ICE Flooding 2015

1. ©DHI
Traditional approaches to flood risk management in the UK have focussed primarily
on the physics of flood water inundation from rainfall, rivers and the sea. An
understanding of the processes involved is critical in defining the level of flood risk
and in establishing an appropriate level of defence. However, communities are
subjected to a range of additional impacts, over and above the quantity and speed
of flood waters, including, for example, the extent and persistence of flood waters
contaminated by foul sewerage and fine sediments.
We believe that accurate modelling of flooding risk and its wider impacts is essential
to deliver sustainable flood risk management for communities and infrastructure.
DHI was a pioneer in the development of truly integrated water modelling software.
Today, our software is unrivalled in respect of flexibility, accuracy and performance;
allowing the widest range of flooding and environmental impacts to be considered.
Combining the MIKE by DHI product family with the MIKE CUSTOMISED by DHI
software technologies encapsulates more knowledge and covers a wider range of
water modelling needs than any similar products.
The convergence of these two strong and proven business lines – into our new
MIKE Powered by DHI brand – is a natural evolution. The unrivalled integration of
our technologies will enable us to provide you and your clients with the ultimate in
understanding.
TRULY INTEGRATED APPROACHES
Using numerical models to support flood risk assessments and flood mapping is not the end of
the process but the beginning. With truly integrated modelling approaches you can:
 Add fully coupled one- and two-dimensional advection-dispersion and water quality
modules to consider the transport of polluted floodwater in rivers, floodplains and pipes.
 Include powerful sediment transport
models in one-, two- or three-dimensions to
assess the effects of sedimentation on
flood risk and vice versa.
 Add three-dimensional groundwater
models to seamlessly and dynamically
model groundwater and surface water
interactions, and even groundwater and
pipe flow interaction.
 Integration with external data sources such
as telemetry and decision support systems
 Use of radar as boundary conditions to the
model as standard
It will be many years before most flood modelling packages will be developed to provide the
above functionality. However, MIKE Powered by DHI software can provide all of the above –
and much more – today.
Our fully integrated approach to flood modelling enables you to go far beyond the capabilities
of competing products, saving time, effort and cost.
OVERVIEW
RECENT ADVANCES IN FLOOD
MODELLING
Over the past 30-years, the industry has
witnessed a revolution in the hydraulic models
used to assess the risk of flooding from the
sea, rivers and rain storms.
These models have evolved from one-
dimensional representations of rivers and their
floodplains to integrated one- and two-
dimensional models – which provide a more
accurate description of overland flows but are
more computationally demanding.
Under the guise of integrated catchment
modelling, pipe flow models have been
included, however, many integrated
catchment models ignore groundwater. The
water cycle is a naturally closed system and
there is no distinct boundary between
groundwater and surface water – it is one
water. Accordingly, for true integrated
catchment modelling, water must not be
generated or lost (for example, by infiltration)
from the system.
The industry has recently benefited from
technical innovations in computer hardware to
speed up the simulations of large, high
resolution two-dimensional models.
It is likely that the next frontier of flood
modelling will include some of the following:
 A move to probabilistic modelling for
forecasting purposes
 The need for modular and scalable real-
time forecasting, warning and operational
control tools networks and floodplains
 Advanced one-, two- and three-
dimensional sediment transport and
morphology models for rivers, floodplains,
estuaries and coastlines
The future for the flooding sector is online and
in real-time. It’s our belief that the required
solutions can be more than just flood
modelling - they are beyond flood modelling.
DHI DELEGATE PACK - ICE FLOODING 2015 PHOTO: ISTOCK © ON-AIR
BEYOND FLOOD MODELLING
Application of DHI Technologies to develop integrated solutions to flooding and its
wider impacts

2. ©DHI
2
LOCAL AREA WEATHER RADAR INTEGRATION
Climate change can be expected to affect prevailing patterns of
precipitation with extreme rain events becoming more frequent
and more intense. This will increase the pressure on water
infrastructure. Warning and forecasting systems provide
necessary tools for authorities and operators to plan ahead and
make the informed decisions. However, the greatest uncertainty
when modelling the response of drainage systems to rainfall is the
rainfall itself.
The standard approach is to use rainfall measured by one gauge
but traditional rain gauges provide data with low temporal and
spatial resolution. When using rain gauges, it must be assumed
that the rainfall is homogenous over the whole model area, which
may be as large as a whole city. For the prediction of potential
surface water flooding as a result of extreme rain events, this
assumption is not valid.
Weather radars, in contrast to rain gauges, provide high resolution
data over a relatively large area, the equivalent of many synthetic
rain gauges in one installation.
DHI has developed a cost effective and efficient Local Area
Weather Radar (LAWR) to provide high resolution rainfall data.
The system can detect the first raindrop falling and track the
precipitation as it evolves. This provides accurate rainfall data with
high spatial resolution, which is suitable for input to flood warning
and forecast models.
ONLINE, WEB-BASED FORECASTING AND WARNING
TOOLS WITH COMPUTER AIDED REAL-TIME CONTROL
MIKE URBAN can be fully integrated within our MIKE
CUSTOMISED platform - a unique software platform for building
IT systems for decision support and information management - in
order to deliver real time functioning capabilities and on-line
modelling of smart water networks.
DHI DELEGATE PACK - ICE FLOODING 2015
LAWR ADVANTAGES AND INTEGRATION
 Distributed rainfall measurements in a spatial resolution
ranging from 500x500 m to 100x100 m with a 5 minute or 1
minute time resolution up to 20 km from the radar
 Online animation of rainfall within the complete LAWR range
 Up to a few hours' forecast (online) of coming rain events for
use in optimisation of flood response, sewer and treatment
plant operation
 Fully integrated with the MIKE software which facilitates the
import of LAWR data, visualisation of the event over the
model and its catchments and simulation with distributed
rainfall
The image above shows a rain event imported into MIKE URBAN. It
illustrates a classical problem - only part of the drainage system is
receiving rain. If a user wants to analyse such an event based on a
single gauge several kilometres away it would yield a very poor result.
CASE STUDY: DHI BATHING WATER FORECAST SERVICE
Aarhus is Denmark’s second largest city, with 310,00 inhabitants.
The Aarhus project was a forward-looking one and was a co-
operation between Aarhus Municipality and Aarhus Water.
The project was driven by rapid city development and the need to
integrate water into the urban space. The aim was to improve
local riverine and harbour
bathing waters to hygienic
levels and provide ancilliary
benefits (for example, river
restoration, mitigation of
flooding risk, climate change
adaptation, etc). The project
comprised:
 The analysis and forecast
of water quality in the harbour, and the optimisation of
capacity of the drainage system and the wastewater
treatment plants
 A 50 million EUR investment in infrastructure (consisting of
retention basins, disinfection at WWTP and basin and
increased hydraulic capacity at WWTP)
 An optimised, Radar-based control system (consisting of
integrated real time modelling/control of sewer system and
WWTP, and an early warning system).
The project successfully delivered
hygienic bathing water in Lake
Braband and in the harbour and
improved water quality in the River
Aarhus. The bathing water forecast
service provides the public with
information on bathing water quality via
an App and a web-based public
warning system.
ABOUT DHI
DHI are the first people you should call when you have a challenge
to solve in a water environment. Whether it is a river, a reservoir, an
ocean, a coastline, within a city or a factory. Our world is water, and
our knowledge of water environments is second-to-none. It
represents 50 years of dedicated research, and real-life experience
from more than 140 countries.
We strive to make this knowledge globally accessible to clients and
partners by channelling it through our local teams and unique
software. So whether you need to save water, share it fairly,
improve its quality, quantify its impact or manage its flow, we can
help. Our knowledge, combined with our team’s expertise and the
power of our technology, hold the key to unlocking the right solution
DHI Water Environments (UK) Ltd
OVIC, Ocean Way
Southampton, SO14 3JZ
United Kingdom
+44 (0)2380 381961
mikebydhi.uk@dhigroup.com
www.mikebydhi.com