Acknowledgements
Mawddach-Wnion catchment location map
Publications related to the project

1. Introduction

1.1 Objectives of the study

Development of the Mawddach flood forecasting system
Synopsis of chapters
Flooding in the Mawddach and Wnion catchments
Hypotheses


1.2 The Study Area

Geology
Geomorphology
Soils
Vegetation
Industrial development
Summary

2. Meteorology

2.1 Meteorological Principles

Theories of midlatitude cyclone structure
Orographic effects on rainfall
Convective storms
Summary


2.2 Rainfall in the Mawddach catchment

Rainfall monitoring
Classification of rainfall patterns
The extended rainfall period of February 2004
July 2001 exceptional rainfall event
Summary


2.3 Meteorological modelling

Using atmospheric soundings
Summary


2.4 The MM5 modelling system

Configuring and running the MM5 model
Frontal rainfall events
Statistical analysis
Rainfall radar
Optimisation of MM5 models using a neural network
Structure of frontal events
Squall line convection
Summary

3. Catchment Hydrology

3.1 Hydrological modelling systems

Summary


3.2 Hillslope hydrology

Subcatchments and river reaches
River channel surveying
Hydrograph recording
Soil shallow stormflow
Watershed Modelling System
Results of model runs
Summary


3.3 Sediment movement

Sediment accumulation around Dolgellau
Approaches to sediment modelling
GSTARS sediment models for the Mawddach catchment
Summary


3.4 River and floodplain processes

Dolgellau flood modelling
Effects of floodplain forestry on water flow
Calibration of floodplain forestry models
Simulation of floodplain forestry schemes for the Wnion valley
River-groundwater interactions
Afon Wen groundwater model
Summary


3.5 Peat blanket bogs

Hydrology of blanket bogs
Blanket peat in the Mawddach catchment
Waen y Griafolen case study
Waen y Griafolen groundwater model
Summary


3.6 The Mawddach estuary

Tidal flows in the estuary
Estuary hydrological modelling
Upper basin model
Sediment modelling
Summary

4. Integrated catchment modelling

4.1 Integrated meteorological-hydrological models

Requirements for a Mawddach integrated model
Mathematical basis for the hillslope model
Summary


4.2 Developing the Mawddach hillslope model

Creating an initialisation file
Running the hillslope program
Summary


4.3 Validation of the hillslope model

Validation for runoff monitoring sites
Channel routing
Waen y Griafolen blanket bog model
Summary


4.4 Results of runs of the integrated model

Configuration for distributed processing
Frontal storms of February 2004
Convective storm of July 2001
Summary

5. Discussion

5.1 Development of a flood forecasting system

5.2 Meteorology

Meteorological modelling
Future developments in meteorological modelling


5.3 Hydrology

Hillslope runoff
River flows
Groundwater effects
Peat blanket bogs
Floodplain overbank discharge
River sediment
Tidal estuary


5.4 Catchment modelling

6. Conclusions and Recommendations

References

Appendices

A: User guide for the Hillslope Model

B: Subcatchment descriptions

C: Hydrograph site calibration

D: Output from the GSTARS sediment model

July 2001 - Mawddach and Wnion
February 2004 - Mawddach and Wnion

E: Storm Rainfall Maps
Maps for 2002
Maps for January-April 2003
Maps for May-July 2003