| Popis: |
The objective of this study was to characterize the watershed of the Five Finger brook at St Quentin (New Brunswick), mapping it, identifying the problematic sites of point source and diffuse pollution in order to assess the state of the watershed and gain knowledge on its use by the local population. A data base characterizing the spatial organization of the watershed was installed in a GIS (geographical information system). Various information were structured in the forms of individual layers (soil type, soil drainage, agricultural activities, forest cover, beaver dams, localization of cottages and septic tanks, road network, hydrographic network, erosion hazard, coliformes rate and turbidity, slope and outdoor activities). The risks or factors influencing the pollution of the brook were gathered in various categories. The second stage consisted in the multicriterion analysis and the weighting of the factors according to the risks of pollution and the distance to the hydrographic network and the water intake (outlet). The various balanced factors were then integrated in the GIS starting from a mathematical model of linear combinations (weighted Overlay) using the Model Builder module of ArcGIS 9.1. The final stage led to the establishment of a very fine cartography of zones at risk of pollution and thus to the determination of particularly vulnerable zones. |
