River Flooding and Management

How do systems ideas help us to understand physical processes that operate in a river

basin?

The study of water systems in the atmosphere and river basins.

The units and links in the hydrological cycle.

The hydrological cycle.

The storm hydrograph and how it responds to changes.

The river basin as a local system.

The river basin as a system of inputs, flows, stores and outputs.

(b) How does river flooding illustrate the interaction between natural processes and human

activity?

The different causes of river flooding.

Physical causes of river flooding.

The activities of people that can cause river flooding.

The effects of river flooding

Some strategies for flood management are more sustainable than others

Key Terms Definitions

Key Term Definition

Evaporation

Condensation

Infiltration

Percolation

Throughflow

Groundwater flow

Surface Runoff

Groundwater store

Interception

Transpiration

Saturated

Permeable

Impermeable

Precipitation

Soil

Rock

The Hydrological Cycle

Key Term Definition

Drainage Basin

Watershed

Confluence

Tributary

Source

Mouth

What would happen if….

1. There was a lot of intense rainfall in the basin?

2. There was only a little rainfall in the basin?

3. The whole area had been deforested?

4. The basin was contained a lot of impermeable surfaces?

Peer Assessment

Circle all the connectives – CATTs

Highlight in one colour inputs

Highlight in another colour processes

Highlight in another colour the stores

Highlight in another colour the outputs

Describe the route water may take when falling in a drainage

basin, using inputs, stores and processes.

(5 marks)

A rivers response to a rainfall event

Hydrographs

Match the terms

Key Term Definition

Discharge

When the discharge in the

river begins to increase.

Peak Rainfall

The time between Peak

Rainfall and Peak Discharge

Peak Discharge

When Discharge in the river

begins to fall again

Rising Limb

The amount of water

passing a given point at a

given time

Falling Limb

The highest amount of

rainfall

Lag Time

The point at which water is

at its highest

Flash response – water gets to

the river quickly

Lag response – water gets to the

river quickly

Flooding

How might the following factors lead to flooding?

Physical Factors How does the factor lead to flooding?

Intense Rainfall

Thin Soil

Impermeable Geology

Steep Valleys

Confluence of a river

Human factors Deforestation

Urban areas

Climate change

Managing Flood Risk in the UK

Carlisle Case Study, Cumbria

The Carlisle Floods of January 2005

Carlisle is situated on the flood plain of the River Eden with three rivers meeting in the city. The catchment

covers approximately 2400km2 and is home to approximately 244,000 people. The catchment is mainly

rural, with only 1% classified as urban: the main urban areas are Carlisle, Penrith and Appleby.

Carlisle has a history of flooding with flood events recorded as far back as the 1700s. In recent years there

have been significant floods in 1963, 1968, 1979, 1980, 1984, and recently in 2005.

Across the catchment, the January 2005 flooding affected 2,700 homes. In Carlisle three people died, 1,844

properties were flooded and there was significant disruption to residents, businesses and visitors. The cost of

the flooding was estimated at over £400 million. The flooding followed prolonged heavy rain, and was

caused by a combination of floodwater from the Rivers Eden, Pettereril and Caldew and localised flooding

from sewers and road drainage.

As a result of this flooding, the Environment Agency has prepared a flood management plan.

The catchment of the River Eden is in Cumbria, rising in the hills of the Lake District. It reaches the sea at

the Solway Firth. The catchment is made up of the Rivers Eden, Eamont, Irthing, Petteril and the Caldew, as

well as smaller rivers and streams draining into the Eden estuary.

<img

src="/image/page/GA_FloodingCarlisleDrainageBasin.jpg" alt="Drainage basin of the River Eden" />

The catchment has a history of flooding with Carlisle, Penrith and Appleby at greatest risk. The flood risks

to people and property within the Eden catchment are from:

Limited capacity at the Thacka beck culvert, which causes flood risk to Penrith The River Eden, which affects several urban areas including Carlisle, Kirkby Stephen, Appleby and Lower

Crosby The Rivers Caldew and Petteril, which affect Carlisle Flooding from the River Eamont at Eamont Bridge

Topography

The upper parts of the catchment are dominated by the mountains of Skiddaw and the surrounding fells. The

rocks here are hard and volcanic, soils are thin and the gradients of many tributaries are steep, so these

watercourses have a rapid run-off response to flooding. In the lower reaches rivers flow through wide,

shallow valleys.

The Eden channel itself has a steep gradient upstream of Kirkby Stephen. The head of the catchment is

around 690m, falling rapidly to 160m at Kirkby Stephen. Below Kirkby Stephen, the Eden's glaciated valley

opens out and the channel gradient reflects this change: the River Eden steadily loses height at around 1.8m

per km to Appleby at 123m some 21km downstream.

From Appleby, the Eden continues through the lowland valley to Carlisle, 9m, falling at a fairly constant

rate of 1.4m per km over its 80km journey from Appleby. The valley floor is over 2.5 km wide in many

places. This forms extensive areas of floodplain washlands which are an important feature of the catchment.

Hydrology

In the Eden catchment there is a significant contrast in mean annual rainfall between the upstream and

downstream ends of the catchment, related to the topography of the catchment.

In the upland tributaries upstream of Penrith in the Eamont catchment, average annual rainfall exceeds 2800mm on Helvellyn

Around Carlisle and on the coastal fringe, this is reduced to about 760mm

The average annual rainfall for England and Wales is 920mm

Read and Highlight the main causes of the flooding in Carlisle in the article

above

To what extent were Physical factors responsible for the Carlisle flooding?

Describe the pattern of rainfall and discharge for the River Eden in January 2005

What were the impacts of the flooding?

Annotate the photograph and the OS map to show the human features affected by the

flooding

Flood Management

Strategies

How does it prevent

flooding?

Advantages

Disadvantages

Soft Engineering

Monitoring of the river

level

Soft engineering

Land Use Zoning

Soft Engineering

Afforestation

Hard Engineering

Widening and Deepening

and Straightening the

River

Hard Engineering

Building a Dam upstream

Hard Engineering

Building Embankments

STAKEHOLDERS:

- Home Owners - Local businesses - Local Council - National Government - Emergency Services - Insurance Companies - Flood Defence Engineers - Flood Management Researchers - Tax Payers - Car Owners - Environmentalist - Meteorologists - Local residents

Explain why different stakeholders have different views on how to manage river flooding?

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Colour code the stakeholders who would be

for or against building flood management

strategies

The Decision: Flood Management Strategies for Carlisle

Option 1: Monitoring the river level and providing a warning system for local people

Option 2: Floodplain Zoning – the local authorities dividing up the floodplain into different land uses and

enforcing these by law

Option 3: Hard Engineering at a local level, straightening and enlarging the river channel and also building

flood defences such as levees

Option 4 : Hard Engineering at drainage basin level, building Dams and Reservoirs in the Upper course of

the river.

a) Chose one of the above options, and explain why you think it is the most sustainable,

b) Suggest possible disadvantages of your chosen option

c) Select one of your rejected options and state why this methos is not as sustainable as your option

d) Explain why one flood management method alone is unlikely to solve the issue of flooding in

Carlisle

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DME - Geography

Level 1 (1-4 Marks) Level 2 (5-8 Marks) Level 3 (9-12 Marks) Level 4 (13-16 Marks)

Gives one or two reasons for choice. develops one reason for choice ( using

PEE)

developed explanation of choice Thorough development ( using PEE)

in reasons for choice and rejection

explains one reason with detail give reasons why the other choice was

rejected

explanation of why the chosen

option is more sustainable than

the other option

explanation of why the chosen

option is more sustainable than the

other option using S.E.E

basic development of choice and

reasons for rejecting the other option

attempts to discuss sustainability explanation of why one method

alone will not solve the problem of

flooding

Developed explanation of why one

method alone will not solve the

problem of flooding

written work contains some mistakes

in grammar and spelling

mostly accurate spelling and grammar

spelling grammar and punctuation

are accurate

Good use of geographical

terminology. Very accurate and

precise written language, spelling

and grammar

Overall Mark:

:

What went well:

Even better if:

What they actually did in Carlisle on the River Eden