Quantifying the extent of surface water runoff around the Maltese Islands using remote sensing

Abstract

The Maltese Islands are experiencing rapid development in coastal regions. High intensity – low duration rain events on the islands have resulted in severe flooding issues. Due to impervious surfaces that comprise the urban fabric, most rainwater is lost as runoff into coastal waters. Runoff carries several contaminants from urban and agricultural areas and deposits them in coastal waters resulting in adverse environmental and socio-economic impacts. The study investigates this phenomena using remote sensing techniques. The first phase involved using MEdium Resolution Imaging Spectrometer (MERIS) data collected between 2002 and 2012 to compute a monthly climatology for chlorophyll-a (chl-a) and total suspended matter (TSM). These two parameters were compared and analysed during wetter and drier months. The second phase of the project involved processing near real-time SENTINEL-2 imagery using the Case 2 Regional CoastColour (C2RCC) processor in SNAP to investigate storms at high resolutions. The study identified several hotspots that highly correlated with valleys identified in the 2nd River Basin Management Plan. Results also quantify the extent of chl-a and TSM blooms after rain events. The methodology and products of this study can prove helpful in monitoring techniques in line with the Water Framework Directive and Marine Strategy Framework Directive.