Learning Objectives: To compare the different holistic options available for flood management. 19 December 2013 Learning Outcomes: Essential – you will know the two main flood management strategies. Stretch – you will explain a range of soft engineering strategies. Challenge – you will comment on the advantages and disadvantages of one flood management strategy. How can flood management be carried out in a holistic way?

Need more HOLISTIC approach to flood management that looks at whole catchment area/drainage basin

1.Forecast and warning What is it? In UK rivers are constantly monitored by EA (Environment Agency) Records of river discharge are held to help predict future flood events Uses river data and weather forecasts to predict flood events Automatic rain gauges are also important to use as forecasts could be unreliable (automatically sent to central computer where flood duty officer interprets information) Risk is calculated for each 100m square in the rivers catchment into 3 categories: 1 – Low = flooding chance in the year is 0.5% 2 – Moderate = flooding chance in the year is 1.3% or less (but more than 0.5%) 3 – Significant = Higher than 1.3% in the year (1 in 75 chance)

1.Forecast and warning What is it? (CONT…) Website and phone lines are available for people to call and find out their risk of flooding (Floodline and EA website floodmap) In York automatic phone warnings are issued to inhabitants in potential flooding zones and flood wardens visit homes

1.Forecast and warning Advantages Local authorities and residents have time to prepare for flood event Can be used to inform development planning

1.Forecast and warning Disadvantages Forecasts can never be 100% accurate Does little to actually stop floods, just tries to limit damage.

2. Land use management (Floodplain zoning) What is it? Records for historic flood events can help to predict extent of future flood Return periods for different magnitudes (flood recurrence intervals!) can be linked to areas on floodplain most likely to be affected so that zones of risk can be mapped out: Zone A – Prohibitive Zone = area near channel with high flood risk. Only essential waterside development allowed. Zone B – Restrictive Zone = little development allowed and what is allowed should be flood proofed eg important facilities at higher levels. Best suited to low-intensity or low-value land use eg playing fields and car parks Zone C – Warning Zone = areas further away and on higher land can be used for more diverse range of development eg residential and business. Inhabitants are made aware of flood risk though and given advice.

2. Land use management (Floodplain zoning) What is it?

2. Land use management (Floodplain zoning) Advantages Limits damage to local infrastructure Allows river to flood naturally with minimal damage Reduces cost of flood events

2. Land use management (Floodplain zoning) Disadvantages Can reduce the amount of land available for development (big issue these days with need for housing ever increasing) Can reduce value of land (bad if you owned it before flood zoning occurred!)

3. River Restoration (Naturalisation) What is it? Removing any hard engineering and restoring them to their original state. Idea is that land that is allowed to flood naturally from rainfall events will soak up much of the excess water before it reaches main channel and therefore reduce flooding. Includes: -reintroducing meanders -Controlled access for cattle eg putting in wooden rail system to prevent trampling of river bank -Planting willow hurdles and other vegetation on banks to help support them

3. River Restoration (Naturalisation) Advantages Cheaper More natural and kinder to environment More aesthetically pleasing Much more sustainable – humans should adapt to the shape of rivers.

3. River Restoration (Naturalisation) Disadvantages Much of the land that will be affected is often being used already eg as a residential area People may have to be re-located Reduces availability of land for future development

4. Wetland and river bank conservation What is it? Wetlands are valuable wildlife habitats that benefit from flooding Restoring peat bogs can help to create natural water storage that can help to prevent flooding in other areas EXAMPLE: Nene Washes -Found upstream from Peterborough -Act as overspill for R.Nene at times of high flow -EA use sluices that allow water to be released onto washes when discharge of river becomes too high

4. Wetland and river bank conservation Advantages Benefits local wildlife in addition to flood reduction Much more sustainable Can become a local tourist attraction which may benefit the economy

4. Wetland and river bank conservation Disadvantage Despite long term advantages, local people may not appreciate the short term disadvantages such as being relocated (similar issues to river restoration)

Key issue for any management decision is COST-BENEFIT ANALYSIS Eg how many people/buildings will be protected if we spend X amount. Is it worth it?

-Read the case study and make notes: Soft engineering: River Quaggy restoration scheme, UK. Use page 36 of the Philip Allan text book in order to create a detailed case study of this soft engineering scheme in south east London.

May (c) There is a need to make clear why soft engineering strategies are preferred to hard engineering or vice versa. This is the likely route so there should be reference to the advantages of soft engineering and possibly also the disadvantages of hard engineering. There will probably be some description of the relevant strategies that may be adopted. Alternatively, candidates may disagree with the statement and provide advantages of hard engineering and disadvantages of soft engineering. The final option is to perceive the complementary nature of the two approaches and discuss this aspect. Advantages of soft engineering are likely to refer to its greater sustainability, its limited interference with a natural system, the ability to improve the environment at times and to work with natural systems so that wetlands and habitats may be restored/created, the relative affordability. Disadvantages of hard engineering relate to the extent to which there is change to the natural system and questions over its sustainability – the large scale of building dams and their environmental impact, as well as economic and social costs. Similarly, channelisation means that the flood risk may be increased downstream and habitats destroyed. Advantages of hard engineering may relate to their effectiveness, especially in the short term, associated schemes for HEP, irrigation which give other advantages. Disadvantages of soft engineering relate to ineffectiveness in already built-up areas, the fact that flood warnings allow preparation but are not preventing damage from flooding. They will be seen as reducing the scale of risk rather than preventing flooding. The actual content will depend on the specific strategies considered and whether there is exclusive discussion of soft engineering strategies only. There may be reference to case studies – such as River Quaggy, London, Lincolnshire, Oxfordshire (Cherwell), Ouse, Jubilee River Channel, Carlisle, Three Gorges Dam, Colorado etc. (15 marks)

May 2011 Level 1 (Basic) 1-6 marks Identifies soft and/or hard engineering strategies. Refers to simple reasons why soft engineering is better. Some use of appropriate terminology present at the higher end. Coastal flooding response – if relevant, generic aspects. L1 Identifies strategies L1 Simple reasons given Level 2 (Clear) 7-12 marks Describes strategies and advantages and / or disadvantages of soft and / or hard engineering. Begins to discuss why soft engineering strategies are better (or an alternative option). Uses strategies to illustrate points – will illustrate one aspect only or with imbalance e.g. advantages of soft engineering may be discussed with no reference to hard engineering. Case study material may be included in a descriptive way. Appropriate geographical terminology is used. L2 Begins to discuss Level 3 (Detailed) marks Clear, purposeful discussion that seeks to put a case for/against soft engineering or is aware of the complementary nature of the strategies. Advantages and disadvantages of soft and hard engineering are discussed. Strategies are effectively used to illustrate concepts. Case studies are used to make points. Specific terminology is used throughout. L3 Purposeful discussion – puts a case