Présentations Colloques

Oral Presentation
Session 4.01: Innovative economic instruments and institutions for achieving sustained groundwater use. Integrated socio-economic and biophysical modeling for groundwater and conjunctive use management
Barnett Steve
Policies and tools to promote economic use of groundwater in South Australia
The increasing demand for high quality food by the growing middle classes of Asia represents a great economic opportunity for South Australia. Groundwater resources already supports the production of food, dairy products and premium wines, and there are several policies and management tools in place that will assist the potential increases in groundwater extraction for irrigation within sustainable limits. All the major good quality groundwater resources are managed through statutory Water Allocation Plans (WAPs) which set sustainable limits for extraction, rules for the allocation and trading of water entitlements and resource monitoring requirements. The WAP must seek a balance between economic, social and environmental water demands. Water is allocated for the environment first, then economic and social users. Over the past 20 years or so, the management approaches in these Plans have evolved from being rigid and doctrinaire, to now being more flexible and consultative. Essentially the Plans should be able to accommodate new information and understandings of the groundwater resource that may emerge during their 10 year life span, as the following examples demonstrate. In South Australia, the determination of sustainable extraction limits has traditionally been based on estimates of recharge, particularly for unconfined aquifers. Experience has shown that these estimates have large uncertainties and are highly variable both in time and space, which often leads to overly conservative extraction limits. New approaches are being introduced which allow for the use of storage in robust aquifers, and resource condition limits (RCLs) to manage extraction levels. These RCLs could be water or salinity levels which if exceeded, could cause degradation of the resource or ecosystems. Identifying these limits requires both technical expertise and community consultation. In fully allocated areas, the trading of water entitlements is a very useful management tool which can maximise the use of groundwater within sustainable limits. Trades can be permanent (sale) or temporary (lease), and should be controlled by rules to minimise impacts on the resource, ecosystems or other users. Again, these rules have recently evolved to be flexible enough to allow exceptions if the proponents can demonstrate through additional investigations that no adverse impacts will occur. Aquifers are generally very robust and processes generally occur over large time frames. Adaptive and flexible management supported by extensive monitoring, can significantly contribute to further economic development through sustainable groundwater extraction.