Summary:

The Białka stream is a tributary to the Biała river with a basin area of 31.4 km². In its upper course the catchment is situated on the south-eastern slopes of the Beskid Śląski Mountains. The research was conducted was to compute the area of the Białka river upper catchment limited by a planned dam. The area computations were conducted automatically by GPS device (GARMIN GPS map 76S) from the recorded trace which proceeded along the catchment boundaries. The catchemnt boundaries were marked by the watershed line passing through the highest peaks in this region: Szyndzielnia (1023 m a.s.l.). Klimczok (1117.0 m a.s.l) and Magura (1115.0 m a.sl) and the site of the planned retention reservoir. The conducted measurements comprised the surface leveling of the catchment fragment. The measurement was made using GPS technology for determining location points, whereas the altitudes of points were determined by GPSmap 76S built-in altimeter. The digital barometrical altimeter was calibrated each time prior to measurements to known points of the base line. The points were recorded automatically with time interval of every 10 seconds, whereas the characteristic points were recoded using MARK functions and a description was added. The data was elaborated initially using Trip & Waypoint Manager software by Garmin. The missing elevation points were determined by Kriging data interpolation method. On the basis of obtained data a grid network was created which provided a basis to develop digital maps of the are surface.