Impact of roads on the landscape of a suburban area

Transcription

1 Impact of roads on the landscape of a suburban area D. Marušić & T. Stazić Faculty of Civil Engineering, University of Split, Department for Roads, Croatia Abstract New planned roads change the landscape of the suburban area through which they run. In order to evaluate this change, it is necessary to define landscape values of a suburban area that roads passes through and define the road corridors that influence the natural, cultural and anthropological values of the explored area. Since the route of the road is not only defined by landscape values, but is also defined by minimum construction costs, by land topography or by land use, obviously several alternative routes will appear. The analyses of route alternatives bring out criteria that are the basis for evaluation of the solutions in order to determine the one with minimum impact on the landscape. The influence of roads on the landscape of a suburban area will be presented for the example of the planning of a road from Dubovica cove to the settlement of Sv. Nedilja on the island of Hvar (Croatia). Keywords: road, landscape values, construction costs, land topography, land use. 1 General considerations The intention of this paper is to present a methodological procedure that attributes importance to the protection of landscape values in physical planning especially when the route of a road should be selected. Landscape can be defined as the environment perceived that mirrors the evaluation of the people environment relation over the centuries. There are many natural and human factors and processes that interact, and react to the natural and cultural elements of the landscape. The natural components are made by natural forces and form the ecological functioning of the landscape. The

2 822 Urban Transport X cultural components are made by society to adapt the environment to improve the living conditions. Landscape values are the natural and the cultural elements together with their composition, organization, dynamics and relationships in a way of individual and society treat. In the processes of spatial development, the landscape values are a specific form of all its possible uses wherein its value is defined in the context of landscape development, use, protection, changes or absence of changes and use. Identification of landscape values should be based on a systematic framework for all the factors affecting the landscape. The formation of this framework primarily falls upon the national institutions. However, the efficiency of the landscape management depends upon an integrated approach of all interested parties, such as national government, local management and individual companies. Roads are planned and used for transport of people and goods. Roads form networks cross the landscape and cause the pressure [1] on landscape and on the surrounding environment. In the landscape, those networks present barriers for natural corridors and cause fragmentation of the landscape. Consequences of these are the cutting up of natural corridors, the braking up of homogeneous parts into nonhomogeneous parts and the changing of eco-systems. On top of this, landscape image is changed with new shapes and colours that naturally do not belong in it. Since the pressure capacity of the environment is limited, the requirement of minimal influence on the environment is established on a new infrastructure. Landscape and its values have to be considered during the process of road incorporation into the surrounding area. It is important to take as much relevant interest into account as possible. 2 Methodology The methodology of landscape impact assessment contains the following analytical principles [2]: landscape analysis, landscape diagnosis, synthesis-value ascription and landscape impact assessment. 2.1 Landscape analysis Landscape analysis is a process for identification and valuation of landscape features and functions which make the structures of the landscape [3]. The recognition and classification refer to types of areas, natural corridors for their ecological connection and their distribution in the landscape. The classification is performed according to the following features: type of culture, structure, altitude above sea-level, terrain slope, nature of the soil and other protective social functions. The identification phases include the inventory of the area on which the impact of the particular project is foreseen. Collection of the information pertaining to the study area forms the landscape data basis which should contain [4]: features and values of individual factors in landscape formation, evaluation

3 Urban Transport X 823 of the influence exerted by the interaction of individual factors in the formation of an integral landscape outlook and assessment of the benefits and sensitivity of each landscape section upon the introduced changes. 2.2 Landscape diagnosis Within the entire planning procedure it is possible to put forward a great number of assessment models, wherein the individual evaluation, i.e. ranking of values, contributes to the total planning synthesis. Therein the value is defined as the difference between the planned and the current state of the landscape. In planning the use of the landscape, the optimisation of the land use is carried out by assessment analyses of the attractiveness and vulnerability and by the selection of the evaluation criteria. The assessment analysis of attractiveness represents the estimation of the landscape economic capacity and the values scale can be named at national, regional or local levels. The vulnerability analysis is represented by the threats to the landscape in the planned space due to its possible use, so that the vulnerability analysis has to be divided in order to enable the optimisation during the determination of the land use. The final objective of the assessment is the division of space into landscape units referred to more-or-less well-defined and bordered pieces of land, which can be attributed certain values. According to the previously proposed objective it is possible to develop the following models [5]: a Developmental model for the preservation of production potentials and Vulnerability models for the preservation of environmental, cultural-landscape and visual values. The assessment criteria are environmental values, visual values and cultural landscape values. The assessment criteria are determined for each model separately. 2.3 Synthesis-values ascription Integrated evaluation of the landscape is more than the mere sum of individual evaluations of both natural and anthropogenic values. It defines the typical features of the landscape and its autochthonous values. The integrated evaluation of the landscape is primarily based upon the positive feelings and the experience of belonging to a certain space and the pleasure incited by the landscape. The landscape basis of a studied area (as a spatial-planning basis) represents the synthesis of the spatial values (natural, environmental, cultural-historical, aesthetic and economic) and it defines the areas of common landscape features with labels such as suitability, sensitivity or vulnerability, i.e. exposure to threats. The assessment criteria of threats are divided into several levels. Atmospheric conditions form the first level. Land use forms the second level. Created landscape types, monocultures to rich biocenoses, form the third level. Finally, variations according to specific features form the fourth level.

4 824 Urban Transport X 2.4 Landscape impact assessment The landscape assessment is a procedure used to assign values, expressed in measurement or quantity units, to the landscape and its sections or certain phenomena. Within the planned task the landscape assessment is a procedure for determining the suitability of the landscape use. Consequently, landscape assessment can be understood as a procedure for determining, i.e. revealing, relationships in the landscape which create our preferences, expectations and interests towards valuable structures which are constituent parts of a given landscape. The concept of landscape assessment stresses its use in many spheres of human activities. The assessment methods can be define as independent specific procedures for a certain activity and/or as multi-layer assessment procedure or process for determining the landscape suitability Both procedures refer to complex landscape structures and their relationships as carriers of values resulting from our preferences, wishes, interests and expectations regarding their properties. Consequently, the assessment procedure assigns the landscape and its structures, as objectively established physical phenomena, special importance, i.e. suitability for achieving the planned objective and interest for the social community or individuals, which actually represents a subjective aspect of value distribution. The aim of landscape impact assessment is a preventive landscape protection which envisages the possible unfavourable landscape effects of each activity (project such as new road in a road network) in the early phase of its preparation, in order to reduce these unfavourable effects to the lowest level and to achieve the highest possible level of landscape protection. The main objective of landscape impact assessment is to preserve the environmental stability, i.e. its capacity to accept the changes caused by the external factors and to retain its natural characteristics. 3 Application of landscape evaluation on the selection of road route Settlements on an island need roads for communication with each other. New roads and modernization of existing ones mean better connection of settlements and improve the living conditions in them and in their surrounding areas. Nowadays, the settlement of Sv. Nedilja is connected with settlement of Hvar (both are on the island Hvar, Croatia) with a one track road which leads through a short but small tunnel that buses could not pass through. A man needs 45 minutes to reach the Hvar from Sv. Nedilja, and this can be done only by car. The shortest way might be a new road cross the southern hillside of the island. This road might shorten the travel time form mentioned time to 10 minutes and will have technical elements, especially the width of road, to allow all motor vehicle traffic.

5 Urban Transport X 825 Selection of the road route is made by using the described methodology. The study area is bordered with sea on the South, the tops of the hills on the North, the settlement area of Sv. Nedilja on the East and the existing road in the Dubovica cove on the West. The researched area belongs to the main landscaped units of the Republic of Croatia named as Costal region of central and southern Dalmatia [4]. Inside these main landscape units it is possible to define the landscape units of the studied area for better presentation of landscape elements. The landscape analysis of the studied area is based on the natural values, land use and cultural values. The landscape analysis brings out the landscape units [6] that are presented on the map of the researched area (Figure 1). Detected landscape units are: 1) Sea area a region of the sea (from the sea level to the sea bottom) wide 200 m from the coastal line; 2) Seashore a region of the land between the coastal line and the forest border or agricultural-area border; 3) Water-worn; 4) Forest; 5) Maquis (underbrush); 6) Church and historical buildings; 7) Settlement area with traditional centre; 8) Vineyards, walls built without binding agents. Road influences on the landscape are valuated by landscape criterions, which are: i) Preservation of the landscape from the point of its originality; ii) Quality of the existing landscapes features; iii) Change of the landscape features caused by infrastructure: iv) Visual values. The last criterion includes the visualization of the side hill "without" and "with" the new road. It is measured by the road parts that are not visible from sea level. The process of landscape changes considers three alternatives of road route (Figure 1): Var. A and Var. B are technical and traffic solutions of the road route, and Var. C is a consequence of applying the forth landscape criterion on the studied area. Overlaying the landscape units map and the road routes plans determines the possible physical changes of the landscape. Physical changes are presented: by land area which could be taken by the road route; by the distance from the roadroute-canter-line to the settlement centre, or to protect buildings and by invisibility of the road from the sea level. The land area which the road will take should be as small as possible (i.e. called minimum demand). The distance from the road-route-centre-line to the settlements and the invisibility of the road from sea level should be as large as possible (i.e. called maximum demand).

6 826 Urban Transport X study area border seashore line beach cavern tunnel road from Hvar to Stari Grad Var. A Var. B Var. C Landscape units 1) sea area 2) seashore 3) vatter-worn 4) forest 5) maquis (underbrush) 6) church and hystorical building - church - historical building 7) settlement area settlement traditional center 8) vineyards, walls bilt without binding agents B B B Fi 1 M f l d i i h d l i Figure 1: Map of landscape units with road route alternatives. Research area: Dubovica cove settlement of Sv. Nedilja (Island of Hvar, Croatia). The method "weight sum" [7] brings out numerical values on which the final minimum demand is formulated. Because of this the values of physical change with maximum demand are involved in the process of evaluation as reciprocal values. Table 1 shows the of landscape units, values assigned to physical changes for each alternative of the road route (Var.A, Var.B, Var.C) and weights (w) assigned to the landscape units. Figure 2 shows the ranking of alternatives. Table 1: Evaluation of road route. Landscape units Var.A Var.B Var.C w Sea area[m 2 ] ,06 Forest [m 2 ] ,15 Maquis (underbrush) [m 2 ] ,45 Vineyards, walls built without binding agents [m 2 ] Church and historical buildings [m -1 ] ,10 0, ,001 0,001 0,20 Visual values [m -2 ] 1,97775E-06 1,82648E-06 2,17096E-06 0,04 sum 1,00

7 Urban Transport X 827 Figure 2: Ranking of alternatives. 4 Conclusion Landscape values and the landscape changes caused by a road should be involved in the road planning process. Landscape analyses, based on collected information (landscape data basis) for the studied area, bring out landscape values of an infrastructure (such as a road) interested area. The final objective of the assessment is the division of space into homogeneous spatial units which have attributed values. The results of the landscape analyses can be seen on the landscape map which shows the spatial mosaic-like pattern of landscape elements. The concept of landscape impact assessment can be defined as a process for determining the landscape suitability for a certain project (such as road infrastructures). It refers to complex landscape structures and their relationships as carriers of values resulting from our preferences, wishes, interests and expectations regarding their properties. Overlaying the map (landscape and road plan) together with determining appropriate landscape criteria and giving appropriate weights to landscape units, results in ranking of various road route alternatives. The preference ranking helps in the decision making process on the suitability of each alternative. References [1] Antrop, M.: Background concepts for integrated landscape analysis. Agriculture, Ecosystems and Environment. 77 (2000) [2] Marušić, D.: Selection of the route for the Adriatic-Ionian highway considering its environmental impact. International seminar on the impact of the future Adriatic-Ionian highway on the economic development of the region. Conference proceedings. (2002) [3] Fabos, J. Gy., Joyner, A. Jr: Landscape plan formulation and evaluation. Landscape Planning 7 (1980) [4] Ministry of Environmental Protection and Physical Planning: An overview of the state of biological and landscape diversity of Croatia with the protection strategy and action plans. (Prepared by Jasminka Radović). Zagreb, Croatia (2000).

8 828 Urban Transport X [5] Ministry of Physical Planning and Construction & Faculty of Agriculture University of Zagreb: Landscape conceptual and methodological support for Croatian landscape basis. (Prepared by Matija Salaj and Nataša Furlan-Zimmerman). Zagreb, Croatia (1999). [6] Marušić, D. et al: Environment impact assessment study of the new planned road from the Dubovica cove to the settlement of Sv. Nedilja on the island of Hvar. Faculty of Civil Engineering University of Split. Split, Croatia (2002). [7] Buffa, E. S.; Dyer, J.S.: Management science and operation research. Model formulation and solutions method. John Wiley & Sons, Int. Sidney-Toronto (1977).