W11 - Flood management

Question 1

Why is important to manage ecosystem services?

Answer 1

Resources that ecosystems can provide  difficult to put a value on nature
Framework is useful to ‘monetise’ nature  helpful to put things in perspective for non-geographers

Question 2

What are some supporting ecosystem services?

Answer 2

• Habitats for animals
• Water cycling
• Soil formation
• Nutrient cycling
• Primary productivity

Question 3

What are some provisioning ecosystem services?

Answer 3

• Providing land for farming/irrigation
• Drinking water
• Hydropower
• Trade routes
• Water for industry
• Land for building on

Question 4

What are some cultural ecosystem services?

Answer 4

• Mental health benefits – blue space
• Tourism – brings money into economy
• Recreation
• Education
• Cultural history
• Sense of place

Question 5

What are some regulating ecosystem services?

Answer 5

• Nutrient cycling
• Flood control
• Water quality
• Water quantity
• Sediment supply

Question 6

What do the descriptive different colours of water mean?

Answer 6

Blue: surface and freshwater, stored in snow, stream, lake, wetland, and subsurface

Green: embedded in the evapotranspiration cycle through vegetation (natural systems, forestry, and agriculture)

Grey: polluted wastewater from urban environments that does not contain a significant faecal burden or industrial contamination (showers, laundry, and kitchen washings)

Black: wastewater in a sanitation context which is likely to contain significant pathogen burden and organic matter (toilets and latrines)

Question 7

What are the flood risk management strategies acting to reduce the probability of flooding?

Answer 7

Hard Engineering
o Maintenance of existing flood defences
o Construction of new flood defences
o Construction of flood control schemes (e.g. storage basins)

Source water management and Natural flood management
o Maximise water storage/flow attenuation capacity of the catchment (land use control – wetlands, forests and increasing infiltration on agricultural land)

Planning and enforcement
o Enforcement when activities of riparian owners are detrimental to flood risk
o Minimise new development on flood plain/high risk areas
o Sustainable urban planning

Question 8

What are the flood risk management strategies acting to reduce the consequences of flooding?

Answer 8

More complete flood risk mapping
o understanding where flooding is likely to occur
o Including pluvial (surface water) flooding

Promoting awareness of flooding
o Operating and improving flood warning systems
o Improving actions of individuals and organisations to minimise consequences
o Providing and improving flood incident management

Promoting resilience and resistance of properties already in flood plain/high risk areas
o 2.4 million properties on floodplain in England!
o Waterproof doors, airbricks etc
o Flood insurance

Question 9

What are the hydrological factors to consider for flood managers

Answer 9

meteorological factors + factors controlling water delivery to channel + channel capacity

Question 10

What are the traditional engineering approaches to flood risk reduction?

Answer 10

• Focus on fluvial flooding
• Focus on channel capacity
• Preventing the likelihood of flooding (e.g. over-banking).

Hard engineering approach to water and channel management
o Focus on flooding at problem locations – doesn’t tackle issue of flooding at source
o Embankments – disturbs and churns the environment
o Flood relief channels
o Move water through the system faster.

Question 11

Infrastructure to redirect/store flow:

Answer 11

New Danube, Vienna (Bruce, 2019; Hurby, 2021)
Designed to 1-in-10,000 year event
* Success story in terms of hard engineering approaches
* Entirely man-made channel that runs about 25km through Vienna
* The new Danube is basically cut off from the main Danube for most of the year – become part of the city
* Able to direct all of the extra water and sediment to the extra channel
* Would have been very expensive but has been built to last

Salford flood storage basin
Cost £10 million
Building a bunch of levies that allow for low quality land to be flooded – prevents water from reaching high value areas

Question 12

Infrastructure to limit flow

Answer 12

Thames Barrier
* Designed in the 1970s to withstand what they thought a 1-in-1,000 year flood was to 2030
* Cost £534 million (>£1.6 billion today)
* Operational from 1982
* Should operate to 2060-70 – their climate change and sea level rise predictions were more intense than they were
* Thames Estuary 2100 team already planning replacement
* All of the hard engineering approaches have knock on effects in other places

Question 13

Keswick hard engineering example:

Answer 13

• Glass flood defence wall
• But what if the event magnitude exceeds the 1 in 100 year event?
• Flood defences failed
• December 2015
• £2m just to save the pencil museum
• Massive £6m investment of the wall becomes useless and needs maintaining pretty fast

Question 14

Dredging to increase channel capacity?

Answer 14

• Limited evidence that dredging is that effective as a flood control
• Rivers are very good at self-regulating
• Cost ~£12 per m3 so process vary from £10,000 to > £2 million depending on scale

Question 15

Challenges to hard engineering options

Answer 15

• How do you decide which defences to prioritise?
• Increased awareness of need to manage whole catchments (spatial interactions)
• Growing appreciation that flooding systems are dynamic over time and flood risks increasing (e.g. climate change)
  o We can’t all have massive defences
• Can we really stop flooding happening?
  o Management rather than elimination?
• But what are ‘acceptable risks’ from flooding?
• How land is used
  o Loss of local land – parks dug up to make flood defences
  o Die off of marine life at the River Tees due to dredging higher upstream

Question 16

What is Soft Engineering, Working With Natural Processes (WWNP) and Natural Flood Management (NFM)

Answer 16

• Managing flood risk by protecting, restoring and emulating the natural regulating function of catchments and rivers
• Has the potential to provide environmentally sensitive approaches to minimising flood risk, to reduce flood risk in areas where hard flood defences are not feasible
  o Maybe a village too small etc.
• increase the lifespan of existing flood defences.
• Working with nature to reduce flood risk

Question 17

What are the Environment Agency 2018 ‘Working with Natural Processes’ report Categories of NFM Intervention?

Answer 17

• River and floodplain management
• Woodland management
• Run-off management
• Coast and estuarine management

Question 18

The basis for NFM

Answer 18

• Human activities have altered the hydrological function of most river basins to reduce natural attenuation of flood waves
• It is possible to restore the basin to a more naturally functioning hydrological system
• There are also natural kinds of infrastructure (e.g. woody debris dams, bunds) that can be used as an alternative to hard engineering solutions
  (Lane, 2017)

Question 19

What are NFM Interventions trying to achieve? (Lane 2017)

Answer 19

• Been around for around 10-15 years
• Said that it worked  people began to make their own defences
• Hydrograph attenuation
  o Increase upstream storage during extreme events
  o Manipulation of hillslopes to reduce rapid runoff
  o Increase attenuation within channels and the drainage network

Question 20

Types of river and floodplain management:

Answer 20

River restoration: reinstatement of natural processes and features in a river
Floodplain restoration: Restoration of the hydrological connection between rivers and floodplains
Leaky/woody barriers: pieces of wood installed in channel, river corridor or floodplain to manage water
Offline storage areas: areas of floodplain adapted to retain water in a managed way

Question 21

Types of river restoration:

Answer 21

Embankment removal
Re-meandering
Deculverting

Question 22

Types of floodplain restoration:

Answer 22

Beaver reintroduction
Offline storage
Improving floodplain connectivity

Question 23

purpose of Leaky/woody barriers

Answer 23

slows the flow, sediment traps

Question 24

types of runoff management

Answer 24

Soil and land: soil aeration, arable systems, grassland systems, hedges and buffer strips
Headwater drainage: hedgewater management, peatland restoration
Runoff pathway: ponds, swales, sediment traps

Question 25

types of headwater drainage:

Answer 25

Farming community engagement Blanket bog restoration Blocking drainage ditches

Question 26

types of runoff pathways:

Answer 26

Leaky barriers on hillslopes runoff storage ponds Bit off offline storage Increases carrying capacity

Question 27

Types of woodland management:

Answer 27

Catchment woodland: total area of all woodland within a catchment Cross-slope woodland: smaller belts of woodland across hill slopes Floodplain woodland: land within the fluvial floodplain, subject to regular flooding Riparian woodland: land adjoining a river channel, usually narrow e.g. <5m on either side

Question 28

Purpose of woodland management:

Answer 28

Reduce generation and conveyance of flood flows by the water use by trees Increased soil infiltration beneath woodland Increased hydraulic roughness exerted by woodland Reduce soil erosion and sediment delivery

Question 29

Does NFM work? +ves/-ves

Answer 29

* Excellent on the different approaches tried, and the different types of interventions * Lots of case studies * Uses a very useful ‘what we know/don’t know’ framework BUT * Dominated by small scale studies * Place specific * Scientific evidence of variable quality * Highlighted more knowledge gaps than were filled in * Focussed on loads of small studies that might not be applicable to other areas – how to scale up

Question 30

What is the scientific evidence base for NFM?

Answer 30

Dadson et al. (2017) * NFM can work in small catchments (<20km2) * Not yet demonstrated for large catchments * NFM can be effective for smaller floods * Contribution of NFM to extreme (large) events is uncertain * But implication that many small interventions could combine to produce large benefits * There are some key challenges to demonstrating success of NFM * There are so many different confounding factors that it’s hard to see differences

Question 31

Difficulties in evidencing NFM at large scales

Answer 31

Scaling up is difficult because: o It is hard to experimentally manipulate large catchments o Lots of confounding variables/changes Most studies sample before-after, so influenced by synoptic meteorology Short duration of many studies precludes capture of large events Many studies use modelling approaches to upscale o Models are uncertain, particularly for large catchments o Models are not always persuasive to public/policymakers o We don’t have enough empirical data on all the processes (i.e. exactly how debris dams slow the flow) Upper Severn and Avon Catchment * All models are wrong (but some are useful

Question 32

Will restoration reduce flood peaks

Answer 32

Increased water store within storms (water tables and soil water storage; increased surface storage) – Holding water back on the hillslope and/or Slowing delivery of water by reducing overland flow and channel water velocity (surface and channel roughness) – vegetation and barriers reduce flow velocity Shuttleworth et al., 2019

Question 33

How do you know if any hydrograph change is not just because of synoptic variation (i.e. you had a particularly dry period after the intervention)?

Answer 33

Measure before and after and control

Question 34

What are low flows?

Answer 34

* Flow of water in a stream during prolonged dry weather * Seasonal * Natural component of the flow regime in any river or stream * Use flow duration stats to define o e.g. 7Q10 - lowest 7-day average flow that occurs on average once every 10 years * Predictable

Question 35

What is a drought (river)?

Answer 35

* More than low stream flows * Water availability for various designated uses * Defined as reduction in surface water storage, decrease of stream flow discharge and lowering of groundwater levels over large areas, over one or more consecutive years * Difficult to predict

Question 36

What are the water quality issues in catchment systems

Answer 36

* Organic pollution * Sewage * Agricultural runoff – nutrient pollution (N and P) * Heavy metal concentration * Sediment + contaminated sediments * Emerging pollutants o Volatile organic compounds o Microplastics

Question 37

Why are there Increasing episodes of sewage release?

Answer 37

* Increasing populations * Increased urbanisation and impermeable cover, therefore higher urban discharges * Climate change, increased storm intensity and increased urban runoff o Sewage systems made in the 19th century – can’t handle the amount of runoff and sewage * The ‘discharge consent’ system allows disposal of liquid waste by companies * Combined sewage and runoff systems

Question 38

What is the EU Water Framework Directive?

Answer 38

* “Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for community action on the field of water policy” * Requires that all inland and coastal waters within defined river basin districts must reach at least “good status” (originally by 2015 or 2027) * Defines how this should be achieved through the establishment of environmental objectives and ecological targets for surface waters * Adopted into UK law in 2003 * Thinking about water quality on a catchment scale  before this catchments weren’t thought of as units

Question 39

Key features of the WFD 1

Answer 39

* Establishes river basin districts (RBD) as the basic management units * For each RBD a river basin management plan (RBMP) must be developed by the ‘competent authority’ (e.g. the Environment Agency in UK) * Each RBMP must include a programme of measures for achieving water quality protection and improvement * Defining water quality and measures to improve it * Prime aims are environmental, but RBMPs also need to consider economic and social needs * An integrated approach * Requires systematic assessment of water quality status of all water bodies * Requires extensive monitoring programmes * RBMPs aim to o Prevent further deterioration of water quality o Achieve good status for all water bodies

Question 40

But just what is ‘good status’?

Answer 40

* Status level = combo of ‘chemical status’ and good ‘ecological status’ * Importance of High (near natural) status as a reference * Good status only ‘slight change’ from natural conditions --> what is a 'slight change'?

Question 41

How might we establish high status (natural conditions) reference conditions for our water bodies?

Answer 41

Lake Windermere has high concentrations of phosphorus, causing eutrophication (see Maberly, 2009) Paleolimnology o Can see what was living and died in the lakes o Diatoms – single celled organisms that are sensitive to water quality o Cumming (1999)

Question 42

Steps of the EU WFD

Answer 42

1. Define ‘high/good status’ 2. Characterise (in detail) river basin districts, including environmental impacts of human activity 3. Assess present water quality conditions 4. Identify water quality management issues and pollution control measures 5. Consult with interested parties over these measures, costs and benefits 6. Implement agreed control measures 7. Monitor improvements in water quality 8. Review progress and 9. Revise water management plans

Question 43

North West River Basin Management Plan 2022 Reasons for not achieving good status

Answer 43

by business sector * Agriculture and rural land management * Water industry * Urban and transport

Question 44

Managing diffuse pollution from rural areas from EU water

Answer 44

Environment Agency/Natural England Agricultural and rural land management (farm businesses) Water industry and rural land management

Question 45

Managing diffuse pollution from rural areas from EU water --> Environment Agency/Natural England

Answer 45

* check and ensure compliance against environmental permits against requirements of a wide range of environmental legislation. * use opportunity mapping to identify and promote locations where woodland creation can achieve multiple benefits for the environment * Provide advice and training to farmers in some priority catchments through an approach such as Catchment Sensitive Farming

Question 46

Managing diffuse pollution from rural areas from EU water --> Agricultural and rural land management (farm businesses)

Answer 46

* comply with permits relating to spreading of waste to land for agricultural benefit, pig and poultry units, etc. * comply with the action programme measures within the Nitrate Pollution Prevention Regulations 2015 * voluntarily participate in Countryside Stewardship and Countryside Productivity schemes to prevent deterioration, improve water quality

Question 47

Managing diffuse pollution from rural areas from EU water --> Water industry and rural land management

Answer 47

work together in drinking water safeguard zones to reduce the need for water treatment as a result of nutrients or pesticides to meet drinking water standards.

Question 48

Aims of Catchment sensitive farming Run by Natural England

Answer 48

* Save farms money by introducing careful nutrient and pesticide planning, reduce soil loss and help farmers meet their statutory obligations such as NVZs, * Deliver environmental benefits such as reducing water pollution, cleaner drinking water, safer bathing water, healthier fisheries, thriving wildlife and lower flood risk for the whole community Workshops, tailored advice, capital grants

Question 49

How can we Reduce the need for water treatment?

Answer 49

* Buffer strips/riparian corridors * Headwater restoration

Question 50

Managing pollution from wastewater NW river basin management plan 2015 Role of Environment agency:

Answer 50

* grant and review environmental permits to the water industry, manufacturing and other sectors to protect the environment from pollutants in discharged effluent. * work with the water industry to develop a long-term strategy for sewerage to prevent deterioration of permitted discharges and minimise risks to the water environment from misconnected sewerage. * carry out a review of areas sensitive to eutrophication, in relation to the Urban Waste Water Treatment Directive (UWWTD) and make recommendations to Defra. * enforce restrictions and bans on the use of certain chemicals (with H&S inspectorate)

Question 51

Managing pollution from wastewater NW river basin management plan 2015 Role of local government:

Answer 51

* consider the impact on water quality in planning/development/management of new buildings and infrastructure.

Question 52

Managing pollution from wastewater NW river basin management plan 2015 Role of all sectors:

Answer 52

* consider the Marine Policy Statement and marine plans in decisions that affect marine and coastal environments

Question 53

Managing pollution from wastewater Work with the water industry – engineered solutions

Answer 53

* Retention storage * Can be released more slowly when the system is able to cope * High-rate clarification treatment o Sewer separation - would require changing the systems below ground

Question 54

Managing pollution from wastewater Work with the water industry – enforce policy

Answer 54

* Implementation of regulation such as discharge consents on point sources, permits and environmental damage legislation * Provision of pollution prevention advice and campaigning * Improvement of continuous and intermittent sewage effluent discharges * Policy is only as good as the current structures that are in place - Tory government slashed Environment agency funding

Question 55

Managing pollution from urban areas Sustainable Drainage Systems (SuDS)

Answer 55

Limited infiltration in urban environments → drainage networks overwhelmed SuDS use a sequence of techniques that together form a management train. To control flow velocity and pollutants May include: * source control methods (decrease the volume of water) * pre-treatment steps, such as vegetated swales or filter trenches (remove pollutants) * retention systems (delay discharge to watercourses) * infiltration systems such as infiltration trenches and soakaways * water enters the system slower – doesn’t overwhelm sewage systems

Question 56

WFD +ves

Answer 56

Many extremely positive aspects! * Integrative and catchment-based approach * Relies very heavily on key concepts and information from catchment science * Uses extensive, systematically monitored water quality data * A focus for tackling diffuse pollution * Optimises water quality management strategies for individual catchments through River Basin Management Plans  recognises that individual areas have their own management needs

Question 57

WFD -ves

Answer 57

* agreeing protocols and systems for classification o What is ‘slight’ deviation from high status? o What exactly should/can be measured? * there can be exclusions (water bodies where you don’t need to reach good status) * Constraints on realising the RBMPs and slow progress to good status * economic barriers (resourcing the plans) * political and institutional barriers * moving targets (e.g. climate change, Brexit) – things happen that are unexpected