Presentation by Ruben Imhoff, Deltares, at the Delft-FEWS International User Days 2020, during Delft Software Days - Edition 2020. Monday, 2 November 2020.

1. Radar rainfall nowcasting techniques for
operational water management
An opportunity for your operational systems?
RUBEN IMHOFF1,2
THANKS TO: CLAUDIA BRAUER 1, AART OVEREEM 1,3, HIDDE LEIJNSE3, KLAAS-JAN VAN HEERINGEN 2,
ALBRECHT WEERTS1,2 & REMKO UIJLENHOET1
1 W A G E N I N G E N U N I V E R S I T Y - 2 D E L T A R E S - 3 R O Y A L N E T H E R L A N D S M E T E O R O L O G I C A L I N S T I T U T E ( K N M I )

2. A short introduction to nowcasting
Aangepaste versie van : Germann et al., J. Atmos. Sc., 2006

3. An example nowcast for the Netherlands
Reference Rainymotion
DenseRotation

4. Zooming in on a
catchment
Example for the area
around catchment the
Regge (957 km2 - east
of the Netherlands)

5. Some conclusions: based on a large sample
analysis of nowcasting techniques for 1,533 events
Skill was found to depend on:
1) Event type and duration: Increasing for longer events, skilfull
lead times range from 25 min (1-h events) to 116 min (24-h)
2) Season: Decreasing skill towards summer
3) Location: Increasing in the downwind direction
4) Catchment size: Increasing with larger catchment size
Average absolute error per season

6. Current work: hydrological analysis of
the 1533 events using Delft-FEWS
Reference pySTEPS deterministic (S-PROG) pySTEPS probabilistic
+15 hours ahead
Dwarsdiep (Noorderzijlvest)

7. Do you want to
know more?
Join the break-out session on radar
rainfall estimation and nowcasting
tools (today 17:05 – 18:00)!
• From reflectivity to rainfall rate
• Pre- and post-processing of radar
images
• Nowcasting
• Usage in Delft-FEWS
Ruben.Imhoff@deltares.nl