dsd-int 2014 - openmi symposium - integrated environmental modelling, andrew hughes, british...

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Integrated Environmental Modelling applied to the Thames Basin, UK: Linking models

using OpenMI to allow multi-scale simulation of groundwater processes

Hughes (with lots of other contributors, but notably: Bricker, Jackson, Mackay, Mansour, Peach, and Upton)

OpenMI day – Delft Software Days 31st October 2014


Study Area


Hydrogeology

• Thames river basin consists of 20 groundwater systems • Focus on:

• Cretaceous Chalk • Jurassic Limestone


The Chalk Aquifer Chalk • Highly permeable with

fractures and solution enhancement

• Palaeogene in the central part leading to groundwater confinement

• Rivers are sustained by groundwater input

• Use of fully distributed groundwater model


The Limestone Aquifer Limestone

• Characterized by its complex fractured structure

• Very responsive to recharge

• Well drained by rivers • Groundwater discharge

runs over non-aquifers and onto the Chalk

• Groundwater discharge is simulated using semi-distributed groundwater model


Hydrogeological complexity


Role of the Palaeogene and karst in the Chalk groundwater system in the Pang-Lambourn


Importance of the Palaeogene deposits?

Chalk

London Clay

Lambeth Group


Colne Valley - Adits

Note alluvium, sands and gravel, and river terrace deposits


Adit Abstraction Systems Modelling Wall Hall Pumping Test

Distance from shaft (m)

Modelled levels after 100 days pumping


Cotswolds limestones

Upper Jurassic

Middle Jurassic

Lower Jurassic

Oxford Clay

Great Oolite (GO)

Inferior Oolite (IO)

Lias

N

S

LIAS

IO FE GO

FullersEarth


Great Oolite GW level Great and Inferior Oolite GW level

Geology in 3D using GSI3DTM


Conceptual understanding Cotswolds Cotswolds


• Semi-distributed model of aquifer system: single head calculated in each “bucket”.

• Designed to be incorporated into a multi-aquifer model of Thames catchment.

• Code is OpenMI compliant to link with other components.

Numbering shows ID of each “bucket” Rivers are represented as distributions of level for each “bucket”

Cotswolds – modelling approach


Linking multiple models in OpenMI


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Jan-91 Sep-93 Jun-96 Mar-99 Dec-01 Sep-04 Jun-07 Mar-10 Nov-12

Cell 14Churn at Perrot's Brook

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Jan-91 Sep-93 Jun-96 Mar-99 Dec-01 Sep-04 Jun-07 Mar-10 Nov-12

Cell 13Coln at Fossebridge


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Cell 5Thames at West Mill Cricklade

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Jan-93 Sep-95 Jun-98 Mar-01 Dec-03 Sep-06 Jun-09 Mar-12

Cell 1Thames at Eynsham


Need for Model Linking

A

R

Q R A

Q

GW Abstraction

Return flow to Thames at Oxford

River flow at Reading

Treated wastewater returned to Thames at Oxford

Groundwater abstraction regulated by flow at Reading

River flow

Pumping rate

50 Ml/d

150 Ml/d


River Flow

Abs

tract

ion

rate

Overland flow Recharge

Baseflow

Current Suite of Models

Chalk •2D TV distributed model •Inputs: recharge, spring flow, abstractions •Outputs: baseflow, groundwater head

Recharge •2D distributed model •Inputs: climate (rainfall and PET) •Outputs: overland flow, soil moisture, recharge

Limestone •Semi-distributed model (variably sized units) •Inputs: recharge •Outputs: baseflow, groundwater head

River Thames •1D river routing algorithm •Inputs: overland flow, baseflow •Outputs: total flow

WM module •Inputs: river flow Outputs: pumping rate, discharge to river


River Flow

Abs

tract

ion

rate

Overland flow

Recharge

Recharge

Thames

Baseflow

The Open Modelling Interface (OpenMI) Standard


Results

A

R

Q


Boreholes

• Groundwater typically exploited using them

• Complex situation – lots of mechanism

• Scale issue: regional flow 10s km, but boreholes operate on cm scale

• Challenge in terms of modelling them


Multi-scale Groundwater Modelling

Radial Flow Model ZOOMQ3D Radial-Cartesian Coupling

OpenMI



Radial Flow Model

• Finite difference approximation • Darcy-Forchheimer (non-linear flow) • Logarithmic radial node spacing • Vertical layering • Vertical & horizontal heterogeneity

• Partially or fully penetrating borehole • Borehole storage • Borehole casing & screening • Seepage face development



Radial Flow Model Radial-Cartesian Coupling

SPIDERR Flow Model •Hybrid radial-Cartesian method applied in petroleum reservoir models • Limitations of grid construction BUT • Quick, simple & user friendly



Radial Flow Model Radial-Cartesian Coupling

ZOOMQ3D OpenMI

• OpenMI standard for linking models • Data exchange maintains consistency between two models • Quick and easy to link several borehole models • Make use of existing regional models



SPIDERR Flow Model ZOOMQ3D OpenMI

Pumping Rate Parameterisation

Boundary Flows Recharge & Leakage


Study Area


Model Application

1. Calibration of SPIDERR Flow Model to pumping test data 2. Coupling of SPIDERR Flow Model with ZOOMQ3D regional model

3. Historic simulation and comparison with operational data 4. Abstraction scenarios to inform DO assessment

to Thames Water operational supply borehole to inform assessment of Deployable Output


Model Application 1. Calibration of SPIDERR Flow Model to pumping test data

Modelled and observed drawdown for a step- drawdown and constant rate test at the

abstraction borehole


Model Application 2. Coupling of SPIDERR Flow Model with ZOOMQ3D regional model

3. Historic simulation and comparison with operational data

Modelled and observed groundwater levels in the abstraction borehole

Modelled (coupled and uncoupled ZOOMQ3D ) and observed baseflow in

the River Kennet close to the abstraction borehole


Model Application 4. Abstraction scenarios to inform DO assessment

Modelled groundwater levels in the borehole under increasing rates of abstraction

Modelled baseflow in the river under increasing rates of abstraction

Updated DO assessment using modelled data suggests the borehole may be capable of sustaining

a higher rate of abstraction under drought.


Conclusions • This a demonstration of how OpenMI technology

offers flexibility to link models o Models can be of different structure (Fully

distributed versus semi-distributed groundwater models)

o Models can be of different nature (groundwater models, river models, management modules)

o Models can operate at very different scales (regional groundwater flow, river reach, borehole)

• While OpenMI technique is not straight forward to use, it is a more pragmatic approach than building one model that represents all processes

dsd-int 2014 - openmi symposium - integrated environmental modelling, andrew hughes, british...

Science

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groundwater systemsfocus

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thames basin

groundwater confinementrivers