Groundwater dependent ecosystems in the upper Darling River floodplain NSW, mapped using Landsat satellite data

Groundwater dependent ecosystems (GDEs) rely on access to groundwater on a permanent or intermittent basis to meet some or all of their water requirements (Richardson et al., 2011). The Tasselled Cap percentile products created by Digital Earth Australia (2023) were used to identify potential GDEs for the upper Darling River floodplain study area. These percentile products provide statistical summaries (10th, 50th, 90th percentiles) of landscape brightness, greenness and wetness in imagery acquired between 1987 and present day. The 10th percentile greenness and wetness represent the lowest 10% of values for the time period evaluated, e.g. 10th greenness represents the least green period. In arid regions, areas that are depicted as persistently green and/or wet at the 10th percentile have the greatest potential to be GDEs. For this reason, and due to accessibility of the data, the 10th percentile Tasselled Cap greenness (TCG) and Tasselled Cap wetness (TCW) products were used as the basis for the assessment of GDEs for the upper Darling River floodplain study area. This data release is an ESRI geodatabase, with layer files, including:-      original greenness and wetness datasets extracted; -      classified 10th percentile greenness and wetness datasets (used as input for the combined dataset); -      combined scaled 10th percentile greenness and wetness dataset (useful for a quick glance to identify potential groundwater dependent vegetation (GDV) that have high greenness and wetness e.g. river red gums)-      combined classified 10th percentile greenness and wetness dataset (useful to identify potential GDV/GDE and differentiate between vegetation types)-      coefficient of variation of 50th percentile greenness dataset (useful when used in conjunction with the scaled/combined products to help identify GDEs)For more information and detail on these products, refer to https://dx.doi.org/10.26186/148545.ReferencesDigital Earth Australia (2023). Digital Earth Australia User Guide. Richardson, S., E. Irvine, R. Froend, P. Boon, S. Barber, and B. Bonneville. 2011a. Australian groundwater-dependent ecosystem toolbox part 1: Assessment framework. Waterlines Report 69. Canberra, Australia: Waterlines.

依赖地下水的生态系统（Groundwater Dependent Ecosystems, GDEs）依托永久性或间歇性获取地下水，以满足部分或全部用水需求（Richardson等人，2011）。本研究采用澳大利亚数字地球（Digital Earth Australia, 2023）生成的缨帽变换（Tasselled Cap）百分位产品，用于识别达令河上游洪泛平原研究区的潜在依赖地下水的生态系统。该类百分位产品可对1987年至今获取的影像中的地表亮度、绿度与湿度进行统计汇总，涵盖10分位、50分位、90分位三个统计量。10分位绿度与湿度值代表评估时段内最低的10%观测值，例如10分位绿度代表植被覆盖度最低的时期。在干旱区域，10分位下持续呈现绿度与/或湿度特征的区域，成为依赖地下水的生态系统的潜力最高。基于上述原因及数据可获取性，本研究选用10分位缨帽变换绿度（Tasselled Cap Greenness, TCG）与缨帽变换湿度（Tasselled Cap Wetness, TCW）产品，作为达令河上游洪泛平原研究区依赖地下水的生态系统评估的基础数据。

本次发布的数据为ESRI地理数据库（ESRI Geodatabase），包含以下图层文件：
- 提取得到的原始绿度与湿度数据集；
- 经过分类的10分位绿度与湿度数据集（用作组合数据集的输入数据）；
- 经过归一化组合的10分位绿度与湿度数据集（可快速识别具备高绿度与高湿度特征的潜在依赖地下水植被（Groundwater Dependent Vegetation, GDV），例如河岸红桉树）；
- 经过分类并组合的10分位绿度与湿度数据集（可用于识别潜在的依赖地下水植被/依赖地下水的生态系统，并区分植被类型）；
- 50分位绿度数据集的变异系数（与归一化/组合产品结合使用时，可辅助识别依赖地下水的生态系统）。

如需了解该类产品的更多详细信息，请访问：https://dx.doi.org/10.26186/148545。

### 参考文献
1. 澳大利亚数字地球（2023）. 澳大利亚数字地球用户指南.
2. Richardson, S., E. Irvine, R. Froend, P. Boon, S. Barber 与 B. Bonneville. 2011a. 澳大利亚依赖地下水的生态系统工具箱 第1部分：评估框架. Waterlines报告第69号. 澳大利亚堪培拉：Waterlines出版社.