Flood risk management strategies in Europe
Pooja Shankar
Mat Nr: 3303937
ABSTRACT: Catastrophic floods endanger lives and cause human tragedy as well as economic losses. Floods area natural phenomena but through right measures can reduce their likelihood and limit their impacts. In addition to social and economic damage, floods have a severe impact on the environment, for example when installations holding large quantities of toxic chemicals area inundated or wetland areas are destroyed. The coming decades are likely to see a higher flood risk in Europe and greater economic damage. To support the transition from traditional flood defense strategies to a flood risk management approach to a basin scale, Europe has adopted a new Directive in 2007 (2007/60/EC). One of the major tasks of these directives is where the member states involved in carrying out flood risk management plans. To comply with the directives, mapping of flood hazards and risk in each territory is necessary which forms the basis of flood risk management plans. This paper gives an overview of detailed functions off stages of a flood risk directive with respective illustrations and the measures taken to accomplish the EU wide regulation for flood risk in Europe.
KEYWORDS: Flood risk cause and types, EU wide regulation, EU directives strategies, and measures.
1. INTRODUCTION
Floods are among the world's most frequent and damaging types of a disaster which affect the lives of millions annually all over the globe. Over time with population growth and climate-related factors aggravated by urbanization, the social, economic and political processes have increased. This would continue to increase the human exposure and its vulnerability to floods in future. Nevertheless, the social, scientific and legal studies on the transboundary flood risk management are rare, fragmented and limited in scope. At the same time, the collaborative measures and strategies for transboundary floods i.e., floods that originate in one country and then propagate downstream to another are poorly understood. In general terms, a flood event is generally where water temporarily covers land outside its normal confines. Whereas, flood risk is a possibility of loss, damage or any undesirable scenario and has two components: (1) Probability of an event occurring (2) Impacts associated with the event. This paper aims to explain the EU directive step by step plan, process and its measures undertaken to mitigate the prospective flood risks which Europe could face.
2. CAUSES FOR FLOODING
Flooding is normally caused by natural
events such as prolonged excessive rainfall and thunderstorms over a short period of time, high tide combined with storm conditions, ice jams and poor insufficient drainage networks and inadequate maintenance of watercourses. The reason behind these causes can be explained under three categories as follows:
2.1 Overflow due to heavy rains:
After heavy rain, the river bursts its banks and the water engulfs the entire valley far from its precipitation zone. The other tributaries add to the flow of water causing a flood event.
2.2 Water accumulation in basins:
In normal weather conditions, water is absorbed into grounds and merges with the water table. When the ground is saturated, the water builds up in low line areas. Runoff quickly fills the valley in heavy rain condition resulting in a flood.
2.3 Urbanization in flood-prone areas:
Excess water passing through drainage system accumulates in low line zones. It is now in bad shape due to excessive land use, coverage of land due to buildings and impermeable surface like concrete.
3. TYPES OF FLOODING
Although flood itself is a unique phenomenon, it is further classified into different types based on their causes, namely:
3.1 Coastal flood or surge flood:
As the name suggests, coastal floods occur in areas which lie in the coast of the sea, ocean or other large bodies of open water. It is typically a result of extreme tidal conditions caused by severe weather. These are produced when high winds from a hurricane and other storms push water onto the shore. This is often the greatest threat associated with a tropical storm. The severity of coastal flood is determined by various factors which include strength, size, speed and the direction of the storm. To determine the probability and magnitude of a storm surge, the coastal flood models consider this information in addition to data form historical storms of the affected area along with the density of nearby development.
3.2 Fluvial flood or river flood:
This type of flood occurs when excessive rainfall over an extended period causes a river to exceed its capacity. This is also caused due to snow melts and ice jams. The damage from river flood can be widespread as the overflow affects smaller river downstream often causing dames and dikes of rivers to break open and swamp the adjacent areas. The severity of river floods is measured by the amount of precipitation in an area, duration of the precipitation, previous saturation records of soil and the terrain surrounding the river system. The flood water accumulation depends on regions. In hilly areas, floods can occur in minutes after a heavy rain whereas in flat areas flood water rises slowly and often remain for days. To determine the probability of river flooding, it is necessary to consider the past and forecasted precipitation, current river levels, and temperature.
3.3 Pluvial flood or surface flood
Surface water flood is caused when heavy rainfall creates flood event which is independent of an overflowing waterbody. It is commonly believed that one must be near a waterbody to be at risk. Pluvial flooding debunks the myth, as the urban areas are also prone to flooding. Intense rain saturating urban drainage system and runoff water from rain on hillsides that are unable to absorb water are few examples. Pluvial flooding generally occurs in combination with coastal and fluvial flooding. These floods are capable of significant property damage.
4. EUROPE FLOOD HISTORY
Catastrophic floods cause human tragedy, endanger lives and bring heavy economic losses. In addition to social and economic losses, these floods also have severe environmental consequences, for example when installations holding large quantities of toxic chemicals are inundated. Since 2000, floods in Europe has resulted in at least 700 deaths, displacement of about half a million people and approximately EUR 25 billion in insured economic losses. The following figure shows the flood impact in Europe from 1950-2005.
Figure 1: Major flood disasters in EU, Bulgaria and Romania 1950-2005
Numbers in the map represent each flood event. During this period 3539 floods of all types occurred globally, of which 298 of them took place in the current EU member states. This cost around 5500 lives and resulted in about US$ 106 billion in damage. 01-23: being flush floods, 24-44 being river floods and 45-47 which is storm surge floods. The triangulated features on the map represent very large regional events.
5. EU WIDE REGULATION
Throughout the centuries Europe has suffered many floods and urban planning is serious and a growing challenge. The coming decades are likely to see a flood risk in Europe and greater economic damage. Fluvial flooding is the most common type of flood in Europe. The following figure represents the recurrence of a flood in Europe between 1998 and 2005.
Figure 2: EEA based on a global archive of recurrence flood events
Certain areas are more affected than others. Between 1998 and 2005 north-western Romania, south-eastern France, central and southern Germany, northern Italy, and eastern England experienced the highest concentration of repeated flooding.
Many measures are undertaken like constructing rive dikes and using sandbags. But these are just measures to avoid and encounter flooding up to an extent. For the estimated probability of prospective flood events, thee measures do not suffice to reduce the impacts associated with floods. Hence EU flood risk directives came into existence in 2007.
6. EC FLOOD RISK DIRECTIVE
Directives 2007/60/EC, assessment and management of flood risk or also called Flood risk directives entered into force on 26 November 2007. Unlike a regulation it does not set rules on how the objective must be achieved, which means the directives does not set any priority. Each member state (MS) can set a goal collaboratively and decide what national measures are needed. This gives the MS lot of room to choose their own approach. The flood risk directives work in coordination with the water framework directive. Flood action programme where the Flood risk management plans and the river basin management plans are coordinated through Public participation procedures. These reinforce the rights of the public to access flood risk information and to have a say in the planning process.
Figure 3: Flood risk directive existence
7. EC FLOOD RISK ACTION PLAN
The FD requires that wherever a significant flood risk is identified, maps must be drawn to show its potential extent and consequences of flooding. Based on the maps generated, the MS's must establish a Flood risk Management plan with an aim to reduce the risk associated with an acceptable level. Within this plan, a wide range of measures is considered to achieve the goal, which is dependent on the nature and scale of the issues. To aid this process, the FD has a 3-phase approach. The detailed action plan measures are explained in the following phases:
Figure 4: Three phase FD action plan
Phase 01: Preliminary flood risk assessment
This is the first stage of FD where a preliminary flood risk assessment must be conducted by MS's for each river basin districts. The task to be completed by 22 December 2011. The assessment conducted is based on available or readily derivable information such as records and studies based on long-term developments. However, the assessment of potential adverse consequences for future floods, which cannot be derived from the floods in past is optional. According to Art 13.1, the FD has an exception to this obligation. The MS’s may not undertake the flood risk assessment under two cases:
1. The areas for which MS’s have carried a risk assessment and concluded before 22 December 2010, that a potential can be expected or exists.
2. The areas for which MS's had decided before 22 December 2101, to prepare flood risk maps, flood hazard maps, and Flood risk management plans.
The preliminary risk assessment must be reviewed and to be updated if necessary by 22 December 2018 and further subjected for reviews every six years thereafter.
Phase 02: Development of flood hazard maps and flood risk maps
The second stage is the drafting of flood hazard maps and flood risk for the areas where there is a potential flood risk. This must be completed by 22 December 2013. The flood hazard maps show the probability of flooding and hydrological situation of a flood event whereas the flood risk maps identify the adverse consequences of floods. The flood hazard maps cover the geographical area which could be flooded according to floods with low probability or extreme event scenarios, floods with medium probability (whose return period is likely ≥100 years), floods with high probability where appropriate.
Figure 5: Conceptual framework of flood hazard maps and flood risk maps
Maps with flood extents and depths are
considered as the most important parameters when it comes to mapping flood hazards. However, other parameters such as velocity, duration, propagation, the rate of rising water are also important depending on the region. For instance, there are maps which shows the rate at which water rises in Austria and Luxembourg for which the flow velocity is mapped. Similarly, in Hungary and the Netherlands propagation maps of flooding polders are created for the entire territory. Shown below is an illustration of different parameters for flood mapping:
Figure 6: Flood map types considering different parameters.
a.) Historical flood map.
b.) Flood extent map.
c.) Flood depth map
d.) Flood danger map.
e.) Qualitative risk map.
f.) Quantitative (damage) risk map.
Maps showing other parameters always relate to a single return period, as it is practically not possible to depict say, for instance, velocities of several return period on a single map. De Moel et al. (2009) point out that several countries have good starting points to map their national flood hazards, but that very few countries have maps that include detailed information on the consequences of flooding. Maps currently available are mostly used for emergency and spatial planning, but flood zones in these maps serve mainly as guidelines. Where it is legal to regulate floodplain, development using flood zones (France and Poland for instance) the practical problems encountered limit the mitigating effects of such binding legislation.
In addition, producing flood risk maps is expensive and is dependent on the data available. As a result, the ability to produce flood risk maps differs significantly between different countries due to knowledge, availability of technical infrastructure to collect data, modeling and mapping and financial resources.
Phase 03: Flood risk management plans
These plans must be completed and published by 22 December 205 and be reviewed, if necessary updated by 22 December 2021, every six years thereafter. The MS must establish Flood Risk Management plans for each river basin district. The basis of the plans should be provided by the flood hazard maps and the flood risk maps. In the Flood Risk Management plans the MSs must establish “appropriate objectives for the management of flood risks†for the areas with potential significant flood risks. The focus hereby must be on “the reduction of potential adverse consequences of flooding for human health, the environment, cultural heritage and economic activity, and, if considered appropriate, on nonstructural initiatives and/or on the reduction of the likelihood of floodingâ€. The measures for achieving these objectives must also be included in the plans.
Where international river basin districts (IRBDs) fall entirely within the territory of the EU, the MSs should aim to draft a single international Flood Risk Management Plan or a set of Flood Risk Management plans coordinated at the level of the IRDB , if the MSs are not able to produce such plans, they should produce Flood Risk Management plans covering the part of the IRBD located within their territory, and as far as possible coordinated at the level of the IRBD (Art. 8.2 of the FD).
8. OTHER BINDINGS
According to article 10, FD states that “In accordance with applicable Community legislation, Member States shall make available to the public the preliminary flood risk assessment, the flood hazard maps, the flood risk maps and the flood risk management plans.†The other bindings include:
1. Catchment basin approach: flood risks are to be considered for the entire catchment basin.
2. Safety chain: measures must address the reduction of risks, reducing the probability and/or consequences, crisis management and aftercare (prevention, protection, and preparedness).
3. Risk approach: objectives and measures are based on an assessment of the flood probability and the potential consequences of a flood event.
4. Sustainability: the flood risk assessment and the preparation of the flood risk management plans should consider other EU directives and the consequences of climate change.
5. Solidarity or non-transference of risk: The Member States should refrain from measures that would increase the risk of flooding in the other Member States unless these measures have been agreed upon among the Member States.
6. Recently public engagement and harmonization with WFD (water framework directive) are in place
9. CONCLUSION
There are many flood mappings in the European countries. Most of the illustrations identified in this paper were initiated in the recent decades. Even though a conceptual framework exists, there is a wide variety to create flood hazard and risk maps. Flood extent maps are the most commonly used flood maps, produced in about 80% of the countries. As risk has a broad definition, and various methodologies to quantify between different countries, this could lead to a wide variety of risk maps which will be difficult to compare. This creates a problem while setting up management plans. However, few countries in Europe must make a step towards hazard maps as most of the other countries comply with EU Flood Directive (2007/60/EC). There are 69 transboundary catchments in Europe. With climatic changes an increasing urbanization, it is more prone to have flooded in the future. To mitigate the impact level in a short period of time, it is necessary to have directives or its jurisdiction from each country. The way flood management is approached is therefore strongly dependent on national approaches, which will say the least decrease in the speed of harmonization of Flood Risk management in Europe.
10. REFERENCES