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Hydrogeology in the Hydrogeology in the Limpopo BasinLimpopo Basin
Overview of key hydrogeological Overview of key hydrogeological units in the Limpopo basin in units in the Limpopo basin in
Mozambique, South Africa and Mozambique, South Africa and ZimbabweZimbabwe
6/16/20096/16/2009
Why Hydrogeological UnitsWhy Hydrogeological Units Insight into groundwater potential for the Insight into groundwater potential for the
basinbasin In sight of where to apply water conservation In sight of where to apply water conservation Because water conservation is affected by Because water conservation is affected by
hydro geological units’ characteristics such ashydro geological units’ characteristics such as storage capacity ( porosity related)storage capacity ( porosity related) residence time (underlying units related)residence time (underlying units related) thickness of the weathered overburden (direct thickness of the weathered overburden (direct
relationship between water yielded to thickness) relationship between water yielded to thickness)
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Geology of Limpopo basin in MozaGeology of Limpopo basin in Moza
6/16/20096/16/2009
31.5° 32° 32.5° 33° 33.5° 34° 34.5°
31.5° 32° 32.5° 33° 33.5° 34° 34.5°
-25.5°
-25°
-24.5°
-24°
-23.5°
-23°
-22.5°
-22°
-21.5°
-25.5°
-25°
-24.5°
-24°
-23.5°
-23°
-22.5°
-22°
-21.5°
conglom erates, silts in terca lated w ith m arine sands
CRETACEOUS
K A R O OJURASSIC
QUATERNARY &RECENT
R ecent a lluvium C oasta l dunes, m obile dunes
Interior dunes, consolidated dunes includ ing rem obilised & longitudanal
arg illites, areanous fluvia l sandstones & m udstones, other superfic ia l deposits
arg illites re lated to m arine terrraces
Ferrigenous arid sands
m ixed calcerious sands
conglom erates in terca lated w ith vo lcanics of Karoo age
rhyolites
S E N A
E LE FA N TE S /S IN G U E D EZE
C H E R IN G O M A
M A ZA M B AM IOCENE
PALEOCENE
GEOLOGICAL LEGEND
C haila
M A N JA C A ZE
C higubo
M achaila
C H IC U A LA C U ALA
M A SSIN C IR
D indiza
XA I-XA I
M A N H IC A
M A G U D E
C H O KW E
G U IJA
L i m p o p o R
i v e r
S a v e R i v e r
Mozambique Hydrogeology Mozambique Hydrogeology
mostly sedimentary rocks or unconsolidated mostly sedimentary rocks or unconsolidated sediments, with minor hard rock lithologies.sediments, with minor hard rock lithologies.
primary porosity aquifers with high groundwater primary porosity aquifers with high groundwater storage capacity.storage capacity.
Coarse grained sediments give abundant Coarse grained sediments give abundant groundwater; fine grained sediments are poor groundwater; fine grained sediments are poor aquifers. aquifers.
Coastal regions and areas along the main river Coastal regions and areas along the main river channels are most promising. channels are most promising.
Regular recharge is important in terms of ensuring Regular recharge is important in terms of ensuring good fresh water quality. good fresh water quality.
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The Hydrogeology of the Limpopo Basin in Mozambique.
Period Rock types GroundwaterPotential
Quaternary
Holocene
Pleistocene
Alluvial
Marine / lacustrine alluvials
Very good
Very good
Upper
Tertiary
Lower
Miocene
Palaeocene
Ferrigenous arid sands
Mixed calcareous sands
Very good
Very good
Upper
Cretaceous
Lower135-63 my
Conglomerates + silts + marine sands.
Conglomerates +Karoo volcanics
Silts – poorSands - good
Good
Jurassic 180-135 my Rhyolite, Basalt,alkaline rocks. Very poor.
For the unconsolidated sediments: •Active recharge will be a very significant factor in determining water quality
•Grain size will determine well yields 6/16/20096/16/2009
28° 28.5° 29° 29.5° 30° 30.5° 31° 31.5°
28° 28.5° 29° 29.5° 30° 30.5° 31° 31.5°
-22°
-21.5°
-21°
-20.5°
-20°
-22°
-21.5°
-21°
-20.5°
-20°
O lder G neiss C om plex
Serpentin ite and pyroxenites
D olerites and G abbros
G ranophyre, gran ite and syenite
G neisses of various ages
INTRUSIVE IGNEOUS ROCKS
U ltram afic lavas and in trusions
Basaltic vo lcanics w ith in terca la ted sedim ents
Andestic and dacitic m etavo lcanics
M etasedim ents, fe ls ic m etavo lcan ics
G niesses of various ages
G lacia l beds, m udstones, coal m easures and sandstones
G rits, sandstones and silts tones
Basalt
R hyolite
Sandstone, e tc.
A lluvium and other superfic ia l deposits
CRETACEOUS
KARO O
BEITBRIDG E
SHAM VAIAN
BULAW AYAN
SEBAKW IAN
G REAT DYKE
JURASSIC
TRIASSIC
PERMIAN
EARLYPRECAMBRIAN
VARIOUS AGES
LATE JURASSIC
PLEISTONE &RECENT
Younger granites, granodiorite-adam ellite
TABLE OF FORMATIONS
SYSTEM O RG R O U P
IN TER N ATIO N AL
Geology of limpopo basin in ZimGeology of limpopo basin in Zim
6/16/20096/16/2009
Zimbabwe HydrogeologyZimbabwe Hydrogeology mostly of crystalline basement igneous and mostly of crystalline basement igneous and
metamorphic rocks. Minor occurrence of sedimentary metamorphic rocks. Minor occurrence of sedimentary rocks in the basin. rocks in the basin.
secondary porosity features such as fracture zones secondary porosity features such as fracture zones and the weathered regolith. and the weathered regolith.
Small scale water supplies available from granitoid Small scale water supplies available from granitoid crystalline lithologies; greenstones are more crystalline lithologies; greenstones are more favourable. favourable.
Karoo lithologies can provide moderate and Karoo lithologies can provide moderate and occasionally large scale groundwater supplies. occasionally large scale groundwater supplies.
Large-scale groundwater supplies restricted to Large-scale groundwater supplies restricted to alluvial aquifers along the major rivers.alluvial aquifers along the major rivers.
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Hydro-geological unit
Main lithologies Groundwater occurrence Average range of borehole depth (m)
Average range of sustainable borehole yield (m3/d)
1 Achaean Granite and Gneissose rocks
Principally in weathered and fractured zones. 10-35m thick
40-50 in African surface. 30-40 on post-African surface
50-100 in African surface. 10-50 in post African surface
2 Greenstone Belts - Bulawayan metalavas and Shamvaian metasediments
Associated with weathering of Bulawayan strata to 50m and fracturing in Shamvaian strata
30-50 in Bulawayan 40-60 in Shamvaian
100-250 or more in Bulawayan 10-25 in Shamvaian
3a
Karoo Sequence has been divided into 5 sub-units.Batoka Basalt
Controlled by weathering and fracturing from 30-70m below surface
40-60 20-100
3b The Forest Sandstone Saturated sandstone generally confined aquifer
50-100 50-300
3c The Escarpment Grit Saturated sandstone and grit. Generally confined except in Zambezi Valley
50-70 100-300
3d The Madumabisa Mudstone
Associated with shallow weathering or sandy intercalations which water strike between 40-70m occur
50-70 10-25
3e The Upper and Lower Wankie Sandstone
Saturated sandstone confined aquifer 100-150 100-500
4 The Cretaceous Sandstones
Deep zones of primary features possibly shallow weathering along drainage lines
70-100 10-50
5 Kalahari sands Saturated unconsolidated sands and consolidated pipe sandstone
70-100 100-1000
6 Alluvial Deposits Primary porosity and permeability in gravel lenses, sand layers
20-70 100-5000
Hydrogeological Units – Limpopo Basin Zimbabwe
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Geology of limpopo basin in S.AGeology of limpopo basin in S.A
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26° 27° 28° 29° 30° 31°
26° 27° 28° 29° 30° 31°
-26°
-25°
-24°
-23°
-26°
-25°
-24°
-23°Sandstones, shale , m udstone, coal
B asa lt, pyroclastics in terca la ted w ith sandstones
R hyo lite , dacite , pyroclastics
S andstone, sha le , lim estone
U nconso lidated superfic ia l deposits, lim estone,cong lom erate , sandstones
M etased im ents
C onglom erate , quartz ite , sha le, lim estone, lavas
U ltrabasic to basic in trusives
M igm atite , gn iess
C onglom erate , quartzite , shale , phylite , tillite , lavas
G ran ite
Q uartz ite , shale, conglom erate, andesite
D olom ite , chert, cong lom erate , quartz ite , sha le , tillite
Q uartzite , shale , cong lom erate
Q uartz ite , sha le , tillite , andesite , chert, jasp ilite , lim etsone
Q uartz ite , sha le , horn fe ls , lavas, pyroclasts, chert, jasp ilite , lim etsone
Q uartzite , shale , hornfe ls , andesite , chert, tu ff, lim etsone, conglom erate
M igm atite , gn iess, h igh grade m etam orph ic rocks
Pyroclastic fe ls ite
G abbro , norite , chrom itite , m agnetite
G ranophyre
G ranites, fe ls ite , tu ffaceous & sha ly sed im ents,agg lom erate
Lava, sandstone, conglom erate , s ilts tone, greyw acke
Sandstone, cong lom erate, s ilts tone
A lka lis , basic to u ltrbasic in trusives, carbonatite
T illite , sandstone, sha le
Shale , sandstone, grits tone, coa l
KAR O O
STO R M BER G
ECC A
D W YKA
KRAN SBER G
N YLSTRO O M
BUSH VELDIN TR U SIVEC O M PLEX
LIM PO PO BELT
PRETO R IA
M ALIM AN I
D O M IN IAN
JURASSIC
TRIASSIC
PERMIAN
PR
EC
AM
BR
IAN
TERTIARY &RECENT
CARBONIFEROUS
W ATER BER G
CRETACEOUS
PILAN SBERG INTR USIVEC O M PLEX
GEOLOGICAL LEGEND
AR C H AEAN G R EEN STO N ES
South Africa HydrogeologySouth Africa Hydrogeology Geology quite complex. Geology quite complex. Quartzites / basal conglomerates (Dominion group) Quartzites / basal conglomerates (Dominion group)
and Karst limestones (Malimani & Pretoria group) at and Karst limestones (Malimani & Pretoria group) at the base of the sequence have high to very high the base of the sequence have high to very high potential. potential.
Crystalline basement complex rocks have low to very Crystalline basement complex rocks have low to very low groundwater potential, except Archean low groundwater potential, except Archean greenstones, which have medium potential.greenstones, which have medium potential.
Indurated and metamorphosed sedimentary rock also Indurated and metamorphosed sedimentary rock also have low potential. Karoo has generally low have low potential. Karoo has generally low potential. potential.
Recent unconsolidated sediments and alluvial Recent unconsolidated sediments and alluvial material have high potential. material have high potential.
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Hydrogeological units of S.A.Hydrogeological units of S.A.
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ConclusionsConclusions
Very varied hydrogeological unitsVery varied hydrogeological units Different GW potentialDifferent GW potential Implication = Different conservations potentialImplication = Different conservations potential Need to expand this to assess potential for Need to expand this to assess potential for
conserving waterconserving water
6/16/20096/16/2009
Thank youThank you
6/16/20096/16/2009