Technical report

File type: PDF

Burford MA, Waltham N, Irvine D, Cartwright P, Brooks A, Faggotter SJ (2024). Better management of catchment runoff to marine receiving environments in Northern Australia. Report to the Reef and Rainforest Research Centre, Cairns, Queensland.

2025

Overview

There are many catchments in northern Australia where increased catchment development is proposed. This is largely in the form of irrigation development but also increased cattle stocking rates. Given the relatively low levels of such development in many catchments to date, there is a strong desire to maintain the integrity of coastal and marine receiving environments after the implementation of future developments. The baseline understanding of water quality in receiving marine environments and in the contributing catchments is very limited across much of northern Australia, making management and other development decisions very challenging. However, there are examples of intensive grazing and irrigation developments in northern Australia, e.g. in the Lower Burdekin Delta, adjacent to the Great Barrier Reef coastline, where lessons can be learnt to fast-track understandings and management and set testable hypotheses about the potential impacts of development in other northern catchments. Additionally, studies have been done on the potential impacts of water development on estuaries, coastal floodplains and the coast in other areas of northern Australia, e.g. Gulf of Carpentaria. This project aims to take advantage of these existing examples to improve the quality of decision-making around the impact of terrestrial runoff on the marine environment, providing a template for decision-makers.

Specifically, this project aimed to:

  1. In a literature review, summarise what is known about the impacts of terrestrial runoff on the productivity and health of marine environments in northern Australia and examine the relevance for four catchments with proposed development, i.e., Gilbert and Flinders (Qld), Daly (NT) and Keep (WA) rivers.
  2. Using current and historical satellite imagery over the study catchments with flow hydrographs, define the distribution of freshwater river plumes for sediment and nutrients, and their relationship to river flow to examine future plume extent under future development and climate scenarios.
  3. Examine changes in mangrove distribution using change analysis modelling to determine greenness of mangrove forests in study locations and relationships with catchment hydrology.
  4. Test hypotheses developed for the Flinders and Gilbert systems on other river systems earmarked for further water development to determine the critical nature of nutrient inputs from catchments in fuelling estuarine and coastal productivity, and potentially assess groundwater contributions to estuarine flow using isotopic measures.
  5. Share information with key stakeholders to disseminate knowledge from these studies and propose methods for future modelling, monitoring and research to fill in knowledge gaps.

 

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