Water quality and climate change

Dr Glenn Watts

Evidence Directorate

19 March 2011

Structure

Drivers of change in water quality

Possible impacts

Modelling - scale and thresholds

Implications for adaptation

Drivers – temperature

2080s medium emissionsSource UKCP09

Rainfall

2080s, medium emissionsSource UKCP09

Winter flows

2050s medium emissions, long term average changes

Source CEH – Environment Agency “future flows”

Summer flows

2050s medium emissions, long term average changes

Source CEH – Environment Agency “future flows”

Possible impacts of climate change on water quality

Mobility and dilution of contaminants

Chemical reaction rates

Sediment mobilisation, transport and deposition

Impacts in Wales

Urban dischargesFlashy riversReduced dilution

AgricultureNutrient leaching

UplandsDissolved organic carbon and colourSediment loads and depositionAcidification – from intense rainfall and droughts

LakesTemperature and eutrophication

Mine waste mobilisation

Modelling questions: scale

field

reach catchment

Modelling questions:thresholds

Do current approaches cope with changes of state?

Empirical and conceptual models

State change

threshold

input

response

Climate change adaptation

Uncertainty cascade

Climate model

Hydrological model

Chemical model

Ecosystem model

Approaches to adaptation

Best estimate plus uncertainty

Scenario planning – exploring risk tolerances

Probabilistic approaches

Climate sensitivity

Why examine the impact of climate change on water quality?

To inform effective adaptationUnderstand possible impacts

Evaluate different management responses

Improve approaches to regulation

A strategy for adaptation

Willows and Connell 2002

Further research

Processes and responses

Thresholds and climate sensitivity

Links from field to catchment scale

Possible adaptation measures

Catchment scale management measures

Summary & conclusions

Climate change affects flow and thermal regimes

Water quality response complex

Questions: field scale to catchment scale

thresholds and climate sensitivity

Do we understand adaptation measures?