Flooding in Western Ukraine: Causes, Lessons Learned, and Potential to Avoid Harmful Future Effects
Posted on 29.09.2020
On 12-26 June 2020, the deterioration of weather conditions and large volume of atmospheric precipitation in the Transcarpathian, Chernivtsi, Ivano-Frankivsk, Lviv and Ternopil regions of Ukraine caused sharp rises in the water level of rivers and flooding of territories. Adverse weather affected 300 settlements, damaging over 14,000 dwellings and destroying or partially destroying 940 km of roads and over 300 bridges. According to preliminary estimates, the total amount of direct material damage is UAH 1.5 billion.
The team of the Global Environment Facility’s Dniester Project, which is being implemented by the UNDP, OSCE and UNECE in Ukraine and Moldova, has talked to Kostiantyn Danko (KD), Head of the Laboratory of Flood Risk Assessment and Management, the Ukrainian Hydrometeorological Institute of the State Emergency Service (SES) of Ukraine and the National Academy of Sciences of Ukraine (UkrHMI), and to Kanstantsin Tsitou (KT), Senior Researcher, the Central Research Institute for the Integrated Use of Water Resources (CRIIUWR) of Belarus, and learned why Ukraine failed to fully prevent the effects of floods in June 2020 and what should be done to mitigate the devastating effects of such emergencies in the future.
What is the main cause of flooding and why can’t it be completely prevented?
KT: Following the historical tradition, people have always lived and conducted their economic activities near water, so there have always been floods. They are natural phenomena which cannot be prevented. One needs to understand that the floodplain area of all rivers is a temporarily flooded area. The problem is that humans can partially make things worse while living in an area that is flooded from time to time. Farming in coastal areas can aggravate the effects of the disaster and to some extent accelerate the flooding process, while the lack of information about a potential deterioration of meteorological conditions or its underestimation makes locals unprepared for the effects of flooding.
Currently, Ukraine uses the principle of integrated water resources management, which involves taking into account all types of water resources within the boundaries of river basins and their use, as well as involving all stakeholders, including the public, in decision-making. Also, along with the efforts to improve and maintain the proper condition of aquatic ecosystems, it is necessary to take into account the factor of flooding and its adverse effects on the population, environment, cultural heritage, and economic activities.
Can we say that regulations on water conservation areas and riparian zones have been violated on a large scale in Ukraine?
KT: No, since people are not prohibited from living near water, and water conservation zones are often developed without regard to possible flooding zones. The EU approach says that people living near water bodies should be properly informed about possible risks and decide for themselves whether or not such risks are acceptable to them. Additionally, territorial land management agencies also carry out outreach activities and inform about possible hazards for certain structures, buildings, dwellings, etc.
KD: If the terrain of the river valley allows for economic activities to be carried out comfortably, then settlements will most likely be established along such river banks. In this case, flooding of areas by river waters does not come as a surprise for residents of the settlements. Living near the river, they are familiar with the nature of river flooding and with the possibility of rising water levels. While working on the Dniester project, we communicated with locals who witnessed the disastrous floods in 1941, 1969, 2008 and 2010, and for them such events have become part of their life.
KT: By the way, nowadays, corporate and private property insurance for properties located in the areas with a high risk of flooding is becoming relevant everywhere.
What should be done to mitigate the effects of flooding?
KT: Most importantly, it is necessary to change the thinking paradigm and the approach of government authorities to water resources management. Unfortunately, many people perceive flood control only as flood mitigation. However, the clearing of areas, the purchase of pumping stations for pumping water, the delivery of drinking water to the population and the allocation of funds to restore dwellings are not the actions that will help avoid such disaster in the future. A global approach is to conduct a flood risk assessment for each river basin area. Since flood risk management is time-consuming and costly, it should be dealt with only where this problem is urgent.
KD: When it comes to specific measures, then, first, it is necessary to increase the carrying capacity of riverbeds, especially small ones, which have suffered from clogging, and also to revise, where possible, the width of the inter-dam space in order to expand it. Second, it is necessary to inform people about possible emergency. For some settlements located on river banks, even 30% of the monthly precipitation rate is almost a 100% guarantee of flooding. Thus, the up-to-date information on the amount of precipitation provided by the Hydrometeorological Centre can directly help warn the population about the potential of flooding. Additionally, Ukraine now has a possibility of developing an early warning system based on automatic hydromet stations, most of which are located in the basin of the Tisza and the Dniester rivers. Such network of automatic hydromet stations enables to warn the population in advance about the danger of potential flooding by informing about the amount of atmospheric precipitation, the intensity of precipitation, the intensity of the water levels rises in rivers, etc.
Essentially, the idea is that everyone who wishes to do so can go online and see data about the water level, the speed of the water flow at a certain gauging station, about the danger of area flooding, etc. However, for this to be done, it is necessary to perform a number of complex calculations and modelling of the water flow and flooding of areas under various scenarios, at the preliminary stages of the development of such a network.
Has a flood risk assessment been carried out in Ukraine?
KT: This process is currently underway. A preliminary flood risk assessment in Ukraine was carried out by the joint efforts of the EU APENA project, the GEF Dniester project and the Ukrainian Hydrometeorological Institute (UkrHMI). As a result of such work, areas of potential significant flood risk were identified throughout the country in the areas of river basins. The most dangerous are the Danube, the Dniester, the Tisza, the Prut and the Seret river basins. One has to understand that all rivers can overflow, but if this phenomenon does not have adverse effects on the human life and health, environment, cultural heritage and economic activities, such flooding is not a problem and does not need further research.
KD: Such flood risk assessment is only the first step toward a broader objective of developing a Flood Risk Management Plan. After identifying the areas at risk of flooding, it is necessary to carry out mapping under various scenarios, sometimes the most extreme ones. Consideration is given to flooding scenarios with the probability of occurrence once every 10, 100 and 500 years. In this context, two types of maps are being developed – flood hazard maps and flood risk maps. The latter create an understanding of the scale of potential effects on human life and health, infrastructural and industrial facilities, cultural heritage, and nature. It is on the basis of such maps that a government planning document – a Flood Risk Management Plan – is prepared. This document should contain flood risk management objectives for a specific area, as well as a set of flood risk prevention measures.
What measures exist to prepare for emergencies?
KT: A common feature of all emergencies is the lack of time for planning as it is necessary to act immediately. Therefore, the main point in preparation is the coordination of actions of local authorities and the State Emergency Service in responding to an emergency. Generally, there exists a unified integrated approach – awareness of the situation in a potentially dangerous area, understanding of the nature and scale of the hazard, a fully prepared response plan with a clear distribution of roles and functions, and the availability of mitigation tools. Unfortunately, today we see only the last component being actively implemented.
What are the engineering means of flood protection?
KT: Europe is already moving away from the practice of building permanent dams due to their high cost and complexity of technical placement. In order to preserve the landscapes, locals also often oppose dam construction, being supporters of the approach “Informed is forearmed.” Temporary flood protection dams, which can be built as a construction kit for a period of high water levels in rivers, are becoming popular.
The principle of “give water more space” is effective, thus ensuring the free flow of water. This can be achieved through the renaturalization of riverbeds and adjacent floodplains (automatic restoration of rivers to their natural state), improving the floodplain’s natural ability to retain water. This method helps restore the watercourse after its drainage and deepening.
The main “non-engineering” measure is to warn the population. If on plain rivers the water rise is not rapid and we have a day to alert the population, then on mountain rivers it is hours at the most. However, on the other hand, it is possible to forecast a flood situation based on the predicted amount of precipitation in a given area and on the basis of the data from automatic hydromet stations that measure the water level in rivers in an automatic mode. Next, using hydraulic modelling, we can formulate a more or less accurate forecast for areas downstream. As such, the alerting of the population is a function of the State Emergency Service, but it should also be based on the hydrometeorological information of the Hydrometeorological Centre and the hydraulic modelling results.
KD: another “non-engineering” measure is to work with local authorities in order to minimize settling in particularly dangerous areas and prevent clogging of watercourses.
It is also necessary to educate the population to develop behavioural skills in the event of an emergency (for example, brief advice in the form of leaflets in English, Ukrainian or Romanian — author’s note).
How do you assess the condition of protective structures?
KD: During the preliminary flood risk assessment, we met with local water sector experts. The first thing we noticed is that there are very few such structures. During the recent flood, overflows and destructions of dams were recorded, which also indicates that the dams do not cope with their protective functions.
KT: Again, according to the EU approach, engineering measures, especially in mountainous areas, often cannot fully protect the area and save the situation. The water level in rivers can rise by more than 10 m, the speed of the water flow easily destroys bank protection structures. Dams can overflow and burst.
Can deforestation be named as one of the main reasons for flooding in Ukraine this year?
KT: Afforestation is one of the main measures to mitigate the adverse effects of waters worldwide. Forest, shrubs, grass allow the floodplain to absorb water more efficiently and reduce the flow rate. Of course, deforestation in the catchment area worsens the flood situation, but this cannot be said to be the main cause of flooding.
Is climate change also an indirect cause of flooding?
KD: The main manifestation of climate change in terms of flooding is a change in the recurrence intervals of very high floods. For example, the floods in 1998 and 2001, in terms of height of the water level rise, corresponded to the recurrence probability of once every 10 years. However, the high floods recurrence interval of three years casts doubts even on statistical methods for assessing the occurrence probability of these natural hydrological phenomena. The floods that occurred in 2008, 2010, 2019 and 2020 only confirm this trend. Floods are often the result of sudden, prolonged rains. Amid climate change, we observe a tendency towards an increase in the frequency of such precipitation, its amount and intensity. Therefore, the situation speaks for itself.
What are you working on under the GEF Dniester project?
KT: We are developing a draft first national flood risk management plan for the Dniester River Basin, which may serve as a model for the development of similar plans for other potentially hazardous areas. We have already conducted a preliminary assessment of the risk of flooding in the Dniester river basin in Ukraine, identified 103 rivers with a total length of 4303 km, for which there is a significant potential risk of flooding. Currently, within the framework of the GEF Dniester project, we are developing detailed flood hazard maps and flood risk maps for the following rivers: the Opir River in the Lviv Region, the Bystrytsia, the Bystrytsia-Solotvynska, the Bystrytsia-Nadvirnianska rivers in Ivano-Frankivsk Region and the Kuchurgan, the Turunchuk, the Dniester rivers in Odessa Region. A series of electronic flood maps, which will be available to all the stakeholders, are planned to be presented by November 2020. Further, we would like to develop a flood risk management plan for these areas including measures to reduce the risks of flooding and the adverse effects of waters.
Another issue of interest in the flood risk management topic is the role of hydropower plants (HPPs) in reducing and preventing the disastrous effects of flooding. Thus, according to Mykhailo Khoriev, Deputy Minister, Ministry of Environmental Protection and Natural Resources of Ukraine, the role of the Dniester HPP during the June floods should not be underestimated. It is thanks to the Dniester reservoir, which was involved in cutting the peak of the flood, that it became possible to save the riparian areas downstream – in Vinnytsia region, the Republic of Moldova, and Odessa region. At that time, the inflow into the reservoir was about 4000 m3/s, while the discharge did not exceed 2000 m3/s. According to Mr. Khoriev, if the amount of discharge was greater, the flooding of cities such as Mohyliv-Podilskyi and Yampol, the Republic of Moldova, as well as the Odessa-Reni highway would be inevitable.
According to Liudmila David, Head of Civil Protection Department, the General Inspectorate of Emergency Situations, the Ministry of Internal Affairs of the Republic of Moldova, the information about the planned increase in discharges from the Dniester HPP, which was provided in advance by Ukrainian colleagues, gave them time to make decisions to prevent the flooding of certain areas. The expert believes that it is necessary to continue and strengthen bilateral cooperation in water resources management between countries. According to Ms. David, the establishment of the Dniester Commission should contribute to this process.
Petro Kropotov, Chief Specialist of the Emergency Prevention Department, the State Emergency Service of Ukraine, confirmed that a number of measures have been taken to inform the Ukrainian and Moldovan sides about the hydrological situation in the Dniester River basin as part of the implementation of the Work Plan of the Working Group on Emergencies of the Dniester Commission, the SES, the UkrHMC, and the UkrHMI. The information included hydrological hazard assessments for the Dniester basin rivers, hydrological forecasts and forecasts of water discharge from the reservoir and at gauging stations. Mr. Kropotov said that the UkrHMC of the SES of Ukraine regularly provides central and local authorities with hydrometeorological forecasts.
Besides, Ukrainian and Moldovan emergency management authorities, in cooperation with interested central and local authorities, are actively working on the implementation of Directive 2007/60/EC of the European Parliament and of the EU Council on the assessment and management of flood risks. In addition to the preliminary flood risk assessment described above in the interview, the experts are developing a legal framework in accordance with EU standards. More detail about this work will be provided in the next following materials.
The flood risk management plan for the Moldovan part of the Dniester basin has been prepared by experts from the Italian company BETA Studio, with financial support from the European Investment Bank. The GEF Dniester Project supports the development of the flood risk management plan for the Ukrainian part of the basin. The structure and the development of the future Plan are coordinated with the Moldovan colleagues. The GEF Dniester Project is also working on a joint draft document of Moldova and Ukraine, which will provide a summary of flood control measures for the transboundary sections of the Dniester river basin.