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) Model Design & Construction CloudGMS 67 Grid Code Det Storage (mm) LAI Root Depth (mm) 1 10 0.3 15000 2 10 0.3 5000 3 10 0.3 5000 4 10 0.3 10000 5 10 0.3 6000 6 10 0.3 7000 7 10 0.3 1000 8 10 0.3 15000 9 10 0.3 10000 10 10 0.3 10000 5.2.9. Unsaturated zone flow (UZ) Unsaturated flow is one of the central processes in most model applications using MIKE SHE. The unsaturated zone is usually heterogeneous and characterised by cyclic fluctuations in the soil moisture as water is replenished by rainfall and removed by evapotranspiration and recharge to the groundwater table. Unsaturated flow is primarily vertical since gravity plays the major role during infiltration. Therefore, unsaturated flow in MIKE SHE is calculated only vertically in one-dimension, which is sufficient for most applications. MIKE SHE includes an iterative coupling procedure between the unsaturated zone and the saturated zone to compute the correct soil moisture and the water table dynamics in the lower part of the soil profile (DHI, 2016). There are three options in MIKE SHE for calculating vertical flow in the unsaturated zone: The full Richards equation, which requires a tabular or functional relationship for both the moisture-retention curve and the effective hydraulic conductivity. The full Richards equation is the most computationally intensive, but also the most accurate when the unsaturated flow is dynamic. The simplified gravity flow procedure, which assumes a uniform vertical gradient and ignores capillary forces. The simplified gravity flow procedure provides a suitable solution when the primary interested is in the time varying recharge to the groundwater table based on actual precipitation and evapotranspiration and not the dynamics in the unsaturated zone. The simple two-layer water balance method suitable for shallow water tables. The simple two-layer water balance method is suitable when the water table is shallow and groundwater recharge is primarily influenced by evapotranspiration in the root zone. In areas with deeper and drier unsaturated zones, the model does not realistically represent the flow dynamics in the unsaturated zone. Due to the presence of a thick unsaturated zone and apparent time lags in recharge, the gravity flow process model has been selected for this study as it provides a suitable solution when the primary interest is time varying recharge. It is also computationally less intensive than the full Richards equation. The Governing Equation for the unsaturated flow using the simplified gravity flow procedure requires information about two hydraulic functions with respect to water content (q): the hydraulic conductivity function, K(q), and the soil moisture retention curve y(q).