Rapid Flood Hazard Monitoring:Forming situational flood extent layersPaul Drury. 28th March 2017

• Site-specific Environmental Consultancy

• Precision/Global Flood Hazard Mapping

• Probabilistic Flood Catastrophe Models

• Develop Flood Forecasting & Monitoring Systems

• GIS and remote sensing Technology Development

Ambiental: what we do…

Working together to mitigate flood risk

• Working with Telespazio since 2014

• Completed 2 projects under SSGP phase 1

• Completing SSGP phase 2 project

• Now launching service for flood monitoring

Key aim of our work…

To assist central commanders, emergency responders, loss adjusters, insurers and infrastructure managers to better focus flood risk reduction, resilience and adaption efforts.

Problem statement…

• It is challenging to obtain an up to date and accurate view of flooding situations when events unfold.

• Satellite based SAR data can be of great benefit but has limitations, especially in urban areas.

• Historically it has taken a long time to get quality data to decision makers and emergency responders.

1

TRIGGER

ALERT

2

PRIORITISE

LOCATION

3

TASK SATELITE

4

CAPTURE IMAGE

5

PROCESS

DATA

6

DELIVER PRODUCT

Workflow concept

Flood risk priority map for satellite tasking

Formed through ranking all locations in terms of their flood hazard potential and population density

Process of flood extent production

Module 1:Domain Set Up

Module 2:Cross Section

Set Up

Module 3:Dataset

Assimilation

Module 4:Product

Compilation

Module 1:Domain Set Up

Domain setup

Generate floodable area through buffering max extent of existing fluvial flood models…

Discard all grid cells located away from rivers and floodable areas…

Extract supportingdatasets for the area of interest

• Defines the area in which the post-processing will happen and discards non-floodable land away from rivers.

• This is an optimisation step which reduces computer run times.

Cross sections• Lines emanating out each side of a river channel • Represents a 1-dimentional modelled flood surface• Processes sections against ruleset

Module 2:Cross Section

Set UpSmoothing river centrelines and generating river level cross-sections.

Data assimilation

• SAR derived flood polygons above height of modelled surface given a lower confidence than those below it.Module 3:

Dataset Assimilation

Extract flood surface elevations for each cross-section using Ambiental’shydraulically modelled flood surface…

Product compilation

• SAR derived polygons converted to node points.• New flood extent fills in gaps between data when

topography determines that land neighbouring high confidence data should be flooded.

SAR flood polygons are processed to node points

Module 4:Product

Compilation

Data gaps filled in to produce product at various confidence levels

Captured flood extent from Telespazio

Carlisle (Dec 2014)

Post-processed extent from Ambiental

Carlisle (Dec 2014)

Comparison with EA Carlisle 2015 flood

extent (draft)

Carlisle (Dec 2014)

Historic event back testing

Carlisle York Somerset Maidenhead

Stakeholder engagement

• Cost savings via (i) more informed deployment of temporary flood defences, and (ii) reducing the need for ground surveys and inefficient allocation of loss adjuster resources

• More timely delivery of flood extent maps, in a useable format, for the international (re)insurance community so as to better estimate losses and allocate capital

• More accurate flood predictions by focusing on the areas of greatest potential impact and enhancing EO image capabilities with robust hydrological modelling

Benefits of service to end users

paul.drury@ambiental.co.uk

linkedin.com/company/ambiental-technical-solutions

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twitter.com/floodexpert

www.ambiental.co.uk