Application of the groundwater health index (GHI) as a water monitoring tool.

Under various legislations, NSW Department of Planning, Industry and Environment (DPIE) is required to ensure the sustainable and integrated management of groundwater, as well as providing for the protection of water sources, their associated ecosystems, ecological processes and biological diversity.The ongoing provision of clean groundwater depends on healthy groundwater ecosystems containing microbes and invertebrates (stygofauna). These biota improve water quality and aid water flow. Without the sustainable management of groundwater, it is likely that the health of these ecosystems will decline, with consequence of declining groundwater quality and availability, which may result in increased costs for groundwater extraction and water treatment to make water fit for purpose.In 2011, a groundwater ecosystem monitoring program began in northern NSW. From this, the Groundwater Health Index (Korbel & Hose 2011; Korbel & Hose 2017) was developed. This method allows groundwater health to be assessed and monitored using a combination of biological and water chemistry variables. Since 2017, this method has been utilised in Europe as a potential framework for adoption in the Groundwater Framework Directive, with recent publications demonstrating its use in assessing groundwater health (e.g. Di Lorenzo et al 2020).This project aimed to fill critical knowledge gaps and enable the performance monitoring of WSP and WRP strategies for groundwater dependent ecosystem and to meet water quality management plan targets for GDEs.The project sampled groundwaters in shallow alluvial aquifers of the Lachlan, Murrumbidgee and Murray sub-catchments of the southern Murray-Darling Basin (MDB) within NSW. It has successfully provided:· Documentation of the extent and condition of subterranean GDEs in the region· A first ever assessment of the groundwater microbial and invertebrate biodiversity in the region· Baseline data on groundwater chemistry and groundwater water levels· Improved groundwater ecosystem sampling methodologies· Application of the GHI to assess overall groundwater health within these 3 sub-catchmentsThe outcomes from this work highlight the biodiversity contained within aquifers of the MDB, and their roles in the maintenance of water quality. The method employed provides an improved groundwater management program, shifting from the current approach of monitoring water levels and occasional sampling of physico-chemical parameters such as pH, electrical conductivity, to an approach that considers groundwater biodiversity and the maintenance of ecosystem function and services. It will allow for future assessment of potential groundwater health decline and promote ecological sustainability and natural resource stewardship, while concurrently improving the capacity for the future management of this resource.

根据各项立法要求，新南威尔士州规划、产业与环境部（NSW Department of Planning, Industry and Environment，DPIE）需确保地下水的可持续综合管理，并对水源及其相关生态系统、生态过程与生物多样性提供保护。清洁地下水的持续供给依赖于包含微生物与无脊椎动物（stygofauna）的健康地下水生态系统。此类生物可改善水质并助力水流。若无法对地下水实施可持续管理，此类生态系统的健康水平大概率会下降，进而导致地下水水质与可获取量降低，可能抬升地下水抽取与水处理的成本，以满足用水需求。

2011年，新南威尔士州北部启动地下水生态系统监测项目，并由此开发了地下水健康指数（Groundwater Health Index，GHI；Korbel与Hose，2011；Korbel与Hose，2017）。该方法可结合生物学与水化学变量，对地下水健康状况开展评估与监测。自2017年起，该方法已被欧盟用作《地下水框架指令》（Groundwater Framework Directive）的潜在采用框架，近期已有研究成果证实其在地下水健康评估中的应用（例如Di Lorenzo等，2020）。

本项目旨在填补关键认知空白，支撑对依赖地下水的生态系统（groundwater dependent ecosystem，GDE）的WSP与WRP策略的绩效监测，并满足GDE的水质管理计划目标。

项目在新南威尔士州境内的墨累-达令盆地（Murray-Darling Basin，MDB）南部拉克伦、默伦比奇与墨累子流域的浅层冲积含水层中开展地下水采样，目前已成功达成以下成果：
· 明确该区域地下GDE的分布范围与现状
· 首次完成该区域地下水微生物与无脊椎动物生物多样性评估
· 获取地下水化学与地下水位的基准数据
· 优化地下水生态系统采样方法
· 应用GHI对上述3个子流域的整体地下水健康状况开展评估

本研究成果凸显了墨累-达令盆地含水层中蕴藏的生物多样性及其在维持水质方面的作用。本次采用的方法推动地下水管理方案升级，从当前仅监测水位与偶尔采样分析pH、电导率等理化参数的模式，转向兼顾地下水生物多样性、生态系统功能与服务维持的模式。该方法可用于未来地下水健康退化风险的评估，助力生态可持续性与自然资源管护，同时提升该地下水资源的未来管理能力。