The project adopts two pilot case study catchments (Evrotas and Pinios) in Greece, and aims to develop a conceptual hydrologic model, through the use of water stable isotope ratios (¹⁸O/¹⁶O, ²H/¹H). It also aims to understand and describe the water mixing processes and interactions between precipitation, surface runoff and groundwater flows. Moreover, nitrate isotope ratios (¹⁵N/¹⁴N, ¹⁸O/¹⁶O) will be used to reveal the water pollution origin and the main biogeochemical processes in the study areas, which will allow proper designing of protective measures for the river catchments.

The project includes a systematic sampling programme at representative monitoring sites, where river water samples are collected and analyzed for stable isotopes and other physicochemical parameters.

Hydrological models will complement the in-situ discharge measurements and validate the areas’ conceptual models and water budget estimates. All the above information will be used to prioritize pollution sources and suggest specific management and restoration measures for achieving good water quality status, in the long term. The project’s duration is 3 years and is implemented under the International Atomic Energy Agency’s Global Network of Isotopes in Rivers (GNIR) under contract #24263.

Schinias-Marathon is a coastal wetland in Greece and a National park, which partly suffered from drought in the past and currently from ecological degradation (fish-kills) due to anthropogenic pressures in the wetland, such as the altered water regime due to the rowing center that was constructed for the Olympic Games in 2004. The wetland is fed by groundwater discharges originating from an upstream spring called Makaria. The rowing center diverted the spring water to two interconnected semi-natural lakes, which recharge the wetland through overflow. The wetland is also close to the sea and thus it is influenced by seawater.

The project will apply isotope techniques to assess water dynamics in the wetland.

Monitoring the isotopic ratios (¹⁸O/¹⁶O, ²H/¹H) of wetland components (rainwater, surface water, groundwater) coupled with radioactive tracers, such as ²²²Rn, and hydrochemical assessment approaches will result in better understanding of wetland’s function and susceptibility to water deficit due to climate change or anthropogenic activities. The project’s duration is 3 years (2022-2024) and is implemented under the International Atomic Energy Agency’s Coordinated Research Project “Isotopic Assessment of the Impacts of Climatic and Hydrological Changes on Wetland-groundwater Ecosystem Interactions (F33027)” under contract #25029.

Almost 70% of the Kifissos River catchment is urban and prone to pollution mainly due to multiple land-uses and its proximity to different pollution sources, such as wastewater discharge points, on-site sanitation systems for domestic and institutional sources, industrial effluent discharge spots, agricultural activities and solid-waste disposal sites. The river receives secondary treated urban wastes and effluents from septic tanks, which have elevated BOD, NO₃^–, E-coli and other substances of water pollution.

The objective of the project is to apply nitrate isotopes to trace and assess N sources and dynamics in the Kifissos River catchment facing nitrate pollution from multiple anthropogenic activities.

Coupling the isotopic ratios of nitrate (¹⁵N/¹⁴N, ¹⁸O/¹⁶O) with hydrochemical assessment approaches and particularly with Compounds of Emerging Concern (CECs) will result in efficacious remediation efforts and measures in the catchment to help meet the objectives of WFD 2000/60/EC. The project’s duration is 3 years (2022-2024) and is implemented under the International Atomic Energy Agency’s Coordinated Research Project “Improving Understanding of Nitrate Sources in Connected River and Groundwater Systems Through Linking Nitrate Isotopes and Contaminants of Emerging Concern (F32010)” under contract #24998.

The catchment area of the Great Prespa Lake is unique with high ecological value (it is protected under international and European legislation – Natura 2000 site, RAMSAR, etc.), while it is hydrologically connected to lake Ohrid and Drin River basin. The Great Prespa Lake is linked to the Small Prespa Lake through a channel.

The project primarily concerns the monitoring on a monthly basis of physicochemical and hydromorphological parameters in the rivers and streams of the Great and Small Prespa lakes’ basins, the installation and operation of automatic water monitoring stations and the evaluation of the respective measurements, in collaboration with the Society for the Protection of Prespa (https://www.spp.gr/). A complementary activity was launched and involves the systematic collection of water samples to be analyzed for isotopic variables (e.g., δ¹⁸Ο and δ²Η of H₂O) with the aim to investigate the evaporation status and the interaction of the Lakes with the local rivers/streams and groundwater.

HCMR participates by providing technical and scientific advice regarding the evaluation of the above data and writing guidelines for optimal management of the relevant catchment area.