From Evidence to Action: Whole-catchment approaches to linking flood risk management and WFD measures

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1 From Evidence to Action: Whole-catchment approaches to linking flood risk management and WFD measures Nick Hardiman Royal Society for the Protection of Birds A wealth of research has been devoted to the importance of lateral connectivity of rivers and floodplains for biodiversity particularly for the specific quality indicators for the WFD, such as fish and invertebrates. But what part do measures beyond the floodplain take in delivering WFD objectives, and just how much crossover is there between these measures and techniques to manage flood risk, or diffuse pollution in the wider environment? Identifying such synergies could have important legal implications for meeting a number of other water-related EU Directives, and could also be far more cost-effective in the long term. This paper aims to explore 1) the key techniques that are being used to promote these multiple benefits, 2) the limitations to optimising these benefits simultaneously, and 3) the barriers to transforming evidence for where they do work into wider action on the ground as common practice. The paper focuses upon the UK context, but with underlying principles taken from the background paper (particularly 8, 9, and 10) for this symposium that are relevant for most EU states. Although the WFD does not contain specific flood risk management prescriptions, morphological damage for flood risk management is one of the most widespread pressures on water bodies in England. Approximately 36,000 km of rivers are maintained for fluvial flood defence and 1.2 million hectares of land are managed by drainage authorities; combined, this dominance of traditional approaches to managing flood risk has led to an estimated 85% of lowland rivers in England being physically altered, removing both lateral and longitudinal connectivity for fish, invertebrates and macrophytes. Beyond the watercourses themselves, wetlands that significantly influence the hydrology, water quality and ecology of surface water bodies, such as blanket bogs, have themselves been altered or damaged to the extent that flow regimes and sediment dynamics in WFD Water Bodies are affected. New approaches to flood risk management involve making space for water throughout catchments, and attempting to work more with natural processes to slow the movement of run-off or floodplain conveyance. The WFD similarly requires restoration of river and coastal hydro-morphology adversely impacted by flood management and land drainage schemes, unless these impacts can be justified through derogation. Derogations include stringent tests of technical feasibility, disproportionate cost and better environmental options so if a technique is to be 1

2 used for both WFD delivery and flood risk management, it will have to satisfy the tests of costeffectiveness for each simultaneously the evidence below suggests this could be difficult to achieve in some cases. The key techniques where synergies have been explored are: 1) The restoration of upland soil hydrology, particularly in blanket bog through the blocking of drainage channels used to enable forestry and more intensive sheep grazing. This removes preferential pathways for the transferral of water downslope to water bodies, regulating the hydrograph and having some effects on local flooding that may propagate downstream. It may also restore important habitats and Natura 2000 sites, maintain the carbon storage function of peatlands by avoiding the drying and oxidising of peat, and thereby also reduce dissolved organic carbon inputs to important drinking water sources. The RSPB partnership project with the water company United Utilities in Lancashire is an example of this, but our experience has shown that the effects on flood management, dissolved organic carbon release and carbon storage are far from straightforward, even if the WFD benefits are more clear. The effect of upland restoration is likely to be highly site specific. 2) Farm management techniques, such as planting woodland to intercept rainfall, farm wetlands as temporary balancing and storage ponds to trap run-off, and conservation tillage. Again, managing sediment delivery is a key WFD benefit, but diffuse nutrient pollution can also be reduced through the use of buffer strips of grass or woodland, which enhance soil infiltration rates. The RSPB Hope Farm initiative aims to incorporate some of these measures whilst running at a similar profit to surrounding farms, to demonstrate effectiveness of small measures for nature conservation. However, modelling at other demonstration farms has suggested that, in order to achieve any substantial flood management benefit at a catchment scale, the area under woodland or storage pond would have to be so high as to be economically unfeasible for each individual farmer. Nevertheless, there are likely to be some synergies where agri-environment schemes can be harnessed and targeted effectively. Reducing the efficiency of arterial drainage is, however, likely to yield some significant flood risk management benefits downstream; studies have shown a combination of field and arterial drainage for agriculture can increase downstream flood peaks by 60 % in some areas, despite protecting individual parcels of land. 3) River and floodplain restoration, whereby natural processes are entirely restored, is likely to provide the greatest direct contribution to WFD goals, because of the high degree of dependency that quality indicators such as fish and invertebrates have upon dynamic floodplain features and habitat heterogeneity for their life cycles, refugia, feeding, shelter an so on. However, the impact of restoring connectivity upon the potential spread of invasive species must also 2

3 be considered, and other vulnerable biodiversity may be detrimentally affected by exposure to catastrophic flood events as natural processes are restored. This could become relevant for the Ecological Status of a water body if it incorporates a Protected Area (e.g. Natura 2000 site) designated for the biodiversity exposed to that risk. However, there is significant potential to achieve synergies with flood risk management through floodplain restoration if undertaken at sufficient scales, both through dynamic attenuation function and through increased storage capacity. These benefits will be less predictable than under the more controlled conditions of a washland, however, and the ability to manage diffuse water pollution may also be less effective if sediment-bound pollutants are flushed back into the riparian system by a large flood event. 4) Sustainable Urban Drainage and riparian management, to deliver the WFD requirements to control diffuse urban water pollution. The restoration of the River Quaggy in London is often heralded as an example of how biodiversity, water quality and public amenity benefits may be combined - yet it remains an exception. What hinders wider application of these synergistic measures? Currently, the stalling point in the UK is that there is not enough scientific evidence that both WFD and the flood risk management benefits can be maximised simultaneously at a catchment scale. Often, measures need to be highly targeted spatially or temporally to ensure benefits are maximised, and the parameters may differ between targeting to address diffuse pollution and flood management. Traditional operational approaches dominate the mindset, scheme appraisal systems and funding streams of the Environment Agency the Competent Authority for WFD delivery and the lead flood risk management body. However, with new legislation in the pipeline and a renewed campaign to manage the water environment sustainably into the future after serious flood events in 2007, the Environment Agency and other statutory and non-governmental organisations are at last beginning to understand the need to learn by doing. 3

4 PowerPoint From Evidence to Action: Whole Catchment Approaches to linking flood risk management and WFD Measures Nick Hardiman, Water Policy, RSPB HQ WFD and flood risk management: Buy one, get one free? WFD has no specific flood risk management prescriptions, but Floods Directive should dovetail with its implementation Morphological damage is one of the most widespread pressures on water bodies in England & Wales often due to flood defence and drainage. Measures in the wider catchment are likely to be critical to successful WFD delivery WFD requires modifications causing adverse impacts on Water Bodies to be removed, unless they can be justified through derogation Can we reduce flood risk and improve the water environment to meet WFD objectives simultaneously? 4

5 Making Space for Water and the Programme of Measures Restoring upland hydrology on blanket bog Rural land management in the lowlands Restoring the natural dynamics of rivers and floodplains Sustainable urban drainage Managed re-alignment of the coast Upland restoration Drainage dries peat, leading to oxidation and CO 2 / DOC release Restoration could reduce water colouration and improve upland BAP priority habitats RSPB-United Utilities SCaMP project, Lancashire: blocking drainage channels, grazing management, tree planting Project designed primarily for nature conservation will the flood risk benefits follow? 5

6 Upland restoration Flood risk management benefits Raising water levels can reduce storage but: Blocking ditches removes preferential flow paths Coarse vegetation further slows run-off by up to 100 times Highly dependent upon effective targeting Lane et al, University of Leeds, 2003 Upland restoration Towards Good Ecological Status Water quality objectives: Article protect water bodies at source to avoid deterioration - reduce pressure on drinking water purification Environmental objectives: Article 4.1 and Annex V - sedimentation affects hydromorphology of upland streams - spawning fish and invertebrates would benefit from reduced sediment input - benefits for water-dependent Protected Areas (Natura 2000) in the uplands 6

7 Rural land management Modern farming has led to increased soil erosion, panning and, in some areas, downstream muddy flooding Conservation tillage and restoring woodland & wetland features as nutrient buffers could help farmland biodiversity, and improve soil & water quality. RSPB Hope Farm (Cambrideshire), Nafferton Farm (Northumberland) integrating business, wildlife and pollution control Flood risk management benefits are being modelled Rural land management Flood risk management benefits 1 on-farm wetlands Discharge reduction and time to peak dependent upon optimal siting of farm wetlands Scale-dependent T Q Quinn et al,

8 Rural land management Flood risk management benefits 2 soil water & drainage Catchment woodland can intercept precipitation and enhance soil infiltration/storage capacity, if sufficient cover is achieved Woodland Trust, 2008 Soil water retention capacity needs to be increased markedly to achieve measurable impact on peak flows Defra, 2004 Arterial drainage can increase flood values by up to 60% in some areas; protecting parcels of agricultural land may increase downstream flood risk Bailey & Bree, 1981 Rural land use Towards Good Ecological Status Environmental objectives: Article 4/1 and Article 7 - diffuse pollution one of key pressures impacting ecological health of Water Bodies - silt deposition a major cause of morphological degradation in rivers & lakes - Protected Areas directly impacted both by diffuse pollution and drainage - Drinking Water Protection Zones Diffuse pollution measures: Article 11(e) - Member states required to take action to tackle diffuse pollution - Reducing run-off is key in reducing sediment, phosphate and pathogen loads 8

9 River and floodplain restoration River and floodplain restoration has a major part to play in achieving WFD objectives Flood management benefits depend on complex interplay between water storage and dynamic attenuation function of channel morphology and floodplain vegetation River and floodplain restoration Flood risk management benefits Example of wet woodland in river buffer strips: - reduced time to peak by 26 mins - backwater effect m 3-400m upstream - could be more significant at catchment scale Forestry Research, 2004, River Cary River Devon catchment project WWF,

10 River Restoration Towards Good Ecological Status Article 4: Ecological objectives - Fish use floodplains for refuge, feeding and breeding - Invertebrate and plant abundance and diversity increases with floodplain connectivity Peacock, RSPB, 2003 Article 4.1 (a)(iii): HMWBs - Not all washlands are ecologically beneficial, - Strict tests apply to HMWB designation - Building in multiple benefits at the design stage most effective way to reach Good Ecological Potential Urban areas An example from London River Quaggy restoration project: Channelised and straightened for flood defence in 1970s No access, impoverished flora and fauna. River restoration Centre re-naturalisation of 0.5km of floodplain as part of wider catchment flood management plan Sinuous channel, native wetland flora reestablished from local sources Geomorphological dynamics and ecological regeneration began within one year 10

11 Sustainable Drainage Systems Flood risk management benefits SUDS can mimic nature, storing water where it falls rather than flushing it out to nearest water body Systems can be designed to fail safe, with residents have clear signs of rising water levels as opposed catastrophic failure Reconnect communities to water cycle and flooding Urban areas Towards Good Ecological Status Article 4 Ecological Objectives - Urban runoff poses significant threat to status of urban water bodies. - Deliberate dumping of waste and runoff from roads, pavements and gardens can deliver cocktail of pollution to rivers. Article 11(e) Measures to tackle Diffuse pollution - Permeable paving, vegetated swales, ponds & wetlands can trap & breakdown pollutants - Accidental spillages easy to spot before they enter a water body 11

12 Conclusions (1): WFD and flood risk management synergies River and floodplain restoration strategies should be regarded in the wider context of environmental objectives and ecosystem services which may be efficiently achieved through a meaningful and strategic adjustment and combination of measures under different directives and land management programmes TRUE, BUT... Regardless of their primary driver, measures are likely to require correct spatial targeting to be effective. Sometimes, the spatial targeting required for different outcomes will not be the same. The WFD and flood risk management benefits of a project will usually be highly site-specific, and there may be perverse outcomes (e.g. invasive species) Conclusions (2): WFD and flood risk management synergies A favourable outcome for WFD biodiversity indicators does not necessarily mean a benefit for wider nature conservation objectives for a site Synergies tend to be optimised at greater spatial scales All benefits (WFD, flood risk management, water quality, climate change etc) need to be understood in the long-term context, as short term effects of measures may be quite different. 12

13 Conclusions (3): From evidence to action The synergistic environmental effects of river and floodplain restoration are far from being fully exploited and multiple environmental effects are still neglected The presence of synergies presents a challenge in itself; when does a project stop being flood risk management and start being WFD or biodiversity-funded? Funding is often tied to specific issues, in specific departments. Sustainable flood risk management is not yet a statutory duty of the Environment Agency the competent authority for WFD delivery, and for flood defence. Change will not be easy; how do we get landowners to accept changes in their land use and how do we make sure statutory bodies deliver? BEWARE of drawing general conclusions as to what is possible from specific successes or failures. Thank you Nick Hardiman Water Policy RSPB Countryside Conservation The Lodge Bedfordshire UK 13