Multitemporal Mapping of Chlorophyll–α in Lake Karla from High Resolution Multispectral Satellite data

Abstract

With the aquatic environments being excessively stressed by human activities, the need for monitoring critical quality parameters continuously and at large spatial scales is greater than ever. Tο this end, the goal of this study was to exploit remote sensing data for water quality estimation towards the development of a long-term monitoring protocol for aquatic systems. High resolution, multitemporal data were employed along with in-situ measurements for key water quality parameters. After establishing relations between the satellite and in-situ data, multitemporal geospatial maps of Lake Karla were produced and validated, indicating that the observed chlorophyll-α is fluctuating throughout the year. In particular, a high correlation rate (r2 > 89 %) for Chl-a was derived through a linear regression model while certain mismatches occurred due to frequent cyanobacterial blooms that were mainly observed in the quite shallow parts of the lake. Moreover, the spatiotemporal analysis revealed a gradual slight decline in average chlorophyll-α concentrations from the beginning of 2011 and onward. The lake regions which were affected the most were the shallow ones, so it is necessary to better distribute the sampling locations within the lake in order to better quantify the fluctuations of water quality parameters. By exploiting high resolution satellite imagery, the proposed methodology implements a low-cost water monitoring system which enables the frequent update of important water quality parameters of any relevant geo-database, towards the efficient development of water management plan for protection and restoration of sensitive aquatic ecosystems.