Inappropriate use of land and poor ecosystem management have accelerated land degradation and reduced the storage capacity of reservoirs. To mitigate the effect of the increased sediment yield, it is ...important to identify erosion-prone areas in a 287 km2 catchment in Ethiopia. The objectives of this study were to: (1) assess the spatial variability of sediment yield; (2) quantify the amount of sediment delivered into the reservoir; and (3) prioritize sub-catchments for watershed management using the Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated using SUFI-2, GLUE, ParaSol, and PSO SWAT-CUP optimization algorithms. For most of the SWAT-CUP simulations, the observed and simulated river discharge were not significantly different at the 95% level of confidence (95PPU), and sources of uncertainties were captured by bracketing more than 70% of the observed data. This catchment prioritization study indicated that more than 85% of the sediment was sourced from lowland areas (slope range: 0–8%) and the variation in sediment yield was more sensitive to the land use and soil type prevailing in the area regardless of the terrain slope. Contrary to the perception of the upland as an important source of sediment, the lowland in fact was the most important source of sediment and should be the focus area for improved land management practice to reduce sediment delivery into storage reservoirs. The research also showed that lowland erosion-prone areas are typified by extensive agriculture, which causes significant modification of the landscape. Tillage practice changes the infiltration and runoff characteristics of the land surface and interaction of shallow groundwater table and saturation excess runoff, which in turn affects the delivery of water and sediment to the reservoir and catchment evapotranspiration.
A premise of stream restoration theory and practice is that it is often futile to attempt to restore a stream at the reach scale (10.sup.1 -10.sup.3 metres) until catchment scale problems have been ...addressed. This study considers reach scale restoration actions undertaken in Bryan Creek, a sand bed river in south east Australia impacted by a sediment pulse, after catchment sediment sources have been addressed. Local scale interventions, which were in-stream sand extraction, fencing to exclude stock and riparian revegetation, were evaluated by quantifying cross-section and thalweg variability, mapping in-stream and riparian vegetation and by classifying the morphology that emerged following each intervention. Following intervention channel reaches moved to one of three distinct states: simple clay bed, eroding reaches dominated by Juncus acutus, and reaches with deep pools and Phragmites australis. Boundaries between the intervention reaches were sharp, suggesting local scale interventions dominate over catchment scale processes. The magnitude and spread of variability metrics were similar between all reaches and differences in variability bore no relation to intervention type, despite the stark difference in post-intervention morphology. These findings suggest that cross-section and thalweg variability metrics are an inadequate proxy for the effectiveness of local scale interventions in accelerating the recovery of sand bed reaches from a bedload pulse. The most important implications for river managers is that local scale interventions can lead to substantial and rapid improvements in condition, and the change in condition of these reaches is almost independent of other reaches. In this case, the key to the pattern of reach scale geomorphic recovery is excluding stock from waterways so that a specific macrophyte can establish, trap sediment and develop pools.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Environmental infrastructure and practices designed to restore and protect aquatic systems are now mainstream. Yet many of these projects are failing to produce the biophysical outcomes that they are ...designed for because of poor maintenance. The success of restoration projects is just as much a consequence of how they are maintained, as it is how the project was initially designed and implemented. Successful maintenance relies on understanding the ecological and biological recovery trajectories of aquatic systems. Some interventions will require ongoing maintenance indefinitely, whereas others will reach a self‐sustaining point where maintenance is no longer required. Different management arrangements are required to ensure the maintenance of different types of project. Those projects that involve high costs should be managed using more robust arrangements, such as legal regulation, compared to those projects that involve lower costs. This paper describes the maintenance required for common river restoration projects and outlines a classification of projects based on maintenance and recovery trajectories. It then considers the types of management arrangements required to ensure maintenance. Finally, these points are illustrated with 3 case studies of typical restoration actions (riparian stock exclusion, fish passage, and restoring large wood loads). Projects that require ongoing maintenance, particularly those that involve high costs, such as environmental flows, require strong management arrangements to ensure successful outcomes. Voluntary instruments are more appropriate for self‐sustaining interventions. Regardless of the chosen management arrangements, monitoring and independent assessment are essential for successful maintenance.
Agricultural practices cause many of the environmental problems in river basins. Changing farmer behaviour to adopt more sustainable practices is a key focus of government policy in many countries. ...There is now a need to assess the effectiveness of projects that promote environmental agricultural behaviour. Most agricultural research that evaluates landholder practices relies on farmers to report about their own behaviour. This behavioural measure, known as ‘self-reporting’, has been widely critiqued because reporting is often biased. Little is known about the reliability of self-reports about environmental behaviour, and even less is known about self-reporting agricultural environmental behaviour. This paper considers the extent that agricultural environmental research relies on self-reported data, presents a case-study comparing farmer self-reports with more reliable observed proxy data, and offers some methods for minimising self-reporting bias, particularly bias related to participant perceptions of social desirability. We compared self-reports about farmer environmental behaviour (preventing cattle from grazing riverbanks) with observed proxy data (e.g., visual evidence of cattle access) and found that more than 60% of self-reports were inaccurate, including both under- and over-reporting of grazing behaviour. We found that self-reporting is less reliable for identifying behavioural determinants compared to using observed proxy data. We also found that farmers experience social pressure to perform environmental behaviours. Thus, we suggest the inaccuracy of self-reported data may be the result of social desirability bias. Substantial investment has been made to assess the effectiveness of government policy for encouraging agricultural environmental behaviour. The success of such programs relies on the accuracy of behavioural data. Agricultural research often depends on self-reported data. Thus, researchers should make efforts to design projects to reduce the likelihood of self-reporting bias.
•Environmental behaviour research relies heavily on self-reported behavioural data.•60% of farmer self-reporting of environmental behaviour was found to be inaccurate.•Self-reporting is a less reliable than proxy data for identifying behavioural determinants.•Social desirability bias may reduce the reliability of farmer self-reports.•Pilot studies, measuring social desirability and computing error, can reduce bias.
Instream wood plays important chemical, physical and ecological functions in aquatic systems, benefiting biota directly and indirectly. However, human activities along river corridors have disrupted ...wood recruitment and retention, usually leading to reductions in the amount of instream wood. In the tropics, where wood is believed to be more transient, the expansion of agriculture and infrastructure might be reducing instream wood stock even more than in the better studied temperate streams. However, research is needed to augment the small amount of information about wood in different biomes and ecosystems of neotropical streams. Here we present the first extensive assessment of instream wood loads and size distributions in streams of the wet-tropical Amazon and semi-humid-tropical Cerrado (the Brazilian savanna). We also compare neotropical wood stocks with those in temperate streams, first comparing against data from the literature, and then from a comparable dataset from temperate biomes in the USA. Contrary to our expectations, Amazon and Cerrado streams carried similar wood loads, which were lower than the world literature average, but similar to those found in comparable temperate forest and savanna streams in the USA. Our results indicate that the field survey methods and the wood metric adopted are highly important when comparing different datasets. But when properly compared, we found that most of the wood in temperate streams is made-up of a small number of large pieces, whereas wood in neotropical streams is made up of a larger number of small pieces that produce similar total volumes. The character of wood volumes among biomes is linked more to the delivery, transport and decomposition mechanisms than to the total number of pieces. Future studies should further investigate the potential instream wood drivers in neotropical catchments in order to better understand the differences and similarities here detected between biomes and climatic regions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
7.
Achieving change through gully erosion research Wilkinson, Scott N.; Rutherfurd, Ian D.; Brooks, Andrew P. ...
Earth surface processes and landforms,
January 2024, 2024-01-00, 20240101, Letnik:
49, Številka:
1
Journal Article
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This is an introduction to a special issue arising from the 8th International Conference on Gully Erosion, held in Townsville, Australia in 2019. Research has improved understanding of gully erosion ...processes and increasingly emphasizes sophisticated near‐and‐remotely sensed methods to characterize and measure gullies. These data can then be analysed using equally sophisticated models and scenarios can be simulated. These advances improve the capacity to predict gully initiation and development over time and space. It is often assumed that better prediction translates into greater impact and uptake of research to solve real world gully erosion problems. Examples of impressive associations between research programmes and major gully management programmes are evident. However, there has been little assessment of the impact of gully research. We argue for a greater focus on achieving impact including interventions that better manage and prevent gully erosion. Opportunities to deliver research impact are assessed using three indicators of progression towards impact; the practical usability of research, whether it is in use by non‐researchers, and whether it is useful in guiding improvements in management. Like other natural hazards, gully erosion is a phenomenon of the social, economic and environmental context in which it occurs. Defining the contexts and consequences of gully erosion and using these to frame further research is therefore a means to increase research impact. Enhancing collaboration between research disciplines and with practitioners who act on the research, and a greater focus on the translation of results into practice, is another avenue. Expanding the monitoring and evaluation of gully management can better demonstrate the impact of past research and enable further useful investigations. We urge gully erosion researchers to consider the potential impact of their research, including how it can more effectively inform better and more cost‐effective management and political decisions.
Following the 8th International Symposium on Gully Erosion we propose an increased focus on research impact on gully management and prevention, by defining the consequences of gully erosion, enhancing collaboration, focusing on use by practitioners, and expanding monitoring and evaluation.
River relocation is the diversion of a river into an entirely new channel for part of their length (often called river diversions). Relocations have been common through history and have been carried ...out for a wide range of purposes, but most commonly to construct infrastructure and for mining. However, they have not been considered as a specific category of anthropogenic channel change. Relocated channels present a consistent set of physical and ecological challenges, often related to accelerated erosion and deposition. We present a new classification of river relocation, and present a series of case studies that highlight some of the key issues with river relocation construction and performance. Primary changes to the channel dimensions and materials, alongside changes to flow velocity or channel capacity, can lead to a consistent set of problems, and lead to further secondary and tertiary issues, such as heightened erosion or deposition, hanging tributaries, vegetation loss, water quality issues, and associated ecological impacts. Occasionally, relocated channels can suffer engineering failure, such as overtopping or complete channel collapse during floods. Older river relocation channels were constructed to minimise cost and carry large floods, and were straight and trapezoidal. In some countries, modern relocated channels represent an exciting new challenge in that they are now designed to replicate natural rivers, the success of which depends on understanding the characteristics, heterogeneity, and mechanisms at work within the natural channel. We discuss shortcomings in current practice for river relocation and highlight areas for future research for successful rehabilitation of relocated rivers.
•Stream restoration goals may be better achieved working with geomorphic processes.•Feasibility in an urban context requires addressing the causes not symptoms.•We discuss addressing stormwater ...runoff, riparian space and sediment loads.•Legacy land use and social/institutional barriers require greater consideration.
Urbanization of catchments profoundly changes the morphology of streams by increasing stormwater runoff, altering sediment regimes, and limiting space for channel change. Management response commonly involves addressing the symptoms of urbanization by reconfiguration and partial hard-lining of the channel. Mounting evidence suggests, however, that stream restoration goals may be better achieved by addressing the causes of channel degradation at a catchment scale, increasing opportunities to work with geomorphic processes. The challenges of this approach in urban catchments have not been comprehensively explored. In this perspective essay we describe how stream restoration in urban catchments might be better achieved by undertaking activities in the catchment or riparian zone to address the causes, rather than patch the symptoms. We describe the challenges that need to be overcome to address these causes including; excess stormwater runoff, lack of riparian space, altered sediment supplies, legacy impacts on streams from former land use, and social and institutional barriers. We discuss opportunities for each. A more sustainable urban stream solution may be achieved by addressing these issues to reduce the impact of urbanization on stream morphology.
Both public health, and the health of the natural environment, are affected by policy decisions made across portfolios as diverse as finance, planning, transport, housing, education, and agriculture. ...A response to the interdependent character of public health has been the "health in all policies" (HiAP) approach.
With reference to parallels between health and environment, this paper argues that lessons from HiAP are useful for creating a new integrated environmental management approach termed "environment in all polices" (EiAP).
This paper covers the theoretical foundations of HiAP, which is based on an understanding that health is strongly socially determined. The paper then highlights how lessons learned from HiAP's implementation in Finland, California, and South Australia might be applied to EiAP. It is too early to learn from evaluations of HiAP, but it is apparent that there is no single tool kit for its application. The properties that are likely to be necessary for an effective EiAP approach include a jurisdiction-specific approach, ongoing and strong leadership from a central agency, independent analysis, and a champion. We then apply these properties to Victoria (Australia) to demonstrate how EiAP might work.
We encourage further exploration of the feasibility of EiAP as an approach that could make explicit the sometimes surprising environmental implications of a whole range of strategic policies. Citation: Browne GR, Rutherfurd ID. 2017. The case for "environment in all policies": lessons from the "health in all policies" approach in public health. Environ Health Perspect 125:149-154; http://dx.doi.org/10.1289/EHP294.
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CEKLJ, DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
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