Floodplain ecosystems: resilience, value of ecosystem services and principles for diverting water from floodplains

Abstract

This Waterlines report is part of a series of papers commissioned on issues relating to Australian aquatic ecosystems. These Waterlines reports will contribute to improved environmental water management by stimulating discussion, synthesising current thinking, identifying knowledge gaps, and highlighting areas that warrant further investigation. Australian floodplain ecosystems are a valuable resource. Since European settlement, the character of floodplains has been altered by large-scale developments. The scale of human impacts on floodplain ecosystems has greatly increased in recent times, and deciding how to manage floodplains in terms of land and water allocations is of pressing concern. Negotiating the complex hydrological and ecological trade-offs associated with development is now more challenging because of the uncertainties of climate change and increasing demands for ecosystem services, such as water, food and biofuels (Gordon et al. 2008). As a result, recent policy developments have highlighted the need to improve our understanding of impacts on the hydrological cycle, including the prevalence and severity of nonlinear changes in ecosystems. Decisions on water allocation (encompassing scientific, management-agency and engineering processes that are used together to supply and maintain flows in regulated rivers) for floodplain ecosystems are complex but such decisions can be aided through a consideration of the goods and services provided by floodplains as well as the underlying function of floodplain ecological systems. This project examines the consequences of the dislocation of water from floodplains in terms of the ability of their social–ecological systems to adapt to disturbances, such as floods, droughts and development. An increased understanding of the value of the ecosystem goods and services provided by Australian floodplains will assist managers in making decisions about the trade-offs associated with water diversions. This report identifies some of the major economic values of floodplain ecosystem goods and services in Australia. It explores the contribution of the resilience of ecosystems to the economic value of floodplain ecosystem goods and services and the consequences for the management of water resources and floodplains. It describes some of the limitations and constraints on economic valuation from the perspective of resilience thinking, which describes the complex dynamics of social–ecological systems. General principles are then derived to help guide water allocations for Australian floodplains.