High-Res. Flash Flooding Estimation

TroposLeipzig

26. January 2016

-Or why do we measure precipitation?

Matthias B. Schmidt 2

Motivation

Extreme FloodingExamples from June 2011

[http://www.altona.info/2011/06/07/gewitter-regen-hagel-land-unter-in-hamburg/]

Matthias B. Schmidt 3

Motivation

[http://www.spiegel.de/fotostrecke/unwetter-ueberschwemmung-in-hamburg-hagel-in-bayern-fotostrecke-68908-2.html]

Extreme FloodingExamples from June 2011

Matthias B. Schmidt 4

What can we do?

Change weather?Fortunately we can’t

Estimate flooding possibility?We might!

Matthias B. Schmidt 5

X-Band Radars

High spatial resolution (60m)

High temporal resolution (30s)

[http://pattern.zmaw.de/Hamburg.2106.0.html]

Matthias B. Schmidt 7

Masterthesis - Goals

Hydrology: Higher resolution (X-Band) better?

Flash flooding forecasting possible?

Calculation of flooding probability

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Masterthesis - Tools

Shetran“a physically-based spatially-distributed hydrological model“ (J. Ewen et al. (2000))

Radar EnsembleCovariance (U. Germann et al. (2008))

Fractals

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Masterthesis - Shetran

Water Flow componentCanopy interception

Evaporation and transpiration

Surface run-off

Transfer between subsurface and river water

Storage and flow in VSS

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“spatially-distributed“

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Masterthesis - Shetran

“physically based”Conservation of mass

Saint-Venant Eq. (a.k.a. Shallow Water Eq.)

Penman-Monteith Eq.

Boussinesq and Richards Eq.

Numerically solvedImplicit, finite differences

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Statistical Model

Example hydrological model

Inflow I Storage Storage Outflow

Inflow II

∑𝒊

𝑵𝒇 𝒊 (𝒙 𝒊 ) ∑

𝒊

𝑵𝒇 𝒊 (𝒙 𝒊 )

∑𝒊

𝑵𝒇 𝒊 (𝒙 𝒊 )

∑𝒊

𝑵𝒇 𝒊 (𝒙 𝒊 )

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Masterthesis – Shetran

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Masterthesis – Shetran

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Masterthesis – Model Output

Input

Vege

tatio

n

Soil

/

VSS

Run-Off/

Overflow/

Saturation

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Masterthesis – Model Experiments

What is more severe?In terms of hydrology

Precipitation event 1High intensity

Short duration

Precipitation event 2Low intensity

Long duration

Time (5*30min)

1

2

Same Precipitation Amount

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Masterthesis – Model Output

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Masterthesis – Radar Ensemble

Statistically based Radar Ensemble GeneratorCovariance approach

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Masterthesis – Radar Ensemble

3 mm/h

2.5 mm/h2 mm/h

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Masterthesis – Radar Ensemble

3 mm/h

2.5 mm/h2 mm/h

1 mm/h

4 mm/h

2.2 mm/h

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Masterthesis – Radar Ensemble

3 mm/h

2.5 mm/h2 mm/h

1 mm/h

4 mm/h

2.2 mm/h

[01 11

⋯ 0110

⋮ ⋮ ⋱ ⋮ ⋮1100

⋯ 0101]

𝑪=𝑳 ⋅𝑳𝑻

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Masterthesis – Radar Ensemble

[01 11

⋯ 0110

⋮ ⋮ ⋱ ⋮ ⋮1100

⋯ 0101]⋅

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Masterthesis – Radar Ensemble

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Early-Warning System

Concept demonstrationImplementation beyond scope of masterthesis

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Early-Warning System

Houston

“Hamburg, do we have a problem?”[http://

texasstormchasers.com/tag/squall-line/]

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Early-Warning System

[01 11

⋯ 0110

⋮ ⋮ ⋱ ⋮ ⋮1100

⋯ 0101]⋅

Precipitation Ensemble

Ensemble Generator

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Early-Warning System

Shetran

Discharge Ensemble

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Early-Warning System

Shetran

Discharge Ensemble

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Early-Warning System

Houston

“Hamburg, do we have a problem?”[http://

texasstormchasers.com/tag/squall-line/]

“15 out of 25 members issue a warning!”

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Summing Up

Higher Resolution has an impact on results

Time (5*30min)

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Summing Up

Higher Resolution has an impact on results

Flooding estimation might become possible

Matthias B. Schmidt 32

1. http://

www.altona.info/2011/06/07/gewitter-regen-hagel-land-unter

-in-hamburg/

2. http://

www.spiegel.de/fotostrecke/unwetter-ueberschwemmung-in-

hamburg-hagel-in-bayern-fotostrecke-68908-2.html

3. http://pattern.zmaw.de/Hamburg.2106.0.html

4. http://texasstormchasers.com/tag/squall-line/

Literature & Sources

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5. Germann, U., Berenguer, M., Sempere-Torres, D., Zappa, M. (2008)

6. SHETRAN water flow equations (

http://research.ncl.ac.uk/shetran/water%20flow%20equations.pdf)

7. Ewen, J., Parkin, G. and O'Connell, P.E. (2000). SHETRAN:

Distributed River Basin Flow and Transport Modelling System. ASCE

J. Hydrologic Eng., 5, 250-258. (

http://research.ncl.ac.uk/shetran/SHETRAN_ASCE_paper.pdf)

Literature & Sources

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Appendix

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Student Research

Real-time Radar calibrationBased on single pulse data

Dynamic Clutter detectionWithout Doppler and Polarimetry

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Student Research – Radar calibration

Single-Pulse dataTime-critical code necessary

Fortran core

real-time calibration possible

Matthias B. Schmidt 38

Student Research – clutter detection

Difficult: No Doppler, no dual pol

Statistical approachNot only clutter map

Not much recent research (everybody has Doppler)

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Student Research – clutter detection

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