Investigation of the temporal relation of remotely sensed coastal water quality with GIS modelled upstream soil erosion

Abstract

Hydrological processes at the river basin influence the quality of downstream water bodies by controlling the loads of nutrients and suspended solids. Although their monitoring is important for social, economic and environmental reasons, in-situ measurements are too expensive and thus too sparse to describe their relations. The aim of this study is to investigate the temporal relations of soil erosion in the upstream part of river basins with water quality characteristics in the downstream coastal zone, using satellite remote sensing and GIS modelling. Data from satellite missions of MODIS, SRTM and TRMM were used to describe the soil erosion factors of the Universal Soil Loss Equation in three river basins, and MERIS satellite data was used to estimate chlorophyll-a and total suspended matter concentrations in the coastal zone of northwest Aegean Sea in Greece, where the rivers discharge. The resulting time series showed an average correlation of upstream rainfall with downstream water quality, which increased when soil erosion was introduced. Higher correlations were observed with the use of a time lag, revealing a variable delay between the three test sites. Lower correlation coefficients were observed for chlorophyll-a, due to the sensitivity of algae to environmental conditions. The use of free of charge satellite data and easy to operate GIS models renders the findings of this work useful for coastal zone management bodies, in order to help increase aquaculture productivity, predict algal blooms and predict siltation of ports.

Estimating the Future Function of the Nipsa Reservoir due to Climate Change and Debris Sediment Factors

“…Similar approaches, i.e. modeling soil erosion with GIS, have been also successfully implemented at a river basin in Northern Greece [16].…”

Why and How Do We Study Sediment Transport? Focus on Coastal Zones and Ongoing Methods

“…The needs of natural environment managers go beyond these divisions because it would be nonsense to fight coastal erosion without also acting upstream in the watershed. Integrated source-to-sink studies where models of hydrologists and oceanographers interact are still scarce but they are just starting (see, e.g., [338,339]); • integration of time and space scales for long-term landscape changes [178,183,340], and filling the gap between stratigraphic models and process-based sediment transport models [25,341,342]. Now, interdisciplinary approach is expanding beyond nature and life sciences when their topic join societal concerns.…”

Information-Communication Technologies as an Integrated Water Resources Management (IWRM) Tool for Sustainable Development

“…Earth observation together with national statistics, field-based observations, and numerical simulation models are designated as the main source of information for the global monitoring of ecosystem services [29]. A recent study demonstrated that environmental parameters, such as chlorophyll-a (Chl-a) and total suspended matters (TSM), can be investigated at river basin scale through direct and indirect remote sensed observations [30]. On the other hand, in situ measurements for various ecological parameters are limited to a few experiments sites due to severe economic cost, difficulty in accessing the area of interest and a posteriori highly laborious procedures.…”