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The management of the anthropogenic water cycle must ensure the preservation of the quality and quantity of water resources and their careful allocation to the different uses. Protection of water resources requires the control of pollution sources that may deteriorate them. This is a challenging task in multi-stressed catchments. This work presents an approach that combines pesticide occurrence patterns and stable isotope analyses of nitrogen (δ15N-NO3−, δ15N-NH4+), oxygen (δ18O-NO3−), and boron (δ11B) to discriminate the origin of pesticides and nitrogen-pollution to tackle this challenge. The approach has been applied to a Mediterranean sub-catchment subject to a variety of natural and anthropogenic pressures. Combining the results from both analytical approaches in selected locations of the basin, the urban/industrial activity was identified as the main pressure on the quality of the surface water resources, and to a large extent also on the groundwater resources, although agriculture may play also an important role, mainly in terms of nitrate and ammonium pollution. Total pesticide concentrations in surface waters were one order of magnitude higher than in groundwaters and believed to originate mainly from soil and/or sediments desorption processes and urban and industrial use, as they were mainly associated with treated wastewaters. These findings were supported by the stable isotope results that pointed to an organic origin of nitrate in surface waters and most groundwater samples. Ammonium pollution observed in some aquifer locations is probably generated by nitrate reduction. Overall, no significant attenuation processes could be inferred for nitrate pollution. The approach presented here exemplifies the investigative monitoring envisioned in the Water Framework Directive., This work has received funding from the EU Horizon 2020 Research and Innovation Programme through the WaterProtect project (grant agreement No. 727450), the Spanish Ministry of Science and Innovation (Project CEX2018-000794-S), and the Generalitat de Catalunya (Consolidated Research Group 2017 SGR 01404-Water and Soil Quality Unit).

The present study illustrates an original methodology for estimating irrigation requirements and quantifying real water consumption in a long-established Mediterranean rural community (Delta Llobregat, Barcelona, Spain), combining data from remote sensing, field mapping and in situ measurements. Because of land fragmentation and crop diversification, SPOT-5 imagery was used, given its spatial and temporal resolution and spectral attributes. Simultaneously, four flow meters were installed in two representative locations to measure water inputs and outputs every 5 min. Conveyance and irrigation efficiency were estimated for the entire irrigation community. The average conveyance efficiency was 46.8% and the classical and net irrigation efficiency reached 26.4 and 59.8%, respectively, with half of the water volume (55% or 3.2 hm3) returned to the river or diverted to wetlands, the maximum percentage of estimated error being about 3.4%. These results indicate an exceptionally high water loss rate due to the irrigation system (flooding), the ageing conveyance network and urban infrastructure breakdown. The applied protocol proved useful for monitoring low-efficiency irrigation systems in small communities experiencing intense urban and industrial pressures. Copyright © 2016 John Wiley & Sons, Ltd.

The area involving the Lower Valley and Delta of the Llobregat River has a long-standing tradition in Managed Artificial Recharge (MAR) activities. For more than 50 years different MAR activities have taken place, and at present the area provides a catalog of methodologies put into practice. This chapter provides an overview of artificial recharge activities in the river and riverbanks classified according to types, objectives, water sources, and focus. Regarding types, both surface and deep MAR activities can be found at different locations. In terms of objectives, we can distinguish between using opportunity water, resources increment, or improving groundwater quality. Regarding water sources, recharge water may come from the river, a diverted channel, or treatment plants. Finally, regarding focus, activities can be seen as used for scientific purposes, demonstration, or actual industrial activity.