Urban Contingency - 2020 - Sverresborg

Contingency Plan for Sverresborg A Case of A Dam Failure at Theisendammen Laura Flora Podoski Mari Coward Phong Vuoc Tran Robin Surya Ursula Sokolaj

Introduction About the assignment and problem statement To prepare for a flood event, reduce flood impacts and know how to react when a flood is happening, a contingency plan should be created. UNHCR and UN Disaster Management Training programme defines a contingency plan as “a forward planning process, in a state of uncertainty, in which scenarios and objectives are agreed, managerial and technical actions defined, and potential response systems put in place in order to prevent, or better respond to, an emergency or critical situation” (Choularton, 2007).

This report is part of the subject “AAR5220 Urban contingency planning and practice” at the Norwegian University of Science and Technology.

The purpose of this report is to create a contingency plan with a response strategy, an implementation, operational support and preparedness plan, as well as a budget, based on analyses of the given context and scenario. The given scenario for the contingency plan is that Trondheim is a highdensity city, prone to floods due to heavy rainfall.

The municipality has substantial resources and a disaster management authority.

A technocratic approach has been followed, focusing on data collection and extensive analysis, leading to

the compilation of the contingency plan. The vision for this contingency plan is to have control of the situation, making the area more resilient, so that it does not become a catastrophe for residents, businesses or infrastructure in a chosen area of Trondheim. For this context, resilience can be defined as by Walker et al. (2003): “Resilience is the capacity of a system to absorb disturbance and reorganize while undergoing change so as to still retain essentially the same function, structure, identity, and feedbacks.”

Case background As the temperatures are rising due to climate change, Trondheim can become one of Norway’s most vulnerable cities regarding urban flooding (Førland et al, 2007). The municipality of Trondheim is aiming to have an environmentally conscious orientation in its different sectors, emphasizing that Trondheim, as the technological capital of Norway, has a special opportunity to take lead in the global green shift (Trondheim kommune, 2020:1). In order to become a pioneer as a climate and environmentally friendly municipality in Norway, Trondheim compiled a set of goals to be achieved within 2030. Goal number 3 states that “In 2025, Trondheim is robust to meet future climate change.” (Trondheim kommune, 2020:1), which at the time of writing, is within five years.

Figure 1a: Aerial photos of Sverresborg and Theisendammen

The chosen area - Sverresborg Trondheim is the third biggest city in Norway. Byåsen is one of the largest districts in Trondheim with Sverresborg being one of its central areas, with approximately 3500 inhabitants (Eierskapsenheten, 2012). Theisendammen in Bymarka, west of Sverresborg (figure 1a and 1b), is one of the three dams that are in operation in the watercourse in Ila, called Ilavassdraget. It was previously a water supply for the city, but today the lake has no other function rather than being a recreational area for outdoor activities.

It is a relatively small dam, but its proximity to downstream roads and buildings puts it in the highest risk category, meaning that the potential impacts in case of a dam failure would be highly significant. The dam has therefore strict requirements for safety, supervision and maintenance (Trondheim kommune, 2019).

Methodology Structuring the report, the lectures and the assignment description given by Mrudhula Koshy in the course “AAR5220 Urban contingency planning and practice” were used. The six steps of the contingency plan are based on these lectures. In addition, the similar assignments from 2019 have been used as inspiration, both for the structure and the content.

Data collection Most of the findings in this report are based on web search. The following refences are the most consulted. Maps from NVE (The Norwegian Water Resources and Energy Directorate) have been used to locate the vulnerable areas in Trondheim regarding flooding, and to choose an area to focus on. Kristine Nesset Stenvik’s research in “Urban flom som konsekvens av klimaendringer: En GIS studie” (2011) helped create a more specific scenario in Sverresborg. This study is a master thesis, supported by previous experiences of flooding in the area. Google Maps has been used to get an overview of the area and its facilities. For the stakeholder mapping, stakeholders from previous flooding events in Norway have been investigated, in addition to volunteer groups in Trondheim.

As Trondheim municipality plays a major part in preventing flood, their web page has also been used to gather information. The municipality has also provided free geodatabases through their WMS-

Figure 1b: Aerial photos of Sverresborg and Theisendammen

services, that consist of DTM (digital terrain model) and orthophotos. These have been used in GIS to create maps for topography analysis and to create base maps for the illustrations.

Case studies Numerous case studies have been reviewed, however four of them have been chosen as inspiration for this report. They are from very different parts of the world but have similarities to the given scenario regarding density and resource allocation. Learning and analyzing what has already been done helped in understanding the different forms of measures, both structural and nonstructural, that can be taken to prevent flooding.

Field visit The group decided to carry out a field visits seperately to Sverresborg for the site analysis, in order to understand the area from a closer viewpoint. A member of the team used a drone to capture aerial photographs of the current situation, to get an overview from a different perspective as well as use as illustrations for the report. During the field visit, the team decided that the area surrounding Theisendammen and Byåsen shopping mall would be the main focal point in our analysis.

COVID-19 The COVID-19 pandemic has made its impacts on the work with this report. Luckily, the group had

a chance to meet and get started with the project before all face-to-face meetings were restricted.

Later, Blackboard Collaborate has been used for virtual group meetings and a common OneDrive folder was created to better share information and findings. Other than not being able to do a field visit together as a group, the situation has not limited the work too much, as most findings could be done through web searching. However, in an early stage, the group discussed interviewing local residents in Sverresborg, to better understand their view on a potential flood, but this was found difficult to conduct due to COVID-19, and therefore eliminated.

Site Analysis Sverresborg is located approximately 4.5 kilometers southwest of downtown, as shown in figure 2. It is a popular residential area for people that wish to live close to the centre with good transport connections, yet in a quieter neighbourhood. With its versatile facilities, Sverresborg has an important role in peoples’ lives in Trondheim, especially for those living in Byåsen.

Figure 2: Location of the chosen area, Sverresborg

Important Landmarks Figure 3 shows, among other things, the major cultural heritages and public services around Sverresborg. Sverresborg is rich in history, as one of the county’s oldest shopping centers, Byåsen Butikksenter, has been located there since 1962 (Byåsen Butikksenter, n.d.). The church complex in Sverresborg is a spacious parish hosting different activities for its community (Andersen, 2018). Åsveihallen is the main indoor sports hall in the neighbourhood, located right beside the local school called Åsveien skole. Sverresborg Trøndelag Folkemuseum is one of the largest cultural historical museums in Norway. Another public service in the area is Byåsen Disability Housing (in Norwegian Bo- og Aktivitetstilbud), a housing and activity center for disabled people located in south-east of Sverresborg.

Infrastructure The chosen area is well provided with public transportation alternatives. Figure 3 also shows the metro bus route passing through Sverresborg, as well as the tram route further down towards the river. Additionally, the train line passes east of Sverresborg, along Nidelva. The area is also well equipped with multiple bicycle trails and pedestrian sidewalks along the roads.

Documented risks, threats and uncertainties Theisendammen is a relatively small artificial pond situated north west of the Sverresborg area, with a capacity of 2.2 million cubic meters (Myhre, 1996).

However, its closeness to roads and buildings downstream can result in great damage in case of a dam failure. NVE has classified dams by their damage potential in case of a failure. On a scale from 1 to 4, Theisendammen is classified as 4 (Trondheim kommune, 2019).

The analysis by NVE (NVE Atlas, 2020) shows that the chosen area in Sverresborg is not directly threatened by flood hazards in its central part, as illustrated in figure 4. However, there is a caution zone down Breidablikkveien, all the way to Nidelva.

Moreover, the city of Trondheim is mapped according to quick clay risk (NGU, 2015). Figure 4 indicates that there are no specific risk zones for quick clay slides in Sverresborg, but there are sensitive areas further down east, close to Nidelva. A flood

Figure 3: Important landmarks and public transportation lines

in Sverresborg could potentially trigger quick clay slides in this zone, depending on the paths the water will take.

Storm water management in Trondheim Stormwater and snow melting are creating large amounts of precipitation in urban areas with impervious surfaces, often causing flooding (USGS, 2016). The storm sewer systems in cities like Trondheim, are usually constructed long back in time, with a low ability to cope with the increasing amounts of rain (FloodProbe, 2011). When the drainage system reaches its capacity, the floods will take alternate paths as the drainage systems are unable to handle the entire mass. In addition, urban runoff can carry a mixture of pollutants, discharging them into streams and rivers.

Trondheim municipality has identified the areas exposed to risk of flooding. As security measurements, and prevention of future damages to infrastructure or societal functions, it is important to have functional flooding paths, often presented in awareness maps, that can handle these flooding events (Trondheim kommune, 2012).

New urban surface water routes and possible damages A GIS study by Stenvik (2011) shows possibilities for new floodway formations in Sverresborg, in case of urban flood. Figure 5 shows that the main roads – Byåsveien, Breidablikkveien and Osloveien – are most prone to floodwater. Figure 6 is showing residential buildings situated within five meters from the accumulated surface water. They are located in steep terrain, which can cause the water to accumulate speed.

Figure 4: Mapped flood zones and risk zones for quick clay slides in the chosen area

Figure 5: The surface water follows the paved roads down Breidablikkveien and on to Osloveien (Stenvik, 2011, page 57)

History of flooding in Sverresborg In addition to flooding in 1791 and 1844 (Trondheim kommune, 2020:2) caused by dam failures in Kobberdammen and Theisendammen, respectively, another urban flood in the summer of 2007 damaged basements and other properties in Byåsen. In the area along Breidablikkveien, the damage to buildings that was registered coincides with the new flood road preicted by Stenvik (2011).

Many of the recorded damages from the summer of 2007 are in the same areas as the identified flood paths from Stenvik’s analysis.

Stakeholder Mapping The following is an overview of some of the most important stakeholders involved during a flood event in Norway.

National level The Norwegian Water Resources and Energy Directorate (NVE) has governmental responsibility for preventing damage from flooding, erosion and landslides. They provide professional and financial assistance to the municipalities by mapping and securing the most vulnerable areas (Politidirektoratet, 2011). The Meteorological Institute develops forecasts and alerts regarding rainfall. This helps authorities, organizations and residents to predict the consequences of the rainfall (Direktoratet for samfunnssikkerhet og beredskap, 2019).

In case of major accidents and disasters, The Civil Defense can provide extra crew and equipment if the emergency services need support

Figure 6: The possible routes of the urban flood water in Sverresborg (Stenvik, 2011, page 63)

(Sivilforsvaret, n.d.). The Norwegian Home Guard, part of the Norwegian Defense, can assist the police and is important to the County Governor during crisis like flooding, hurricane and larger accidents (Børresen et al, 2020).

Regional level The municipalities act as local emergency response authorities, and they are responsible for coordinating the different stakeholders during a crisis, like a flood event. Different parts of the municipality are contributing with different preventive measures.

Urban planning is the municipalities’ most important sector when working on safety against climate adaptation (NVE, 2020). The Norwegian municipalities also include engineers working with infrastructure and water/wastewater, as well as an emergency organization (Trondheim kommune, 2017).

Other stakeholders on the regional level are the emergency services, including police, fire department and ambulance. One of the fire department’s tasks is to assist in case of a flood event.

The police is responsible for implementing measures as well as organizing and coordinating relief efforts (Politidirektoratet, 2011).

In case of a flood, there are also voluntary groups that can contribute. Trondheim Red Cross has 1000 volunteers and is working together with Trondheim municipality and other emergency services. They focus on helping inhabitants in Trondheim to be prepared to take care of themselves in case of a crisis (Trondheim Røde Kors, n.d.). The Scout’s Emergency Response Group Trøndelag is disposal for emergency preparedness departments in search and rescue operations (Speiderens beredskapsgruppe Trøndelag, n.d.).

Another important stakeholder on the regional level is media, such as TV and radio, and relevant websites or newspapers, like Adresseavisa. They can contribute with information both before, during and after a crisis to inform the inhabitants about the situation.

Local level In case of evacuations, public buildings, such as schools, sport centers and churches, can provide shelter. In Sverresborg, Åsveien school, Åsveihallen and Sverresborg church center can provide close-by shelters or meeting points. Both the school and Åsveihallen are owned by Trondheim municipality (Trondheim kommune, 2020:3; Trondheim kommune, 2020:4). Byåsen Disability Housing (Byåsen Bo- og Aktivitetstilbud) is a public service, provided by the municipality, that also contribute to the same purpose (Byåsen Boog aktivitetstilbud, n.d.).

Byåsen shopping center can provide with shelter, food and supply in a crisis. Buses and trams can be used to transport evacuating people as well as transporting helpers to the critical areas or supplies. AtB is administrating the public transport in Trøndelag (AtB, n.d.).

The ihabitants themselves can do some preventive measures. In preparedness, establishing green roofs or making sure that gutters are free of leaves can be such measures. It is also important that the inhabitants are prepared for a possible flood event and know how to respond.

Case Studies Denmark Following the cloudburst of 2011 in Copenhagen, new plans like the Cloudburst Formula were developed, which shifted the focus from closed drainage systems to blue-green surface solutions.

These new measures aimed to not only solve the future extreme weather problems, but also create new urban spaces for recreational and social purposes. This duality in usage will in a long-term perspective be cheaper compared to the traditional model that does not add any recreational value (The Source, 2016). These forward-thinking solutions are the reason of studying the Copenhagen case, and have become inspiration for the physical implementations.

As seen in figure 7, attention is paid to the street infrastructure. By different interventions such as permeable surfaces, roadside beds and rain beds, roads remain functional during flooding events and protect other areas by detaining and storing some of the water. Another example of these multifunctional measures are water detention pools within playing fields and sport facilities (figure 8). These pools will be flooded during heavy rainfall, but during drier periods, the pools can act as paddle tennis courts, skate parks or other recreational areas (The Source, 2016). A similar idea is followed for green areas as well, as seen in figure 9. While making the city more vibrant and livable, these areas provide flood storage in the case of cloudburst (American Society of Landscape Architects, n.d.).

Figure 7: Surface solutions (The Source, 2016)

Figure 8: Water detention pools - hard surfaces (The Source, 2016)

Figure 9: Floodable park (Landezine, 2015)

Figure 10: How the elements link together (Flood Community of Practice, 2018)

Figure 11: The three steps in managing a flood (Flood Community of Practice, 2018)

Australia Flood Community of Practice is a membership between Queensland Government, James Davidson Architect and several other engineers, researchers and consultants which aims to provide expertise on flood risk and water management.

Taking inspiration from the Water Futures book by James Davidson Architect, after the flood event of January 2011, a vision for a livable and water smart South East Queensland was built. The case has been studied because the physical interventions proposed aim to build resilience and are well integrated into a framework. These solutions are adapted to different terrains and environments both built up and natural (figure 10) - but work together organized in three steps as in figure 11, to reduce flood impact across all the different landscapes (Flood Community of Practice, 2018).

South Korea South Korea is another country experiencing heavy rainfall with an increasing frequency due to climate change. Following the flood in Seoul in 2011, the city proposed a new disaster prevention system (Kim, n.d.). This case has been studied because of its combination of structural and non-structural measures into a progressive response strategy, where progressiveness refers to the different types of action that need to be taken according to the increase in the level of hazard. This is visualized in the diagram in figure 12, which describes the management procedure for the flood disaster situation in case of heavy rainfall. The procedure is divided into three stages - readiness, warning and alarm stage - classified according to the amount of rainfall (Kim et al., 2007).

Figure 12 also describes the procedure of checking water stages and reservoir volume to prepare for any flood disaster. In case of damages reported for lives or properties, then they have the procedure to be followed for a flood damage counteraction (Kim et al., 2007).

Figure 12: Management procedure for the flood disaster situation in case of heavy rainfall (Kim et al, 2007)

Turkey The Emergency Action Plan prepared for the Seyhan Dam located in the city of Adana, Turkey has been studied because it provides emergency procedures specifically prepared for a scenario revolving around a dam failure. Among measures to be followed to minimize property damage and loss of life, importance is given to preparation of inundation maps, formation of warning systems, and especially organization of evacuation plan.

As shown in figure 13, the evacuation routes, the time of transportation and the safe zones should be determined ahead for the safe evacuation of the people.

Figure 13: Flood inundation area and evacuation routes to safe zones in Adana (Gazioglu et al., 2014)

Contingency Plan

Sverresborg. The main focus for the contingency plan will be on the extreme scenario, in order to prepare for the worst-case prognosis.

Scenario Based on the given scenario explained initially, the situation has been detailed and divided into a neutral, moderate and extreme scenario. Table 1 shows the similarities and the differences between the three scenarios, and table 2 the possible damages, respectively.

All three scenarios take place in springtime with heavy rainfalls, as well as snow and ice melting.

In both the moderate and extreme scenario, the current urban drainage system cannot cope with the amount of water runoff. In addition to the heavy rainfall, the worst-case scenario includes a dam failure, meaning that the dam mechanism in Theisendammen is blocked, preventing the water from exiting the reservoir in the designed watercourse towards Ila, shown in figure 14. Instead, the water is predicted to overflow and leave the pond in the direction of Sverresborg (see figure 15 and figure 16). In this case, both the increased spring precipitation and the water from Theisendammen will flood the streets of

Based on the aforementioned GIS study (Stenvik, 2011), the group decided to focus on Breidablikkveien and Osloveien, as the most vulnerable settlements, public transportation and cultural values are located along or in connection to these two roads, as shown in figure 17. Byåsen Butikksenter, Åsveien school and the roundabout at the end of Breidablikkveien are considered as the most vulnerable public structures along the estimated flood ways. As the water is flooding down towards Nidelva, it could gather at the lower points, interrupting important parts of the infrastructure, like the metro bus, the tram line and the train line. Additionally, several other public services could be affected indirectly, such as Sverresborg church, the sports facilities and Trøndelag Folkemuseum Sverresborg. High amount of water discharged into Nidelva could cause inundation in other areas down the river, like St. Olav’s Hospital. The topography of the area and major damages caused by previous floods were also taken into consideration when defining the most vulnerable areas for this scenario.

Table 1: Similarities and differences of the three types of scenarios

Scenario and influence factor

Neutral

Moderate

Extreme

Heavy rainfall: Due to extreme weather

Yes

Yes

Yes

Spring: Snow and ice melting

Yes

Yes

Yes

Drainage system: Sufficient capacity

Yes

No

No

Dam failure: Blockage

No

No

Yes

Table 2: Possible damages for the three different scenarios

Neutral

Moderate

Moderate

No critical consequnces

•

• • •

•

• •

•

Reduced transportation accessibility Overloaded urban drainage system Basement flooding Disruption of public services Hinderance in mobility, education and business Economic loss

• • • • • • • • •

Infrastructural collapse Collapse of the urban drainage system Significant property damage (houses, cultural heritage, businesses) Isolation and shutdown of public services and business Lack of supplies of basic goods to Sverresborg Very high economic loss Normal life disrupted for the city overall River pollution/Sea pollution Quick clay slides down by Nidelva Flooding of Nidelva Loss of livelihoods Loss of lives

Figure 14: The location of the dam failure mechanism and the estimated waterflow, Theisendammen

Figure 15: Estimated direction of the water when overflowing the pond, Theisendammen

Figure 16: Steep terrain down Breidablikkveien and into the neighbourhood of Sverresborg

Figure 17: The area assumed to be inundated in the extreme scenario

Response Strategy This contingency plan aims to increase the resilience of the neighborhood around the vulnerable area, while accepting the low probability of the possible hazard. Therefore, the vision is to control and embrace overflowing water from the dam throughout the area so that the transportation system, the daily life of the inhabitants, their properties and businesses, and certainly their health and safety are not affected.

In responding to the worst-case scenario, the strategies that will be used are divided into

two solutions that can be implemented in different time frames. The ultimate goal is to turn Sverresborg into an area resilient to floods, through infrastructural interventions. However, since it takes time to construct them, it is important to have an emergency response to deal with the potential flood event in the meantime.

Emergency Response in Sverresborg will follow some of the key points of the cases of South Korea and Turkey, which are progressive responses, public participation, and evacuation plan. As for the Long-Term Physical Interventions, infrastructural developments can be done to cope

Figure 18: Flooding management procedure in case of dam failure

with and lessen the impact of overflowing water from Theisendammen, inspired by the case studies in Denmark and Australia.

Implementation Plan Emergency Response Figure 18 illustrates the progressive emergency response procedure. The actions are listed according to each emergency status, and they will be enacted depending on how critical the situation is.

In the earliest stage, there are two actions that need to be performed continously throughout the following stages: monitoring the weather, to forecast possible heavy rainfall, and monitoring the dam water level. If there is a rapid increase

in the dam’s water level from rainfall or snow melting, the next stage needs to be enacted.

In the Readiness stage, the residents will get notifications about the current condition and the possible upcoming hazard in order to gain awareness. This could, for instance, be in the form of SMS or other predetermined information sharing platform. At the same time, an official team with a purpose of managing flooding situations, prepares to patrol the vulnerable areas that have been determined by the flood mapping.

If the current drainage system water continues to increase, the process will move on to the Warning stage. Participation from the inhabitants will be needed in order to get more accurate data, meaning that communication with the residents must be maintained. A flood-fighter

team will need to prepare and bring flood control equipment to the site. This can be a temporary wall to control flood stream (figure 19) and/or door barriers (figure 20).

In case the dam fails, the next stage, Closure, will be enacted. For this stage, temporary equipment is expected to be distributed. Activities, such as businesses and education will be closed, and the public transit route will be assigned to alternative routes. In this stage, families in vulnerable houses can evacuate the area by private vehicles or by service vehicles, provided by the flood-fighter team or AtB. Figure 19: Temporary lightweight wall to control flood stream (Screenshot from Noaq Flood Protection AB, 2014)

In case the water level keeps increasing and the flood equipment is no longer keeping the water away, Evacuation needs to be implemented. As shown in figure 21, three different public buildings can be assigned as evatuation meeting points for the vulnerable area around the flood stream: Byåsen butikksenter for the upstream area near the dam, Åsveien school/Åsveihallen in the middle area, and Byåsen Disability Housing for the houses near Nidelva. These three meeting points can be temporary meeting places before families are evacuated out of Sverresborg.

Figure 20: Door barrier for preventing the water to enter the house (The Blue Pages, n.d.)

Figure 21: A map of evacuation meeting points and alternative route for the bus

Physical Implementation Infrastructure can alter and control the water flow behavior, building up the capacity of the area to respond to the dam failure, while still remaining in a functional state. Similar to the case of South East Queensland, Australia, a framework of physical interventions adapted to the varied landscapes is proposed. The integrated system is aiming to direct the water from the dam to Nidelva is organized in three steps, shown in figure 22.

Green streets are proposed for the adjacent roads, which combine small scale channels and stormwater planters. The road section is slightly sloped, so the water is directed to the edges, and then channeled towards Breidablikkveien.

At the same time, the planters collect and store the water, delaying the time it reaches the main street (American Society of Landscape Architects, n.d.).

Figure 22: Three Steps Strategy

1. Delay The initial aim is to decrease the velocity and volume of the water going from the dam towards the built-up area. In order to achieve this, a secondary reservoir will be built in proximity to Theisendammen, to create flood storage capacity. Some of the water will furthermore be held back and slowed down through buffers in the form of vegetated keylines.

To store higher amounts of water, retention areas are proposed along the streams, in the form of floodable parks or water squares for hard surfaces.

The most important characteristic of these interventions is their dual factor. They protect the area not only from a potential dam failure flooding, but also from general rainfall flooding. Furthermore, they improve the quality of the urban spaces while incorporating recreational functions (The Source, 2016).

2. Embrace The water will make its way through Sverresborg following three streams shown in figure 23, combining underground and surface level solutions.

The structures shown in figure 24 are able to adapt to the presence of water, absorb, store and direct it. Green stormwater infrastructure plays the key role in this. Breidablikkveien becomes one of the main streets channeling the water by turning into a stormwater greenway. Swales on both sides of the street will lead the water towards the river, and also filter, temporarily store and absorb a proportion of it (SuDS, 2020). Permeable pavement is used for the hard surfaces to direct the water away from them. Drainage capacity is increased through stormwater pipes, which further carry water underground (The Source, 2016).

Attention is paid to protection of private property as well. In this regard, vegetation of the property lines to slow water flow and usage of flood resilient materials for building facades are proposed.

3. Dispose Several areas in proximity to Nidelva are composed of quick clay. This has been taken into consideration, while deciding the streams’ location. They have been directed away from these regions to avoid triggering a landslide (Kansas Geological Survey, 1999). When not able to do so, piles and retaining walls are proposed to be designed as a solution (figure 24).

Floodable areas will be additionally constructed nearby the river, in order to spread the volume

Figure 23: The three streams

Figure 24: Retaining wall with tiebacks and buttress beams (adapted from Kansas Geological Survey, 1999)

Figure 25: Breidablikkveien interventions

of water disposed in Nidelva over time, because immense amounts of water can cause inundation further downstream. Experts will need to pay attention to the water quality drained in Nidelva. Infiltration system have proposed in order to avoid pollution of the river.

Operational support plan To carry out the contingency plan, different stakeholders need to cooperate. Figure 26, based on the Stakeholder Mapping, shows the most

important stakeholders involved in this contingency plan and the relationship between them.

The given scenario has a disaster management authority, which in this case would be the Disaster Management Authority of Trondheim municipality. One of their most important tasks is coordinating the different stakeholders (both within and outside of the municipality), and creating a communication and warning system, as well as distributing information together with the online newspaper, Adresseavisa. Urban planners and

landscape architects can develop and design the physical preventative measures together with water and wastewater engineers, as well as direct their implementation. Monitoring Theisendammen as a part of the preparedness plan is also one of the tasks of the municipality.

NVE is another major stakeholder in case of a flood. Their role is essential for the implementation plan, as they map vulnerable areas and contribute with physical preventative measures. Furthermore, the Meteorological Institute will be developing weather alerts, helping Trondheim municipality predict the severity of the flood, and prepare which actions and stakeholders need to be activated.

In case of evacuation, Åsveien school, Sverresborg church and Byåsen Disability Housing work as meeting points or provide close-by shelter. Byåsen shopping center can provide food and supplies if needed. Volunteer groups, like Trondheim Red Cross and the Scout’s Emergency Response Group Trøndelag, will contribute with notifying the inhabitants about the possible scenarios before the flood event and

help them evacuate during the flood. As shown in figure 26, emergency services will also be able to help the residents in case of emergencies, and they will coordinate relief efforts. Depending on how severe the situation is, flood-fighter teams can be formed by the Norwegian Home Guard and the Civil Defense, to keep the inhabitants safe and help with evacuation. AtB can provide transportation of larger groups of people in case of evacuation.

Preparedness plan The following preparedness plan shown in table 3 is based on the implementation plan and therefore divided into Emergency Response and Long-Term Physical Interventions. The preparedness plan involves identifying organisational resources, determining roles and developing procedures and planning for quick and efficient respond for whenever a disaster should occur. These measures improve quality and effectiveness of a response to disaster (IFRC, 2000).

Figure 26: Operational support plan

Implementation Plan

Preparedness Plan Emergency Response • •

Monitoring system and alert system

• •

Updating and observing meteorological data Assigning the committee responsible for the dam functionality Improving the monitoring system with new updated technology Examining and improving the existing warning system

Flood fighter team

•

Establishing the flood fighter team by the Disaster Management Authority

Information sharin platform

•

Deciding on a platform for sharing information from the Disaster Management Authority to the inhabitants

•

Researching and consulting with engineers and flood experts Identifying the equipment to be used Identifying the stakeholders to distribute them to the flood fighter team and the residents

Flood control equipment (temporary flood wall and door barriers)

Evacuation plan

• •

• • • •

Updating the flood map to the latest condition by the Disaster Management Authority and NVE Consulting with water engineers Planning evacuation route and shelters Coordinating stakeholders responsible for the evacuation

Long Term Physical Interventions Building secondary reservoir

• • •

Building green stormwater infrastructure

• • • • • •

Construction of the floodable parks

• • • • •

Private property protection (floodproof materials and property line vegetation)

• • • • •

Designing and consulting with landscape architects/urban planners and water and civil engineers Selecting the construction company Initiating construction Road mapping Designing the interventions appropriate at different roads by the landscape architects and engineers Selecting the construction company Selecting the committee inspecting the process Mapping alternative routes for the construction process period Initiating construction

Locating possible areas Designing the interventions by the team of landscape architects and engineers Selecting the construction company Selecting the committee inspecting the process Initiating construction

Mapping to identify vulnerable areas and buildings Discussions with landscape architects and engineers to identify and design the necessary solutions Informing the inhabitants about possible measures and actions they can take for protection Discussions about subsidy provision for floodproof materials Distribution of plants for property line vegetation

Table 3: Preparedness plan

What

Physical Implementation

Emergency Response

Measure

Main Response

Price Range

· Flood proof materials

· Engineers

· Vegetation of property lines

· Urban planners

I

· Secondary reservoirs

· Engineers

III

· Floodable parks and water squares

· Urban planner/Engineer/ Landscape architects

II

· Green streets

· Landscape architects/ Urban planners

II

· Stormwater greenway

· Engineers

II

· Quick clay solutions

· Engineers

I

· Monitoring Theisendammen

· NVE

II

· Weather forecasts and alerts

· Meteorological institute

I

· Distributing information

· Local newspaper and other platforms

I

· Public alerts/notifications

· Trondheim municipality

I

· Assisting with evacuation

· Trondheim Red Cross and Scouts emergency group

I

· Shelters/meeting points

· Trondheim municipality (Åsveien school /

II

I

Åsveihallen and Byåsen Disablity Housing) and Sverresborg church center

Urban Drainage System

Transport/Mobility

· Flood control equipment

· Engineers

II

· Stormwater pipes

· Water and wastewater engineers

III

· Open stormwater channels and swales

· Water and wastewater engineers

II

· Infiltration systems

· Water and wastewater engineers

I

· Transporting inhabitants to shelter

· AtB

I

· Redirecting the traffic

· Police

I

Table 4: Budget

Budget The financial aspects are critical in managing disasters, as they create a solid foundation for fast recovery, resilience and mitigation for a potential disaster.

For the study of Sverresborg, spatial interventions will require a significant amount of monetary resources.

In the Norwegian State Budget for 2020, the government has granted a total of 1.135 billion NOK to NVE, where 337 million NOK of this is specifically assigned for flooding, landslides and similar disasters (Statsbudsjettet, 2020).

However, in this contingency plan it is chosen not to provide economical calculation in specific numbers. Instead, the measures in the budget will be divided into three price ranges, differentiating between the cheaper and the more expensive measures. The three price ranges are: Low cost (I), medium cost (II) and high cost (III).

Discussion and conclusion The given scenario about floods due to heavy rainfall, combined with substantial resources and a disaster management authority, is quite realistic for the city of Trondheim. This made finding data and background information and understanding the interrelation between the different stakeholders an easier process.

However, there are many assumptions that had to be done throughout the different parts of the contingency plan. After choosing an area, the given scenario was further developed and detailed, resulting in the dam failure hypothesis. The group wanted to look at a unique scenario despite the lack of tactile data and previous experience with dam mechanisms. This brought the challenge of drawing conclusions and making assumptions regarding several elements, such as the direction of the water exiting the dam reservoir, the spread of inundation in the area or the damages caused by the different levels of the scenario. The assumptions were based on previous flood events, case studies and Stenvik’s GIS study, however there is room for inaccuracies.

Moreover, the group was not able to find a lot of data and information on existing safeguards and security measures regarding the south-eastern part of Theisendammen. It was difficult understanding if preventative measures already have been done in Sverresborg, which could have affected the Implementation Plan. Regarding the Physical Interventions, collaboration with experts would be needed to understand possible side effects of the

proposals, and how they will be accomplished in practice. While taking inspiration from the Case Studies, it is considered that the same solutions might not work out in similar ways in a different context. Further expertise would have also been needed for the Budget, which was challenging to concretize with numbers. Therefore, the group chose to propose three categories of financial value for the different elements of the contingency plan, which can also be considered as a source of inaccuracy.

Due to COVID-19, the group project had to face additional challenges. Digital meetings resulted in less in-depth discussions and more individual work.

Furthermore, due to safety reasons, the group was not able to meet potential stakeholders, or conduct meetings with the inhabitants. Communicating with inhabitants through virtual means was considered.

Unfortunately, the group was not able to find an online platform, such as a Facebook group for the area of Sverresborg. Therefore, the group chose to focus on technocratic approaches and the infrastructure in Sverresborg.

Concluding, this work confirmed that a contingency plan is not easy to develop, and it requires much interdisciplinary knowledge regarding the different stages, strategies and implementations. Working on this project has given an insight on how complex such planning is. At the same time, acquiring more knowledge about this topic has highlighted the importance of a contingency plan as a preventative measure.

Figure 27: Aerial photos of Sverresborg

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Unless otherwise stated, the figures and tables are produced by the authors.