Calibration of river system and landscape models for the Fitzroy, Darwin and Mitchell catchments. A technical report to the Australian Government from the CSIRO Northern Australia Water Resource Assessment, part of the National Water Infrastructure Development Fund: Water Resource Assessments

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Hughes, Justin; Yang, Ang; Wang, Bill; Marvanek, Steve; Carlin, Lisa; Seo, Lynn; Petheram, Cuan ORCID ID icon; Vaze, Jai


2017-07-11


Report


154


This report presents methods used in the calibration of landscape water balance and river models, and documents their performance when applied to the three study areas of the Northern Australia Water Resource Assessment. The landscape and river models will be the main tools used in subsequent phases of the Assessment, to investigate the availability and reliability of water supplies and to assess downstream perturbations of flow under historical and future climate scenarios as well as potential development storylines (see companion technical report on river model simulations). Landscape water balance modelling: In the largest study of its type in the tropics, the Northern Australia Sustainable Yields (NASY) project developed estimates of runoff across the north of Australia using lumped conceptual rainfall-runoff models. For the purposes of the Assessment, however, the recently developed AWRA-L landscape water balance model was adopted because it offers benefits in terms of consistently estimating other terms of the water balance (e.g. evaporation, groundwater recharge, soil water storage), particularly in ungauged catchments. The AWRA-L model is a landscape model developed by CSIRO to assist the Bureau of Meteorology to provide water balance estimates across Australia. The model is parameterised largely via (remotely sensed) physical measurements with a few assigned by means of calibration to observed data. It is used to generate consistent estimates of the key terms of the water balance at a high spatial and temporal resolution, including runoff. The Bureau of Meteorology operates an AWRA-L model for Australia, which uses a single continental scale parameter set, which is consistent with their needs. However, for the local scale purposes of the Assessment three AWRA-L landscape models were developed, each locally calibrated to observed streamflow data within the vicinity of the three study areas. Experiments were conducted to assist in the selection of the most appropriate model parameter set and these were used to simulate runoff, soil water storage, evaporation and deep drainage on ~5 x ~5 km grids across the three study areas. Locally calibrated model results were more accurate, particularly at modelling low flows, than the use of a single continental scale or regional climate zone (based on Köppen zones) parameter sets. Under the historical climate (1890 to 2015) the median annual runoff spatially averaged across the Fitzroy, Darwin and Mitchell catchments was 59, 397 and 229 mm, respectively. The percentage of runoff occurring in the wet season (1 November to 30 April) in the Fitzroy, Darwin and Mitchell catchments was 97, 98 and 98% respectively. River system modelling: River models are a genre of hydrological model that are particularly suited to routing flow along regulated river systems and enabling users to explore a wide variety of river regulation, operation and management scenarios. Consequently they can be used to examine a much wider range of potential modelling scenarios than conceptual rainfall-runoff or landscape models. It was necessary to develop river system models for the three study areas because the only catchment with a documented river system model was the Mitchell catchment. In the Mitchell catchment an Integrated Quantity and Quality Model (IQQM) (i.e. a type of river model) was developed by the Queensland Government in 2003 to support the development of the 2004 Mitchell catchment water resource plan. However, in the intervening 14 years new modelling methods and tools and streamflow data against which to calibrate the models have become available. Furthermore the structure of the 2003 IQQM is not well suited to the purposes of the Assessment.


CSIRO


Australia


Northern Australia Water Resource Assessment; NAWRA


Land Capability and Soil Degradation


Published Version (pdf) (91.20MB)


https://doi.org/10.25919/5b86ed6c5dfdd


This report has been placed on the CSIRO repository and may be made available to persons outside of CSIRO for non commercial purposes, in its entirety and without deletion of disclaimers and copyright information.


EP186004


Technical Report (Author)


English


Hughes, Justin; Yang, Ang; Wang, Bill; Marvanek, Steve; Carlin, Lisa; Seo, Lynn; Petheram, Cuan; Vaze, Jai. Calibration of river system and landscape models for the Fitzroy, Darwin and Mitchell catchments. A technical report to the Australian Government from the CSIRO Northern Australia Water Resource Assessment, part of the National Water Infrastructure Development Fund: Water Resource Assessments. Australia: CSIRO; 2017.https://doi.org/10.25919/5b86ed6c5dfdd



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