River valleys

Overall vulnerability

Features assessed:

• River valleys
• Broad, meandering river valleys & riverside meadows
• Reservoir valleys with woodland
• Pastoral river valleys

Special qualities:

• Beautiful views created by contrasting landscapes and dramatic geology
• An inspiring space for escape, adventure, discovery and quiet reflection
• Landscapes that tell a story of thousands of years of people, farming and industry

Feature description:

River valleys are one of the iconic landscape types of the PDNP and they differ depending on the area in which they occur.

In the uplands of the Dark and South West Peak the rivers run through steeply sided valleys while further downstream the valleys open out and include wider floodplains. The valleys within the White Peak are around a combination of permanent rivers and streams and in several locations they have associated tributaries that run dry for periods of the year. For an assessment of these rivers as habitats, see ‘Rivers and streams’ and ‘Vanishing rivers’. In the Derbyshire Peak Fringe, the river valleys are broader with wider floodplains and support marshland habitats and wet grasslands.

The main valleys of the White Peak are the Manifold, Wye and Dove. In the South West Peak, the Hamps and Dane flow, while the Derwent forms the main valley of the Dark Peak. Several other smaller rivers join these larger flows of water. In the Dark Peak there are deep flooded valleys containing reservoirs such as Howden, Derwent and Ladybower (see ‘Reservoirs’).

The majority of PDNP riverside land is pasture for sheep or cattle. There are also some areas of native and plantation woodlands (see ‘Estate lands and designed landscapes’, ‘Woodlands’ and ‘Wet Woodlands’).

How vulnerable are river valleys?

River valleys in the PDNP have been rated ‘moderate’ on our vulnerability scale. This score is due to high sensitivity and exposure to climate change variables, coupled with a variable current condition, but with a high adaptive capacity.

River valleys in the PDNP are generally in functional condition, though as active hydrological systems changes are fast. An increase in rainfall intensity and flooding is the key potential impact of climate change in river valleys. However, natural flood management schemes are part of the Department for Environment, Food and Rural Affairs (DEFRA)’s 25-year plan, and there are multiple management strategies that could be implemented to increase significantly the adaptive capacity of river valleys.

Current condition:

The condition of river valleys in the PDNP is variable and can change very quickly. For example, intense rainfall in November 2019 on already saturated ground saw widespread flooding particularly on low-lying areas resulting in a fatality as well as damage to farmland, roads and properties. Not only does such flooding affect the land and the varied habitats and historic environment found in river valleys, it can also affect water quality. Many PDNP access routes such as roads, railways tracks and even walking routes pass through valley bottoms and they too can be damaged. Valley bottom farmsteads and other buildings are also at risk from damage.

Many issues currently affect PDNP river valleys. Several non-native invasive species associated with water are present. These include mink, signal crayfish, Himalayan balsam and Japanese knotweed. In addition, plantations of non-native conifers are present. These are likely to be affecting water quality, river valley landscapes and water ecosystems. Signs of ash dieback have been found in native woodlands.

Although erosion and sedimentation in river valleys are natural processes, they have been impacted by upstream erosion of peat - in particular contributing to problems of water acidity and siltation of waterbodies like reservoirs within the valleys.

Water quality and river valley habitats have been affected negatively by intensification of agriculture and high levels of livestock, contamination from industry and sewage discharge.

What are the potential impacts of climate change?

Overall potential impact rating

Direct impacts of climate change

River valleys are very sensitive to climate change especially if there is an increase in the intensity and frequency of storm events. Sudden flash storms can cause considerable damage and even loss of life, as occurred in 1989 when the River Dane flooded at Wildboarclough and again in 2019 when the Derwent flooded at Darley Dale. Repeated flooding can alter or damage archaeological and historic features and can have a significant impact on the riparian habitat by damaging nests and burrows, as well as habitats for species such as the water vole and kingfisher.

Fish populations can also be harmed because fish eggs could be washed away with river gravel or be damaged by silt. This would in turn affect recreational fishing in the valleys. Data Certainty: High River valleys are sensitive to changes in rainfall and are vulnerable to flooding which could then affect farming, settlements, and visitor infrastructure. Data Certainty: High

In contrast, hotter drier conditions and low rainfall during summers could that streams and rivers are dry for longer periods of the year. This could then impact aquatic habitats and species by changing the quality of water, river levels and the water flow. This in turn has the potential to impact farming and local water supply in the valleys. Data Certainty: Moderate

Sedimentation or erosion

Changes in rainfall patterns may result in an increase in erosion processes in river valleys. Rivers may become increasingly silted in places due to an increase in catchment-level soil loss. Rivers are highly vulnerable to topographic changes. Rivers may be realigned with changes in river pathways also seeing deeper channelling, meanders being cut-off, and new oxbow lakes formed while riverside farmland may flood more frequently. Archaeological features, especially those associated with former water management and bridges could also be lost or damaged. Data Certainty: High Storm events may affect riverbanks and depositional features, together with riparian habitats used by species such the water vole. It may be that marginal and aquatic vegetation such as water crowfoot beds are washed away. Data Certainty: High

Human behaviour change

Hotter summers could result in the growth in visitor numbers to popular tourist hotspots such as Dovedale. Such a rise would increase fire risk, litter being left and may case the loss of the peaceful quality of the setting. Rising visitor number may also cause significant erosion through footfall and parking. Conversely in some locations numbers may fall, driven by degradation of the natural beauty of the area caused by factors such as tree disease outbreaks, dry rivers and the loss of habitats. Data Certainty: Moderate

Drier summers would be likely to increase demand for water abstraction, while wetter winters may result in installation of new flood defences, dredging and even modification to the river channels to combat an increased risk of flooding.

River ecosystem and habitats are sensitive alteration of river channels. Species associated with rivers may decrease if river levels and channels are modified. River valley processes will be sensitive to changes in farming practice occurring due to climate change. The aesthetics of PDNP river valleys are likely to change, including the historic landscape character. Data Certainty: Moderate

Increased demand for renewable energy may result in river flow being harnessed for energy generation. The addition or modification of reservoirs and installation of hydropower schemes (including small-scale and microgeneration) would affect the landscape, habitats and aesthetics. Data Certainty: Low

Invasive or other species interactions

Fewer frost events during warmer winters may lead to an increased prevalence of diseases that affect woodlands, such as ash dieback. This could alter biodiversity and aesthetics of the valley landscape, and have a significant impact on the rate water reaches the river channel. Data Certainty: Moderate Changes in growing conditions caused by drier summers and wetter winters may lead to an increase in the number and prevalence of invasive and nuisance species. Water and waterside habitats are particularly vulnerable to invasion and dry, waterlogged or damaged soils are more susceptible. This could see changes in biodiversity and the appearance of river valleys. Historic structures could also be affected by invasive species. Data Certainty: Moderate

Nutrient changes or environmental contamination

Increased winter rainfall, run-off and and flooding events could increase the level of nutrients input to riverside meadows, pastures and woodlands. Where pollutants are present at the head of a valley this would also increase potential for contamination to occur over a wide area. This could affect habitats - changing the composition of species present and alter the human use of the landscape. Data Certainty: Moderate

Water quality is sensitive to changes from atmospheric pollution, which could also change water chemistry. Acidification of water could occur as atmospheric carbon dioxide increases, and rivers could be less resilient to eutrophication. As a result, landscape scale changes could occur – to biodiversity, land-use and aesthetics. Data Certainty: Low

What is the adaptive capacity of river valleys?

Overall adaptive capacity rating

Rivers will respond to changing water regimes by adapting their channel form, flow and shape. However, damage to access, farmland and settlements during extreme events will requires long recovery periods. River valley ecosystems will have higher adaptive capacity where natural processes are allowed to take place. Data Certainty: Moderate

There is a diverse range of river valleys throughout the PDNP with a mixture of natural river systems and altered ones, flowing through a range of different bedrock and soil types. Valleys with a higher diversity of habitats and species will have a higher adaptive capacity than those with more homogenous characteristics such as improved grassland, conifer plantations, of even the ash dominated woodlands of the White Peak. Data Certainty: Moderate

Flood Management and Prevention Schemes in DEFRA's 25-year plan for Natural Flood Management include tree establishment, riverbank restoration, building small-scale woody dams, reconnecting rivers with their flood plains and storing water temporarily on open land and Flood Defences. A move towards these type of interventions would increase the resistance and resilience of PDNP valley landscapes. Agri-environment schemes and Woodland Grant schemes are also in currently use. Such interventions can sometimes adversely affect historic features and character. Data Certainty: High

Work to increase the resilience of rivers and river valleys is already being carried out by organisations such as National Trust, Moors for the Future Partnership, South West Peak Partnership Staffordshire and Derbyshire Wildlife Trusts and Trent Rivers Trust. Catchment partnerships are a major potential future resource for work to be undertaken. Data Certainty: High

A variety of management options is available to manage watercourses, to manage farmland, and to promote structural and species diversity within river valleys. Data Certainty: Moderate

Key adaptation recommendations for river valleys:

Improve current condition to increase resilience

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations are aimed at improving the condition of the feature at present, therefore making it better able to withstand future changes to climate.

• Accept that landscape character and habitat types cannot remain static in PDNP river valleys, and that management changes will need to happen to enable resilience to climate change.
• Improve the management of riverside grasslands, and create more wet meadows. They can be used to temporarily store floodwater and reduce the effects of large rainfall events.
• Remove manmade impoundments where appropriate, especially those in small watercourses to help increase habitat quality, decrease downstream flooding and landscape aesthetics.
• Consider the impact on key views when planning adaptations.

Improve current condition to increase resilience: Targeted conservation efforts for important sites and at risk areas

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations are conservation measures aimed at those sites that will have the biggest impact for this feature – either because they are particularly important for the feature or because they are most at risk from climate change.

• Regular monitoring of key sensitive heritage features (such a listed bridges).
• More research is required to better understand the hydrology and role of artificial drainage on low flow river systems.

Improve current condition to increase resilience: Increase structural diversity of the landscape to improve resilience to change

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations focus on increasing the structural diversity of the landscape in which the feature is found. By doing so the condition of the feature, and therefore its resilience to climate change impacts, should be enhanced.

• Management of river valleys should allow space for natural processes to occur. Allow rivers to meander, and exclude livestock to allow space for riverside woodland and scrub to develop in appropriate locations. This should help to control nutrient input and may reduce water temperature increases.
• Manage the whole catchment including the upper slopes to reduce run-off and increase lag-times. Create more clough woodland to reduce flood risk and erosion of valley sides.

Accept changes to feature

These recommendations are about adapting ways of thinking to be accepting of inevitable change. While some changes may be negative, this also presents a chance to seek out any positive opportunities that may be caused by climate change.

• The potential for new reservoirs should be raised as an issue in the review of the Local Plan for the PDNP where this supports climate change adaptation, nature recovery and effective visitor management.