Environmental Values: the Dunajovický and the Kos˘átecký Stream Catchments, Czech Republic

Abstract

Based on research of the river landscape, spatial variability of environmental values and their changes over time, it is possible to identify parameters which are in some way involved in the formation of runoff processes. In this paper the issue of the natural values disturbances in an environment of watercourse and its floodplain is solved on the example of two model sites. These are the lowland catchment areas of small watercourses in the Czech Republic. On basis of the map visualization of collected data, the authors deal with interpretation of the landscape spatial pattern within the context of its ecological stability. To analyze the areas, series of maps are used in the appropriate scale showing the selected indicators related to the environmental values. These indicators are a combination of the field research results and information gathered from the available data sources. The space is devoted to the analysis of relationships between selected environmental indicators of spatial character and their impact on the state of the river network. Analyzed are the consequences of human activities in the riparian zone of watercourses, with regard to the phenomenon of the river continuum degradation and changes in other hydrological variables that may affect the overall security of the floodplain area.

Keywords:

• environmental value
• map
• river landscape
• small watercourse
• ecohydrology
• Czech Republic

1. Introduction

The term ‘environmental value’ represents a comprehensive summary of the information reflecting the current status of the monitored environment, shaped by natural and anthropogenic processes. The acquired information can be also used as a suitable indicator of the nature of the human approach to the affected ecosystem and its spatio-temporal development. These are values which characterize the individual components of studied ecosystems; on the basis of these studies we can make suggestions on the potential health status of the environment. For comparability (and objectivity) of the data collected, it is appropriate to use values which may be expressed quantitatively. The river landscape as an environment in permanent contact with the watercourse, very sensitive to any changes in external input conditions, is a suitable area for research of environmental values. According to Štěrba et al. (2008) it is a landscape which exists in absolute dependence on the river, mostly made up of alluvial deposits that represent the ecosystem created or substantially conditioned by the river. The river landscape is also very often distinguished from its surroundings by a number of specific functions and services, as well as the typical landscape character. The response to changing conditions comes in the form of changes to the default fluvial environment parameters, which adapt to new conditions – most frequently it is a change of channel morphology, riparian zone, nature of the vegetation or hydrologic variables. For a correct understanding of environmental landscape value and its importance, it is appropriate to start from the ‘ecosystem approach’ which perceives humans and their activities as an integral part of the given system (Grumbine, 1994). It follows that apart from knowledge of natural ecosystem components and how they function, an important part of the approach is that human impact should also be considered (Kay, Boyle, Regier, & Francis, 1999). Kay and Schneider (1994) note that these are the components of interaction between human society and the physical environment which should be managed, not just the environment. Therefore it is appropriate to the models within an ecosystem approach to incorporate human activities; human relationship with the natural environment is understood as a way of interpreting and managing a problem (Day and Hudson, 2001).

This paper presents research on ecological features of the riverine environment and the conditional intensity of anthropogenic degradation with emphasis on the issue of modifications in the hydromorphological parameters of the stream channel and its inundation area. Study of the fluvial environment has traditionally involved a quality assessment of conventional approaches to the river system based on hydrobiological and hydrochemical methods. Although these practices are irreplaceable, for example during the process of determining the degree of surface water pollution, the incomplete use of any information obtained on the studied environment is a disadvantage. By combining data obtained through classical approaches and their proper interpretation it is possible to acquire additional indirect information about the characteristics of the studied sites and conditions of their development. Since this project combines both ecology and hydrology (the riverine environment is analyzed within the meaning of an ecosystem understanding of the landscape), it is termed ‘ecohydrology’. Rodriguez-Iturbe (2000) defines ecohydrology as a science that aims to describe the hydrological mechanisms, forming the basis of ecological principles and processes. According to Zalewski (2002) ecohydrology may be understood as a new approach to ensuring sustainable water management. Nowadays it is a dynamic expanding branch of science with the potential for use in the application sector, which is also indicated by the position of ecohydrology as a ‘hotspot’ of many international research projects (Liu et al., 2009).

Apart from the information about the functions and services of local physical processes, research on changes in the riverine environment also provides data about the socio-economic consequences, which are usually in particular relation to the state of the landscape. The search for the nature of these mutual relations between the natural and human components of the landscape represents the current trend, to which for example UNESCO's Ecohydrology Programme is dedicated. According to Hiwasaki and Arica (2007) an important prerequisite for research of the ecohydrological issue is the need for an association of concepts and methodologies from a wide range of scientific disciplines – from environmentally oriented to the social sciences, in order to incorporate multidisciplinary findings obtained under the project.

The paper presents selected results of comprehensive research into environmental health indicators concerning the state of the river landscape in the hinterland of small watercourses. An important part of the research has focused on an analysis of the hydromorphological properties of the streams in lowland areas. The results indicate a dependence between the degree of anthropogenic pressure on the river landscape and the prevailing state of the watercourse. Sites with potential for developing extreme hydrological situations or an increase in damage have been identified. All results are presented with the Main map which is annexed.

2. Methodology

2.1. Study areas

Research on the character of environmental values in the river landscape was carried out within two catchments in the Czech Republic (see overview map shown in Figure 1). Both of the study areas are located in the fertile lowland plain; each of them has different environmental conditions which affect the character of hydrographical network. The areas are also different in terms of specific cultural and socio-economic variables involved in the formation of landscape structure. With regard to forms of land use (see the Main map), these are similar areas (particularly in terms of representation of individual land use categories and their general range), yet a number of differences may be identified, mainly related to landscape and stream management practices.

Figure 1. Location of the selected catchment areas.

The first study area is the catchment of the Dunajovický Stream located in the Dyje-Svratka River Valley in Southern Moravia, about 40 km south of the city of Brno. This is a small catchment of approximately 30 km², drained by the Dunajovický Stream and several very small tributaries. The stream has its source at an altitude of about 210 m asl and after 9.2 km empties into the upper reservoir of the Nové Mlýny Dam (171 m asl), located on the Thaya River. At the mouth of the stream the average flow rate amounts to only 0.03 m³ s⁻¹. The Dunajovický Stream drains sedimentary rocks and is located in a broad, well-developed floodplain, characterized by a low gradient. Intensive agricultural use of the catchment and associated occurrence of numerous channel stream modifications is typical – especially the straightening, shortening and technical adjustment of the lateral profile. In the studied catchment area several rural settlements with less than 3000 inhabitants are located. While the catchment is located on the border of the Pálava Protected Landscape Area (see Miklín, 2012), it is characterized by uniform land use in the form of arable land, which occupies more than 60% of the watershed area.

The second study area is in the Košátecký stream catchment, Mělník Region, in the fertile landscape of the Elbe lowland, about 30 km northeast of Prague. This elongated catchment with an area of 218 km², reaches slightly higher levels of geodiversity, caused by the presence of several different landscape types. Besides the main channel of the Košátecký stream (right tributary of the Elbe River) the selected catchment area is drained by a number of further sub-tributaries. The studied drainage basin includes low-lying and flat areas in its southern half, typical for positions within the wide Elbe floodplain. The northern half of the basin is characterized by a moderately rolling landscape of platforms and hills, with watercourses embedded into a relatively deep valley. The whole basin is an intensively cultivated agricultural area, with a long history of land use. The high level of land degradation significantly modifies the hydrological regime of local watercourses, which are characterized by a significantly different appearance from a relatively natural state. A direct impact of the watercourse management, non-sustainable farming in the watershed landscape and long-term collection of groundwater has seen significant shortening of the permanent water stream during the last century (from more than 40 km of length to only 21 km at present). The catchment area has a total of 21 settlements with about 12,000 inhabitants.

2.2. Data sets and mapping procedure

For implementation, the analysis of environmental values requires a wide range of data that corresponds with the requirements for a multidisciplinary approach to studying the landscape and its dynamics. In the present study various types and different scales of data have been used, depending on the nature of the analyzed processes. The first group of data represents the results of a detailed field survey, focused primarily on the mapping of the variability of morphological parameters in the longitudinal profile of selected watercourses. Secondly, during fieldwork additional information related to the anthropogenic pressure on environmental values of the river landscape were collected – particularly modifications to the runoff characteristics caused by the presence of potential barriers to flow. Variables affecting the volume of runoff were also mapped in the form of river water sampling points or major wastewater inputs (usually in the presence of industrial or agricultural production).

The latter group of data represents information received indirectly, mostly through the analysis of aerial images or maps at a large scale. Many authors propose the use of historical maps for research of the landscape (e. g. Pătru-Stupariu et al., 2011; Skokanová et al., 2012; Bender et al., 2005; Jeleček, 2002; Milanova et al., 1999). The validity of the information discovered was subsequently verified by field research. These findings are primarily related to prevailing floodplain or riparian zone utilization, extended with additional information describing the character of river bank vegetation. The historical development of the drainage network has also been observed, particularly with regard to the dynamics of channel patterns and the related total length of watercourses or river network density in the area of interest. Historical maps have been used, from which an approximate extent of the landscape modified through the presence of watercourses can be indentified.

During the study, all the watercourses in the selected river basins were subjected to field research – i.e. including dried or only periodically active parts of the watercourses. In the predefined profiles, uniformly distributed throughout the catchment area a total of 24 parameters were mapped, describing important phenomena for direct or indirect influence on the hydromorphological characteristics of the channel. The geometric parameters of the channel (e.g. water level width, width of the channel or its recess) were surveyed using a laser rangefinder, while for evaluation of the other mapped properties (e.g. variability and structure of the bottom or type of the bed substrate) expert estimates were used. Based on the data, the watercourse network of the selected catchment area was divided into a number of sections, which are characterized by relatively homogeneous environmental properties. For such defined segments the average value of all parameters analyzed within each profile were calculated. These values represent the set of the input data for calculating a series of indicators, which quantify the environmental status of the fluvial environment.

Local scale information was used for researching the relationship between the variability of the morphology of the watercourses and the consequences on hydrological variables. These results are also used for subsequent study of the process dynamics taking place over the whole catchment area. The multi-scale study provides a method of protection against the loss of important information which cannot be reported on by research carried out at a single scale (Vaughan et al., 2009). According to Phillips (2005), within the context of environmental research of hydromorphological change, it is appropriate to reveal patterns of individual processes ‘across scales’, so as to facilitate the development of recommendations at large scales relevant to management.

2.3. Data processing and analysis

For this research several tools for expressing hydromorphological and environmental degradation were used. The application of a broad spectrum of tools across multiple scientific disciplines, in combination with an application to the model area, represents a relatively innovative approach to the study of river landscapes.

The key indicator exploited in the framework of this paper for expressing the degree of degradation of natural values is the channel maintenance index (CMI). This is a utility, which reflects the most important impact on runoff processes. From the original analytical indicators mapped in the field, synthetic indicators were subsequently derived, representing a summary of the intensity and structure of the river network maintenance. The CMI is defined as:

where T_T is maintenance of the stream route, T_L is maintenance of the longitudinal profile, T_B is maintenance of the channel and T_N indicates the condition of the riparian zone. The CMI can take values between 0 and 5 where 0 indicates the state closest to natural. Calculation of these components is described in Langhammer (2007). The scores were assigned to the intensive indicator categories according to the tabular summaries, provided in the process of evaluating the collected data using the ‘ASTRA’ methodology (Langhammer, 2007). The values of CMI for each stream section were subsequently compared with results of the ecological stability coefficient (ESC), expressed for the area of the riparian zone along the stream (i.e. a distance of about 50 m from the edge of the channel) and also for the whole catchment area (see the Main map). To calculate the ESC a modified version of the original formula defined by Míchal and Buček et al. (1985) was used (as a ratio of ecologically stable and unstable landscape elements), accompanied by expertly specified environmentally significant values of the various cultures (Miklós, 1986). The higher the environmental significance value of culture reached, the more ecologically superior the culture is. The ESC is defined as:

where p_n represents an area of individual culture, K_pn is the coefficient of environmental culture significance and p is the size of the area of interest. Higher values of the coefficient indicate a higher ecological stability of the area and a better state of environmental value. Average values of ESC in the Czech Republic are between 1.0 and 2.5. An overview of the expertly defined coefficient of the environmental culture values for individual land use patterns is shown in Table 1.

Table 1. Coefficient of the environmental culture values for each land use pattern.

Land use	Arable land	Meadow	Pasture	Garden	Orchard	Forest and water area	Built-up area
kpn	0.14	0.62	0.68	0.50	0.30	1.00	0.10

Significant attention has been devoted to the comparative case study research, particularly for morphological parameters of watercourses and anthropogenic impacts. Based on a long-term study of hydromorphological processes and their variability, the group of selected indicators was identified, clearly associated with the kinds of human activity in the river landscape. The most important of these is the difference between water level width (the width of long-term normal water level) and bankfull width (the width of the channel is considered to be the distance between edges of the opposite stream banks) in the longitudinal profile.

It is realistic to interpret the stream segments with low differences between channel and water level widths as sites with higher ecological value. These are locations characterized by lower amounts of anthropogenic stream channel modification (i.e. a relatively good longitudinal stream throughput, lower values of channel recess and no sign of bottom and bank modification). In the riparian zone and whole floodplain, environmentally stable land cover types prevail (mostly forest, shrub and permanent grassland), arable land and built-up areas are minor. The opposite case are segments with very different values between the width of the water level and stream channel characterized by an artificially ‘cocked’ channel, very low depth variability in the cross section and extensive bottom and bank modification (usually stone or concrete pavement). In terms of predominant riparian vegetation there is common occurrence of isolated dominant tree species or discontinuous brush belts. Floodplains here are valuable and used extensively for agriculture. Generally, the following sections may be considered to be very extensively modified parts of watercourse; the most different from the potential natural state of the environment.

Environmental values of the river network related to geometric parameters of channels were further analyzed by calculating the channel capacity coefficient (CCC) as a suitable measure for the identification of the level of degradation conditioned by human activities. Spatial variability of the coefficient can also give evidence about the degree of risk of flood inundation. The channel capacity coefficient is defined as:

Weighting the evaluated categories was performed by expert estimate, based on the anticipated intensity of flow characteristics affected, which results from the structural, morphological and positioning properties of these phenomena (e.g. orientation and dimensions of obstacles, the terrain and inundation area parameters, etc.). The main criteria for expert estimation were the dimensions of each object within the watercourses, which may affect flow characteristics. Furthermore, it was also the distance of these objects from the channel, and the value of risk associated with a potential overflowing of water in the floodplain. A list of weights for potential flow barriers in the mapped catchment area used for calculating the channel capacity coefficient is given in Table 2.

Table 2. Weight sessions for various potential flow barriers in the channel.

Observed phenomenon	Undersized bridge [A]	Barrier in the channel [B]	Reduced channel capacity [C]	Inundation area reduction [D]	Unsuitably situated buildings [E]	Alternation of artificial and natural channel [F]
Weight	1.5	1.2	1.4	1.3	1.0	1.1

3. Results and conclusions

Major anthropogenically conditioned variables that modify runoff processes in the rural, lowland countries of the Czech Republic were analyzed. For the purposes of this study the hydromorphological characteristics of water courses and properties of the whole catchment were analyzed in terms of land use and identification of environmentally stable landscape segments (see the Main map). Both watercourses and land use types were analyzed for temporal evolution using historical maps and data sources. Both study areas are similar in terms of the intensity of human pressure on the hydrographical network, however, significant differences can be identified in the diversity of input conditions. It is particularly the character of relief that affects land use and anthropogenic inputs. By studying partial processes at a small scale, the predominant type of relief from micro to regional scale units may be regarded as a fundamental variable. From the socio-economic sector, the nature of runoff processes should be most influenced by the presence of built up areas in the inundation zones. Intensive land use patterns (e.g. arable land, etc.) that have a negative effect on landscape retention capacity are also reflected. By using selected measures the spatial pattern of variables which directly indicate the status of environmental values were identified. Based on the analysis of map outputs the locations with significance for maintaining ecological stability can be detected. On the other hand severely degraded areas can be identified where it would be useful to consider a change in human approach to the landscape. Human activities are one of the other signs in the spatial configuration changes of watercourse channels. This factor is analyzed within the paper using maps of spatio-temporal channel pattern evolution.

Software

Map design and data processing were performed using ESRI ArcGIS 10.0 software.

Acknowledgements

The research was carried out within the CzechGlobe Centre that is being developed within OP RDI and co-financed from the EU funds and the State Budget of the Czech Republic (project: ,,CzechGlobe – Global Change Research Centre“, Reg. No. CZ.1.05/1.1.00/02.0073). The authors also acknowledge financial support of the project ,,Partnership Climate“, Reg. No. CZ.1.07/2.4.00/31.0056 and the project of specific research – GlobE (MUNI/A/0902/2012), solved by Department of Geography, Masaryk University.