UMB8a: Integrated Catchment Model for Prediction of Radionuclide Riverine Transport

Objective

Develop a catchment model to simulate the radionuclide distribution and transport from Norwegian watershed to ocean. The source of radionuclide is mainly from atmospheric deposition which is generated in case of a nuclear accident to the west of Norway and transported through atmosphere. To simulate the distribution and transport of radionuclide, the chemical and physical transformation of targeted radionuclide need to be abstracted and incorporated into a modeling scheme. Hydrology of case study area will also need to be simulated in order to model the transport of radionuclide through watercourse into fjord and ocean.

Methods

INCA-RAD is developed based on the INCA model family. The model simulates flow and water quality and tracks the flow paths operating in both the land phase and riverine phase. The model is dynamic in that the day-to-day variations in flow and water quality can be investigated following a change in input conditions form point or diffuse sources such as atmospheric deposition, sewage discharges or fertilizer addition. The model can also be used to investigate a change in land use (e.g. moorland to forest or pasture to arable) or a change in climatic conditions. Dilution, natural decay and biochemical transformation processes are included in the model as well as the interactions with plant biomass such as nutrient uptake by vegetation on the land surface or macrophytes in streams.

Results

NIVA has developed a fully functioning model with graphic user interface for catchment radionuclide transport (Cs-137). The model has been test on Vikedalsevla which were divided into five sub-catchments. Test period is 5 years from 19.10.2008 to 14.01.2014 which is the worst case scenario identified by meteorological and deposition modelers from MET and NRPA. This work is a chain of models to work together. INCA-RAD receives data from deposition that was given by NRPA. The modelled water concentrations of radionuclides by INCA-RAD will be used as input for ocean model in MET and ERICA model in NRPA. In the five year period, the bulk water column concentration of Cs-137 is between the 102-104 bq/m3 order of magnitude. Sediment is gathering at bed of Vikedal Lake due to slowing down of water velocity. The radionuclides in sediment at the Lake reach therefore increases though the radionuclide in water column is decreasing. 

Project Manager: Yan Lin