AN INTERNATIONAL WATERCENTRE PUBLICATION AN INTERNATIONAL WATERCENTRE PUBLICATION Assessment of river health in the Gui River Nick Bond, Robert Speed, Chris Gippel, Jane Catford, Liu Wei, Weng Shichuang, Stuart Bunn Assessment of river health in the Gui River AN INTERNATIONAL WATERCENTRE PUBLICATION © Commonwealth of Australia 2012. Reproduced with permission. All rights reserved. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the publishers. Requests and enquiries concerning reproduction and rights should be addressed to the International WaterCentre, PO Box 10907, Adelaide St, Brisbane QLD 4000. Online/print: ISBN: 978-1-921499-09-8 Assessment of River Health in the Gui River. N Bond1, R Speed2, C Gippel3, J Catford4, Liu Wei5, Weng Shichuang6, S Bunn1 1 Griffith University,2 Okeanos Pty Ltd, 3 Fluvial Systems Pty Ltd, 4 University of Melbourne, 5 Pearl River Water Resources Protection Bureau, 6 Pearl River Water Resources Protection Scientific Research Institute. Published by the International WaterCentre Level 16, 333 Ann St Brisbane QLD 4000 Tel: 07 3123 7766 Email: [email protected] www.watercentre.org Date of publication: June 2012 An appropriate citation for this report is: N Bond, R Speed, C Gippel, J Catford, Liu Wei, Weng Shichuang, S Bunn, 2012. Assessment of River Health in the Gui River. International WaterCentre, Brisbane, Australia. Disclaimer This report is presented by the IWC for the purpose of informing discussion. It does not necessarily reflect the views or opinions of the Governments of Australia and China, nor those of the IWC. Information contained in this report was correct at the time of printing and the IWC assumes no responsibilities for its accuracy. AusAID does not guarantee the accuracy, reliability, currency, or completeness of any information contained in the Material. Furthermore, AusAID accepts no legal liability whatsoever arising from any use of the Material. Users of the Material should exercise their own skill and care with respect to their use of the Material. This report is the result of work undertaken as part of the River Health and Environmental Flow in China Project, that was funded under the Australia-China Environment Development Partnership, an Australian Government AusAID initiative. This pilot study was also supported by the Chinese government via a grant under the Commonwealth Scientific Research Foundation (No. 201001021) and as a “948” project (N0. 201007). Partners Assessment of river health in the Gui River AN INTERNATIONAL WATERCENTRE PUBLICATION Executive summary This report describes a river health assessment undertaken in the Gui River catchment, located in the Pearl River Basin in China’s south-east. The objective of the project was to establish a method for selecting suitable indicators of river health and to make an initial assessment of river health in the catchment. Rivers provide a range of goods and services that communities depend on. River health assessments try to assess the ecological condition of rivers and their capacity to continue to provide these valuable goods and services. A science-based assessment can help identify rivers in poor health and the likely causes of the decline in their ecological condition. This information can be used to help prioritise government actions and funding aimed at improving river health. River health assessments can also be used to indicate the effectiveness of earlier management interventions. Reducing pollution to improve water quality and river health is currently a high priority for the Chinese government. Studies such as this one are intended to support these priorities by providing methods for better assessing and understanding the current ecological state of China’s rivers and the different factors that are affecting them. 1.1 Methodology Twenty-five sites across the Gui River catchment were sampled in April 2010 for water quality, benthic macroinvertebrates, fish, algae, and aquatic and riparian vegetation. For each of these indicator groups, a range of different indicators was assessed to determine whether indicator values changed in a predictable way with changes in levels of disturbance in the catchment and whether they were suitable for reflecting changes in river health. To test indicators against levels of catchment disturbance, a primary ‘disturbance gradient’ was generated by assessing land use and land cover upstream of each sampling site. Potential indicators were assessed to see how they varied with changes in levels of disturbance. A secondary water quality disturbance gradient was also used to test the response of biological indicators. This process identified eight water quality indicators and 10 biological indicators as potentially suitable. A simple classification of the catchment based on stream order was used to differentiate between 1st, 2nd and 3rd+ order streams (principally highlands, midlands and lowlands). Reference values for some of the indicators were then determined for the three river classes. Reference values are indicator values that are associated with ‘good’ or ‘bad’ river health scores. Different values are selected for different indicators and these may vary depending on river class. For the Gui River assessment, reference values were set based on existing Chinese standards (e.g. national water quality guidelines), data collected during fieldwork, and various international standards and studies. For each site, the results for each indicator were scaled to produce a score from 0–1, using the reference values for the appropriate river class as benchmarks. These scores were aggregated to produce scores for different indicator groups and sites. Based on these scores, each site was graded on a scale of river health from critical to excellent. In addition to this detailed technical report, a separate ‘report card’ was produced to summarise the study and its results in an easy-to-read format. In addition to the more comprehensive river health assessment based on ecology and water quality, catchment hydrology was used to assess health of a subset of reaches in the main stem of the Gui River. Several methods were trialled, including two existing rapid methods for assessing hydrological alteration and a new method (the Index of Flow Deviation or IFD), developed as part of the project, which used monthly gauged data to assess health based on changes in eight flow parameters. 1 Assessment of river health in the Gui River AN INTERNATIONAL WATERCENTRE PUBLICATION 1.2 Results of the river health assessment The results of the study suggest that the health of the Gui River is compromised in areas with intensive urban and agricultural development, but most sites were deemed to be in relatively good ecological condition. Water quality was generally found to be good, although there were clear trends towards increasing concentrations of nitrogen in agricultural and urban areas, as expected, because river health generally declines from the highlands to the lowlands. The biological indicator groups suggested a poorer level of health than the water quality indicators. In particular, algae, invertebrates and fish indicators suggested some sites were in poor to critical condition.This difference may reflect that biological indicators integrate ecosystem condition and stress over time. The difference also highlights the importance of not relying solely on water quality to assess aquatic ecosystem health. Values of the biological indicators varied depending on local- and catchment-scale land use practices, thought the results were not always consistent. Local land use refers to land use practices in adjacent riparian buffer strips, i.e. strips of land along each side of the river. With only a small sample size, it is difficult to draw firm conclusions about the relative influence of land use at these two scales. At the local scale, however, indicators of riparian condition did reflect the condition of riparian zones (e.g. width and degree of fragmentation). The condition of riparian zones will influence the in-stream river health scores, largely because it controls the degree the riparian zone buffers neighbouring land use. Analysis of monthly hydrological data suggests that stream flow patterns have not been substantially affected by reservoir construction. However, anecdotal evidence suggests that low flows during the dry season have been an issue in recent years. More detailed studies could determine if these periods of extreme low flow are too short to be observed in monthly data and what their potential impacts may be. Local and river-scale effects were also evident from the assessment of physical form, primarily through longitudinal fragmentation and alteration of hydraulic habitats above and below hydroelectric dams. While not well reflected in the limited data collected, longer-term declines in fish diversity throughout the catchment raise questions about factors relating to the health of fish assemblages.As well as potential water quality issues, the effects of barriers and fishing pressure warrant further consideration. 1.3 Recommendations Robust conclusions on river condition can rarely be made on the basis of a single investigation. Values of river health indicators vary naturally in both space and time. Distinguishing natural variation from actual increases or decreases in river health is difficult, especially when limited data is available, which presents a challenge for river health assessments.