head shouJd be constructed t floods coming from the high land areas. the expected yield of the sites proposed under the far option is better than that of nearby option and also it is known that the population of the camp is rising, Jeading to demand of more daily water consumption. Therefore taking the far option site (VES12) as first option for well drilling is recommended. •
As it was observed during the field visit and geophysical investigation the expected drilling system may be complex and therefore deploying well trained and professional hydrogeologist supervisor during drilling of the weiJ is recommended.
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