Wolfgang Gossel, Peter Wycisk: Importance and effects of model - - PowerPoint PPT Presentation

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Wolfgang Gossel, Peter Wycisk: Importance and effects of model - - PowerPoint PPT Presentation

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Wolfgang Gossel, Peter Wycisk: Importance and effects of model couplings in hydrogeology Objectives Implementation Reasons Kinds Behaviour Calibration Two examples for solution of hydrogeological problems How were the groundwater flow and

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SLIDE 1

Wolfgang Gossel, Peter Wycisk: Importance and effects of model couplings in hydrogeology

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SLIDE 2

Two examples for solution of hydrogeological problems

3/26

  • How were the groundwater flow and transport conditions influenced by open pit

lignite mining in the region Untere Mulde/Fuhne?

  • What was the impact of climate change during the last 140 000 years on the

groundwater balances in the Nubian Aquifer System?

?

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 3

Problem and model

Pumpversuch_02102002: Darstellung der Messwerte mit einer logarithmischen Geraden zur Auswertung der Absenkung 0.000 0.010 0.020 0.030 0.040 0.050 0.060 1 10 100 1000 10000 Zeit t [s] Absenkung s [m] B6A B6E B6C logarithmische Gerade, B6C logarithmische Gerade, B6E logarithmische Gerade, B6A

1 2

lg 4 3 . 2 t t s Q T       

Analytical methods Numerical methods

Problem solution with diverse methods:

Statistical methods

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 4

Modelling systems, -tools and models

Changed after Bossel (1992)

„data“

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 5

Modelling systems, -tools and models

Geology (hardrocks, unconsolidated rocks): static, constructive Groundwater recharge: dynamic, GIS-based Surface water: statistic, time series Groundwater: transient, numeric GSI3D GIS, Excel Excel, own programming Feflow

Modelling systems Modelling tools

Computer- implementation Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 6

Suitability of modelling tools

Objective modelling tool

  • Dynamic, variability in

time domain, long time frames

  • 3D spatially variable

resolution according to data availabilty and

  • bjectives

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 7

Complexity of models and necessity of couplings

Nubian Aquifer System Untere Mulde/Fuhne Climatic changes Groundwater flow and transport, density driven Ground- water recharge Surface water Ground- water flow and transport Unsat. zone Geology

Dependent on:

  • Number of compartments
  • Number of used modelling systems
  • Nonlinearity of the functions in modelling systems and the connections of

the modelling systems

  • Number of parameters
  • Heterogeinity of parameters and boundary conditions in time and space

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 8

Pros and Cons of complex models Pros:

  • Substitution of weakly defined parameters (or b.c.) by better

systematical approach

  • Range of objectives increases

Cons:

  • High affinity to instabilities of the coupled modelling systems
  • Sensitivity difficult to measure
  • Scale dependency of parameters in different modelling

systems

  • Technical implementation of interfaces -> solvable

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 9

Kinds of coupling

Objectives Implementation Reasons Kinds Behaviour Calibration

ModSys 1

e.g. flow modelling

ModSys 2

e.g. transport modelling

ModSys 1

Serial coupling (non iterative)

ModSys 2

Parallel coupling (iterative)

ModSys 1 ModSys 2

Periodically synchronized coupling

ModSys 1

Integrated coupling

ModSys 2 ModSys 1

e.g. local model

ModSys 1

e.g. regional model

Horizontal coupling

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SLIDE 10

Coupling construktive geolog. mod. with hydrogeol. mod.

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 11

Sequential and serial coupling, periodically synchronized

145 hydrotopes

Soil (substrate) Land use Depth to groundwater

Jährliche Niederschlagssummen Bitterfeld 100 200 300 400 500 600 700 800 900 1000 1947 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 Mittel Max Jahre Niederschlagssumme [mm] Min Stabw Jährliche Summe der potentiellen Evapotranspiration (ETP) Bitterfeld 100 200 300 400 500 600 700 800 900 1000 1947 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 Mittel Max Jahre Jahressumme ETP [mm] Min Stabw Jährliche Klimatische Wasserbilanz (KWB) Bitterfeld
  • 500
  • 400
  • 300
  • 200
  • 100
100 200 300 400 500 1947 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 Mittel Max Jahre Jahressumme KWB [mm] Min Stabw

Climatic data

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 12

Nubian Aquifer System: Completely density driven groundwater modelling

Iterative, integrated coupling

Transient groundwater flow model Transient groundwater transport model Transient density coupled groundwater flow and transport model Flow parameters Transport parameters Density parameters B.C. for flow model

Objectives Implementation Reasons Kinds Behaviour Calibration

B.C. for transport model

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Interfaces of modelling systems

Technical problem: Coupling of modelling systems for surface water (SW) and groundwater (GW)

  • Systematical approach: Total discharge of SW doesn‘t influence GW

level but SW level

  • Level and discharge of SW are dominated by catchment abroad of

investigation area

  • Realisation of the Transfer-/Leakage-coefficient in groundwater

modelling system

  • Level-discharge-dependency is implemented in SW modelling

system

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 14

Stability

  • Convergence problems

for numerical solutions

  • Over-/Undershooting at

interpolations or in dynamical models between time steps

  • Oscillations in feedback

between modelling systems

  • Sometimes step back to

„effective“ parameters necessary

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 15

Complex example

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 16

Calibration of coupled models

Dilemma of the geological model:

  • Can not be calibrated on itself but only proven (geometrical

criteria).

  • Importance: „Database“ for unsaturated and saturated zone

modelling

  • Solution: Indecies for the derived model and calibration of ranges of

values Impact of kind of coupling on calibration of models:

Objectives Implementation Reasons Kinds Behaviour Calibration

Kind of coupling Work load Stability Transparency Sequential middle high high Periodically synchronized high high high Iterative low low low Integrated middle low low

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Results of coupled models

Transport model Untere Mulde/Fuhne 1895-2005

Objectives Implementation Reasons Kinds Behaviour Calibration

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SLIDE 18

The future ....

Trends of development of model couplings

  • Horizontal coupling needless or integrated
  • Vertical couplings applicable via integrated solutions, unstable
  • Defined programming interfaces of the tools are good solution, up

to now not user friendly

  • Data base will dominate the applicability of model couplings
  • OpenSource
  • Open standards
  • Documented interfaces

Additional tools, e.g. Modpath, MT3D, RT3D, HUF, UZF, Pre- and Postprocessors

  • Closed Source
  • Open and proprietary stand.
  • Documented interfaces

Integration of transport, density, heat, unsat. zone, discrete features, development of self- made modules

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SLIDE 19

Summary

  • Application of complex models increases
  • Complex models depend often on couplings of modelling

systems

  • Different kinds of coupling have consequences for behaviour,

calibration, results and prognoses of models

  • Systematical application after detailed analyses necessary
  • Trend in hydrogeology towards opening of central parts of

modelling tools via defined interfaces and standards

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SLIDE 20

Thanks

  • Thanks for your attention
  • Thanks to the department for the support
  • Projects for the examples:

SAFIRA I and II: Prof. Dr. Peter Wycisk, Tobias Hubert, (Dr.) Tilmann Steinmetz, Andreas Wollmann, Karsten Sommerwerk, Steffi Schnabel, Gerd Fleck, Oliver Neef, Raik Richter und Holger Fabritius Ad-Hoc-Project „Mulde-Hochwasser 2002 and Austragsdynamik“: Christian Neumann Nubian Aquifer System: Dr. Ahmed Sefelnasr,