Flooded rivers: taking a bird’s eye view
Tue, 08/15/2017

When a river swells beyond its usual patterns,
the impact on its surroundings can be devastating. In 2014, 51 people lost
their lives and over 20% of Serbia’s population were affected by floods when eight rivers spilled over their banks. Photo credit: Dusan Milenkovic /
Shutterstock.com Floodplains
are attractive areas for development, with over 2 billion people living within
the world’s 10 largest river basins
. Yet, they are
also at particular risk from overflowing rivers. Globally, river floods affect
more than 21 million people. By 2030, due to climate change, population growth,
and rapid urbanization, this number
could rise to 54 million.
How can we enjoy the benefits
these locations bring, without putting ourselves at unnecessary danger from
floods?
While it is impossible to fully eliminate flood risk, actions can be taken to
minimize the impact.
A proactive river
basin-wide approach to flood risk management may be one of the solutions.
With a ‘whole systems’ view to manage water resources and minimize flood risk,
it recognizes and balances the relationships and often competing needs of
actors and sectors in a given basin.
Bangladesh, for example, is one of the
most flood-prone countries in the world. Located downstream of over 50
transboundary rivers, it has little control over river volumes discharged into
its territory. Cooperation with countries upstream including India, Nepal and
China is hence critical to managing its flood risk.
However, this is easier said than done. River systems often span multiple
political boundaries and institutional levels, making coordination complex. In
fact, majority of the world’s 263 transboundary basins lack
a cooperative management framework.
What are some of the consequences of lacking
coordination?
Building a reservoir, diverting flows or changing land use are measures that
can impact the functioning of an entire basin. If implemented independently of
the whole system, they can simply move risk from one part of the river to
another. Uncoordinated flood risk management can thus affect the sustainability
of basin resources and increase risks posed by storms and floods.

1.
Understand
the whole river basin: Knowing how a river system functions is critical to understanding
the impacts of various interventions while balancing various interests. For
example, Vietnam is divided into 63 administrative zones that
do not coincide with river basin boundaries, with each zone responsible for the
section of river under its purview. There is a need to integrate knowledge
across the zones to make informed decisions.
2.
Assess
downstream impacts of flood management interventions. Potential
negative impacts of planned interventions must be evaluated prior to
implementation. For instance, the embankment of flood-prone areas may be a
cost-effective way to protect local communities. However, the reduced capacity
for river flood retention upstream can increase peak flows downstream,
threatening infrastructure such as bridges or roads.
3.
Integrate
flood risk management principles into river basin master plans. Flood risk
management actions need to consider the perspectives of all river basin
stakeholders and sectors such as environment, agriculture, and hydropower. For
example, along the banks of the Licungo River in Mozambique,
fertilizing floods can make the production of higher-value organic rice crops
possible.
4.
Use
technology to promote flood risk management. Advanced
technologies such as data monitoring and surveying, simulation modelling, flood
risk and hazard mapping, forecasting and emergency support, are tools that can
facilitate planning, decision making and cooperation to reduce vulnerability to
floods.
River
basin flood risk management requires dedicated balancing between different
needs and interests within a whole river system and their various interests.
Credits: World Bank