Assessing The Impact Of Urban Spatial Development

ASSESSING THE IMPACT OF URBAN SPATIAL DEVELOPMENT
ON URBAN LAKES. CASE STUDY: CRAIOVITA LAKE, CRAIOVA, ROMANIA

Oana IONUȘ, Cristina ȘOȘEA, Marius STOICA

University of Craiova, Geography Department, 13 Al. I. Cuza Street, 200585, Craiova, Romania, Tel: +40(0)251-41.50.77, E-mail: [anonimizat]

Abstract

The main objective of this research is to provide a quantitative assessment of urban spatial dynamics on a urban lake in Craiova municipality. The assessment of local environmental impact is mainly focused on the consequences of the urbanization process (conversion from lakes and wetlands to urban areas) using cartographic data, spatial analyses in GIS and some methods extrapolated from landscape ecology.

This paper also explains the patterns of urban growth within the context of urban planning and economic development based on the case study of Craiovița Lake.

Above all, the spatial stress of urban expansion on Craiovița Lake is mainly dependent upon two factors: disturbance due to the current urban expansion and accessibility to the lake from inhabited areas.

In this paper, the methodology on spatial urban lake evolution was explored from the viewpoint of landscape analysis. Therefore, the main indicators are borrowed from the landscape structure analysis: isolation, accessibility, size, perimeter/area ratio, shape, degree of naturalness and degradation.

The obtained values indicate that the rapid increase of urban built-up areas was related to large-scale degradation of Craiovița Lake: isolation index – 2.16 km, high accessibility, size index – 0.14, perimeter/area ratio – 1.62, shape index – 0.07, low degree of naturalness and degradation index – 20%.

In addition, environmental impact and landscape effects of urban expansion are confirmed by the photos taken during field research.

Most important, the results of this study can provide constructive ideas and insight to urban planners, researchers and managers for linking cartographic data and the impact of urban expansion on lake areas with policy, management schemes and environmental characteristics.

Keywords: urbanization, landscape structure indicators, spatial stress, degradation, Craiovița Lake

1. INTRODUCTION

1.1. International and national framework

Human society depends on water to sustain all of life’s aspects: domestic, agricultural, industrial and recreational. In this context, a sustainable residential area is recognisableby its providing optimal living conditions but, also, by low aggression against the environment (Iojă et al., 2008). All these problems reduce the economic utility of water resources and turn them into vectors for drawing and conveying urban issues: insalubrity, overgrowth of different animal and plant species populations (mosquitoes, aquatic plants etc.), increased peripheral effects, poverty and last but not least, loss of competitiveness, economic or residential attractiveness of the area (Kuznyetsov, 2006).

As a result of a land consuming process, many wetlands have been converted into other types of land use (especially residential or commercial lands) (Bendor, 2009). Wetlands are especially vulnerable to rampant pressures exerted by urban expansion and a great extent of such areas is disappearing because their crucial value to society is not correctly evaluated during the planning process.

Thus, policy makers, scientists and environmental managers need to apply various methods and tools to understand the causes and to control the dynamics of urban landscape and environmental change (Miller & Small, 2003).

The growth of urban and suburban areas has been a dominant phenomenon all over the world. During the 20th century, the proportion of the human population living in urban areas has risen from 14% to over 50% (Platt, 1994). For the ecological health of a city, certain ratio of urban wetlands areas should be maintained.

The appropriate areas of urban wetland should be decided based on factors such as the geographical location, climate conditions and the abundance of water resources (Haifeng et al., 2011).

At the international level, there is urgent demand for scientific research to provide ecological solutions for problems related to urbanization, degradation of freshwater and movement of materials between ecosystems (Palmer et al., 2004).

In Romania and in Craiova, in particular, the slow growing tendency from 16.6 sqm/inhabitant in 1993 to 18.6 sqm/inhabitant in 2010, as it can be seen, is mainly a consequence of the decrease of the urban population (Șoșea&Popescu, 2014), and only in small amount and in the last years of the proper increase of green surfaces (INSSE data, quoted by Cârstea et al., 2013).

Lake waters offer an indication of the health of a city, as similar research regarding the quality of urban lake waters indicated in Bucharest (Cârstea et al., 2013, Pavelescu et al., 2014).

Landscape ecology is becoming increasingly connected to the research domain of sustainability science, as well as methods, tools, data, and experience, for landscape and urban planning and design (Wu, 2006). The direct methods used measure to assess the spatial stress of urban expansion on a urban lake analyze the characteristics of a regional wetland ecosystem (e.g., area, structure, function, well-being) and their change in response to urban expansion (Wang et al., 2008). In contrast, the indirect methods analyze a number of environmental indicators about a wetland ecosystem such as hydrological attributes, vegetation types and structure and urban/transport layout (Chebo, 2009).

1.2. Study area

Craiovița Lake is located in the north-western part of the municipality of Craiova, on the left side of the European road E70, Craiova – Drobeta Turnu-Severin, neighbouring the residential district of Craiovița Nouă (northwards), the residential district Brestei (in the south-west) and Nicolae Titulescu district (in the south-east) (Fig. 1).

Craiovița Lake is a reservoir built along the Cornițoiu stream between 1966 and 1967 (Bălescu, 2004). In 1975, there was a sole lacustrine basin, having an area of 21.29 hectares; in the north, safety embankments had been built for the protection of residential areas existing at the moment (Ciobotea et al., 1997). The purpose of its construction was to attenuate the impact of flood waves and implicitly, to avoid flood frequency in Craiova municipality. In 1985, the whole arrangement covered a surface of about 85 hectares, while the lake occupied 32 hectares.

In 2004, the entire area only covered about 54 hectares (Bălescu, 2004).

Starting with the 1990s, the lake underlay the sewering system whose pipes collected residual and waste waters transporting them to the cleaning treatment plant located in Făcăi (working since the summer of 2011) (Urban Development Strategy. Case Study: Municipality of Craiova, 2011).

Recenty, the development of built areas with residential function resulted in a significant decrease in water quality of Craiovița Lake. This process is largely emphasized by the poor coverage of the public sewage system (especially in the expanding neighborhood Brestei). Therefore, a large proportion of household wastewater was directly or indirectly discharged in the lake (sewer discharge of wastewater from the north-west of Craiova until 2003), contributing to water quality degradation and health issues emergency.

In present, Craiovița Lake covers a surface of 32.476 ha, made up of two unequal lacustrine basins, separated by an isthmus over which there was built a pedestrian bridge which connects Craiovița Nouă and Brestei residential districts (Fig. 2). The eastern lacustrine basin covers a larger surface where small islands covered by reed thicket can be noticed. The western basin has a smaller expansion (about 6 hectares) as compared to the south-eastern basin which has around 27.8 hectares (processed data in ArcGIS Explorer). Both basins are surrounded by reed, bulrush, willows and thus, in time, the area acquired the peculiarities of a wetland.

In the northern part of the lake, between the latter and European Road 70 the park with the same name has been fitted out (Craiovița Park) (Fig. 2). Before the 1990s, together with Romanescu Park, the Botanical Garden and Cornițoiu Park, Craiovița Lake and Craiovița Park were among the main largest recreational urban areas in Craiova (Fig. 3). Between 2000-2003, 90 species were monitored in the area of Craiovița Lake and Park (Bălescu, 2004). From a phenological point of view, the migratory birds predominated as compared to the sedentary ones.

Over the years, Craiovița Park significantly perished because of the inhabitants’ carelessness and the political misunderstandings of the authorities, its former designation as recreational area becoming almost entirely obsolete.

Figure 1. Craiovița Lake spatial aspects

(procesed after topographic map – 1979 and ortophotoplans – 2008)

Figure 2. Aerial view of Craiovița Lake

(Photo by Niță T., 2013)

Figure 3. Craiova municipality – location of main parks and lakes

(Source: Craiova city Hall, Decision 121/2013)

A virtual tour of Craiovița Lake (processed after ArcGIS Explorer), 3.28 km in length (which also represents its perimeter) confirms a minimum 79 m height of its banks in the south-western part and a maximum 85 m height in the north-eastern part (values taking into consideration the 0 level of the North Sea).

Figure 4. Distance and elevation of Craiovița Lake perimeter

(Source: ArcGIS Explorer, accessed in May 2014)

The models of urban growth in the context of urban planning and economic development are based on two indicators whose values are mentioned as examples for Craiovița Nouă residential district, because it was the main factor which had an obvious impact on the spatial dynamics of the study area over the years.

Land cover percent index corresponding to Craiovița Nouă residential district equals 48%, while land use coefficient equals 2.4% (Marinescu, 2006). These values confirm once again the development of the urbanisation process of this neighborhood, initially considered an industrial neighborhood, residence for the persons working on the industrial platform in the western part of the city (Bădiță, 2013).

As compared to the other two neighborhoods (Brestei and Nicolae Titulescu), in which maximum four-floor blocks, villas areas and two-floor houses are predominant, in Craiovița Nouă neighborhood ten-floor blocks of apartments are frequent (most of them built during 1980-1990 period). Moreover, in the years following 2000, new residential areas for social purposes have been built by the Housing National Agency in this neighborhood.

2. DATA AND METHODOLOGY

Environmental impact and landscape effects of urban expansion on Craiovița Lake were assessed based on cartographic data, spatial analyzes in GIS and methods from landscape ecology. Initially, ArcGIS Explorer was used in order to determine the dimensions of the lacrustrine basins, an ESRI product, easy and intuitive to use. ArcGIS Explorer is a GIS (geographic information system) software. Map data is organised into layers, so that we can choose which layers we want to view or query. Subsequently, we can store geographic data by importing layers in GIS environment, draw digital maps and analyse the content of the maps based on attribution data associated with the objects which make up the map.

The main objective of this analysis is to measure the spatial dynamics of Craiovița Lake using landscape structure indicators, components of the patch context (Cook, 2002; DiBari, 2007; Yuhong Tian, 2008; Iojă, 2013): isolation, accessibility, size, perimeter/area ratio, shape, degree of naturalness and degradation.

The direct observations performed on the field during the interval April-May 2014, the analysis of cartographic documents (topographic maps of scale 1:25,000, aerial images of Craiova, edition 2008, resolution 0.5 m, scale 1:5,000), the monitoring of media articles, as well as the discussions with the population, all allowed us to identify the local constraints that the protection of Craiovița Lake must take into account.

3. RESULTS

The landscape structure indicators were calculated and analyzed based on maps (urban expansion and lakes degradation) and collected data (Fig. 5, 6).

The isolation index expresses the quantification of the interconnectivity or isolation degree of the urban recreational areas. While connectivity is measured among a series of landscape elements, isolation addresses the connectivity or lack of connectivity of an individual patch (Cook, 2002). In Craiovița Lake’s case, the isolation index manifests through the value of 2.16 km, which represents the distance from the nearest recreational green area, Cornițoiu Park to point precisely. This distance varies according to one’s location on the bank of Craiovița Lake, the value we have mentioned being designated from the median part of the lake, in the area separating the western from the eastern part of the lake.

Accessibility is a simple measure of the number of physical connections of corridors or patches included within the ecological network (Cook, 2002). In what concerns Craiovița Lake, the accessibility degree is rather high, first of all due to the extension of Brestei neighborhood in its southern part, quite close to the banks of the lake and secondly, as a consequence of its delineation in the north by the European road E70 and the numerous level alleys of Craiovița Park.

The size index transposes in reality through the ratio between the lake’s area and the overall area of the neighborhoods surrounding the lake (processed data after Dolj County Department of Statistics). The value of the ratio between the area of the lake and the area of the neighborhood varies hereunder: 0.14 Craiovița Nouă, 0.41 Brestei and 0.53 Nicolae Titulescu, the lowest value registered by Craiovița Nouă confirming once again the substantial impact of land use and main economic activities within this neighborhood over the lake.

Perimeter/area is a simple ratio and it is calculated using the following formula (Cook, 2002):

Di = P / (2√Aπ), where Di is the perimeter area ratio for patch i (also referred to as patch shape index); P the perimeter of the patch; A the area of the patch.

The value of the perimeter/area ratio for the Craiovița Lake is 1.62, a value that describes the relationship between patch area and boundary length and provides useful information about the potential edge effect that may be present in a specific patch (Cook, 2002). Significant improvement in ecological values can, however, occur with reduction of perimeter area ratio.

The shape index refers to the ratio between the medium length of the lake and its perimeter. (Iojă, 2013). In order to calculate this index, we have used each part of Craiovița Lake’s length (the western and the eastern part), reporting this afterwards to the overall perimeter. In the end, the value of the shape index which resulted for Craiovița Lake was 0.07, which explains the very fragmented banks of the lake, its shape being rather irregular as a result of built-up areas extension to the detriment of natural ones (Fig. 6).

The degree of naturalness is essentially a function of the absence of human impact and represents a measure of variability from the original ecological system (Cook, 2002). Indicators of human impact on Craiovița Lake include the disruption water quality and function, disconnection from original location and form. Concurrently, the visible extension of the Phragmites communis vegetation type can be added as an aftermath (Fig. 7). Inside the eastern lacustrine basin, we have also observed that the aquatic areas (having longitudinal layout) can only communicate through sloughy parcels, which confirms the tendency of evolution towards wetland.

The degradation index of Craiovița Lake consists in determining the percentage values of aquatic and vegetation areas at the level of the overall lake surface. (DiBari, 2007; Iojă, 2013). As observed in Fig. 5, the eastern basin of the lake is highly affected by the eutrophication process, therefore, implicitly, the vegetation areas have extended considerably. In what concerns Craiovița Lake (32.476 hectares), the aquatic areas only represent 6.5 hectares, which solely represent 20% of the total area.

These results at the landscape structure indicate that the intensity of various landscape changes increased due to rapid urbanization.

Figure 5. Degradtion of Craiovița Lake through abatement of aquatic areas (Source: ArcGIS Explorer, accesed in May 2014)

Figure 6. Morphometrical elements of Craiovița Lake (perimeter, length and width) (Source: ArcGIS Explorer, accesed in May 2014)

Figure 7. Aquatic areas and vegetation in the west lacustrine basin of Craiovița Lake: A, B

(Photo by Stoica M., April 2014)

4. DISCUSSIONS

Our mathematical and cartographical results prove the existence of three expansional points in the urban spatial distribution of Lake Craiovița: a commercial center, a communication artery crossing the city and new residential areas of Craiovița Nouă and Brestei neighborhoods. It is momentous to underline the fact that the urban dynamics is indissolubly connected and dependent on the social-economic dynamics of the urban area under discussion. Therefore, most residential areas developed along Calea Severinului Street (European Road 70) (Fig. 8). New residential areas inside Craiovița Nouă and Brestei neighborhoods appeared during a favourable economic period for Craiova (2000-2010) as a consequence of economic urban transport and shopping centers proximity (Billa, Auchan, Penny and Kaufland) (Fig. 1, 9).

Figure 8. European route E70 proximity

(Photo by Stoica M, 2014)

Figure 9. Auchan and Billa Hypermarket proximity

(Photo by Niță N, 2013)

The impact of urban activities was also felt at the level of Craiovița Park, placed between Craiovița Lake and Craiovița Nouă neighborhood, the European road 70 being the line of demarcation. At present, this park is in an advanced status of degradation, having a recreational purpose mostly during holidays or national free days during the warm period of the year, when numerous inhabitants of the neighborhoods situated nearby go out for a picnic or enjoy an open-space barbecue.

If the present status of Craiovița Lake is maintained, the risks are the following: lack of interest for protection and conservation on behalf of the authorities; real estate transactions meant to support the building of residential complexes; extinction of aquatic ecosystem.

5. CONCLUSIONS

Changes in spatial patterns indicate that the lake located in the study area has been extensively disturbed as a result of rapid urbanization, which also indicate internal correlation between urban expansion and wetland degradation. The results indicate that the rapid increase in urban built-up areas was related to large-scale lake degradation, which has been most prominent since 1990 when no development policy regarding the protection of natural areas, parks and lakes in Craiova was implemented.

The correlation between urban and environmental rapid changes could become a serious threat for the urban organism in the future. Consequently, the precise evaluation of the limnological systems should double urban expansion research in order to find the proper means to protect them in front of rapidly changing urban environment. Also, the problem should come into notice for the local authorities, because they hold the solutions and the legislative means to protection. The future planning concerning Craiovița Lake should target reducing fragmentation, maintaining naturalness and improving compatibility of the landscape matrix with the ecological network of the entire city. Also, the area under study should be preserved as such in the interest of the people, for leisure and tourism activities.

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