1. General information
Location and description of the intervention
City or FUA
Hannover
Region
Europe
Native title of the NBS intervention
Gewässerrenaturierung Hirtenbach
Short description of the intervention
The renaturalization of the water canal Hirtenbach project was part of the larger city-wide initiative that aimed at the naturalization of different parts of the city's drainage system including small trenches and streams. The initiative aimed to decrease the risk of floods, improve the water quality, protect the local flora and fauna from the pollution, as well as provide for an additional recreational area for the citizens. (Reference 1)
In 2000, natural remodelling or the creation of near-natural structures began in sections. A 20, 000 m3 retention basin was also built. These actions improved flood protection and ecology of the area, and it provided local recreation opportunities. However, a study conducted in 2014 revealed that the restoration measures brought positive changes, but it was not enough to achieve a “good water status” defined by the European Water Framework Directive. Intensive care from silting and lush plant growth, wide margins, and the reduction of nutrients coming from the drainage and agriculture, need to be addressed. (Reference 2)
A new landscape is expected to be created when the alder trees grow. Waterbirds and waders, as well as insects like dragonflies, bees, butterflies and crickets, have been observed in the area (Reference 3).
The large drainage system of the city of Hannover includes many small trenches and streams with a total length of 152 kilometres. The intervention in Hirtenbach involved renaturalization worked on the total length of approximately 10,5 km (of which 3,3 km in the urban area). (Reference 2)

Address

Hannover
Germany

Location
Point location, which indicates where the NBS takes place
NBS area image
Source of NBS area image
1. Project Hirtenbach Map:
Source: Project Flyer: DER HIRTENBACH AUS DER BÖRDE IN DIE STADT
2. Representation of water restoration:
Source: Project - city website (https://www.hannover.de/Media/01-DATA-Neu/Bilder/Landeshauptstadt-Hannover/Umwelt/Abwasser/Stadtentw%C3%A4sserung/Fotos/07_Gew%C3%A4sser_Gew%C3%A4sserrenaturierung)

Type of area before implementation of the NBS
Other
Please specify “other type of area” before implementation of the NBS
Water Canal
Website of the intervention
https://www.hannover.de/Leben-in-der-Region-Hannover/Umwelt-Nachhaltigkeit/Wass…
Timeline of intervention
Start date of the intervention (planning process)
1999
Start date of intervention (implementation process)
2000
End date of the intervention
2010
Present stage of the intervention
Completed
Goals of the intervention
Goals of the intervention: 1) Purification of water; 2) Renaturalization of the water channel and shore; 3) Protection of fauna and flora from pollution originating from the water and minimizing the negative adverse effects of pollution; 4) Improving the flood protection of the city (Reference 1)




Quantitative targets
Unknown
Monitoring indicators defined
Ecological status; improvement in flood protection (Reference 2)
Sustainability challenge(s) addressed
Climate action for adaptation, resilience and mitigation (SDG 13)
Climate change adaptation
Water management (SDG 6)
Flood protection
Stormwater and rainfall management and storage
Improvements to water quality
Green space, habitats and biodiversity (SDG 15)
Habitat and biodiversity restoration
Habitat and biodiversity conservation
Green space creation and/or management
Regeneration, land-use and urban development
Promote natural styles of landscape design for urban development
Social justice, cohesion and equity (SDG 10)
Social interaction
Health and well-being (SDG 3)
Creation of opportunities for recreation
Climate change adaptation: What were the goals of the NBS?
Reduce the impacts of climate risks events on urban places and communities
Build resilience
Climate change adaptation: What activities are implemented to realize the conservation goals and targets?
Implement sustainable urban drainage infrastructure (e.g. to make space for water)
Renaturalization of rivers and other water bodies
Habitats and biodiversity conservation: What types of conservation goals are / were defined for the NBS intervention?
No information provided regarding the goals of the intervention.
Habitats and biodiversity conservation: What activities are implemented to realize the conservation goals and targets?
Protect and enhance urban habitats
Preserve and strengthen existing habitats and ecosystems
Promote environmentally-sound development in and around protected areas
Create new habitats
Reduce negative impacts and avoid the alteration/damage of ecosystem
Protect species
Undertake specific measures to protect species
Means for conservation governance
Manage biological resources for conservation and sustainable use
Create and use scientific knowledge for conservation
What types of restoration goals are / were defined for the NBS intervention?
Ecosystem-focused
What activities are implemented to realize the restoration goals and targets?
Rehabilitate and restore damaged or destroyed ecosystems
Implementation activities
-Increasing the self-cleaning power of the water canal by the establishment of structurally rich water profiles through the creation of suitable rainwater retention basin and near-natural structures.
-Planting of trees;
-Demolition of bank and embankment protection;
-Installation and greening of edge strips;
-Establishment of water maintenance plans for care and development while respecting the maintenance of a proper drain system;
-Continuous scientific studies of water quality (monitoring) (Reference 1,2)
Type of NBS project
Creation of new green areas
Creation of semi-natural blue areas
Maintenance and management of urban nature
Ecological restoration of ecosystems
Monitoring and maintenance of habitats and/or biodiversity
Management and improved protection of rivers and other blue areas
NBS domain and interventions
Ecological domain(s) where the NBS intervention(s) is/are implemented
Grey infrastructure featuring greens
Riverbank/Lakeside greens
Blue infrastructure
Rivers/streams/canals/estuaries
Green areas for water management
Sustainable urban drainage systems
What is the level of innovation / development of the NBS related to water management?
Medium / High: sustainable urban drainage systems which include water storage and diverts water flooding
Vegetation Type
Grass
Shrubs
Trees
Please specify how many trees were planted
unknown
Amenities offered by the NBS
Unknown
Services
Expected ecosystem services delivered
Provisioning services
Water (surface and ground water for drinking and non-drinking purposes)
Regulating services
Flood regulation
Water purification / filtration
Habitat and supporting services
Habitats for species
Cultural services
Aesthetic appreciation
Recreation
Social and community interactions
Scale
Spatial scale
Meso-scale: Regional, metropolitan and urban level
Beneficiaries
Primary Beneficiaries
Citizens or community groups
Governance
Governance arrangements
Government-led
Please specify the roles of the specific government and non-government actor groups involved in the initiative
The project was designed and implemented by the city of Hannover.
Key actors - initiating organization
Local government/municipality
Land owners
Public space owned by the city
Key actors - Other stakeholders involved (besides initiating actors)
EU body
Local government/municipality
Citizens or community group
Land owners
No information found
Participatory methods/forms of community involvement used
Unknown
Policy drivers
NBS intervention implemented in response to an Regional Directive/Strategy
Yes
Please specify the "Regional Directive/Strategy"
The European Water Framework Directive, which regulates the protection of surface waters and groundwater, sets out the targets for the reduction of pollution and the achievement of good ecologic conditions.(Reference 2)
NBS intervention implemented in response to a national regulations/strategy/plan
Unknown
NBS intervention implemented in response to a local regulation/strategy/plan
Yes
Please specify the "local regulation/strategy/plan"
The project is a part of a larger long-term city initiative that aims at the renaturalization of the streams and canals (Gewässerrenaturierung) that are part of the city's drainage system. (Reference 1)
Mandatory or voluntary intervention
Voluntary (spontaneous)
Please specify other type of voluntary intervention
The city of Hannover implemented the project on its own initiative.
Enablers
Presence of specific city-level GI/NBS vision/strategy/plan - mentioned in connection to the project
Yes
Please specify
The project is a part of a larger long-term city initiative that aims at the renaturalization of the streams and canals (Gewässerrenaturierung) that are part of the city's drainage system. (Reference 1)
Presence of specific city-level GI/NBS section/part in a more general plan - mentioned in connection to the project
Unknown
If there is a relevant strategy or plan, please specify the theme / type of the plan.
Water regulation strategy
Municipal / city level environmental plan or programme
Presence of city network or regional partnerships focused on NBS - mentioned in connection to the project
Unknown
Presence of GI / NBS research project - mentioned in connection to the project
Unknown
Please specify
The investigation commissioned into the state of the water after the project's completion conducted a survey on the fish stocks, evaluation of the structural characteristics of the Hirtenbach stream, an investigation of plants in and around the waters and the micro-organisms living in the aquatic environment.(2)
Subsidies/investment for GI / NBS in the city - mentioned in connection to the project
Unknown
Co-finance for NBS
No
Co-financing governance arrangements
No
Was this co-governance arrangement already in place, or was it set up specifically for this NBS?
Unknown
Financing
Total cost
Unknown
What is/was the Cost/Budget (EUR) of the NBS or green infrastructure elements?
Unknown
What are the total amount of expected annual maintenance costs?
Unknown
What is the expected annual maintenance costs of the NBS or GI elements?
Unknown
Please specify cost savings
Unknown
Please specify total cost (EUR)
Unknown
Source(s) of funding
Public local authority budget
Type of fund(s) used
Earmarked public budget
Non-financial contribution
Unknown
Business models
Risk reduction model
Which of the involved actors was motivated by this model?
Public actor (e.g. municipality)
Type of innovation
Technological
Infrastructural innovation
Please specify technological innovation
The project is an example of a local infrastructural innovation that by a number of restoration works provides a habitat for the flora and fauna, as well as a new recreational area for the citizens.(Reference 1)
Novelty level of the innovation
The innovation is copied/derived from previous initiative(s) without substantial adaptation
Please specify novelty level of the innovation
The project is one of many similar projects conducted by the city of Hannover in the last 20 years.(Reference 1,2)
Replicability/Transferability
The innovation is not referred to as being transferred to new initiative(s)
Please specify Replicability/Transferability
Unknown
Impacts, benefits
Environmental impacts
Water management and blue areas
Improved water quality
Increased protection against flooding
Improved stormwater management
Green space and habitat
Increased green space area
Increased conservation or restoration of ecosystems
Reduced biodiversity loss
Increased number of species present
Description of environmental benefits
-The near-natural design has brought a positive effect with regards to flood protection, urban drainage improvement in water quality as well as on the ecology of the area. With the renaturation of the Hirtenbach and the construction of the rainwater retention basin rapid runoff from the surfaces has slowed down and the close to nature structures improved drainage.
-The near-natural expansion and the water development helps in preventing contaminants (from roads surfaces, roofs and other paved surfaces) to reach the rivers and threaten flora and fauna. In addition to waterbirds and waders, many insects such as dragonflies, bees, butterflies and crickets have been observed in the area. (Reference 1, 3)
As the project states, the renaturalization of water has a positive effect on flood protection, drainage system, water quality as well as on the ecological dynamics of the flora and fauna.
Economic impacts
Unknown
Description of economic benefits
No information was found regarding the economic benefits
Social and cultural impacts
Social justice and cohesion
Improved liveability
Improved access to urban green space
Increased opportunities for social interaction
Health and wellbeing
Gain in activities for recreation and exercise
Description of social and cultural benefits
The near-natural water body brings an increase in urban quality of life through the experience it offers to users by the updated design of the renaturalized areas (Reference 1). It's versatile design generates opportunities for recreational uses (Reference 1).
Planting of trees (Reference 1) increases the green space in the area that is now accessible to the locals.
Type of reported impacts
Achieved impacts
Indicators
Unknown
Environmental, social and economic impacts
Water management (SDG 6)
Flood protection
Stormwater and rainfall management and storage
Improvements to water quality
Green space, habitats and biodiversity (SDG 15)
Habitat and biodiversity restoration
Habitat and biodiversity conservation
Green space creation and/or management
Environmental quality
Waste management
Regeneration, land-use and urban development
Promote natural styles of landscape design for urban development
Social justice, cohesion and equity (SDG 10)
Social interaction
Health and well-being (SDG 3)
Creation of opportunities for recreation
Analysis of specific impact categories
Job creation: The NBS created ...
No information available
Environmental justice: The implementation of the NBS project resulted in ...
Positive distribution of NBS benefits
Improved access to green and/or blue spaces
Negative impacts: Did the project cause any problems or concerns?
No information was found regarding negative impacts of the project
COVID-19 pandemic
Unknown as of July of 2020.
Methods of impact monitoring
Process of recording NBS impacts
Collection of monitoring data continuously throughout the project to aid evaluation
Methods used to evaluate the impacts of NBS
Measurements of biophysical aspects of the NBS (e.g. temperature, water flow)
Evidence for use of assessment
Presence of an assessment, evaluation and/or monitoring process
Yes
Presence of indicators used in reporting
Yes
Presence of monitoring/evaluation reports
No evidence in public records
Availability of a web-based monitoring tool
No evidence in public records
Impact assessment mechanism
Name of any specific impact assessment tools
In order to examine the current state of the Hirtenbach an investigation into the state of the water was commissioned in 2014 by the city of Hannover. This included a survey on the fish stocks, evaluation of the structural characteristics of the Hirtenbach stream, an investigation of plants in and around the waters and the micro-organisms living in the aquatic environment. The assessment showed improvement in the water conditions, but better results are still needed. Despite restoration measures, the Hirtenback needs intensive care due to pollution coming from drainage and intensive agriculture.(Reference 2)



Use of GIS in mapping impacts
No evidence in public records
Citizen involvement
Citizens involvement in assessment/evaluation
Unknown
Mode(s) of citizen involvement in evaluation/assessment
Other
Please specify other modes of citizen involvement in evaluation/assessment
Unknown
Citizens involvement in the analysis of the assessment/evaluation
Unknown
Follow-up to the evaluation / assessment
Unknown
References
Web links relevant to the intervention
Ref.1 (initiative description on city website)
Ref.3 (Additional information from city website)
Documents relevant to the intervention
Attachment Size
Ref.2 (project description) (1.75 MB) 1.75 MB
List of references
1. Hannover.de. (no date). 'Renaturalization of water' ('Gewässerrenaturierung'). Available at:
https://www.hannover.de/Leben-in-der-Region-Hannover/Umwelt-Nachhaltigkeit/Wasser-Abwasser/Gew%C3%A4sser/Gew%C3%A4sserrenaturierung. Accessed 15 July 2020.
2. Hannover.de. (2016). 'The Hirtenbach' (See attachment)
3. Hannover.de. (no date). Hirtenbach. Available at: https://www.hannover.de/Kultur-Freizeit/Naherholung/Natur-erleben/Radfahren/Gr%C3%BCner-Ring/Wasserzeichen/Hirtenbach. Accessed 15 July 2020.
Attachments
Attachment Size
Information about the project (1.75 MB) 1.75 MB
Comments and notes
Comments
Re:2 From what I understand both the target and the outcome.
Re:6 The assessment was commissioned by the city of Hannover and included the activities listed in section 6. I can’t find more information than that.

There was no mentioned dates in the references 1 and 3 so I am unsure if the information reflects the most recent status. There was also no reference found on whether actions or measures were taken after the 2014 study results showed that the renaturation project in Hirtenback were not enough to achieve the required ecological status of the water, as defined in the EU Directive.

Pictures of the NBS
/sites/default/files/nbs/images/Picture%201.%20Aquatic%20plants%20in%20Hirtenbach.jpg
/sites/default/files/nbs/images/Rainwater%20retention%20basin.jpg
/sites/default/files/nbs/images/Water%20level%20check.jpg