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Resilience, which can also be described as absorbing capacity, describes the amount of change that a system can undergo in response to disturbance and maintain a characteristic, self-sustaining regime of functions, processes, or sets of feedback loops. Rivers exhibit varying levels of resilience, but the net effect of industrialized anthropogenic alteration has been to suppress river resilience. As changing climate alters the inputs to rivers and human modification alters the morphology and connectivity of rivers, restoration increasingly considers how to enhance resilience. Characteristics that underpin river absorbing capacity include natural regimes, connectivity, physical and ecological integrity, and heterogeneity. River management emphasizing channel stabilization and homogenization has reduced river absorbing capacity. We propose that the paths to restoring rivers include defining relevant measures of absorbing capacity and understanding the scales of restoration and the sociopolitical elements of river restoration. We provide a conceptual framing for choosing measures that could be used to assess river absorbing capacity. [ABSTRACT FROM AUTHOR]

Direct and indirect human disturbances present major challenges to sustainable management of dryland rivers, impacting upon their role as critical lifelines in arid and semiarid regions. This paper presents an overview of changing human–river relations, knowledges and practices in the management of dryland rivers in western India over the last 4500 years. In ancient times, traditional knowledges underpinned local water harvesting techniques that worked with nature. Subsequent imposition of external values and knowledge frameworks in colonial times applied a command‐and‐control ethos that asserted human authority over rivers. Postindependence, development programmes in the second half of the 21st century further accentuated this legacy, with profound implications for river health. Discipline‐bound approaches to river restoration in recent decades have failed to address these concerns. Using the Sabarmati catchment (~20,000 km2) as a case study, we develop a holistic, transdisciplinary approach that integrates traditional place‐based knowledges and practices alongside scientific understandings and the generative potential of Big Data to show how a plural knowledges model can support proactive and precautionary approaches to sustainable river management. [ABSTRACT FROM AUTHOR]

With the impact and cost of continued river degradation and climate changeinduced extreme rainfall and floods, there is growing urgency to achieve and maintain good river health to meet global sustainable development goals. Upscaling and working with nature-based solutions at regional, catchment and fluvial corridor scales is critical. One way to achieve this is to work within a recovery-enhanced approach to river rehabilitation, incorporating processes of geomorphic and vegetative recovery to build fluvial corridors in areas where they have become fragmented. Geomorphologically-informed cost-benefit analysis has not previously been applied in a riverine or riparian context, at the catchment or regional scale needed. We applied Marxan in a novel manner to undertake the first cost-benefit analysis for geomorphologically-informed rehabilitation of river systems. We estimated that to rehabilitate 75,500 km of streams in coastal catchments of NSW will cost $8.2 billion, comparing favourably to recent single flood event insurance losses, and projected future losses. We developed Marxan scenarios based on three broad approaches to river management: ad hoc and reactive, working with recovery and corridors, across current and future time periods. We found there are considerable current and flow-on future financial and non-financial benefits, and lower initial total and per-hectare rehabilitation costs, by fully adopting working with recovery or corridors approaches and moving away from the ad hoc and reactive approaches which dominate current practice. Implementing targeted rehabilitation based on a rolling sequence over time of corridors scenarios provides optimal holistic solutions to improve geomorphic condition and enhance recovery potential at landscape-scale. Our study demonstrates the use of Marxan as an accessible tool to address prioritisation complexity, and to run and cost landscape-scale rehabilitation scenarios over time. Our study also demonstrates the positive offsite feedbacks that occur through multiplier effects, as recovery occurs, and corridors are built. Geomorphologically-informed decision making becomes more robust, transparent, cost-effective, consistent across catchments, and adaptive to local situations and evolving river management priorities. [ABSTRACT FROM AUTHOR]

Summary Monitoring the condition of returning vegetation over time is essential for effectively managing riparian vegetation. Rapid riparian assessment methods are standard tools for capturing a suite of variables relevant to river health and are accessible to a range of users with different levels of experience. Monitoring efforts are particularly important for rivers undergoing degrading impacts and subsequent management interventions. In coastal catchments of New South Wales, Australia, vegetation is returning to rivers that were historically cleared for agriculture and are now experiencing geomorphic recovery. We present a rapid riparian assessment method for rivers undergoing vegetative and geomorphic recovery in this region. It addresses a gap in available rapid assessments by providing a methodology that can be used at sites with no historical analogue. Our assessment method adapts and extends a widely used method called the Rapid Assessment of Riparian Condition (RARC) to capture the quality of returning riparian vegetation along recovering rivers (rec), including native species diversity and vegetation structure (hence the name RARCrec). The RARCrec incorporates four sub‐indices – vegetation cover, native species richness, proportion of native to exotic species, and features of vegetation health – to produce an overall vegetation condition score that classifies sites as poor, moderate, or good condition. Scores for each sub‐index are assessed for the vegetation strata (groundcover, graminoids, midstorey, vines, and canopy) on the landform units of river bars, benches, and floodplains. The RARCrec has been designed to be sufficiently general for use in the main Vegetation Formations in coastal New South Wales and has been trialled at 36 sites across this region. Assessments can be conducted within half a day by two technically competent users and can be used to monitor vegetation condition over time to inform where to prioritise implementation of management activities. Field methodology and data sheets, including a scoring system, are provided to support the implementation of the RARCrec. [ABSTRACT FROM AUTHOR]

Geomorphic units (GUs) are the landforms that make up the valley bottom and are produced by fluvial processes that determine river structure and function. Mapping of GUs can be used to interpret river type and behaviour and to analyse river condition and recovery processes. The advancement of remote sensing technologies and big‐data acquisition are enabling the development and operationalisation of tools to semi‐automate the mapping of assemblages of GUs across large spatial areas. In this study, we develop a hierarchical method that combines a landscape classification approach (Geomorphons) with supervised classification using light detection and ranging data (LiDAR) and satellite images to semi‐automate the mapping of GUs across valley bottoms. We have also produced a new method for identifying and mapping pools in the absence of bathymetry data. We applied our method on 78 river sections in coastal catchments of NSW, Australia. We were able to identify 20 refined GU types and four further sub‐types of bank‐attached bars. Our method produced GU maps that are consistent with desktop manual delineation from aerial images and digital elevation models. Our hierarchical method offers GU maps with varying accuracy and resolution, accommodating a user's decisions regarding amount of effort invested relative to map quality and accuracy required. Initial runs produce maps with 12 preliminary GUs with 61%–75% consistency when compared to desktop manual mapping. With additional effort and manual corrections, a higher level of GU identification is possible (i.e. refined GU mapping increases the consistency to 70%–81%). The delineation of more intricate sub‐types of GU or sub‐units on compound GUs, which is essential for interpretation of river behaviour, condition, and recovery, still requires on‐site field verification to achieve the best results. [ABSTRACT FROM AUTHOR]

A philosophical and communication shift is needed in river management if we are to meet sustainable development goals and tackle environmental challenges brought about by ongoing anthropogenic and climate change. In some parts of the world, recovery‐enhancement approaches to river management have been adopted, communicated and used for many years. At the heart of these approaches lies an understanding of the biogeomorphic forms, processes and evolutionary trajectories of rivers that differs philosophically from notions of restoration, rewilding or creation of a utopian natural state. Instead, recovery‐enhancement approaches aim to improve the biogeomorphic condition of rivers, recognising that they are dynamic entities and new evolutionary trajectories and novel ecosystems are being created that are now part of the environment. Accepting shifting baselines and moving targets is inherent as boundary conditions (water, sediment and vegetation interactions) continue to be altered under the influence of anthropogenic and climate change, and the impacts of 'unprecedented' wildfires, floods, heatwaves and drought are manifested on the ground. The river management sector has not yet fully adapted to this reality with large amounts of applied science and on‐ground practice still focussed on restoration, re‐engineering and rewilding, words which in themselves produce a false impression of the aims, visions and achievability of river management. Embracing recovery‐enhancement approaches to river management requires a conscious shift in communication strategies and terminology to present more realistic expectations and possibilities for river condition improvement, a responsibility that is incumbent upon us, the scientists and practitioners, who work in the applied science and river management profession. In this Short Communication, I use a case study from eastern Australia to illustrate what biogeomorphic river recovery can look like. I use this to discuss the potential for adoption of a recovery‐enhancement approach to river management more broadly, and call on scientists and practitioners to make a conscious philosophical and communications shift when working in applied science and river management. [ABSTRACT FROM AUTHOR]

Capacity strengthening activities – be that in the form of courses, workshops, seminars – have become embedded in research projects as a requirement for funding and as a means for researchers to demonstrate positive societal impacts. We apply qualitative research techniques including interviews, questionnaires and observations to scrutinise and document an international capacity strengthening course aimed at informing and supporting environmental management practice and policy in the Philippines. We appraise power gradients and dynamics between course instructors and participants from different cultures and geographical locations in the design and delivery of this course. We identify five key factors that course instructors should consider as part of their pedagogy: (i) active learning, (ii) knowledge scaffolding and consolidation, and (iii) situated learning, as well as being attuned to (iv) the language dynamics and (v) expertise and networking within the room when teaching the course. Practical efforts to address these issues require that instructors work with participants to co-produce knowledge, rather than assuming epistemic authority and imposing knowledge. This entails reflexive and adaptable practices before, during and after the course. It is recommended that such practices should be central to projects that include capacity strengthening activities, whether delivered locally or internationally. [ABSTRACT FROM AUTHOR]

Since European colonisation, many coastal rivers of New South Wales (NSW) have been highly modified by channelisation, flow regulation, sediment mining, intensive grazing and agriculture, deforestation, and riparian vegetation and wood removal. Since the late 1980s, nearly 55% of these rivers have undergone a significant 're‐greening' and geomorphic recovery with changes to instream and riparian roughness. However, little research has been undertaken to quantify if there have been any coeval changes in flow hydrology. Approximately 7000 flow hydrographs with one‐hour time‐steps from 117 gauges on 45 study rivers (17 of 20 coastal catchments of NSW) were used to assess changes to in‐channel and overbank hydrology over decadal timeframes. Hydrograph shape and attenuation characteristics for three morphologically defined flow stages were analysed: in‐channel fresh, high flow and overbank flood. Time‐series analysis was used to quantify changes in flow hydrology from the early‐20th century to present and identify trends occurring between known degradation phases (1910s–1940s and 1940s–1980s) and a recovery phase (1990s to present) for these rivers. Our findings indicate that, on average, and for some key examples, changes in flow hydrology are occurring. Flows are slowing and attenuating as indicated by decreases in flood wave celerity and hydrograph kurtosis, skewness and rate of rise and increases in peak‐to‐peak travel time, flood peak attenuation and flood wave attenuation index. The most significant changes have occurred since the 1980s with the most noticeable effects on the behaviour of high flows (around the bankfull stage). However, there is not a consistent direction change in these indicators in all places. We use these findings to categorise the flow mitigation signal of the study regions and catchments and discuss the implication for river and flood management. [ABSTRACT FROM AUTHOR]

Extensive riparian vegetation clearance occurred in many rivers of southeastern Australia throughout the 19th and 20th century, post colonisation. With improvements in river management practices, coincident with a period of minimal flooding, vegetation recovery of riparian corridors has been occurring since the 1980s in all coastal catchments of New South Wales (NSW). However, the catchment‐by‐catchment spatial pattern and temporal trends, trajectories and rates of vegetative recovery remain unknown. We reconstruct a 70‐year time series of change in riparian vegetation coverage for all rivers in coastal catchments of NSW, utilising historical aerial imagery, Landsat and Sentinel data and a manual digitisation and machine learning method. We quantify and statistically analyse decadal trends in woody and non‐woody vegetation coverage along 19 485 km of stream length in 20 catchments. Across the region, there has been, on average, a 40% increase in vegetation coverage along riparian corridors since the 1950s, with some catchments increasing towards a current day coverage of between 60% and 80%. However, the trends vary by subregion and by catchment. An early logarithmic increase occurred up to 2004 on the North coast, and a recent and accelerated exponential increase since 1995 has occurred on the South coast. After a steep initial increase, riparian corridor vegetation coverage has fluctuated on the Central coast since about 1995. We used these linear, exponential and logarithmic regressions to undertake preliminary forecasts of possible future timeframes of riparian vegetation change, based on several climate, management and natural disaster disturbance scenarios. If the current trend continues, riparian vegetation coverage can reach 70% across the region by 2055. However, if management practices change or catastrophic disturbance events such as fire and flood occur, increases in riparian vegetation coverage could be set back by up to 30 to 40 years. [ABSTRACT FROM AUTHOR]

Radiocarbon dates on multiple individual charcoal fragments floating together down the Macdonald River, New South Wales, Australia, have calibrated ages spanning >1700 years. Partial explanations of this range of inherited ages can be attributed to the inbuilt age of living biomass, charcoalisation conditions, hillslope transport and storage and/or valley floor (fluvial) transport and storage, but the contribution of each of these components can be constrained only rarely. These results caution against using radiocarbon dating of charcoal as the sole dating technique to interpret Late-Holocene sedimentary histories. These findings also show that it is unlikely that deposit age has a dependable relationship to charcoal age. [ABSTRACT FROM AUTHOR]

Natural flood management (NFM), a nature‐based solution to flood mitigation where hydrological and biophysical processes are harnessed to reduce flow velocity, erosive energy and flood risk, is an emerging global theme of water and river management. The catastrophic 2021 and 2022 floods in eastern Australia are used to assess the hydrological properties of discrete events and to start an investigation of whether widespread changes in flood hydrology are occurring. We find that most coastal rivers in New South Wales (NSW) had a noticeable decrease in flood wave celerity (increase in flood travel time) when the 2021 and 2022 floods are contrasted with equivalent floods since the 1970s and that several also exhibit increases in flood peak attenuation. For some rivers, there is a coincident trend between these changing flood properties, riparian vegetation regrowth (regreening) and geomorphic recovery over the last +30 years. These may be the first signals that passive riparian management is counteracting some of the more severe hydrological effects of floods on these rivers and that some degree of NFM is possible. Lessons from this work are that there is an immediate opportunity to implement large‐scale NFM in coastal catchments of NSW, but this will only occur if we re‐examine current flood mitigation and adaption strategies and recognise and prioritise nature‐based solutions that include space‐to‐flood and corridors of river recovery, as essential parts of the modern flood mitigation toolkit. [ABSTRACT FROM AUTHOR]