Analysing water quality variability at the Algerri-Balaguer irrigation district (Ebro River basin, Spain)

Agricultural production has been exposed to increased pressure in the latest years due to the combination of different factors. On one hand, indeed, there is an increasing demand for food due to the growth of the world population, on the other, some effects of climate changes, such as temperature increase and land degradation represent an evident threat for freshwater resources. In this context, implementing adequate and sustainably irrigation systems is fundamental, especially for semi-arid areas. The IDEWA (Irrigation and Drainage monitoring by remote sensing for Ecosystems and Water resources management) project, funded by the EU PRIMA program, aims at evaluating the whole performance of the irrigation process by developing innovative irrigation management tools based on readily available multi-sensor remote sensing data. Used input water and drained ones will be monitored together with other parameters (e.g. soil moisture, evapotranspiration, …) to evaluate their impact on downstream ecosystems in two study areas, namely the Ebro (Spain) and Tensift (Morocco) basins.

Among the different parameters considered, water quality variability between input and drained waters has been evaluated by using high-resolution satellite data,  acquired by the Multispectral Instrument (MSI) onboard SENTINEL-2 satellites and by the Operational Land Imager (OLI aboard Landsat-8). Two main in-water constituents, such as the chlorophyll-a (chl-a) and suspended particulate matter (spm) have been investigated. Different algorithms have been tested and assessed also for comparison with in-situ measurements collected during specific measurement campaigns. In this work, we analyzed water quality variability at the outlet of the Algerri-Balaguer irrigation district (within Ebro basin), an intensively irrigated area characterized by a dense network of drainage channels. The achieved results show that the chl-a and spm seasonal variability could be affected by agricultural and hydrological forcing, such as the use of fertilizers and water level variations/fluctuations.