Abstract

The aims of this paper are to present knowledge about the threat of flooding in the upper basins of the Myjava River, obtained using a questionnaire, and to identify the potential lessons for flood risk management. The questionnaire was designed to obtain information about households' experience with flooding, including the type of floods experienced, the locations of flooding, the exacerbating factors contributing to flood risk that they considered to be important and their proposals to minimise the occurrence of flooding. Findings obtained using the questionnaire suggest that: (i) in the upper basins, sheetwash flooding is as important as river flooding and the assessment of flood hazards should include all significant types of flood hazard; (ii) flood risk management in the upper basins should primarily focus on the systematic maintenance of small watercourses and on eliminating local factors that increase the risk of all types of flooding. The building of structures for flood defence should be seen as a last resort when other options are not effective.

Introduction

The approach to solving the issue of flooding has changed in recent decades. It has gradually shifted from traditional flood protection by purely technical measures, to integrated flood risk management (c.f. Brown & Damery, 2002; Plate, 2002; Sayers et al., 2002; Werritty, 2005; Liao, 2014). Due to a change of paradigm in flood risk management, the understanding and assessment of flood risk is also changing. Flood risk assessment, which is based on an integrated approach, emphasises the idea that ‘in evaluating disaster risk, the social production of vulnerability needs to be considered with at least the same importance that is devoted to understanding and addressing natural hazards’ (Wisner et al., 2004). Flood risk is thus no longer considered only as the probability of flooding but also includes ‘the expected loss (of lives, persons injured, property damaged and economic activity disrupted) due to a particular hazard for a given area and reference period’ (United Nations (UN), 1992). Integrated flood risk management, in contrast to the engineering approach, is based on several principles, such as adopting a basin approach to flood management, bringing a multi-disciplinary approach to flood management, reducing vulnerability and risks due to flooding, enabling public participation and preserving ecosystems (Associated Programme on Flood Management (APFM), 2004).

Traditionally, the decision-making in flood management is largely a top-driven engineering-oriented process with little or no public participation. The objectives of public participation in integrated flood management are as follows (APFM, 2006):

  • Provide all stakeholders with full opportunities to share their views and influence the outcome.

  • Build consensus and public support for the outcomes.

  • Build stakeholders' commitment.

  • Ensure implementation of basin flood management plans with full public support.

  • Ensure sustainability of plans and associated decisions.

  • Build resilience of flood-prone communities.

The public is generally divided into several groups (APFM, 2006): (i) government ministries, departments and agencies; (ii) flood-prone communities; (iii) other basin communities; (iv) scientific institutions; (v) registered non-governmental organisations; (vi) voluntary organisations; and (vii) the private sector. However, as mentioned in APFM (2006), full involvement of stakeholders in all decision-making stages is neither realistic nor useful in any given situation. In the participatory process each stakeholder category has a specific role to play and the level of involvement of each stakeholder, depending on the given institutional framework, differs and should be clearly defined.

Flood-prone communities (e.g., households and agricultural or forestry businesses) are considered to be the major stakeholders. Active participation in flood risk management is expected mainly from the communities living in the upper basins (sub-basins of the main river). This is because of their abilities to change the local land cover and land use and their knowledge of the local factors underlying the occurrence of flooding in the headwaters area. In light of this, the experiences of communities living in the upper basins associated with flood hazards are very important and the compilation of this experience is one of the first steps of good flood risk management. The questionnaire has become a widespread means of obtaining information about how different stakeholders perceive flood hazards (e.g., Thieken et al., 2007; Posthumus et al., 2008; Petrolia et al., 2013; Poussin et al., 2015).

The research presented here is based on data obtained using a questionnaire. This survey investigated flooding experienced by households located in upper basins, as well as their ability to cope with the negative impacts of floods and their views on the mitigation of flood risks. A survey of households in six municipalities located in the headwaters area of the Myjava River was conducted during the summer of 2015. Michaleje et al. (2016) presented some of the results of this survey, relating to the perception of flood risk and the legislative framework for public participation in the management of flood risks. The aims of this paper are to present the lessons learned from the questionnaire regarding flood risk in upper basins and to identify the relevant information that they provide for flood risk management.

Characteristics of the study area

The upland area of the upper Myjava basin is located in the north-western part of Slovakia. It has an area of 181.51 km2, which includes the territories of six municipalities: Brestovec, Stará Myjava, Myjava (including the settlement of Turá Lúka, which is now the town district of Myjava), Podbranč, Sobotište and Vrbovce (Figure 1).

Fig. 1.

The Upper Myjava basin (Source: ZB GIS © Geodesy, Cartography and Cadastre Authority of the Slovak Republic, 2015).

Fig. 1.

The Upper Myjava basin (Source: ZB GIS © Geodesy, Cartography and Cadastre Authority of the Slovak Republic, 2015).

The total population of these municipalities in 2015 was 17,344. The total may be broken down by municipality as follows: Brestovec = 945; Myjava = 12,042; Podbranč = 600; Sobotište = 1,485; Stará Myjava = 733 and Vrbovce = 1,539. Settlements within the municipalities are sparsely distributed, which is a typical feature of this region. The basins of the upper part of the Myjava River are characterised by a high risk of flooding (Solín, 2008, 2011). The geology of the area is mainly composed of flysch rocks, such as sandstone and clay marlstones, which have a low permeability. Stankoviansky (1997) and Stankoviansky & Frandofer (2011) studied the geomorphological manifestations of drainage, fluvial and gravitational geomorphic processes (rill and gully erosion, muddy floods and landslides) in this area.

The axis of the river network is the River Myjava, which flows through Stará Myjava, Myjava and Podbranč. In its upper part it is joined by important tributaries, mainly from the right-hand side looking downstream (the Brestovecký, Svacinecký, Smíchovský and Teplica Rivers). The Teplica flows through Vrbovce and Sobotište, while the Brestovecký flows through Brestovec. The Svacinecký and Smíchovský flow into the Myjava River at Turá Lúka.

The soil textures in the upper Myjava basin display very low permeability and values of baseflow index range within the interval from 0.2 to 0.4 (Solín, 2011). This indicates that direct run-off is the major run-off contribution during storm periods. As such, headwater areas in the Myjava basin are characterised by relatively high flood hazard potential. Between 1996 and 2010, the municipalities located in the upper basin of the River Myjava were repeatedly affected by flooding. Podbranč was affected by flooding eight times, Sobotište and Vrbovce six times, Brestovec four times, Myjava 11 times and Stará Myjava five times. A major flood on the Myjava River occurred in June 1999 and the centre of Myjava City was flooded. During this event, extensive damage was caused to property in the local area of Turá Lúka. Over 60 houses were flooded.

Methodology

The first step in the creation of the questionnaire was to clarify the understanding of the word ‘flood’. ‘Flood’ is traditionally considered to mean river flooding, when water starts to pour out of the river channel. The exceeding of a river's maximum capacity due to intense rainfall or snowmelt is the most common type of flood hazard. The hydrological definition of flooding confirms this (Chow, 1956):

A flood is a relatively high flow which overtaxes the natural channel provided for the runoff.’

Fast-melting snow and prolonged or high-intensity rainfall can also cause river flooding in headwater areas. However, the physical attributes of sub-basins together with the impact of local anthropogenic factors also create the conditions for the emergence of other forms of flood hazards. For instance, leaving solid waste on the riverbed, as well as neglecting the maintenance of riverbeds and watercourses, may result in various obstacles in the river channel that can slow down the flow of water, increase its level and cause flooding. In other cases, local factors, such as inappropriate land cover/land use or changes in land cover from logging, may accelerate the occurrence of flooding due to overland flow. The reduced infiltration capacity of the soil of inappropriately managed areas can prevent rainwater or snowmelt from soaking into the soil; instead it will form a thin layer at the soil surface, which, under the influence of gravity and micro-relief conditions, becomes increasingly concentrated as a powerful water flow and gives rise to sheetwash flooding. The term sheetwash as a type of erosion is mainly used in geomorphology. As an example, Smith & Ward (1998) used the term sheetwash flooding in the context of floods to express a certain type of flood in arid or semi-arid areas. However, we consider it as applicable in moderate climatic conditions for the expression of flood hazard outside the flood plain area that is connected with running water down hillslopes.

This broad understanding of flooding corresponds to the definition by Ward (1978):

A flood is a body of water which rises to overflow land which is not normally submerged.’

By definition, in addition to river flooding, areas can be flooded due to water table flooding (the groundwater table rising above the level of the ground), rainfall ponding, sheetwash flooding (the volume or intensity of rain is greater than the retention or infiltration capacity of the soil) or due to the occurrence of ice jams in the river bed (Smith & Ward, 1998).

The questionnaire used in this study is based upon this broader understanding of flooding (Table 1). The basic question was whether a household had ever been affected by flooding. If the household had been affected, other questions relating to the type and location of flooding experienced, as well as flood warnings, were asked. The survey also contained questions, which touched upon the household's awareness of flood hazards (e.g., questions about obstacles in the river channel) and what factors other than precipitation they thought contributed to flooding. The relevant information obtained from these questions was the household's opinion on the effectiveness of current technical flood protection measures and their suggestions for further mitigating the risk of flooding.

Table 1.

Questions contained in the survey concerning the research into flood risk and respondents' awareness of said risk.

1. Has your household ever been affected by a flood? Answer: YES/NO. 
2. Please indicate what type of flood it was. Answer: (i) river flooding, (ii) flooding by water from slopes, (iii) other. 
3. Please state the places that were flooded. Answer: (i) yard and garden, (ii) garage and outbuildings, (iii) cellar, (iv) inside of the house. 
4. Were you warned that a flood was expected? Answer: YES/NO. 
5. Do you think that technical measures (e.g., construction of water reservoirs, polders and channel modifications) are sufficient to reduce the risk of flooding? Answer: YES/NO. 
6. Have you observed any obstructions (building material, waste, wood, etc.) in the watercourses that flow through your town that slow down or prevent the flow of water? Answer: YES/NO – if yes, describe the obstruction. 
7. What do you consider, in addition to long-term or very intense rainfall and rapid snowmelt, contributes to the frequent occurrence of floods in your community? Answer: (a) heavy clay soil, (b) deforestation, (c) inappropriate land use, (d) poor choice of crops, (e) deforestation caused by logging, (f) obstruction of bridges over the watercourses, (g) overgrown and unkempt channels, (h) polluted channels, (i) storing inappropriate material on the river bank, (j) other – give an example, (k) do not know. 
8. Do you have any suggestions for further mitigating the risk of flooding? Answer: describe your suggestion. 
1. Has your household ever been affected by a flood? Answer: YES/NO. 
2. Please indicate what type of flood it was. Answer: (i) river flooding, (ii) flooding by water from slopes, (iii) other. 
3. Please state the places that were flooded. Answer: (i) yard and garden, (ii) garage and outbuildings, (iii) cellar, (iv) inside of the house. 
4. Were you warned that a flood was expected? Answer: YES/NO. 
5. Do you think that technical measures (e.g., construction of water reservoirs, polders and channel modifications) are sufficient to reduce the risk of flooding? Answer: YES/NO. 
6. Have you observed any obstructions (building material, waste, wood, etc.) in the watercourses that flow through your town that slow down or prevent the flow of water? Answer: YES/NO – if yes, describe the obstruction. 
7. What do you consider, in addition to long-term or very intense rainfall and rapid snowmelt, contributes to the frequent occurrence of floods in your community? Answer: (a) heavy clay soil, (b) deforestation, (c) inappropriate land use, (d) poor choice of crops, (e) deforestation caused by logging, (f) obstruction of bridges over the watercourses, (g) overgrown and unkempt channels, (h) polluted channels, (i) storing inappropriate material on the river bank, (j) other – give an example, (k) do not know. 
8. Do you have any suggestions for further mitigating the risk of flooding? Answer: describe your suggestion. 

Researchers distributed the questionnaires in June and July of 2015 to all households in the area of interest (a total of 3,025 households). The exceptions to this were households in the city of Myjava, where delivery was organised by the municipal office. In many cases, direct contact was therefore made between the respondent and the researcher and a personal interview allowed the respondent to clarify certain issues. Municipal mayors gave advance notice to residents about the survey and organised handing over questionnaires to the municipal offices.

The spatial visualisation of responses was an important aspect of the questionnaire analysis. To be able to spatially locate the households affected by river flooding and sheetwash flooding, each questionnaire was assigned a registration number identifying the family house to which the questionnaire was delivered. Processing of the survey results was carried out using a Geographic Information System (GIS). The basis for spatial visualisation of the results was the ZB GIS database created by the Geodesy, Cartography and Cadastre Authority of the Slovak Republic. The database contains more than 150 land cover classes. Two further attributes (i.e., the name of the municipality and address point) provided by ErasData-Pro, Ltd were assigned to the object class ‘buildings’ with the attribute ‘houses’.

Results

A total of 3,025 questionnaires were distributed and 690 completed questionnaires were recovered (i.e., the response rate was 22.8%) (Table 2). This response rate corresponds with the results of similar studies based on surveys; for example, Ludy & Kondolf (2012) reported a 23% response rate, and Hopkins & Warburton (2014) reported 20%. One of the most common reasons why people were unwilling to return the questionnaire was that they did not feel threatened by floods and thus felt that the questionnaire did not concern them. There were also cases where households that had been affected by flooding several times did not return the questionnaire. The reason for this non-submission was a lack of confidence that the questionnaire would solve anything. On the basis of personal interviews with these residents, it can be said that this lack of confidence was due to the reluctance of state and local governments and insurance companies to solve problems related to flooding.

Table 2.

Numbers of distributed and returned questionnaires.

Town Number of distributed forms Number of returned forms Percentage of returned forms 
Sobotište 465 117 25.2% 
Vrbovce 465 123 26.6% 
Podbranč 212 79 37.3% 
Brestovec 304 88 28.9% 
Stará Myjava 256 78 30.4% 
Myjava + Turá Lúkaa 1,323 205 15.5% 
Total 3,025 690 22.8% 
Town Number of distributed forms Number of returned forms Percentage of returned forms 
Sobotište 465 117 25.2% 
Vrbovce 465 123 26.6% 
Podbranč 212 79 37.3% 
Brestovec 304 88 28.9% 
Stará Myjava 256 78 30.4% 
Myjava + Turá Lúkaa 1,323 205 15.5% 
Total 3,025 690 22.8% 

aIn the following sections, the results obtained for the towns of Myjava and Turá Lúka are presented separately.

The results of the survey are summarised in three parts: experiences with flooding, awareness of flood risk and proposals for flood protection measures.

Experiences with flood hazard

From the 690 returned questionnaires, 274 respondents (households) (i.e., 39.7%) said that they had been affected by flooding. Figure 2 shows the percentage of respondents who were at risk of flooding, separated into individual municipalities. The majority of households were at risk of flooding in Turá Lúka and Stará Myjava (60% of households surveyed). In other municipalities, the number of respondents who were at risk of flooding was 30–40%. Respondents were asked when the flooding had occurred (month and year), although in many cases they could not give an exact answer, or gave no answer at all. Therefore, this aspect of flood risk is not included in the results.

Fig. 2.

Percentage of households affected by flooding.

Fig. 2.

Percentage of households affected by flooding.

Flood alert is an important element in protecting against flooding. The share of households in individual municipalities that said they were warned of the occurrence of floods is relatively low and does not exceed 30% (Figure 3). It is possible that some households did not register warnings (members of the household were not at home or did not hear the warning if it was issued at night) and may state that they were ‘unwarned’ due to objective motivations and, thus, this may not be solely attributable to the authorities responsible for flood protection. Especially in the case of local ‘flash’ flooding, whereby the onset of flooding is rapid, issuing a spatially accurate and timely warning is challenging.

Fig. 3.

Flood warning of respondents who experienced flooding.

Fig. 3.

Flood warning of respondents who experienced flooding.

In the case of households that had experienced flooding, there were two important aspects to consider. The first is the type of flooding and the second is the place that was flooded. Flood due to river flooding is significant in four municipalities (Vrbovce, Sobotište, Podbranč and Stará Myjava), where 40–60% of respondents had been affected (Figure 4). In the remaining three villages (Turá Lúka, Myjava and Brestovec) a significant number of respondents (more than 40% of households) in each municipality claimed to have been affected by sheetwash flooding. Threats to households from both river flooding and sheetwash flooding were reported by up to 30% of respondents in Turá Lúka and Stará Myjava. Under the ‘other’ category of flooding, the respondents reported the presence of water in basements as a result of subsurface drain water, or water that had run off from badly sloped roads.

Fig. 4.

Types of flooding experienced by respondents.

Fig. 4.

Types of flooding experienced by respondents.

The location of houses affected by flooding and the type of flooding by which they had been affected, are shown in Figure 5.

Fig. 5.

Location of households in municipalities affected by flooding.

Fig. 5.

Location of households in municipalities affected by flooding.

The responses to the question concerning the places affected by flooding are shown in Figure 6. A relatively high percentage of households in Podbranč and Brestovec (69% and 44%, respectively) stated that they had only had a flooded courtyard and garden. In all other municipalities a high percentage of households (25–45%) reported that, in addition to the courtyard and garden, water had also flooded the basement. In all municipalities the percentage of households reporting that water had flooded the inside of the house was relatively low (10–20%).

Fig. 6.

Locations of flooding in affected residences.

Fig. 6.

Locations of flooding in affected residences.

Awareness of flood risk

Several questions in the survey addressed the issue of flood risk awareness of households in the upper Myjava basin. The first of these concerned the respondent's views on whether structural measures (e.g., the construction of water reservoirs or polders and the adjustment of river beds) were sufficient to reduce the risk of flooding. The majority of respondents in each municipality considered these risk-reduction measures to be adequate (Figure 7). However, nearly 40% of households in Brestovec, Podbranč, Sobotište and Vrbovce felt that they were insufficient.

Fig. 7.

Opinion of respondents regarding the suitability of flood defences.

Fig. 7.

Opinion of respondents regarding the suitability of flood defences.

Figure 8 shows the type and number of obstacles that respondents had observed in watercourses. In all municipalities, the most significant obstacles in the channels were tree branches, solid waste and overgrown vegetation at the bottom and on the banks of watercourses. Deposition of sediment on the beds of watercourses was considered to be more minor.

Fig. 8.

Obstacles observed by respondents in the channels of watercourses.

Fig. 8.

Obstacles observed by respondents in the channels of watercourses.

When considering the respondents' awareness of flood risk, the question of local factors that exacerbate risk of flooding is also important. Respondents were asked to choose from several factors (see Table 1) that could increase flood risk. The proportion of factors that were considered the most important in each municipality is shown in Figure 9. An interesting finding is that in all municipalities, most respondents considered that the most significant factor influencing flood risk was overgrown and unkempt river channels. This was followed by pollution of riverbeds by solid waste and the blocking of the channel under bridges by solid waste. Inappropriate land use and improper cropping patterns of agricultural land were considered to be less significant, together with storing material on the banks of rivers and heavy clay soils. The respondents also attributed little significance to deforestation and land clearance due to logging.

Fig. 9.

Factors considered by respondents to increase flood risk.

Fig. 9.

Factors considered by respondents to increase flood risk.

Proposals for flood protection measures

Respondents' opinions on the factors influencing flood risk were reflected in their suggestions for further flood risk reduction (Figure 10), although this question was only answered by one-third of respondents. They were concerned above all with the systematic maintenance of river channels (i.e., the removal of sediment, waste and invasive vegetation from the riverbed and the pruning and removal of excess bank vegetation). Another, less suggested measure was the adjustment of the channel watercourse, especially deepening (20–30% of the measures proposed). The exceptions were the respondents living in Myjava, where no proposals to adjust the channel were submitted (the Myjava River has already been modified in the central part of the town). In this town, the most commonly proposed measure was the digging of drainage ditches to collect and divert water flowing from fields on slopes, so as not to threaten human dwellings (40% of the proposed measures). Proposals for this type of action also occurred quite frequently in other municipalities (10–20% of the measures proposed), which highlights the frequency of flooding caused by running water from the fields. To reduce the incidence of this type of flooding, proposals were also made for a change in land use, concerning not only the planting of crops, but also the disruption of large monoculture areas (including grass) by planting different vegetation belts (hedges). In Figure 10 some unusual but specific proposals are not included, for example the removal of beaver dams in Vrbovce and Podbranč. Some respondents suggested to better optimise operation of the dams in Stará Myjava and Brestovec, which are built on the River Myjava, as there have been several cases of flooding caused by the sudden discharge of large quantities of water from the reservoirs.

Fig. 10.

Respondents' proposals for reducing flood risk.

Fig. 10.

Respondents' proposals for reducing flood risk.

Discussion

The current flood control infrastructure in the upper Myjava basin includes two dams on the River Myjava in Stará Myjava and Brestovec, which were built in the 1970s and 1990s, respectively, polders in Myjava and Turá Lúka (Svacenicky Brook), which were constructed in 2013 and modification and reshaping of the River Myjava channel in Turá Lúka in 2015. During 2010–2012, under the Landscape Revitalisation and Integrated Management Programme, 147 timber obstructions and 80 diversions were made at creeks and roads in the forests around the municipality of Vrbovce and a few drainage trenches were dug to collect surface run-off from fields around Sobotište and Podbranč.

According to Act no. 7/2010 and its amendments, the Ministry of Environment (MoE) is responsible for preventive flood protection in the Slovak Republic, and, through the administrator of important water courses, Slovak Water Management Enterprise (SWME), undertakes a preliminary flood risk assessment, preparation of flood hazard and flood risk maps and establishment of flood risk management plans and their continuous updating. SWME has other important tasks in the area of flood protection, in particular building, maintaining, repairing and reconstructing preventive measures for flood protection and maintaining the watercourses.

In the preliminary flood risk assessment (MoE, 2011) some sections of the watercourse in the upper basins of the Myjava River where potential significant flood risk exists or may be considered likely to occur were identified by SWME (Table 3). SWME established flood risk management plans for these sections of watercourse (MoE, 2015) and proposed to take the following measures to reduce the likelihood of floods and adverse consequences of floods:

  • construction of a water dam Sobotište on the water course Teplica,

  • construction of polder Cengelka on the Cengelka watercourse in Myjava and watercourse channel regulation,

  • construction of polder Smíchov on the Smíchov watercourse and watercourse channel regulation,

  • construction of polder Padelka on the Hukov watercourse in Turá Lúka and watercourse channel regulation,

  • construction of polder Malejov on the Myjava River and river channel regulation.

Table 3.

Sections of watercourses where potential significant flood risk exists or may be considered likely to occur.

Name of watercourse Section of watercourse
 
Length (km) Municipality 
Beginning End 
Kilometre of river 
Brestovský potok 0.0 4.6 4.6 Brestovec 
Cengelka 0.0 1.9 1.9 Myjava 
Smíchov 0.0 4.8 4.8 Myjava 
Malejovský potok 0.0 0.9 0.9 Myjava 
Teplica 21.2 23.1 1.9 Vrbovce 
Teplica 11.2 17.2 6.0 Sobotište 
Myjava 75.2 81.3 6.1 Stará Myjava 
Myjava 66.9 73.5 6.6 Myjava 
Myjava 53.5 58.5 5.0 Podbranč 
Lulov potok* 0.0 1.0 1.0 Vrbovce 
Name of watercourse Section of watercourse
 
Length (km) Municipality 
Beginning End 
Kilometre of river 
Brestovský potok 0.0 4.6 4.6 Brestovec 
Cengelka 0.0 1.9 1.9 Myjava 
Smíchov 0.0 4.8 4.8 Myjava 
Malejovský potok 0.0 0.9 0.9 Myjava 
Teplica 21.2 23.1 1.9 Vrbovce 
Teplica 11.2 17.2 6.0 Sobotište 
Myjava 75.2 81.3 6.1 Stará Myjava 
Myjava 66.9 73.5 6.6 Myjava 
Myjava 53.5 58.5 5.0 Podbranč 
Lulov potok* 0.0 1.0 1.0 Vrbovce 

* Flood risk considered likely to occur.

Proposals for flood protection should also be part of the territorial plans of municipalities that comprehensively address the spatial arrangement and functional use of land in municipalities. However, the municipalities of Stará Myjava and Brestovec have not developed territorial plans. The territorial plans of the remaining municipalities, with regard to flood protection, only provide territorial reserve for the construction of water reservoirs (Sobotište, Vrbovce) and polders (Podbranč, Myjava) and the determination of the buffer zone of land in widths of 10 m or 5 m for medium and small rivers respectively from the bank-line of watercourses. The territorial plans provide no preventive measures in forests, agricultural land (sometimes only ameliorative channels are listed) or in urban areas. In current territorial plans the line denoting the inundation area, based on which municipalities could regulate land use in riverside areas, is not drawn (MoE, 2015).

In light of the results determined via the survey of households, it is necessary to question what motivations they provide for the consistent management of flood hazards, not only in the upper basin of Myjava River but in headwater areas in general. This study reveals two important facts.

The first is that in upper basins sheetwash flooding is a very important type of flood hazard, which threatens particular locations outside the floodplain area. Therefore it is not sufficient to considered only river flooding in upper basins and a comprehensive assessment of flood hazard is required. In the management of flood hazards it is also important to take into account the application of measures to change land use and forest management, which are aimed at increasing the retention capacity of the soil, or technical measures delaying overland flow in the basin. However, despite the high proportion of households that are at risk due to sheetwash flooding, flood risk management via changes in land cover and land use is given insufficient attention in flood risk management plans and territorial plans of municipalities. In the upper basins of the Myjava River, where poor permeability of soil-substrate complex produces a high potential for flood hazard when aligned with the management of agricultural land and the character of the natural conditions of the area, reviewing and updating the first flood risk management plans is an urgent problem. They must be completed by December 22, 2021 (MoE, 2015).

A legal framework for this aspect of flood risk management has already been created by Act no. 220/2004, which states that every owner or tenant and administrator of agricultural land is obliged to carry out agro-technical measures aimed at protecting and preserving the quality and function of agricultural land and protecting it from damage and degradation. The Research Institute of Soil Science and Conservation professionally monitors the degradation of agricultural land (soil service). Soil degradation includes losses due to erosion by water. Under that Act, the owner or tenant is obliged to carry out permanent and effective anti-erosion protection of agricultural land by implementing measures that include: dedicated agricultural planting and greening, contour farming techniques, crop rotation with a protective effect, crop mulch combined with no-plough farming techniques and any other measures that are determined by the soil service, according to the degree of soil erosion on the agricultural land. Other landscaping on farmland, if it is necessary to deal with the consequences of natural disasters that have a negative impact on the life, health and property of citizens, is regulated by Act no. 331/1991. The government reimburses costs associated with land consolidation ordered by the administrative authority (usually the District Land Office) and the owner is compensated for land subject to landscaping.

The second important fact revealed by this study is that the channels of small watercourses flowing through communities are often overgrown and unkempt. The incidence of solid waste in the channels and materials dumped on the banks, together with overgrown banks, slows down the flow of water, increases its level and causes flooding. In headwaters, area flooding resulting from the impact of local factors is therefore very frequent. The systematic maintenance of small watercourses is considered an essential part of flood risk management in upper basins. The maintenance of riparian vegetation and the removal of sediment from the riverbeds are provided for under current legislation by watercourse administrators. The largest administrator of watercourses in Slovakia is the SWME, which manages 66% of streams. Other administrators are: state forestry organisations, which administer 24%, and organisations managing military forests which are responsible for 2%; 7% of watercourses are not managed at all. The municipal authorities administer only about 1% of the total length of watercourses.

There are two main reasons why small streams are overgrown and unkempt. The first is the long time interval between performing maintenance of small watercourses. Administrators of watercourses are required to carry out maintenance on small waterways around every 10 years (MoE, 2015). However, reduction of flood hazard requires that the maintenance of small watercourses is performed annually, as is the case for medium and large rivers. Second is the fact that municipalities (with minor exceptions) do not administer small rivers. The state organisations within the scope of the Ministry of Environment and Ministry of Agriculture and Rural Development SR are unable to ensure the systematic annual maintenance of watercourses. One possible solution to ensure the systematic annual maintenance of small watercourses is to decentralise their administration from government agencies to municipal authorities. Another solution is increasing the awareness of residents in order to reduce the pollution of watercourses. This is a particular challenge for municipal authorities because the solid waste in channels and materials dumped on the banks of watercourses are a result of the activities of some residents and indicate their low awareness of flood risks.

Consistent management of flood hazards requires ‘that all types of flooding should be managed coherently, thereby including sewer flooding, pluvial flooding and groundwater flooding alongside the traditional coastal and riverine flooding’ (Johnson & Priest, 2008). However, this holistic approach to flood hazard management is not considered in flood risk management plans and territorial plans of municipalities in Slovakia. This is mainly due to the fact that the SWME, which is responsible for flood protection in Slovakia, first enforces its own investments in flood risk management plans (i.e., building water management structures).

An integrated approach to the assessment and management of flood hazard requires some decentralisation of the current centralised organisational model for flood protection and legislation, which would strengthen the position of municipal authorities in flood risk management. In the present state, participation of local municipalities and other stakeholders in decision-making on the management of flood risk is not set by legislation. Local municipalities only have the opportunity to comment on flood protection measures established in flood risk management plans by the SWME. However, it is desirable to equip municipal authorities with powers that enable them to enforce proposals of flood prevention measures relating to both the maintenance of watercourses, and management of forests and agricultural land, as well as arrangement and functional use of urban space in flood risk management plans and territorial municipality plans.

Conclusions

The results of the survey presented in this paper, which took place in municipalities located in the upper catchment of the Myjava River, can be summarised as follows:

  • The percentage of households in municipalities that participated in the survey which had been affected by flooding was 30–60%.

  • The occurrence of sheetwash flooding was slightly more frequent than river flooding (36% and 32% of respondents, respectively). There are some differences between municipalities in terms of the predominant form of flooding.

  • Gardens, courtyards and cellars were the most frequently flooded sites. Flooding of the inside of houses was rare.

  • Most respondents considered technical flood protection measures to be adequate. However, a few respondents cited technical measures as insufficient to reduce the flood risk (40% of respondents in four municipalities).

  • Tree branches, solid waste, riverbeds clogged by sediments, and overgrown vegetation were the most common obstacles seen in river channels.

  • Overgrown, polluted, silted and unkempt riverbeds, along with obstruction of various bridges over waterways, are considered to be important causes of flood risk.

Two lessons can be learned from the results of this survey:

  • The assessment of flood risk in upper basins should be coherent and all significant types of flood risk should be embedded within it. It is not sufficient to confine flood risk management to river flooding only.

  • Flood risk management in upper basins should be primarily focused on the systematic maintenance of small watercourses and the elimination of local factors that exacerbate all types of flooding in the headwater area. Building engineering structures should be seen as a last resort and used where other options are not effective.

The results of the survey provided useful information about the nature of flood risk in the upper Myjava catchment, which can be used to update proposed flood risk management plans and territorial plans of municipalities.

Acknowledgements

This article was written under Project No. 2/0038/15 Flood Risk Assessment and Integrated Management on the Regional Level funded by the VEGA Grant Agency of the Ministry of Education of the Slovak Republic. Moreover, we are grateful to Zuzana Veselovská for her support in carrying out the survey.

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