Maksym Gusyev

Project Associate Professor

Institute of Environmental Radioactivity, Radioisotope Geoscience Division, Radiological Hydrology


My research experience has been in numerical modeling of environmental radioisotope transport, groundwater and surface water flow, and floods and droughts under present and future climates.

Main Focus of Research

  • Surface water and groundwater flow and radionuclide transport modeling
  • Environmental tritium monitoring investigations
  • Understand catchment-scale water movement with environmental tracers
  • Investigations of floods and droughts under climate change

Fields of Research

Environmental modeling, water flow and radionuclide transport, environmental tracers


Numerical modeling, water circulation, tritium radioisotope, climate change


Japan Geoscience Union (JpGU), European Geoscience Union (EGU)

Research Overview

My radiological hydrology research focuses on the isotope-enabled numerical modeling with environmental radio and stable isotopes for understanding water and nutrient movement, transit times, and interactions on watershed and river reach scales. Environmental tracers can provide information of groundwater and surface water mixing and serve as calibration targets of catchment-scale water movement for coupling hydrological models, groundwater flow and isotope transport. For my research in Ukraine, I addressed water quality issues including contamination from Chernobyl Nuclear Power Plant (NPP) during my Engineering Degree study and working experience. In the US, I focused on numerical modeling development to better represent water and nutrients interactions between groundwater storage and discharge points such as wells, wetlands, rivers and lakes and my PhD research focused on the development and improvement of surface water and groundwater modeling. My research methods were applied to modeling shallow groundwater interconnected with surface water wetlands in the hummock and swale terrain of the Sheyenne National Grassland in North Dakota by applying regional Analytic Element Method (AEM) model for the inset local scale US Geological Survey (USGS) finite-difference MODFLOW model with artificial neural networks funded by the US Department of Agriculture.

Following my PhD Defense in 2010, I took the Groundwater Scientist position at the National Isotope Centre (NIC) of the Crown Research Institute of Geological and Nuclear Sciences (GNS Science), which has been responsible nationwide isotopic investigations in New Zealand. My research combined long-term time-series data of GNS Science environmental tracers in rivers and wells for applying isotope-enabled groundwater flow and transport models. For example, I combined hydrogeology and ultra-low level tritium (3H) radioisotope data of surface water and groundwater samples for improving 3-D groundwater MODFLOW flow, particle MODFLOW and tracer MT3DMS transport simulations in Lake Taupo catchments and tritium-calibrated MODFLOW/MODPATH/MT3DMS models were used to represent nitrate contamination entered into the subsurface due to the past 50 years nitrate applications in Waikato Regional council for keeping the pristine Lake Taupo water quality. Tritium (3H) radioisotope with the half-life of 12.32 years provides unique information for surface water investigations with the isotope-enabled models based on its properties: 1) a cosmogenic radioisotope generated in the upper atmosphere, 2) water movement tracer as a part of water molecule, and 3) non-reactive in groundwater and aquifer matrix as well as surface water evaporation. For the Tasman District Council, I investigated effects of increasing groundwater abstraction on river flows and ecosystem functioning in the Upper Motueka Catchment, which is the UNESCO pilot catchment, by developing coupled finite-element FEFLOW and custom-built river flow routing models, to investigate effects of increasing climate change and groundwater abstraction scenarios on river flows and the ecosystem functioning in the Upper Motueka Catchment. On a national level, I was leading the development of New Zealand technical guidelines for capture zone delineation for wells, springs, small lakes and wetlands to maintain water quality due to anthropogenic activities.

Moving from GNS Science to Public Works Research Institute (PWRI), Japan allowed me to bring the advanced numerical modeling technology with environmental tracer knowledge to better characterize the subsurface groundwater storage, which is the main contributor of baseflow river discharge especially during droughts and it is usually lacking representation in distributed catchment-scale hydrological models and rainfall-runoff-inundation models for flooding. From Japan, I have greatly expanded my research in Japan and internationally for water cycle characterization on issues of floods and droughts, water infrastructure management, and climate change in various river basins of Asia, Europe and West Africa regions. For example, I developed new standardized indices of precipitation, soil moisture, groundwater recharge and dam inflow to investigate past and future socio-economic droughts under climate change in Theme D of the 5-year SOUSEI Program in the Monsoon Asia and in the Pampanga (the Philippines), Chao Phraya (Thailand), Solo (Indonesia), and Indus (Pakistan) River basins by improving dam module in the distributed hydrologic block-wise TOP (BTOP) model and transferred new methodology to ICHARM’s Master students. In addition, I have also been involved in flood hazard and risk investigations in many river basins of Master students Thesis research and managed implementation of water disaster platform to enhance climate resilience in Africa in the eleven countries of the Niger and Volta River basins.

My PWRI research in radioisotope hydrology focused on surface water, groundwater flow and mass transport modeling with the BTOP model, which has groundwater mean travel distance as a calibration parameter, and implemented a pilot PWRI-funded project (2014-2016) to apply GNS Science ultra-low level 3H analysis capabilities with stable isotopes in headwater catchments of the Ishikari River basin, Hokkaido. As the result of my radioisotope research, environmental tritium-tracer with the ultra-low level analysis capabilities has been re-introduced to Japan leading to the follow-up PWRI-funded project (2017-2020) in the Chikuma and Tone River basins as well as tritium-radioisotope monitoring in precipitation of using medium-level tritium analysis at Hirosaki University to confirm natural tritium levels across Japan. This international research impact has been recognized by the International Atomic Energy Agency (IAEA) leading to the IAEA Expert/Lecturer appointment and the IAEA jointly with the Ministry of Foreign Affairs appointed me as the Alternate National Project Coordinator (ANPC) of Japan for the Asia-Pacific Region under the RAS/7/030 (2016-2019) and RAS/7/035 (2020-2023) Projects. My research in radioisotope hydrology utilized young and old groundwater tracers to evaluate fresh groundwater potential in fractured rocks (deep wells) and alluvium (shallow wells) and to examine recharge mechanism of spatially groundwater–surface water linked systems by developing numerical models for the study areas of interest..

A few words

I am very excited to be part of the IER Team by incorporating the results of the experimental and monitoring studies of the IER team on Radiological Hydrology and to answer practical questions of water and radionuclides circulation in the terrestrial environment on stream, sub-catchment, and catchment flow systems under land-use and climate change scenarios. To help Fukushima Prefecture situation, I plan to simulate radionuclides transfer in surface water by water runoff with particulate 137Cs sediments in river channel, flooded area and reservoir by further extending the numerical modeling technology developed in the IER in 2013-2021 and to develop numerical models of groundwater and surface water interactions in Fukushima watersheds for 137Cs. I am also interested to participate in the studies of tritium fluxes in groundwater of Fukushima Daiichi NPP due to the issue of future anthropogenic tritium discharge to the marine environment and would like to continue monitoring of tritium radioisotope in precipitation, rivers, reservoirs and groundwater across Japan. In addition, I would like to make contribution to the SATREPS Team on modeling groundwater transport of 137Cs and 90Sr in the watershed of the Chernobyl NPP site and Cooling Pond and hope that my IER activities would help Ukraine’s situation and quick recovery.



Bachelor of Engineering Degree from National Technical University of Ukraine (NTUU “KPI”), Kiev, Ukraine


Engineering Diploma in Ecology and Environmental Protection from NTUU “KPI”, Kiev, Ukraine


Master of Science in Environmental Science from Indiana University, USA with Dual Major:
1) Water Resources;
2) Environmental Chemistry, Toxicology and Risk Assessment.


Ph.D. in Environmental Sciences from Indiana University, USA

Curriculum vitae


Researcher/Adjunct Faculty, Indiana University, USA


Groundwater Scientist II, Crown Research Institute of Geological and Nuclear Sciences (GNS Science), New Zealand


Researcher/Lecturer, International Centre for Water Hazard and Risk Management (ICHARM) under the auspices of UNESCO, Public Works Research Institute (PWRI), Tsukuba, Japan


Project Associate Professor at the Institute of Environmental Radioactivity, Fukushima University