Development of a Groundwater Model for the Western Davenport Plains
Knapton, Anthony; CloudGMS Pty Ltd
Northern Territory. Department of Environment, Parks and Water Security
E-Publications; E-Books; PublicationNT; WRD Technical Report 27/2017
Western Davenport Water Control District
CloudGMS has been commissioned by DENR to develop a numerical groundwater model of the aquifers within the central area of the WDWCD to improve confidence in the sustainability of the groundwater resources, as this is the area within the WCD with greatest potential for intensive development.
Made available by via Publications (Legal Deposit) Act 2004 (NT); Prepared for Dept Environment and Natural resources
Executive summary -- 1 Background -- 2 Physical -- 3 Available data -- 4 Conceptual model -- 5 Model design & construction -- 6 Parameter estimation -- 7 Water balances -- 8 Sensitivity analysis -- 9 Predictive scenarios -- 10 Conclusions -- 11 Reference -- 12 Document history and version control -- Appendix A - Groundwater level hydrographs - Appendix B - Alek range horticultural farm sub-regional modelling
Groundwater; Northern Territory; Western Davenport Water Control District; Conceptual mode
Northern Territory Governmnet
WRD Technical Report 27/2017
ix, 127 pages : colour illustration and maps ; 30 cm
Attribution International 4.0 (CC BY 4.0)
Northern Territory Government
https://hdl.handle.net/10070/842058 [LANT E-Publications: Development of a Groundwater Model for the Western Davenport Plains, version 1.1]
Western Davenport WCD Groundwater Model (v2.0) Parameter Estimation CloudGMS 76 software, which, along with extensive documentation, can be downloaded from http://www.pesthomepage.org. The steady state model was completed using the PEST code. Due to factors discussed in section 6.5.1 the transient model parameter estimation was completed using the PEST implementation of the covariance matrix adaptation evolution strategy (CMAES) optimisation code (Hansen et al, 2003). 6.1.2. Objective function The objective function or phi (F) is a measure of the discrepancy between the observed values and the values determined by an estimation model. The smaller the objective function indicates a better fit of the model values to the observed values. The objective function in groundwater models typically comprises many different types of target data, for example, hydraulic heads or gauged flows. In the Western Davenport groundwater model only heads are available. The PEST suite of programs uses the weighted sum of squared residuals (WRSS) as the target objective function. 6.1.3. Measure of goodness of fit' The goodness of fit of the modelled to the observed data is often measured using a simple statistic. Statistics used in this study to describe the fit of final model output values to observed values include: The weighted sum of squared residuals (WSSR). This is the default measure utilised by the PEST suite of programs uses as the target objective function to assess goodness of fit'. <..= = >?<0 A)0 B(#0)CD 1+ 02 where Wi is the ith observation weighting yi is the ith observed value f(xi) is the ith predicted value The root mean squared error (RMS): =E. = F ?<0 A)0 B(#0)CD 1+ 02 H where Wi is the ith observation weighting yi is the ith observed value f(xi) is the ith predicted value The scaled root mean squared error (SRMS) is the RMS divided by the range of measured heads and expressed as a percentage. Weights are sometimes introduced to account for different levels of confidence in different measurements. .=E. = 100 J F ?<0 A)0 B(#0)CD 1+ 02 H where Wi are weights between 0 and 1; and H is the range of measured heads across the model domain.