INTERNATIONAL ASSOCIATION OF HYDROGEOLOGISTS Australian National Chapter NSW Branch

2009 Seminar Series

This presentation is made available by IAH NSW in the interests of promoting discussion, critique and exchange of knowledge.

The content, products, methods, equipment, findings or recommendations of these presentations are not endorsed by IAH NSW or by UNSW who has offered to host the presentations on their website www.connectedwaters.unsw.edu.au Geophysical Imaging for aquifer recharge investigation in Western NSW.

By: Dr David Allen Groundwater Imaging Pty. Ltd. PhD - National Centre for Groundwater Management, UTS. [email protected] 279 Fitzroy St, , NSW 2830 Ph 02 6882 7465 Mob 0418 964097 A palaeochannel beneath an irrigation canal

Blue = Low EC Recharge Gravel, Sand

Red = High EC Clay Major (600m wide) Saline Water prior stream extends to >12m deep

Log10 Depth Scale 0.1 to 12m Why use Electrical Conductivity Imaging for Recharge Investigation

• reveal spatial details • EC responds clearly not observable by any and conclusively to more economically recharge pathways viable means

LOW EC HIGH EC • Lack of Clays • Clays • Low Saturation • High Saturation • Fresh pore water • Saline pore water • Impervious fresh rock • Weathered rock At depths significant to groundwater investigation, EC imaging may be conducted

• on water, using • on land, using Transient geo-electric streamers Electromagnetics (TEM) Depth Canal ticks bed Identifying depths on 3D EC curtain images Canal seepage investigation Seepage Conduits interpreted beneath the CIA using submerged streamer geo-electric data

• Seepage slides from CIA have been removed from the distributed version of this talk for confidentiality reasons Submerged geo-electric streamers are ideal for canal seepage investigation because they exhibit: • Good depth resolution under canal beds • Negligible artifacts from canal depth • Negligible artifacts from bank proximity Vertical Section through Murray Basin sediments - Coleambally

Percolation pathways

Modified from Pucillo, K. (2005) QUATERNARY PALAEOCHANNEL EVOLUTION AND GROUNDWATER MOVEMENT IN THE COLEAMBALLY IRRIGATION DISTRICT OF , PhD Dissertation, University of Wollongong. A comparison of sediment electrical conductivity beneath inland rivers of the Murray Darling Basin,

All plotted with a Murray Darling Basin Composite colour stretch MacIntyre and Barwon Rivers comparison sites

Murray comparison sites , Texas comparison sites , Moree

Namoi River,

Macquarie River,

Lachlan River, Hillston

Murrumbidgee River comparison site

Billabong Creek, Jerilderie Dumaresq River

Glenarbon Cunningham Weir Weir Texas, Qld 10km

Log10 Depth scale from 0.4 to 50 m No groundwater EC correlation with South Callandoon proximity of the river to ring tanks is evident

Deeper low EC

EC near the riverbed is higher at the points where the river intersects the edge of its immediate floodplain Stuartville Kanowna An example of small fine grained prior stream deposits amid extensive floodplain deposits and a shallow brackish water table

Some correlation between groundwater EC just below the river bed and the proximity of the river to ring tanks and canals is evident Gwydir River EC image with Murray Darling Basin Composite colour stretch , Gunidgera Weir () to Mollee Weir (Narrabri) with Murray Darling Basin Composite Colour stretch sub-river EC

Composite Murray-Darling Basin Colour Stretch

Log10 Depth Scale EC with Composite Murray Darling Basin Colour Stretch Murrumbidgee near Leeton Rice based farming and state forest Cross and long section of the at Gogeldrie Weir between the Coleambally and Murrumbidgee Irrigation Areas Geo-electric survey with Murray Darling Basin Composite Colour Stretch and Log10 Depth Scale

24 Darling River at Wilcannia Geo-electric survey with Murray Darling Basin Composite Colour Stretch and Log10 Depth Scale

Acquisition funded by Central Darling Shire Council & Darling River at Menindee plus Lakes Pamamaroo and Menindee Geo-electric survey with Murray Darling Basin Composite Colour Stretch and Log10 Depth Scale

Menindee Lake data – 1994 from O’Neill - WRC All other data – 2006 from Allen – funded by Country Energy - 0-60 km upstream of Mildura. Viticulture and uncleared land above fossil hypersaline groundwater discharge deposits Murray River – Wentworth to Mildura Murray River – Waikerie 1 and 2a salt water interception schemes – Vitculture and citrus End of constant colour scheme river comparison. Macquarie River

Geo-electric and associated run-of- river data Macquarie River EC 8m below the river bed

Inferred Inferred predominantly Aquiclude losing/disconnected river overlying with holes highly permeable unconsolidated deep valley fill infringing on folded basement rock with saline fracture zones and granite plutons Macquarie River Interpretation Summary From the weir upstream - Inferred predominantly losing/disconnected river overlies highly permeable unconsolidated deep valley fill infringing on folded basement rock with saline fracture zones and granite plutons

Narromine Weir

Inferred Aquiclude with holes

Linear Depth Scale Macquarie Modelled Resistivity Images - Key

EC histogram and colour stretch for the entire Macquarie River dataset.

River water EC 400uS/cm

Lithologies encountered in drillers logs near the Macquarie River EC, Salinity, and Soil Texture relationship for the Macquarie River dataset Comparison with Tempest data and Geological Maps

Photo sourced from http://www.fugroairborne.com/service/tempest.php

The 8m deep geo-electric depth slice has been superimposed over various datasets. Due to river incision, direct comparison of Tempest depths and Geo- electric depths is not appropriate. Due to river incision, the 8m geo-electric depth slice should correspond most directly to the 15-20m Tempest depth interval. Lachlan Fold Belt Source: Eastern Lachlan Orogen Basement Geology of the Macquarie River Site Geosciences Database Version 2. Sept 2006. and GAB Geology TIMBREBONGIE TIMBREBONGIE FALLS 2,100 1,050 0 2,100 Meters beneath the NSW Dept. of Primary Industries. Macquarie River ¯ Palaeovalleys Beware – the level of detail presented here

Surat Basin smoothes over features detected gDbtbt under the river. In places, it can be

NARROMINE assumed that the 8533 new information Unnamed Ocean Crust (Ord-Camb) presented in the Tempest survey and NARROMINE this report will result

Sto in modification of

gDbyeo1 Exxo2 Toongi this map. Timbrebongie Granite Gp Undiff

gDbyeo4

Glennie Ridge Granite Oxxkm Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest Total ISBN 978-1-921498-17-6 Magnetic Intensity

TMI colour The TMI data stretch is linear principally indicates deep structures of the basement rock. The significance of these will be explained using the other datasets. The level of smoothing of this TMI data precludes identification of the depth of features evident. Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest ISBN 978-1-921498-17-6 Digital Terrain Model

DTM colour Subsurface valleys stretch is linear are indicated by slight broad topographic lows Aureole (ie. transition from peneplain to depositional plain). An aureole around a small granite north of the river is evident as a sharp topographic high. Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest EC at ISBN 978-1-921498-17-6 5-10m depth The River at Tempest colour stretch is equal Narromine turns area. north and crosses No attempt to standardize the over the aureole of a Tempest and Geo-electric granite (shown). This colour scales has been made because they are drastically is a very shallow different. feature indicating When comparing depths that the buried beware that the river is incised northern valley is sharply 6 to 12 metres deep. relatively shallow Horizontal smoothing of the and confined at this Tempest data has blurred most of the details evident in the point. geo-electric data. The 0-5m deep Tempest data is not shown because its altitude correction and horizontal smoothing is badly affected by river incision. Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest EC at ISBN 978-1-921498-17-6 10-15m depth Tempest reveals Tempest colour stretch is equal Lachlan Fold Belt area. regolith weathering No attempt to standardize the and wider shear Tempest and Geo-electric colour scales has been made zones. Resistive because they are drastically poorly weathered different. fold belt rocks and When comparing depths more recent beware that the river is incised sharply 6 to 12 metres deep. freshwater and gravel filled Horizontal smoothing of the Tempest data has blurred most palaeovalleys are of the details evident in the represented by low geo-electric data. conductivity but can only be differentiated by their geometry. Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest EC at ISBN 978-1-921498-17-6 15-20m depth

Tempest colour stretch is equal The discontinuous area. aquiclude evident No attempt to standardize the in geo-electric Tempest and Geo-electric data north of colour scales has been made because they are drastically Narromine Weir is different. presented in the When comparing depths Tempest data as a beware that the river is incised slight increase in sharply 6 to 12 metres deep. the valley Horizontal smoothing of the conductivity. Tempest data has blurred most of the details evident in the geo-electric data. Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest EC at ISBN 978-1-921498-17-6 20-30m depth Tempest colour stretch is equal The upper area. reaches of the No attempt to standardize the geo-electric Tempest and Geo-electric colour scales has been made survey cross because they are drastically Tempest different. conductivity When comparing depths trends suggesting beware that the river is incised sharply 6 to 12 metres deep. that the underlying Horizontal smoothing of the Tempest data has blurred most palaeovalley of the details evident in the passes through a geo-electric data. Inferred gorge. buried gorges Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest EC at ISBN 978-1-921498-17-6 30-40m depth

Tempest colour stretch is equal By 30m deep, area. Tempest is No attempt to standardize the observing a Tempest and Geo-electric colour scales has been made combination of because they are drastically relatively fresh different. basement rock and When comparing depths gravel valley fill beware that the river is incised sharply 6 to 12 metres deep. both of which appear to have Horizontal smoothing of the Tempest data has blurred most similar resistivity. of the details evident in the Dominant features geo-electric data. are basement conductors of little significance to this study. Macquarie River Tempest data sourced from: Noteboom, M., and Geo-electric Stenning, L., 2007, Resistivity at 8m Lower Macquarie River TEMPEST AEM Survey, NSW, below the river bed Final Data (P1140), superimposed over Geoscience Australia GeoCat # 67211 Fugro-Tempest EC at ISBN 978-1-921498-17-6 60-100m depth

Tempest colour stretch is equal area.

No attempt to standardize the Tempest and Geo-electric colour scales has been made because they are drastically different.

When comparing depths beware that the river is incised sharply 6 to 12 metres deep.

Horizontal smoothing of the Tempest data has blurred most of the details evident in the geo-electric data. 1. Turkey Farm Reserve to Mack Reserve

The Macquarie River at Mack Reserve – photo courtesy of Rob Brownbill Macquarie River – Inferred 300m wide Turkey Farm Reserve to palaeochannels Macks Reserve.

Geo-electric EC data 8m below the river bed

A high EC aquiclude is dominant north of the Aureole shown. As fine sediment deposition occurs behind constrictions rather than just beyond them, it is suggested that a very recent reversal of flow direction has occurred in this valley. The aquiclude is dissected in places by inferred 300m wide gravelly palaeochannels as shown. From adjacent drillhole logs, however, it is not completely clear what component of the aquiclude is saprolite and what is alluvial.

Evidence of a metamorphic aureole around a granite (to the south) indicates that basement is shallow here and the Macquarie Palaeovalley is constricted The aquiclude pinches out here Macquarie River - Turkey Farm Reserve to Macks Reserve. Gravel filled channels (see drill logs) incise clay substrate Inferred losing/ An aquiclude north of disconnected this line is overlain by inferred river sand and river recharging gravel 4m or more sands and gravels deep of unknown at least 30m deep saturation (EC much lower than the overlying river water suggest that it is unsaturated). The aquiclude appears to extends to at least 20m deep and may be part saprolite, part alluvial.

Linear Depth Scale 3. Narromine Weir to Webb Reserve Macquarie River – Narromine Weir to Webb Reserve

Geo-electric EC data 8m below the river bed Macquarie River – Narromine Weir to Webb Reserve

Lachlan Fold Belt Rocks Outcropping in the Macquarie River

EC 8m beneath the river bed Macquarie River – Narromine Weir to Webb Reserve. Metamorphic Rock Inferred basement Inferred alluvium (outcrops in river) shear zones filled gullies

This relatively straight part of the Macquarie River is situated right on the side of a large steep buried valley (see drill logs) and much of Inferred it rests right on folded Lachlan Fold Belt rock. Various outcrops (see basement spur photos) indicate that some of the resistive substrate is folded rock (concave down) and granite. Other parts of the resistive substrate could be unsaturated sand and/or gravel and these may be distinguished by the concave down or concave up natures of their boundaries respectively. Conductive anomalies are believed to represent Inferred seepage through basement rock shear zones while intermediate resistivities could unsaturated sand/gravel represent either seepage occurring through alluvium or just various degrees of basement rock weathering. It is envisaged that a series of down to a confining layer sharp gullies cut through the buried basement directly under this (possibly saprolite as part of the river resulting in very spatially complicated hydrogeology. suggested by drill logs). See 3b images for more detail.

Linear Depth Scale Macquarie River – Narromine Weir to Webb Reserve.

Linear Depth Scale 4. Webb Reserve to Brummagen Creek Some granite outcrops in the Macquarie River Conglomerate at Brummagen Creek termination

Boggy river gravel Conglomerate at Brummagen Creek It is suggested that this cobble cementation at Brummagen Creek is the result of mixing of river water with brackish groundwater inflow driven by flow along a fault co-incident with the creek. Macquarie River – Webb Reserve to Brummagen Creek termination looking from the south.

Linear Depth Scale Inferred gravel Macquarie River – filled gully Webb Reserve Drilling Site

Inferred saprolite Inferred unsaturated Inferred zone beneath river sediment (note resistivity is Inferred too high to suggest Granite filled Granite Inferred Inferred steep (outcrops weathered brackish saturation brackish Inferred (outcrops shear zone Sediment in river) valley in river) baseflow groundwater filled Inferred steep weathered valley shear zone

Unknown Inferred Slate Inferred Slate (see bore log) Inferred gravel filled Granite steep valley (outcrops (see bore in river) logs)

Resistivity

Macquarie River – Webb Reserve to Brummagen Creek termination. 10 100 1000 Lower Gwydir River

Geo-electric and associated run-of- river data Gwydir River – EC 8m below bed Gwydir River – EC 8m below bed Gwydir Raft Brageen Crossing (log jam) Drilling Site Old Gwydir Gwydir (North Arm) South Arm Gwydir Ginham Yarraman Bridge River (Gwydir Drilling Site north arm) Gwydir Tyreel River Weamatong

Crossing Carnee Lucksall Tyreel

Tyreel Boolooroo Regulator The Big Leather Weamatong Crossing Tyreel Regulator and Weir EC beneath the Lower Gwydir River

Linear Depth Scale 0 to 50m EC beneath the Lower Gwydir River

Log10 depth scale 0.2 to 50m Lower Gwydir River Summary of Inferred interpretation Tyreel Regulator

Brageen Crossing – river bed is directly over permeable sediment

Coarse sediments extend deeply where Clay the old Gwydir River intermittently Big Leather : Heavy rejoins the present extends 2m and Clay encountered beneath clay extends 2m south channel more beneath the Ginham just upstream beneath the bed but the bed of the Gwydir Raft suggests is underlain by that the Ginham passes off permeable sediment a prior stream gravel at this point. Log10 depth scale River bed is in direct contact with permeable sediment extending generally to a depth of 12 to 15 m and underlain by either clay or moderately permeable sediment as indicated. Gwydir Photos Gwydir Survey – Yarraman Bridge

Crossing suspended logs in the Gwydir South Branch north of Morcott

Gwydir Survey – Crossing clay bed just downstream of Yarraman Bridge Weamatong Crossing (just downstream of Brageen Crossing) Upstream of Brageen Crossing

Gwydir Raft, Gwydir south branch – the Gingham Tyreel north of Morcott Lithologies encountered in drillers logs Lower Gwydir Modelled near the Gwydir River Resistivity Images - Key

EC histogram and colour stretch for the entire Gwydir River dataset.

EC, Salinity, River and Soil Water Texture relationship for the Gwydir River dataset Lower Gwydir River EC 8m below river bed

Locations of Bores EC beneath the Lithological Lower Gwydir River Log Graphics

Linear Depth Scale 0 to 50m EC beneath the Lithological Lower Gwydir River Log Graphics

View from the South

Linear Depth Scale 0 to 50m River incision 2 to 10m EC beneath the Lithological Lower Gwydir River Log Graphics

View from the North

Linear Depth Scale 0 to 50m River incision 2 to 10m Gwydir River -Weamatong to Carnee

Brageen Crossing

Numerous Yellow and Red Bellied Black Snakes were encountered Gwydir River -Weamatong to Carnee (Morcott)

Log10 Depth Scale Gwydir River -Weamatong An intermittent thin (typically 2m) Brageen Crossing to Carnee (Morcott) veneer of heavy clay is evident as humpy outcrops in the river. Interpretation

Inferred permeable sediments extend to between 4 and 10 metres deep and overly inferred clayey sediment. The Old Gwydir – degree of variation evident suggests inferred permeable that the substrate is made of numerous sediment extends channel deposits with only a small percentage of overbank deposits. beyond 25 metres deep

The water table in this vicinity is claimed by farmers to be beyond the depth of this survey however even the maximum resistivity observed here suggests that sub-river sediment is at least very moist.

Log10 Depth Scale Gwydir River - Tyreel From the Western boundary of Tyreel to the Tyreel Regulator

The Gwydir Raft Gwydir River – Tyreel – EC 8m below the river bed Tyreel Western Gwydir Boundary North Arm, Gingham Short survey 40m wide deep channel Sounding

Gwydir Raft

Sounding

The Big Leather, Gwydir South Arm

Gwydir South Arm 3 to 5m wide channel Gwydir River EC 1m below the river bed Tyreel Station Gwydir River Tyreel Station Gwydir River Tyreel Station

2 to 6m of stiff clay evident as humpy outcrops in the river

Beneath the stiff clay, sediment appears to be the same as east of Gwydir Raft – the the raft – ie. laterally variable large river channel gravels, pebbles and clays abruptly stops and is clogged with logs

River sourced recharge in this vicinity is inferred to be either very high (through the gravel and pebble rich sediment) or non-existent (through the stiff clay). Gwydir River Tyreel Station River incision 1 to 5 metres Gwydir River – Tyreel Weir to Boolooroo Weir

Clay obstruction downstream of Yarraman Bridge Gwydir River – Tyreel Weir, Yarraman Bridge, Boolooroo Weir – EC 8m below the river bed

An interesting soil feature corresponds to the location Yarraman Bridge of a deep stiff clay feature Drilling Site outcropping in the river

Boolooroo Weir

A marked increase in sub-river EC occurs at this kink in the river Tyreel Regulator and Weir Gwydir River

Tyreel Weir to Boolooroo Weir Yarraman Bridge Boolooroo Weir

Tyreel Weir

Interpretation All findings here are inferred

The river jumps to the south as it crosses vertical clay boundaries extending from the bed right down A semi-continuous inferred River bed in direct contact beneath the upper aquifer. clay aquiclude underlies 12 with a permeable aquifer to 15m of highly permeable approximately 15m thick sediment which is in direct overlying slightly less contact with the river bed. permeable, or more saturated sediment.

Linear depth scale from 0 to 50m Gwydir Video – Access at http://www.youtube.com/watch?v=j1tCiC1CDRk (Compressed)

2 minutes

by M. Toft & D. Allen Dumaresq River

Geo-electric and associated run-of- river data RLPB reserve drilling site (2)

Cunningham Weir Smithfield lane drilling site (1) Dumaresq 2008 survey EC 8m beneath the river bed. Texas beds outcrop Inferred impermeable Texas, Qld 10km Permian rock

Granite Inferred fault controlled saline inflow Lithologies encountered in drillers logs near the Dumaresq River Dumaresq Modelled Resistivity Key

EC, Salinity, and Soil Texture relationship for the Dumaresq River dataset

River water EC histogram and colour stretch for the entire Dumaresq River dataset. EC beneath the Dumaresq River

River incision: 4 to 12 metres Linear depth scale 0 to 50 m Dumaresq River EC EC Depth Slice 8m beneath river bed Upper Tarwoona

Smithfield lane Texas Beds drilling site (1) (Permian) outcrop in river

Inferred Permian basement rock

Permian Granite Tor

Old Tarwoona Homestead Lachlan River Geo-electric and associated run-of- river data Lachlan River EC 06DStreamGonowlia 8m below 05Sounding 07GonowliaWeir river bed 04PackingShed 03Sounding

02RailwayBdg

01Hillston Lachlan Modelled Resistivity Images - Key

EC histogram and colour stretch for the entire Lachlan River dataset.

Lithologies encountered in drillers logs near the Lachlan River EC, Salinity, and Soil Texture relationship for the Lachlan River dataset Hillston Weir Pool Hillston

Bridge Inferred clay Drilling aquiclude Inferred moist site EC 8m sand and/or gravel below Drillsite river bed River incision: Banks steep and View from North West 3m high

Because the river water is more conductive than most bed sediments, those sediments may contain air however the difference in EC is too small to confirm such a conclusion made with reference to the sediment texture specific colour scales.

Inferred moist Hillston Bridge Drilling Site sand and/or gravel

Riverwater 700uS/cm

Inferred clay Log10 Depth Scale aquiclude 07GonowliaWeir + 06DStreamGonowlia & 05Sounding EC 8m below river bed 07GonowliaWeir

06DStreamGonowlia

Gonowlia Weir Drilling Site

05GonowliaWeir River incision: Banks Gonowlia Weir moderately steep Below Weir - 4m Above Weir - 2m

Gonowlia Weir Drillholes Note: GW273046 is invisible because it is outside the viewing frame This section of river uniformly overlies inferred moist sand Riverwater 700uS/cm and/or gravel Billabong Creek - Jerilderie

Geo-electric and associated run-of- river data 102 02McCaughey

103 Modelled Resistivity Images - Key EC histogram and colour stretch for the entire Billabong Creek dataset.

Lithologies encountered in drillers logs near Billabong Creek

EC, Salinity, and Soil Texture relationship for Billabong Creek dataset

104 EC 8m below Billabong Creek Bed 03Algudgerie

05Jerilderie 02McCaughey 01Kurraroo 04Cemetery

Algudgerie Creek Weir McCaughey Weir

Too shallow and boggy for practical survey Jerilderie Kurraroo Reserve Drilling Site Cemetery Reserve Drilling Site Weir

105 Inferred 1m thick freshwater filled unconsolidated silt bed beneath creek

Inferred freshwater filled palaeochannels break the lateral uniformity of the rest of this site.

Log10 Depth Scale Inferred Consolidated clay and sandy clay containing old saline water: Green = partially saturated Red = fully saturated 106 River incision: banks here are gently sloping and Inferred prior streams more than rise about 2 metre above the water 30 metres deep containing fresh which ranges from Inferred 12m deep water below 12 metres. about 10 cm deep prior stream sand to 1m deep.

Water level coincides with a gradual increase in ground EC with respect to increasing depth. Data is broken up here due to navigation problems caused by presence of sloppy deep mud- bars overlain by numerous fallen trees in very shallow water

107 by David Allen, National Centre for Groundwater Management, UTS, [email protected] , Bryce Kelly, UNSW School of BEES and Ke Ye, National Centre for Groundwater Management, UTS. Contents Key Depth slices on satellite imaging Interpretation Bore water EC comparison 3D curtain images 2007 bore log analysis 2008 bore log analysis Depth slices Apparent resistivity Surface Water Analysis Flood recharge mound Comparison with some other rivers

The boat and geo-electric array used on the Namoi River Note the river incision and bank height River recharge hosted in clays and clay bound sediments River water or Brackish groundwater from other sources hosted in various

sediments Frequency

River recharge hosted in sands and gravels

Sediment texture group

100% WATER (NO SEDIMENT

SANDS <10% Clay

SANDY LOAMS 10-25% Clay

LOAMS 25-30% Clay

CLAY LOAMS, LIGHT CLAYS 30-45% Clay

MEDIUM, HEAVY CLAYS >45% Clay EC data at a depth of 1m below river bed Gunidgera Creek Weir

Wee Waa Bridge CRDC Mollee Weir Research Station

Wee Waa

EC data at a depth of 4m below river bed EC data at a depth of 32m below river bed

EC beneath the Namoi River Mollee Clay Gravel Weir Gunidgera Gravel & Coarse Sand Weir

Shale Inferred recharge Inferred fuzzy sink boundary of river sourced flow

Bore lithologies lifted 8m to account for river incision

Log10 Depth Scale EC depth slice at 4m below river bed 2008 Bore log analysis

Contents: • Views of the entire dataset (TOO MANY BORES) • Views of bores just close to the river • Views of Mollee Weir to the CRDC research station • Views of CRDC Research Station to Wee Waa Bridge • Views of Wee Waa Bridge to Gunidgera Weir Lower Namoi Bores and geo-electric data comparison – Gunidgera Ck Weir to Mollee Weir

See also Zoomed in Sub-sampled images – they are more comprehensible

River incision: 3 to 10 m View from the south Linear Depth Scale from 0m to 40m River incision: 3 to 10 m Geo-electric Equipment Description An exponentially spaced electrode array for use on watercourses

Presented by [email protected]

I (Amps) Potential Electrodes - exponentially spaced Current Boat Electrodes V(Volts)

a Apparent Conductivity (Siemens/m) p n a = I (1/(a+pn) - 1/pn - 1/(a+pn+1) p n+1 Z (metres of depth) + 1/pn+1) / (2x3.14 V) Electric fields are distorted across conductivity contrast boundaries

Presented by [email protected]

I (Amps) Potential Electrodes - exponentially spaced Current Boat Electrodes V(Volts)

a Apparent Conductivity (Siemens/m) p n a = I (1/(a+pn) - 1/pn - 1/(a+pn+1) p n+1 Z (metres of depth) + 1/pn+1) / (2x3.14 V)

Current penetration vectors

Conductivity Contrast Upper layer less conductive than lower 100m Symmetrical Exponential Array

144m Exponential Bipole Array

100m Dipole Dipole Array Argo based river surveys Argo Based River Surveys Ai Air vent Data is located Greenspan during Smartlogger postprocessing using a time AirAi vent index merge EC sensor pH sensor

Rubber seals

Sump

Flushing point at gravitational sediment accumulation point

Pump, flow sensors, auto-restart, and intake filter all attached to the back of the water vessel. Outlet

Towards quick survey past canal obstacles

Transient Electromagnetic Imaging for aquifer recharge investigation in Western NSW. Planning for Managed Aquifer Recharge near

Towed TEM Photos Towed TEM Photos

Towed TEM on a plastic sheet – geophysics on a shoestring

ONE TEM SOUNDING

Note : Spiker will not resolve shallow features particularly in resistive terrain even though shallow information is present in the TEM data. This deficiency is more pronounced when slingram data is forced into Spiker which assumes co-incident loop configuration. 20 m MILDURA WEIR CLIFFS SALT INTERCEPTION SCHEME

River Salt Load Increase Geo- per kilometer is represented by the diameters of the spheres electric and ranges from -0.6 to 3.9 Survey tonnes/km/day MILDURA WEIR MALLEE CLIFFS SALT INTERCEPTION SCHEME

River Salt Load Increase per kilometer is represented by the TEM diameters of the spheres and ranges from -0.6 to 3.9 Survey tonnes/km/day Braided Stream Deposits A problem with induced polarization and/or super-paramagnetic effects 15

Strongly affected soundings 10 with the receiver coil near the transmitter loop

5

0

Centre Nulled

-5 1m outside

TEM Response TEM (Inverse (uV/Amp)) Sinh 2m outside

End of Ramp 4m ouside -10 7m outside

17m oustide -15 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 Gate time Log10(mS) Towed TEM – Slingram Arrangement

Receiver Coil Means of Transmitter Loop propulsion Towed TEM data

See next slide for manageable presentation Towed

800 TEM 750 700 650 data 600 550 500 450 400 350 300 250 200 150 100 50

Resistivity (ohm.m) 40m Depth Slice Deep Electrical Conductivity Imaging

• is suited to recharge pathway investigation • Recharge pathways from surface water bodies are clearly identified by geo-electric survey. • Potential recharge from dry land is best identified by towed or airborne EM equipment configured to resolve an appropriate depth interval. The need for recharge management

• Large scale artificial recharge has been proposed regularly over the years for agriculture by hydrogeologists. This presentation shows that, to achieve this, weirs have been installed in appropriate places along inland rivers.

• Potential artificial recharge schemes such as proposed for the Namoi back in 1994 by Woolley et al. are now of great potential for water value adding via re-regulation. Woolley, D., Forest, J., Green, J., Latty, K., Williams, R.M., 1994, Proposals for Artificial Recharge in the Namoi Valley: Dept. of Water Resources Technical Services Division, July, TS94.061