Modelling and/or Measuring? (in Water Management)

Ali AbbasiFrank Ohne AnnorNick van de Giesen

Water Resources Staff MeetingTUD-WRM04-02-2016

Introduction Model Validation/Verificati

on

Challenges … Making Decisions!

Water Bodies Classification 0-D/1-D/2-D/3-D Models? Open-Source & Free or Commercial Tools? Processing Measurement (EC) Cost Effective? Generalizable? Verification & Validation? Scales (e.g. ABL) Numerical Issues (Convergence, etc.) Numerical Approaches (FVM/FEM/…)? Computational Resources (HPC, Cloud-

Computing, etc.)? ….

Hello Cloud! (Global)

Hello Cloud?! (Netherlands)

Measuring or Modelling?!

• Expensieve • Mostly in One point (in few

locations)• Difficult • Technical Expertise• Control quality!• Calibrattion (the Equipment)

• Real Values?• (Effects of) Unknown

Parameters? • Ready to Use? • Using in Model Verification• ….• ….

Measurements

Measurement or Simulation?!

• Inexpensieve / Cost-effective?• (Effective) Parameters?• (Algorithm) Sensitivity• Validation (Challenge!)• Computational Resources• Mathematical Issues• Bad / Good Model?

• Cost Effective• Spatial Distribution • Temporal Distribution• Understanding the Process• Desinging / Evaluation• Generalizable?• …

Simulation

Measurement or Simulation?!

Reliability of Measurements?

Data Quality Control?

Measurements for Model Validation

(Which / How)?

Simple or Complex Model?

Good / Bad Models?

Interaction (Impact) of the Data (Quality)

and Model?

Simplifying the Model? Yes/No?

…

Measurement or Simulation?!

All models are fake.But some can be

useful.

Measurement or Simulation?!

(Climate)Models are unreliable.

"[Models] are full of fudge factors that are fitted to the existing climate, so the models more or less agree with the observed data. But there is no reason to believe that the same fudge factors would give the right behaviour in a world with different chemistry, for example in a world with increased CO2 in the atmosphere." (Freeman Dyson)

Tools/Software

Free of charge & Open Source Software

Commercial Software

Tools/SoftwareCommercial Software The Easy Road?!Free/OS Software The Hard Road?!

The easy road often becomes hard, and the hard road often becomes easy (Robert Kiyosaki)

Tools/Software

“Taking the Exit for the Hard Road”

Parallel Computing• Parallel Simulation• Decomposing, Reconstructing, etc.• The optimized Number of CPUs

Parallel Computing

A graphical representation of Amdahl's law. The speed-up of a program from parallelization is limited by how much of the program can be parallelized. For example, if 90% of the program can be parallelized, the theoretical maximum

speed-up using parallel computing would be 10x no matter how many processors are used.

Computational Resources

PC (6 CPUs, 24GB Memory)

HPC03(Remote Sensing Department) as a GUEST!

HPC-Cloud SURFsara

Visualizing• Parallel Visualizing!• Big Data• Paraview/Gnuplot/…

Thank You

Comments Please …. !