State Transmissivity Estimates for Hydrogeology Cross-Cutting Project

## **Abstract** \n\nThe dataset was derived by the Bioregional Assessment Programme from multiple source datasets. The source datasets are identified in the Lineage field in this metadata statement. The processes undertaken to produce this derived dataset are described in the History field in this metadata statement.\n\n\n\nA method for estimating Transmissivity from Specific Capacity data which can be commonly found in Australian state groundwater databases was tested. Results indicated that the method generally is accurate to within an order of magnitude of Transmissivity values derived from time-drawdown pump test data. The method was therefore deemed suitable for application across the available state groundwater databases (NSW, QLD and Vic) to obtain approximate Transmissivity values. The method was applied to the available data, yielding greater than 25,000 Transmissivity estimates across NSW, QLD and Vic. These may be particularly useful in data poor areas of the bioregional assessment regions, and may also prove useful for constraining the estimation of hydraulic properties between data rich areas. Attention is also drawn to the potential for applying this method for identifying zones of enhanced aquifer permeability resulting from the presence of fractures and faults within aquifers.\n\n## **Dataset History** \n\nThis dataset used state groundwater databases as source data (see lineage) and followed the following methodology to produce final transmissivity estimates:\n\n\n\n(Bradbury and Rothschild 1985) developed a method to estimate Transmissivity from specific capacity based on the Cooper-Jacob approximation to the Theis equation. The solution requires that a storage coefficient value be assumed. The solution is considered to be relatively insensitive to S (Bradbury and Rothschild 1985); (McLin 2005). The Theis solution is for a confined aquifer. The marginal error introduced to the T estimate by using the Theis solution for an unconfined aquifer is small relative to the other sources of error (pers.comm. Ken Bradbury, 2012) e.g. airlift data is generally of poor quality. There are solutions for either partially penetrating wells or fully penetrating wells. Knowledge of the hydrostratigraphy at each borehole is required in order to account for partial penetration. Additionally, without hydrostratigraphic interpretation of each borehole, it is not possible to assign the results to particular hydrostratigraphic units. Thus, it is proposed that the cross-cutting work be aimed towards estimating the Transmissivity for all bores with available data to do so. It becomes the responsibility of the project teams to assign these results to hydrostratigraphic units and then to undertake statistical analysis to understand the variation of hydraulic conductivity in each hydrostratigraphic unit and interpret/ use these results in a meaningful way.\n\nThis method cannot be considered a substitute for a dedicated pumping test; errors should be considered potentially significant. The TGUESS approach (Bradbury and Rothschild 1985) enables sensitivity analysis to be undertaken in a relatively straight-forward way. (McLin 2005) notes that the value of applying this method may assist with recognising uncertainty in the estimation process.\n\n\n\n\n\nT=Q/4πs ln(2.25Tt/(r_w^2 S))\n\nwhere, T = transmissivity \\[L2/t\\]; Q= discharge \\[L2/t\\]; s= drawdown in the well \\[L\\]; t= pumping time \\[t\\]; S= storage coefficient \\[dimensionless\\]; rw= radius of the well \\[L\\]\n\n\n\nFor full methodology and more information see the word document report within this dataset\n\n## **Dataset Citation** \n\nBioregional Assessment Programme (XXXX) State Transmissivity Estimates for Hydrogeology Cross-Cutting Project. Bioregional Assessment Derived Dataset. Viewed 31 May 2018, http://data.bioregionalassessments.gov.au/dataset/db6643ff-f4ec-4aa3-9f5d-afdce1bce5b1.\n\n## **Dataset Ancestors** \n\n* **Derived From** [NSW Office of Water Pump Test dataset](https://data.gov.au/data/dataset/d8f1062f-97d5-4d78-9ca8-b5719fe3fced)\n\n* **Derived From** [QLD Department of Natural Resources and Mining Groundwater Database Extract 20131111](https://data.gov.au/data/dataset/827e70b3-29d5-4e89-8d59-a93bc499de60)\n\n* **Derived From** [Victorian Groundwater Management System Dec 2012 (superseded)](https://data.gov.au/data/dataset/0e144947-4b0c-4c31-b605-9ecabdf2730b)\n\n## **摘要** 本数据集由生物区域评估计划（Bioregional Assessment Programme）从多份源数据集衍生而来，源数据集信息已在本元数据声明的“谱系（Lineage）”字段中注明，该衍生数据集的制作流程详见本元数据声明的“历史（History）”字段。 本研究针对从单位涌水量（Specific Capacity）数据估算导水率（Transmissivity）的方法展开了测试，这类数据常见于澳大利亚各州地下水数据库。测试结果显示，该方法的估算结果与基于降深-时间抽水试验数据得到的导水率值的误差通常在一个数量级以内。因此，该方法被认为适用于现有各州地下水数据库（新南威尔士州（NSW）、昆士兰州（QLD）、维多利亚州（Vic）），以获取近似导水率值。本方法已应用于现有数据，在新南威尔士州、昆士兰州和维多利亚州范围内得到了超过25000条导水率估算值。这些估算值在生物区域评估区域的数据匮乏地区尤为实用，同时也可用于约束数据丰富区域之间的水力特性估算。此外，该方法还有望用于识别因含水层内存在裂隙与断层而形成的高渗透性含水层带。 ## **数据集历史** 本数据集以各州地下水数据库为源数据（详见“谱系”字段），并遵循以下方法流程生成最终导水率估算值： 布拉德伯里与罗斯柴尔德（Bradbury and Rothschild，1985）基于针对泰斯方程（Theis equation）的库珀-雅各布近似法（Cooper-Jacob approximation），提出了一种从单位涌水量数据估算导水率的方法。该求解方法需要预设储水系数值，且被认为对储水系数$S$相对不敏感（Bradbury and Rothschild，1985；McLin，2005）。 泰斯求解方法适用于承压含水层。针对潜水含水层使用泰斯方程所引入的导水率估算边际误差，相较于其他误差来源而言相对较小（私人通信，肯·布拉德伯里，2012）——例如，气举测试数据通常质量较差。 该方法包含非完整井与完整井两种求解方案。若要考虑非完整井效应，需掌握每个钻孔的水文地层学信息。此外，若未对每个钻孔开展水文地层解译，则无法将估算结果分配至特定水文地层单元。因此，本次跨领域研究的目标为：利用现有数据对所有符合条件的钻孔开展导水率估算。后续项目团队需自行负责将这些结果分配至水文地层单元，随后开展统计分析以明确各水文地层单元的水力传导率变化规律，并以合理方式解读、应用这些结果。 该方法不能替代专门的抽水试验，其估算误差可能较大。TGUESS方法（Bradbury and Rothschild，1985）可相对简便地开展敏感性分析。麦克林（McLin，2005）指出，应用该方法有助于识别估算过程中的不确定性。 公式如下： $$ T = frac{Q}{4pi s} lnleft( frac{2.25 T t}{r_w^2 S} ight) $$ 其中，$T$为导水率（Transmissivity），单位为$[L^2/t]$；$Q$为抽水量，单位为$[L^2/t]$；$s$为井内降深，单位为$[L]$；$t$为抽水时长，单位为$[t]$；$S$为储水系数，无量纲；$r_w$为井半径，单位为$[L]$。 完整方法流程与更多详情请参阅本数据集内的Word文档报告。 ## **数据集引用** 生物区域评估计划（Bioregional Assessment Programme）（XXXX）. 水文地质跨领域项目州级导水率估算值[数据集]. 生物区域评估衍生数据集. 2018年5月31日查阅, http://data.bioregionalassessments.gov.au/dataset/db6643ff-f4ec-4aa3-9f5d-afdce1bce5b1. ## **数据集溯源** * **衍生自** [新南威尔士州水务局抽水试验数据集（NSW Office of Water Pump Test dataset）](https://data.gov.au/data/dataset/d8f1062f-97d5-4d78-9ca8-b5719fe3fced) * **衍生自** [昆士兰州自然资源与采矿部20131111地下水数据库提取数据（QLD Department of Natural Resources and Mining Groundwater Database Extract 20131111）](https://data.gov.au/data/dataset/827e70b3-29d5-4e89-8d59-a93bc499de60) * **衍生自** [2012年12月维多利亚州地下水管理系统（已废弃）（Victorian Groundwater Management System Dec 2012 (superseded)）](https://data.gov.au/data/dataset/0e144947-4b0c-4c31-b605-9ecabdf2730b)