Hydrostratigraphic model of the Gambier Basin and South West Murray Basin

A three-dimensional hydrostratigraphic model of the entire regional groundwater flow system that includes the Gambier Basin and the south western Murray Basin has been produced. The domain of this model stretches from the Dundas Plateau in Victoria to the Padthaway Ridge in South Australia and includes the Lower Limestone Coast and Padthaway Prescribed Wells Areas in South Australia, as well as part of the Border Designated Area (Zones 1A/1B to 6A/B and part of Zones 7A/B). The domain of the hydrostratigraphic model was governed by the boundaries of the South East Regional Water Balance Model, which is being developed as part of a Goyder Institute for Water Research project. This groundwater flow model required a hydrostratigraphic model that covered the whole regional groundwater flow system that encompasses the Lower Limestone Coast Prescribed Wells Area. This is the first cross-border hydrostratigraphic model to be produced for this region. The hydrostratigraphic model includes five layers, Layer 1: the Quaternary Limestone Aquifer, Layer 2: the Upper Mid-Tertiary Aquifer (Gambier / Murray Group Limestone Aquifer), Layer 3: the Upper Tertiary Aquitard, Layer 4: The Lower Tertiary Aquifer (Mepunga Formation) and the Lower Tertiary Confined Aquifer (Dilwyn Sand / Renmark Group Aquifer) and Layer 5: the Pre-Cainozoic Sediments and Basement (however, the model does not include data for the base of Layer 5). The model includes the following datasets: Topographic Surface: • SA/VIC State 1 second Digital Elevation Model (DEM), later updated with a version that includes lidar DEM data where available. Top of Layer 2 (Top of Gambier / Murray Group Limestone): • 2,697 stratigraphic data points for the South Australian portion of the model domain. • 209 stratigraphic data points for the Victorian portion of the model domain. Top of Layer 3 (Top of Aquitard): • 733 data points for the whole model domain, including Victoria. Top of Layer 4 (Top of Dilwyn Sand / Renmark Group) – Layer 4 includes the Pember Mudstone and Pebble Point Formation. • 874 stratigraphic data points for the South Australian portion of the model domain. • 83 stratigraphic data points for the Victorian portion of the model domain. Top of Layer 5 (Top of Basement): • 243 points for the South Australian portion of the study area. These were restricted to the Murray Basin (northern) portion of the study area. • Contours of basement outcrops in the northern part of the SA portion of the study area. • Contours derived from petroleum well and seismic data for the southern portion of the South Australian part of the study area. • 63 points on the Victorian portion of the study area. The hydrostratigraphic model was created in an ArcGIS framework and is available as an ArcGIS geodatabase. The parent datasets described above are also available in ArcGIS format. This study was supported by The Goyder Institute for Water Research

本研究构建了涵盖甘比尔盆地（Gambier Basin）与墨累盆地（Murray Basin）西南部的完整区域地下水流系统三维水文地层模型。该模型的研究范围北起维多利亚州邓达斯高原（Dundas Plateau），南至南澳大利亚州帕德塔韦岭（Padthaway Ridge），包含南澳大利亚州的下石灰岩海岸指定井区（Lower Limestone Coast Prescribed Wells Areas）与帕德塔韦指定井区（Padthaway Prescribed Wells Areas），以及边界指定区域（Border Designated Area）的部分区域（1A/1B至6A/B分区，以及7A/B分区的部分区域）。本水文地层模型的范围由东南区域水平衡模型（South East Regional Water Balance Model）的边界所确定，该水平衡模型作为戈伊德水研究所（Goyder Institute for Water Research）项目的一部分正在开发中。此地下水流模型需要覆盖包含下石灰岩海岸指定井区在内的完整区域地下水流系统，本模型为该区域首个跨境水文地层模型。本水文地层模型共包含5个地层单元：
1. 第1层：第四纪石灰岩含水层（Quaternary Limestone Aquifer）
2. 第2层：中上新统上部含水层（甘比尔/墨累群石灰岩含水层，Upper Mid-Tertiary Aquifer (Gambier / Murray Group Limestone Aquifer)）
3. 第3层：上新统上部隔水层（Upper Tertiary Aquitard）
4. 第4层：下第三系含水层（梅蓬加组，Mepunga Formation）与下第三系承压含水层（迪尔温砂岩/伦马克群含水层，Dilwyn Sand / Renmark Group Aquifer），其中第4层包含彭伯泥岩与佩布尔角组（Pember Mudstone and Pebble Point Formation）
5. 第5层：前新生代沉积物与基底（Pre-Cainozoic Sediments and Basement），但本模型未包含第5层底部的相关数据。

本模型所使用的数据集如下：
• 地形表面数据：采用SA/VIC州1秒分辨率数字高程模型（Digital Elevation Model, DEM），后续针对可获取激光雷达（lidar）数据的区域，更新为包含激光雷达DEM数据的版本。
• 第2层顶部（甘比尔/墨累群石灰岩顶部）数据：
- 模型范围内南澳大利亚州部分区域共2697个地层数据点
- 模型范围内维多利亚州部分区域共209个地层数据点
• 第3层顶部（隔水层顶部）数据：
- 包含维多利亚州在内的整个模型范围内共733个数据点
• 第4层顶部（迪尔温砂岩/伦马克群顶部）数据：
- 模型范围内南澳大利亚州部分区域共874个地层数据点
- 模型范围内维多利亚州部分区域共83个地层数据点
• 第5层顶部（基底顶部）数据：
- 研究区域南澳大利亚州部分区域共243个数据点，且仅覆盖研究区域内的墨累盆地（北部）部分
- 南澳大利亚州部分区域北部的基底露头等值线数据
- 南澳大利亚州部分区域南部的基底等值线数据，源自石油钻井与地震数据
- 研究区域维多利亚州部分区域共63个数据点

本水文地层模型基于ArcGIS框架构建，可通过ArcGIS地理数据库（geodatabase）获取，前文所述的源数据集同样支持ArcGIS格式。本研究得到戈伊德水研究所（Goyder Institute for Water Research）的资助。