Review of Australian groundwater recharge studies

[摘要] EXECUTIVE SUMMARY:The primary requirement for management of water resources in any region is an accurate water balance. This, in turn, requires estimation of groundwater recharge and discharge rates and, where possible, knowledge of their spatial distribution. The amount of time and money water managers are willing or required to spend on estimating recharge/discharge depends on many factors but is primarily decided by the value of the groundwater resource, the likely scrutiny of the decision and data already available.This report provides background information to address the issues of regional measurement of recharge in data poor areas and, more importantly, estimation in areas where more detailed studies are not deemed warranted. The report reviews studies in Australia where recharge rates have been estimated empirically, excluding those made in irrigation areas and those estimates generated from modelling approaches. A companion report looks at studies in Australia where vegetation discharge has been estimated. As well as providing a comprehensive database of field based measurement, these reviews also identify parameters associated with climate, soils, regolith, near-surface geology, landforms and vegetation that collectively influence recharge and discharge rates. The availability of mapping of these parameters or possible surrogates is addressed in a third report associated with this project. Together, these form the deliverables for Phase 1 of this project.In this review, a database of 4386 recharge estimates has been compiled from 172 studies throughout Australia. These studies utilised one or more of ten different methods for estimating recharge. About 78% of the estimates were made using a steady-state chloride mass balance approach either of the groundwater (76%) or of the soil water (2%). A further 9% used the transient chloride mass balance of soil water method to estimate deep drainage. The remaining recharge estimates (13%) were computed using the watertable fluctuation, water balance and environmental tracer methods. In spite of the size of the database, the spatial coverage across Australia is inconsistent, with some regions (Mallee) very well represented whereas other regions (e.g. Gippsland) have no published estimates. Most of the more detailed studies are in South-Eastern Australia although there are a considerable number of estimates for Northern Australia (using the steady-state chloride mass balance of groundwater method) as a result of the recent Northern Australia Sustainable Yields project. Recharge estimates to fractured rock aquifers are very poorly represented in the database, particularly for detailed studies. This is a reflection of the difficulties in estimating recharge in these complex environments.

[发布日期] 2010-08-25 [发布机构] CSIRO

[学科分类] 地球科学(综合)