Case study:Investigating the impact of floodplain woodland on flood flows in the River Cary catchment, Somerset

From RESTORE
Jump to: navigation, search
0.00
(0 votes)


To discuss or comment on this case study, please use the discussion page.


Location: 51° 3' 32", -2° 43' 10"
Edit location
Loading map...
Left click to look around in the map, and use the wheel of your mouse to zoom in and out.


Project overview

Edit project overview
Status Complete
Project web site http://https://www.therrc.co.uk/sites/default/files/projects/28_cary.pdf
Themes Flood risk management, Habitat and biodiversity, Land use management - forestry, Monitoring, Water quality
Country England
Main contact forename Huw
Main contact surname Thomas
Main contact user ID
Contact organisation Forest Research
Contact organisation web site http://www.forestresearch.gov.uk/
Partner organisations Forestry Commission, Environment Agency
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Project picture

Project summary

Edit project overview to modify the project summary.


The project was established as a modelling study to investigate how the planting of floodplain woodland can affect flood flows. The River Cary is a major tributary of the River Parrett in Somerset (Map 1) with extensive areas suitable for floodplain woodland restoration. A 2.2km long reach was selected to simulate the impact of different woodland planting scenarios on a 1% annual exceedance probability (AEP) event. Hydraulic roughness parameters were changed in one and two-dimensional hydraulic models to represent a shift from grassland to floodplain woodland. The results suggest that there is considerable scope for using strategically placed floodplain woodland to alleviate downstream flooding. Floodplain woodland dissipates flood energy, reducing flood velocity and increasing local water depths. This can reduce downstream flood peaks but increase upstream flooding due to the backing up of floodwater. The planting of 133ha of floodplain woodland along a 2.2km reach of the River Cary was predicted to increase local flood storage by 71% and delay the flood peak travel time by 140 minutes.

Monitoring surveys and results

This case study hasn’t got any Monitoring survey and results, you can add some by editing the project overview.

Lessons learnt

This case study hasn’t got any lessons learnt, you can add some by editing the project overview.


Image gallery


ShowHideAdditionalImage.png


Catchment and subcatchment



Site

Name Cary
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started
Works started
Works completed
Project completed
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources Forestry Commission

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Flood risk management
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor establishment of woodland
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

Link Description

Supplementary Information

Edit Supplementary Information