22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

CLUES-GW: A Simple Coupled Steady State Surface-Groundwater Model for Contaminant Transport

27 Sep 2019, 10:10
15m
Conference room 1.B ()

Conference room 1.B

Oral Topic 8 - Groundwater quality and pollution processes Parallel

Speaker

Dr Channa Rajanayaka (The National Institute of Water and Atmospheric Research, New Zealand)

Description

Increasing nitrate-N (N) concentrations in fresh waters is impacting adversely on New Zealand’s environmental and economic resources. We developed a simple catchment model, CLUES-GW, that provides mean-annual contaminant load and concentration estimates for surface water. CLUES-GW represents an extension of the existing CLUES, the Catchment Land Use and Environmental Sustainability model (Elliott et al. 2016)*. CLUES-GW includes up to two groundwater reservoirs under each surface water sub-catchment. The groundwater reservoirs exchange water with the adjacent (groundwater) reservoirs. The shallow reservoir also exchanges water with the surface-water streams. The runtime of the model is approximately 4 seconds, and so the quick runtime allows extensive model calibration, uncertainty and scenario analyses. The model was applied to two case study catchments to investigate N transport. The first catchment, Hauraki is located within the Waikato region of New Zealand and consists of 7,295 sub-catchments. Monte Carlo parameter conditioning from 10,000 parameter realisations was used to identify the best 200 ‘posterior’ parameter sets. The posterior parameter distributions were used to examine the N loads and concentrations at key locations under the current N loading dynamics and a hypothetical future scenario of 20% reduction in N loading. The second catchment, Mid-Mataura in the Southland region of New Zealand, is relatively smaller and has 1,535 sub-catchments. The model was calibrated using PEST software against measured river flows, and N loads and concentrations. An approach was developed to disaggregate model outputs, of mean-annual contaminant loads and concentrations, to daily timesteps using a rating-curve relationship between measured flows and concentrations. The calibrated model output along with the relationships developed for disaggregation were used to develop daily N concentration timeseries using flow data. The daily N concentration timeseries will be used as a management tool to assist with land and water management within the catchment.

  • Elliott, A.H., Semadeni-Davies, A.F., Shankar, U., Zeldis, J.R., Wheeler, D.M., Plew, D.R., Rys, G.J., Harris, S.R. (2016) A national-scale GIS-based system for modelling impacts of land use on water quality. Environmental Modelling & Software, 86: 131-144. http://dx.doi.org/10.1016/j.envsoft.2016.09.011

Primary authors

Dr Channa Rajanayaka (The National Institute of Water and Atmospheric Research, New Zealand) Dr Sandy Elliott (The National Institute of Water and Atmospheric Research, New Zealand) Dr Jing Yang (The National Institute of Water and Atmospheric Research, New Zealand) Dr Ude Shankar (The National Institute of Water and Atmospheric Research, New Zealand)

Presentation Materials

There are no materials yet.
Your browser is out of date!

Update your browser to view this website correctly. Update my browser now

×