concepts and science for coastal erosion management coastal state indicators for coastal erosion...

Concepts and Science for Coastal Erosion Management

Coastal State Indicators for Coastal Erosion

James Sutherland

HR Wallingford



• Indicators used in many fields to assess progress in implementing policy

• Coastal State Indicators are a “reduced set of parameters that can simply, adequately and quantitatively describe the dynamic-state and evolutionary trends of a coastal system.” – Jiménez and van Koningsveld, 2002



Coastal State Indicators (CSIs) should be:

• Relevant

• Measurable

• Responsive to disturbance in known way

• Anticipatory

• Integrative– Combining data and knowledge of processes to

assist in implementing a policy



Functions of Coastal State Indicators:

• Assess condition of environment

• Compare across situations

• Monitor trends

• Diagnose problems

• Anticipate need for intervention



Coastal State Indicators at Pilot Sites


Coastal State Indicators for Coastal Erosion CSIs used to implement policy


Coastal State Indicators for Coastal ErosionSite Strategic Objective Tactical Objective

Holland coast Safety, sustainable values and functions

Dune strength

Hold the line

Adapt to SLR

Hel Peninsula Preserve peninsula Maintain beach width

Danube Delta Sustainable development Reduce erosion

Costa Brava Carrying capacity, safety of infrastructure

Maintain beach configuration

Inch Sustainable tourism Prevent damage

Pevensey Bay Sustainable risk mgmt Hold the line



• Policies have implicit physical characteristics

• E.g. Hold the line:– Position– Standard of protection


Coastal State Indicators

• Dune strength, Barrier width, Backshore width, Dune zone width, Dune zone height, Total barrier volume

• Testing coastline, Beach width, Barrier crest position, Shoreline position,

• Coastal foundation, Shoreface volume, Coastal slope



Prevention of breaching

• Dune strength, Barrier width, Backshore width, Dune zone width, Dune zone height, Total barrier volume



• Dune strength– Erosion during storm



Maintain position

• Testing coastline, Beach width, Barrier crest position, Shoreline position,



• Coastline position:

MCL

Momentary coastline: MCL,

Testing Coastline: TCL,

Basal Coastline, BCL

TCL is CSI (MCL is not)

BCL is threshold



• Coastal foundation, Shoreface volume, Coastal slope– Large scale and long term,– Provide boundary conditions for other CSIs,– Coastal foundation is coastal area multiplied

by rate of sea level rise,– Coastal slope is an indicator of the relative

risk of inundation and the potential rapidity of shoreline retreat.



Why do we need CSIs?

• We have data and models

• These form evidence for decision making

CSIs are appropriate



Why CSIs are appropriate:

• Direct link to policy

• Communication with policy makers and stakeholders

• Skills of coastal managers:– Not numerical modellers– Not necessarily coastal scientists/engineers

• Use of resources



• Derived from analysis of system– Understanding state of system – Given a policy to implement– Chosen a means to implement the policy– Require thresholds– Adaptive management



• Are being regularly used at three pilot sites;

• Are being developed at the other three.

• Not just data

• Integrate policy, system understanding and modelling

• Usable and communicable

concepts and science for coastal erosion management coastal state indicators for coastal erosion...

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