Ecosystem Service Provision from Natural Resource Management Interventions in the Gwydir Catchment, North-Western New South Wales: Spatial Bio-Economic Evaluation at Catchment, District and Farm Scales

Abstract

This study examined the utility of an ecosystem service approach to guide natural resource management (NRM) decisions in relation to maintaining and restoring natural assets, based on the spatial integration of ecological and economic information, at catchment, district and farm scales. Changes in ecosystem service provision were assessed based on land and water resource management interventions being facilitated in New South Wales (NSW) through regional authorities, using the Gwydir catchment (26 660 km²) in north-western NSW as a case study. A method was developed to describe the relationship between wetland inundation and river flow and to establish the resultant ecosystem goods and services from environmental flow (EF) provision. This study used simulated data from the NSW government's hydrological Integrated Quality and Quantity Model (IQQM) over 112 years (1890–2002) for three scenarios: no development (ND), the Murray–Darling Basin Commission (MDBC) 'cap' (the maximum level of water abstractions capped in 1994) and EF. Four ecosystem services were quantified: (1) waterbird-breeding events - simulations predicted a waterbird breeding event in the Gwydir wetlands every 2 years under the ND scenario, every 3 years with EF, and every 5 years under the MDBC cap; (2) habitat provision - the long-term mean monthly area of the wetlands under the ND, MDBC cap, and EF scenarios was 11 514 ha, 3003 ha, and 5041 ha, respectively; (3) improved grazing from flooded pastures - an extra 2000 ha of wetlands will be available for grazing as flood waters recede under the EF scenario; and (4) biodiversity benefits - likely re-introduction and survival of eight species of native fish which potentially occurred in the Gwydir catchment. The trade-off for EF provision was an annual diversion of 40 GL from the allocation to irrigation.