Water resources management in karst aquifers –a Lower ... · Water resources management in karst...

transcript

M. Sauter(1), S. Schmidt(1), M. Abusaada(2), T. Reimann(3), R. Liedl(3) and T. Geyer(1)

(1) Geowissenschaftliches Zentrum, Georg‐August‐Universität Göttingen, Göttingen, Germany

(2) Palestinian Hydrology Group, Ramallah, West Bank

(3) Institut für Grundwasserwirtschaft, TU Dresden, Dresden, Germany

International Conference on Integrated Water Resources Management

Dresden, 12.10.2011

Water resources management in karst aquifers – a concept for the Lower Jordan Valley?

DEM and outcrops of carbonates in the Lower Jordan Valley

Green colour: carbonates

DEM and outcrops of carbonates in the Lower Jordan Valley

Green colour: carbonates

Groundwater

carbonate aquifers

resource

in the

region.

Conceptual

of karst

systems

Double porosity

behaviour‐

Conduit

system

fissured

matrix

High permeability

of karst

systems‐

Lack of surface

water‐

Exploration of groundwater from

low‐elevation springs in valleys

Problems‐

Difficult

to study‐

Surface

and subsurface

catchments

do not

conincide‐

Low probability

of wells

intersecting

channel

network

Double porosity

behaviour‐

Present

of conduit

system

High permeability

of karst

systems‐

Lack of surface

water‐

Exploration of groundwater from

low‐elevation springs in valleys

Problems‐

Difficult

to study‐

Surface

and subsurface

catchments

do not

conincide‐

Low probability

of wells

intersecting

channel

network

In the area of the Jordan Valleysome cities and villages depend to

a much greater extent on spring water than on pumped water

(Jericho, Auja, Wadi Sir).

Conceptual model of karst systems

Example: Auja spring

Mean discharge Auja

(1967 ‐

2000) 9 Mio. m³/a

Rusteberg et al.

Example: Spring discharge Auja and Sultan / West Bank

Auja: maximum discharge shortly after rainiest month and

sometimes drys up towards the end of the winter season.

Sultan: Stable discharge without high response to precipitation

changes recharge area far away from the

spring and larger storage volume

Example: Spring discharge Auja and Sultan / West Bank

Deficit and Potential for Regulation (Kresic and Stevanovic 2010)

Secure additional quantities of water during periods of increased demands

Sufficient aquifer replenishment during wet seasons, otherwise water table

decline is guaranteed

Implies engineering interventions to control spring flow and managing spring

water contribution

Management concepts

Active management

‐ Underground / Spring dams

Increasing water level may yield to an increase

of the hydraulic head in the aquifer retention effect

‐(Over)pumping

‐Managed aquifer recharge

Passive management

The optimal use of the discharging groundwater under natural discharge

conditions.

Active and passive management require modeling approaches to predict impact

on spring discharge, water levels and water quality

Shallow karst vs. Deep karst

Dynamic phreatic storage

Static phreatic storage

Dynamic vadose storage

Dynamic surfaceStorage (snow pack)

Deep karst Shallow karst

Aquifer basePhreatic zone

Vadose zone

a)Dynamic phreatic storage

Vadose zone

Shallow karst (Seichter Karst, Jura Type)• no significant storage below elevation of spring

discharge• no opportunities for additional groundwater extraction beyond natural outflow

• tends to dry up due to gravity drainage at the sloping base

Vadose zone

Deep karst

(Tiefer Karst,

Vauclusion Type)• discharge at a lateral boundary

(e.g. river valley)• displays considerable storage

volume below the discharge level

Overpumping of the Lez system (Avias 1995, Fleury et al. 2009)

Overpumping of the Lez system

Data: BRGM Montpellier

Discrete modeling approach ‐

CAVE model (Liedl et al. 2003, Birk et al. 2005, Reimann et al. 2011)

Karst aquifer CAVE

Fissured matrix

Conduit system Discrete pipe network

MODFLOW

Concept Numericalmodel

Carbonate Aquifer Void Evolution

Link between hydraulic, transport and genesis

( )cfex hhQ −= γ

⎟⎟⎠

⎞⎜⎜⎝

⎛+−=

f Re51.2

71.3log21

*1.10 avD =

Flow in the pipes

Transport in the pipe network

Transfer

Lhagv cΔ

hc =Δ

Darcy‐Weisbach Colebrook‐White

h_c, h_f head, L distance, f friction factor, e roughness height, a conduit diameter, g gravitational acceleration, v. friction velocity, D dispersion coefficient

Forward modelling of large scale pumping tests in synthetic karst aquifers with different conduit networks

Catchment area: 7 x 8 km2; Conduit volume: 150 000 m3; Pumping rate: 1 m3s‐1

Hydraulic heads in the fissured matrix during pumping

Pumpingwell

Discrete modeling approach ‐

CAVE model (Reimann et al. 2008)

First steps

Set‐up of a geological model for the area of investigation and aquifer characterisation

Upper aquifer

Aquiclud

Aquitard

Lower aquifer

Torsten Lange, Sebastian Schmidt

Conclusions

Model techniques are available

Technical requirements for active management

FIRST ‐

Requires comprehensive research to get knowledge of aquifer geometry and characteristics:

Storage properties and the aquifer transmissivity

Degree of karstification and position of karstification base

Deep or shallow aquifer systems

Socio‐economic‐environmental requirements for active management

Environmentally sound

Economically feasible (e.g. energy costs for pumping)

Political willingness

Sultan spring

Acknowledgements

PWA, MEKOROT, Al Quds University

BRGM Montpellier

Town Montpellier and Conseil Général de l‘Hérault

VEOLIA Eau à

Montpellier

BMBF (Federal Ministry of Education and Research)

DFG (German Research Foundation)

Planning and evaluation of karst management activities ‐

Modelling approaches to simulate flow in karst aquifers ‐

(Teutsch and Sauter 1991, Sauter et al. 2006)

Classification of distributive parameter models (SCPE, "Single Continuum Porous Equivalent", DCPE "Double Continuum

Porous Equivalent“, HM, "Hybrid Model", DSFS "Discrete Single Fracture Set", DMFS "Discrete Multiple Fracture Set“)

(from Teutsch & Sauter 1991).

Karst settings, karst management and model applications

Management type Problem type Setting Model type

Active Management Hydraulic Basin control Continuum models

Hydraulic Conduit control Hybrid models

Structural Subsurface dams Hybrid models

Passive Management Hydraulic Surface storage Hydrological models

Hydraulic Vadose storage Transfer functions

Hydraulic Phreatic storage Continuum models

Dam construction

Increasing water level may yield to an increase of the hydraulic

head in the aquifer

retention effect

Advantages of underground dams

Mimimal loss of water by evaporation

Water qualitiy – no salinisation, no eutrophication, less sedimentation than in surface dams

No problems with compensation or relocate people

Disadvantages of underground dams

Possible leakage

Not predictable storage amount

High costs and uncertain results

Requirements

Identification of the existence of preferential flow pathways (Sebasatian: Jericho ‐

Dujuk)

Bottom of the spring is in contact with the impermeable aquidard

and srrounded by

impermeable material laterally

(Kresic and Stevanovic 2010)

Examples (Kresic and Stevanovic 2010)

Overpumping of the Lez catchment area (Fleury et al. 2009)

Deep aquifer system close to the Mediterranean Sea

Install pumps in submerged channels below spring elevation

Overpump the system in periods of high water demand during summer

Duyuk spring

• EC

• Temperature

• Water level

Sultan spring

• EC

• Temperature

• Water level

• pH

• Turbidity

First steps

Spring monitoring for aquifer characterisation

Conceptual model carbonate aquifers

Example: Auja catchment (Lower Jordan Valley)

Spring regulation

Classification of karst environments

Overview: Management strategies

Examples from other regions

Investigated system: part of the conduit system

Scale: catchment scale

Disadvantage: characterisation of a small part of a karst aquifer

Investigated system: fissured matrix blocks

Scale: local scale

Disadvantage: small scale tests

Artificial tests

Global approaches with natural source

Investigated system: conduit system, fissured matrix blocks

Scale: catchment scale

Disadvantage: unknown input signal

Characterisation techniques (Geyer 2008)

Discrete modeling approaches ‐

scenario (Reimann et al. 2011, WRR)

( ) 00

2=−+

∂∂

+⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

+∂∂ ssgA

Geological cross‐section

http://exact‐me.org/overview/p0809.htm

Discharge generation in karst environments (Hobbs and Smart 1986)

Questions:

Map with well fields

and springs?

Number

of springs

in the

region

Multiparametersonde …

Karte lower

aquifer

GEORG-AUGUST-UNIVERSITÄT GÖTTINGEN

The Lower Jordan Valley (LJV)

Countries: Jordan, Israel and PalestineClimatic conditions: arid to semi-arid Evaporation: 2000 to 2500 mm /aPrecipitation: 50 to 700 mm /aElevation: -400m to 1200 mMain Sources: Spring discharge and GWProblems: water scarcity, pollution, gw-over-exploitation, salinization etc. Similarity of water resources systems and challengesHigh Risk of water related conflictsSustainable development urgently requiredJoint management of WR urgently required

Water resources management in karst aquifers –a Lower ... · Water resources management in karst...

Documents