APPLICATION OF GEOGRAPHIC INFORMATION-SYSTEMS (GIS) IN LAKE MONITORING WITH SUBMERSED MACROPHYTES AT LAKE CONSTANCE - CONCEPTION AND PURPOSES

In 1993 submersed vegetation of Lake Constance was mapped on base of a erial photographs. The estimation was the third of its kind since 1967 and 1978, including a period of fast eutrophication until the late se venties (caused by the use of phosphatic detergents) and a subsequent period of decreasing trophy, due to the international efforts of the r iparian states in eliminating phosphate from waste water. The well kno wn sensitivity of submersed macrophytes to changes in water quality le aded to marked changes in aquatic vegetation communities during the se venties and could help now again in success control of the redevelopme nt measures of the riparian states. The use of GIS enables to create g eographically referenced maps of distribution areas of single species or species groups and to analyse social preferences and changes in sup erficial area and locations of species during the investigation period of nearly 30 years.