تجزیه و تحلیل الگوهای قایق رانی در پارک ملی Biesbosch با استفاده از تکنولوژی GIS

National parks with large flows of visitors have to manage these flows carefully. Methods of data collection and analysis can be of help to support decision making. The case of the Biesbosch National Park is used to find innovative ways to figure flows of yachts, being the most important component of water traffic, and to create a model that allows the estimation of changes in yachting patterns resulting from policy measures. Recent policies oriented at building additional waterways, nature development areas and recreational concentrations in the park to manage the demands of recreation and nature conservation offer a good opportunity to apply this model. With a geographical information system (GIS), data obtained from aerial photographs and satellite images can be analyzed. The method of space syntax is used to determine and visualize characteristics of the network of leisure routes in the park and to evaluate impacts resulting from expected changes in the network that accompany the restructuring of waterways.

Before authorities decide to limit visitor numbers in nature reserves, they could try to implement policies directed at obtaining a more balanced distribution of visitors. However, as it is difficult to predict how visitors will react to measures taken, one could try to model their behavior. Pedestrian flow models based on space syntax have been used successfully to solve problems of crowding in city centres. In nature areas, particularly wetlands, where a substantial portion of visits are made with yachts, one could therefore draw upon the similarity that exists between the behavior of pedestrians in streets and that of navigators in waterways. The Biesbosch National Park in the southwestern part of the Netherlands near the estuary of the Rhine River is one of the largest and few remaining fresh water tidal areas in Europe. The park consists of a large number of rivers, streams and creeks with grass and reed lands in between, and forms part of a national network of leisure routes for yachts. The park is situated between two large urban zones: the southern wing of the Randstad Holland, with the cities of Rotterdam and Dordrecht, and the urban region consisting of the cities of Breda and Tilburg in the western part of the province of North Brabant. This favorable location between areas of high population density and the growing popularity of yachting has resulted in a large recreational pressure. There is now a huge demand for berths in yacht basins with good access to leisure routes around the national park. For the past 25 years, there has been a policy to stabilize the number of yachts in the national park. The most radical measure was implemented in 1994 with the declaration of a ban on the extension of berths in yacht basins within a radius of 15 km around the centre of the national park (Schouten, 2005). This policy, known as the stand–still principle, is presently a point of discussion for the stakeholders in the region. Local authorities in the region are confronted with a shortage of berths, resulting in large waiting lists. The main question is whether there are alternatives for this principle without the nature values of the park area being endangered. To assist in finding answers to this question, a number of investigations have to be made, among them the following: • How have yachting patterns in the national park been developed over the past decade? • How can we model these patterns to be able to evaluate the effects of policy measures related to the restructuring of waterways and the creation of additional recreational concentrations in the national park?

The above analysis shows that space syntax is a useful method to study the effects of changes in the leisure route network. New segments corresponding with axial lines with a strong local integration, connectivity and control will probably result in new high-density areas for yachts. Such measurements appear when relatively dense substructures of waterways are constructed, as is the case with the Aakvlaai. The construction of similar substructures, such as the Noordwaard and the Zuiderklip, and permitting yachts there, is therefore a suitable measure to relieve pressure on the core cluster by establishing a more even distribution of yachts, which will simultaneously increase the capacity for yachts in the national park. The model indicates that opening the new substructures to yachting will probably result in higher yacht densities in other parts of the national park: within the new substructures themselves and on the link Ruigt–Steurgat. The existing high-density areas will then have relatively less locational advantages, and that will probably result in lower densities there if there is no substantial increase in the number of yachts entering the national park. With the establishment of recreational concentrations and concomitant new waterways in the northern part of the national park, yachts will be more attracted to that part. A balance could then be created with regard to yacht densities between the northern and southern part. Such a distributional policy will further increase the capacity for yachting in the park without much negative effects on its nature values. However, to realize a substantial relief of environmental pressure, the location of environmentally sensitive areas must be taken into account. This demands a careful assessment of decisions regarding the access of waterways to yachts. In general, the addition of new sections to the network of leisure routes will affect yachting patterns. Translating them to a space syntax base figure will provide different morphological measurements, which can be shown by means of axial figures. The study has shown that leisure routes with a high yacht density and axial lines with high measures of local integration and control are related to high-density areas for yachts. From such figures, therefore, deductions can be made regarding the expected behavior of yacht owners, which could help park authorities with the formulation of policies oriented at influencing this behavior.