GIS and Remote Sensing in Hydrology, Water Resources and Environment (Proceedings of ICGRHWE held at the Three Gorges Dam, China, September 2003). IAHS Publ. 289, 2004, 301-307

Abstract A submersible multi-channel fluorescence probe was recently introduced in Lake Kinneret, Israel, that enables the determination of phytoplankton density, in terms of chlorophyll a concentration, in real time, and provides information on the contribution of colour-classes to the bulk of algal biomass. Using the GIS Arcinfo software package we could also derive information on the distribution of phytoplankton in different water layers. We found that the vertical distribution of phytoplankton in the epilimnion was mostly fairly uniform, and can be reliably represented by a water layer where the phenomenon of fluorescence quenching is not detectable, i.e. at the depth of 4–6 m. When motile algae dominated the lake phytoplankton the layer of maximum chlorophyll concentration was used. The capability for phytoplankton mapping, almost synoptically, provides an expedient tool for acquisition of ground-truth information for the calibration and/or validation of information derived by remote-operated sensors, carried on-board aircraft or satellite.

Key words chlorophyll a; fluorescence quenching; phytoplankton mapping