River Rehabilitation Research Articles

Developing river rehabilitation scenarios by integrating landscape and hydrodynamic modeling for the Ciliwung River in Jakarta, Indonesia

Landscape visualization and modeling has progressively merged over the last decade providing ever increasing accuracy and realism. As powerful as visualized landscapes may be, there is a need to integrate them with numerical models to simulate real world dynamics, and by doing so, move beyond a purely visual evocative expression to one which is physically grounded in reality. In this paper, we present an approach that integrates landscape and hydrodynamic modeling through the modification and testing of point cloud data to assess the flooding of the Ciliwung River in Jakarta, Indonesia. We propose a series of 6 scenarios along the 40km course of the river corridor ranging from the governments’ “normalisation” proposal to a green infrastructure scenario by our team. Through such flood simulations we have found that the severity of the floods can only be contained by implementing the extensive normalized canal that is planned, however, the scale of the intervention at hand and the possible impacts further downstream need to be carefully weighed in. Likewise, while the green infrastructure scenario can be seen as a possible alternative to flood management, it is unlikely to mitigate the effects of the most severe of floods. In reality, a careful combination of the two extreme scenarios of a new concrete channel and a green corridor will likely provide the best balance between flood mitigation and riparian restoration. The integrated modeling approach presented here provides a possible platform to further refine such a scenario into one which best caters to all stakeholders in the Bogor, Depok and Jakarta regions.

Assessment of River Habitat Quality in the Hai River Basin, Northern China.

We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01) and urban land (r = 0.998; p < 0.05); and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01). Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated.

Developing and using geomorphic condition assessments for river rehabilitation planning, implementation and monitoring

Frameworks for assessing geomorphic river condition constitute a core part of the river management process, providing a critical platform for environmental decision‐making and associated actions. The evolution of approaches for assessing the geomorphic (also called physical, morphological, or hydromorphological) condition of rivers has shifted from a design and development phase in the late‐1990s and early 2000s to application and use of approaches for assessment, monitoring, and rehabilitation decision making. In this paper I review the core geomorphic principles that are embedded in more sophisticated, process‐based frameworks, and demonstrate how the information generated through use of these frameworks can be used to guide management choices, change management activities or opt‐out of management activities as part of precautionary river management practice. I propose that a key challenge now faced by geomorphologists and managers is to move beyond the development of more new frameworks, and consolidate efforts to use, test, and adapt existing approaches and datasets to achieve river management visions and objectives framed around improving river condition. WIREs Water 2015, 2:649–667. doi: 10.1002/wat2.1100This article is categorized under: Water and Life &gt; Conservation, Management, and Awareness Engineering Water &gt; Planning Water

Designing forward with an eye to the past: Morphogenesis of the lower Yuba River

The early geomorphic evolution of the lower Yuba River (LYR), northern California, up to 1906 is reconstructed using cartographic, documentary, topographic, and stratigraphic evidence. The importance of early river mining is identified along with rates and patterns of floodplain aggradation and channel incision at the turn of the 20th century. The LYR is a classic example of anthropogeomorphic transformation of a river by episodic hydraulic mining sedimentation. This was followed by channelization, damming, dredging, and other engineering works to redirect, contain, and stabilize channels. These geomorphic changes and engineering controls continue to govern channel and floodplain form and process, control the trajectory of river responses, and constrain flood control, water quality, and aquatic ecosystem management options.Returning a river system to a prior condition should not be the primary goal of river rehabilitation projects, especially if hydrologic inputs have substantially changed. Reconstructing former conditions may be impractical and unsustainable under modern circumstances. Instead, fluvial systems should be designed and managed for present inputs and processes while anticipating future conditions. Rapid changes in land use and climate that generate changes in runoff and sediment loadings are likely to generate morphological instability, and these changes should be considered in the design and management of fluvial systems. The past geomorphic evolution of fluvial systems should also be considered in design and management decisions to recognize trajectories and suppressed tendencies. Recognition of trends and system vulnerabilities may avoid potential blunders, such as removing critical stabilizing works. Complex causalities may be difficult to reconstruct from geomorphic form alone, however, due to process-form dynamics. Detailed research on the geomorphic and engineering history of a river is essential, therefore, if substantial changes and morphologic instabilities have occurred.

Opportunities for improving the foraging potential of urban waterways for bats

The rapid rate of urbanisation over the past century has occurred over a relatively small proportion of the earth's surface, yet it has had considerable ecological impact at a global scale. Urban waterways have historically been regarded as a disposable resource for human benefit which has had severe biological consequences. River rehabilitation schemes are attempting to address this; however restoration is frequently undertaken with minimal scientific input and fails to improve biodiversity. Many bat species are strongly associated with aquatic or adjacent riparian habitats but respond negatively to the built environment; however, we know little about the utilisation of urban waterways by bats. We therefore conducted a wide scale, multi-species study that examined how local habitat characteristics and the composition and heterogeneity of the surrounding landscape influence bat presence and activity along urban waterways. We recorded a total of 19,689 bat passes of seven species/genera from 30 urban waterways throughout the U.K. We show that the built environment can negatively affect a variety of species from the riparian zone up to 3km from a waterway. Additionally, Myotis sp. activity was greater in waterways bounded by steep banksides and clear of invasive plant species. We also found differences in the response of two cryptic pipistrelle species to the built environment at multiple spatial scales indicating the difficulties of assessing how adaptable even morphologically similar species are to urbanisation. Beneficial urban waterway rehabilitation schemes for bats require management at multiple spatial scales. At a local scale, retaining a vegetated riparian zone, with a reduction in invasive aquatic plant species, is likely to benefit a variety of taxa. At a landscape scale, our results show that the influence of the built environment can stretch a considerable distance highlighting the necessity for conservation funding to be spent on the implementation of landscape scale environmental improvement schemes which encompass the entire urban matrix.

Realizing the value of fluvial geomorphology

ABSTRACTFluvial geomorphological forms and processes exert a fundamental influence on riverine processes and functions. They thereby contribute significantly to beneficial services for humanity, yet remain largely undervalued. Major ecosystem service studies to date tend to overlook the contribution of geodiversity and geomorphological processes, particularly of fluvial geomorphology, to human well-being. Yet, management of the water environment which overlooks fundamental driving processes, such as those encompassed by fluvial geomorphology, is inherently unsustainable. Inferences from the literature highlight a broad range of contributions of fluvial processes and forms to the four ecosystem service categories of the Millennium Ecosystem Assessment, contributing to system functioning, resilience and human well-being. Fluvial geomorphologists can help society better address sustainability challenges by raising the profile of fluvial forms and processes to continuing human well-being and system resilience. To achieve this, we identify three challenges: (1) cross-disciplinary collaboration, addressing interrelations between biodiversity and geodiversity as well as broader scientific disciplines; (2) quantification to an appropriate level and, where possible, mapping of service generation and benefit realization; and (3) persuasive demonstration projects emphasizing how investment in this aspect of the natural environment can enhance service provision and net human benefits. We explore lessons learnt from case studies on river rehabilitation, floodplain management, and mapping ecosystem services. We contend that linking fluvial geomorphology to societal well-being outcomes via the language of ecosystem services provides a pathway towards social and economic recognition of relevance, influencing policy-makers about their importance and facilitating their ‘mainstreaming’ into decision-making processes. We also advance a prototype conceptual model, guiding fluvial geomorphologists better to articulate the contribution to a sustainable flow of services through better characterization of: (1) interactions between anthropogenic pressures and geomorphology; (2) how forms and processes contribute to ecosystem services; and (3) guidance on better management reflecting implications for service provision.

Changing the Course of Rivers in an Asian City: Linking Landscapes to Human Benefits through Iterative Modeling and Design

AbstractConcerns over water scarcity, climate change, and environmental health risks have prompted some Asian cities to invest in river rehabilitation, but deciding on the end goals of rehabilitation is a complex undertaking. We propose a multidisciplinary framework linking riparian landscape change to human well‐being, providing information relevant to decision makers, in a format that facilitates stakeholder involvement. We illustrate this through a case study of the densely settled, environmentally degraded, and flood prone Ciliwung River flowing through metropolitan Jakarta, Indonesia. Our methodology attempts to respond to this complexity through an iterative approach, strongly based on conceptualization and mathematical modeling. Nested hydrologic, hydrodynamic, and water quality models provide outputs at catchment‐, corridor‐, and localized site‐scales. Advanced 3‐D landscape modeling is used for procedural design and precise visualization of proposed changes and their impacts, as predicted by the mathematical models. Finally, participatory planning and design methods allow us to obtain critical stakeholder feedback in shaping a socially acceptable approach. Our framework aims at demonstrating that a change in paradigm in river rehabilitation is possible, and providing future scenarios that balance concerns over flooding, water quality, and ecology, with the realities of a rapidly growing megacity.

Disentangling the effects of habitat suitability, dispersal, and fragmentation on the distribution of river fishes.

Habitat suitability, dispersal potential, and fragmentation influence the distribution of stream fishes; however, their relative influence and interacting effects on species distributions are poorly understood, which may result in uncertain outcomes of river rehabilitation and conservation. Using empirical data describing 17 relatively common stream fishes, we combine (1) species habitat suitability models (MaxEnt) with a (2) species dispersal model (FIDIMO) and a (3) worst-case scenario of the influence of river fragmentation on dispersal. Using generalized linear mixed models, we aimed to uncover the role of these factors in explaining the probability of presence. Simulations over nine years allowed for assessing the relative importance of dispersal over time for structuring species occurrences vs. the importance of habitat suitability. Models combining all three structuring factors performed consistently better in predicting the spatial occurrence patterns than models including only single factors. Our results confirmed that distribution patterns of stream fishes are jointly controlled by species dispersal and habitat suitability. An increase of 0.1 habitat suitability probability more than doubled the odds of species occurrence; an increase of 0.1 dispersal probability yielded a 14-fold increase of the odds of species occurrence. Temporal simulations revealed that over short time frames (1-2 years) dispersal from nearby source populations is four times more important than habitat suitability for species presence. However, over longer time periods, the importance of habitat suitability increases relative to the importance of dispersal. Surprisingly, fragmentation by migration barriers did not appear as a significant driver of occurrence patterns. Concluding, these findings demonstrate the importance of the spatial arrangement of suitable habitats and potential source populations, as well as their relative position in relation to barriers. We emphasize considering the direction of connections within river networks and the dispersal abilities of fishes, as well as providing (access to) new, suitable habitat for successful river rehabilitation.

The conceptual foundation of environmental decision support

Environmental decision support intends to use the best available scientific knowledge to help decision makers find and evaluate management alternatives. The goal of this process is to achieve the best fulfillment of societal objectives. This requires a careful analysis of (i) how scientific knowledge can be represented and quantified, (ii) how societal preferences can be described and elicited, and (iii) how these concepts can best be used to support communication with authorities, politicians, and the public in environmental management. The goal of this paper is to discuss key requirements for a conceptual framework to address these issues and to suggest how these can best be met. We argue that a combination of probability theory and scenario planning with multi-attribute utility theory fulfills these requirements, and discuss adaptations and extensions of these theories to improve their application for supporting environmental decision making. With respect to (i) we suggest the use of intersubjective probabilities, if required extended to imprecise probabilities, to describe the current state of scientific knowledge. To address (ii), we emphasize the importance of value functions, in addition to utilities, to support decisions under risk. We discuss the need for testing “non-standard” value aggregation techniques, the usefulness of flexibility of value functions regarding attribute data availability, the elicitation of value functions for sub-objectives from experts, and the consideration of uncertainty in value and utility elicitation. With respect to (iii), we outline a well-structured procedure for transparent environmental decision support that is based on a clear separation of scientific prediction and societal valuation. We illustrate aspects of the suggested methodology by its application to river management in general and with a small, didactical case study on spatial river rehabilitation prioritization.

Integrating Geomorphological Assessments and Oral Histories in Catchment Management: Implications for the Mulgrave River, Northeastern Australia

The dramatic decline in the integrity of Australian river systems in recent decades has seen the development of landcare and catchment management groups across the continent as the main facilitators of river rehabilitation works. There is growing concern for the need to develop adaptive management frameworks that assist informed decision making through the integration of social and geomorphological knowledge into catchment planning. In the Mulgrave River Catchment of northeastern Queensland, difficult management decisions have to be made with limited access to knowledge of natural processes and baseline geomorphological data. To date management decisions have been based almost exclusively on oral histories that state that point bars are accreting and the river is becoming shallower due to bank erosion. As a result bank stabilisation and removal of sand from within the channel have been recommended in the absence of any geomorphological assessments. This study compares oral histories of river bank erosion in the Mulgrave River with geomorphic evidence to highlight the need for integrated landscape scenario planning. The results of grain size analysis of bank and bed material from 27 locations, involving 47 samples, suggest that bank erosion cannot be delivering sediments to point bars. Furthermore, qualitative analysis of historic parish maps and aerial photographs shows that there has only been moderate bank erosion at three locations along the Mulgrave River since European settlement. The study demonstrates the important role that geomorphological investigations have for catchment management and the need for management frameworks that integrate geomorphological processes and landholder priorities for sustainable river management.

Quantitative assessment of the relationships among ecological, morphological and aesthetic values in a river rehabilitation initiative

Promoting community support in rehabilitation efforts through incorporation of aesthetic considerations is an important component of environmental management. This research utilised a small-scale survey methodology to explore relationships among the ecological and morphological goals of scientists and the aesthetic goals of the public using the Twin Streams Catchment, Auckland, New Zealand, as a case study. Analyses using a linear model and a generalised linear mixed model showed statistically significant relationships between perceived naturalness of landscapes and their aesthetic ratings, and among ratings of perceived naturalness and ecological integrity and morphological condition. Expert measures of health and the aesthetic evaluations of the public were well aligned, indicating public preferences for landscapes of high ecological integrity with good morphological condition. Further analysis revealed participants used ‘cues to care’ to rate naturalness. This suggests that environmental education endeavours could further align values with these cues in efforts to enhance approaches to landscape sustainability.

Local tributary widening for river rehabilitation

AbstractThe hydro‐morpho‐sedimentary processes in confluence hydrodynamic zones (CHZ) subject to a local widening of the tributary were investigated in a series of laboratory experiments that were representative of the 20 major confluences of the Upper Rhone River in Switzerland. Three discharge ratios (low, intermediate and high ratios of tributary to main channel discharge) were investigated for each of four tributary configurations (reference configuration with constant tributary width and three geometries of the local tributary widening). In all experiments, the local tributary widening caused substantial morphodynamic changes in the CHZ and moderate sediment redistribution in the post‐confluence channel. At the entrance of the local widening, the tributary main flow corridor gradually widened. Towards the confluence mouth, it narrowed and deflected in downstream direction because of a zone of flow stagnation at the confluence upstream junction corner. Dry zones and flow stagnation zones occurred in the widening zone outside the tributary main flow corridor. The results indicate that a local tributary widening considerably enhances the variability of bed substrate, velocity and depth in the CHZ, and offers an appropriate habitat for a wider range of biota than the homogeneous channelized reference configuration. None of the investigated experiments resulted in adverse impacts on water surface elevation and thereby flood safety. On the basis of the laboratory experiments, the appropriate geometry of the local tributary widening is discussed, and quantitative guidelines for practical application are proposed. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Rapid bioassessment of the effects of repeated rotenone treatments on invertebrate assemblages in the Rondegat River, South Africa

The potential collateral effects of eradicating invasive fishes in streams necessitate the monitoring of invertebrate communities during treatment. In an environmental rehabilitation programme, non-native smallmouth bass were removed from the lower reaches of the Rondegat River, Western Cape, South Africa, in 2012 and again in 2013 using the piscicide rotenone. A monitoring programme tracked the ecological response of organisms to these activities using quantitative sampling of macroinvertebrates on stones and the ISO-certified SASS5 rapid bioassessment method for assessing macroinvertebrate community integrity. We recorded a significant decrease in macroinvertebrate densities from the stones-in-current biotope following both rotenone treatments. The average score per taxon (ASPT) declined after the first treatment, indicating a loss of taxa sensitive to diminished water quality, then recovered prior to the second treatment, and subsequently no decline was detected after the lower dose used in the 2013 treatment. The SASS values were too variable to reveal trends. The ASPTs indicated that the community may have been resistant to low dose and resilient to high dose, due to inter-treatment recovery following the 2012 treatment, suggesting that the invertebrate assemblage is resilient to the conservative use of rotenone for localised river rehabilitation when upstream sources of recruitment exist.

The habitat use of young-of-the-year fishes during and after floods of varying timing and magnitude in a constrained lowland river

Globally, channelisation and artificial levee construction have reduced rivers to single-thread channels isolated from their floodplains. These modifications may be particularly detrimental to fish during floods, because of increased severity of conditions in the main river channel, prevention of fish finding refuge in floodplain habitats, and stranding of fish when floodwaters recede after artificial levees are ‘over-topped’. Notwithstanding, few studies have examined the habitat use by young-of-the-year (YoY; age 0+ year) fish in constrained lowland rivers during floods in slackwaters (main channel with little or no discernible current) and after floods on floodplains. This study investigated the community structure and density of 0+ fish species before (main river), during and after floods of varying timing and magnitude in the River Yorkshire Ouse, a constrained lowland river in north-east England. Slackwaters provided refuge for high densities of mainly eurytopic 0+ fishes during floods and high densities of 0+ fishes were found stranded on floodplains after floods. Community composition in slackwaters during floods and on floodplains after floods was significantly different to the main river catches during average daily flows, possibly related to species-specific morphology and behavioural responses to elevated flow. Despite there being floods of greater magnitude during the winter, peak densities of 0+ fish stranded on floodplains occurred in the summer, and probably related to habitat use immediately prior to floods. Fish were also found stranded on floodplains actively managed to store floodwater to protect property and are presumed to permit safe egress for fish. The results are discussed in relation to lowland river rehabilitation, which is particularly important because of potential conflicts between obligations under various European directives to improve the status of fish populations in degraded rivers (Water Framework Directive) whilst at the same time minimise flooding of societal assets (Flood Directive).

Remnant riparian vegetation, sediment and nutrient loads, and river rehabilitation in subtropical Australia

A decline in the ecosystem health of Australia's Moreton Bay, a Ramsar wetland of international significance, has been attributed to sediments and nutrients derived from catchment sources. To address this decline the regional management plan has set the target of reducing the loads by 50%. Reforestation of the channel network has been proposed as the means to achieve this reduction, but the extent of revegetation required is uncertain. Here we test the hypothesis that sediment and nutrient loads from catchments decrease proportionally with the increasing proportion of the stream length draining remnant vegetation. As part of a routine regional water quality monitoring program sediment and nutrient loads were measured in 186 flow events across 22 sub-catchments with different proportions of remnant woodland. Using multiple linear regression analysis we develop a predictive model for pollutant loads. Of the attributes examined a combination of runoff and the proportion of the stream length draining remnant vegetation was the best predictor. The sediment yield per unit area from a catchment containing no remnant vegetation is predicted to be between 50 and 200 times that of a fully vegetated channel network; total phosphorus between 25 and 60 times; total nitrogen between 1.6 and 4.1 times. There are ~48 000 km of streams in the region of which 32% drain areas of remnant vegetation. Of these 17 095 km are above the region's water storage dams. We estimate that decreasing the sediment and phosphorus loads to Moreton Bay by 50% would involve rehabilitating ~6350 km of the channel network below the dams; halving the total nitrogen load would require almost complete restoration of the channel network. Copyright © 2014 John Wiley & Sons, Ltd.

Application of hydrological models for agri-environmental management based on international and national experiences

The ecological restoration of surface water flows requires the use of complex GIS and hydrological models. The HEC -RAS and MIKE11 programs calculate the hydraulic characteristics of runoff using the geometry and bed resistance the of flows. The presentation of some possible applications made through an example of the Berettyó, which is an extremely regulated river. The river belongs to the meandering category by Parker's classification system, which uses the relationship of the slope-Froude number and the depth- width ratio. Three coefficient of the four determining factor (entrenchment ratio, slope of water level, width-depth ratio) also indicates a mediocre to high sinuosity, while the river regulations established nearly straight bed-line. The standard water flow rates and characteristics have been determined based on the modeled Froude and Reynolds numbers. The flow conditions shifted to the laminar type by the changed line drawing which is ecologically lower status. Based on the results the morphological and ecohydrological river rehabilitation is appropriate.

River Rehabilitation With Cities In Mind: The Eskişehir Case

Akarsular ve kentler eski uygarliklardan bu yana daima suregelen icsel baglar icerisinde olmuslardir. Pek cok kentin can damari olarak akarsular, ulastirma, enerji, kullanma suyu, sulama, ticaret ve rekreasyon gibi bircok isleve sahiptirler. 19. yuzyilin sonlariyla birlikte, cogunlukla kentlesmenin etkileri akarsu ve akarsu kiyilarinin onemini azaltmaya baslamistir. Akarsular atiksu kanallarina donusmus ve kent yasamindan koparilmis hale gelmislerdir. Onyillarca ihmal edildikten sonra kentsel akarsular, sorunlarin cozulmesi icin ozellikle 1970’lerden bu yana iyilestirme konusu olmaya baslamistir. 1990’lara gelindiginde kentsel akarsu iyilestirmelerindeki bu bagimsiz ve tek boyutlu uygulamalar yerine, kentsel akarsu rehabilitasyonunda sorunlari kapsamli bicimde ele alan yeni tutumlar on plana cikmaya baslamistir. Bu yazida, icinde bulundugumuz 2000’li yillarda, kentsel akarsularin iyilestirilmesi kavraminda genel cagdas kuresel anlayisin iki yonlu oldugu iddia edilmektedir: Oncelikle, kentsel akarsular artik yalnizca kentsel altyapi unsurlari olarak kabul edilmemekte, doganin yenilenmesinin ve kentsel ekolojinin onemli temelarini olusturmaktadirlar; bu yonleriyle kentsel ekolojik surdurulebilirlik icin yasamsal bir katki saglarlar. Ikinci olarak, bir yandan da tarihi alanlar, kentsel anitlar ve odak noktalari gibi ogeleri barindiran kentsel kurgunun ayrilmaz parcalaridirlar. Bu anlamda kentlilerin kentleri ile bag kurmalarinda onemi olan kentsel imge ve kimliginin olusmasina destek olurlar. Makalede, bu ikinci yon ele alinmakta, kentsel akarsularin ayrik kentsel bilesenler yerine cevresiyle birlikte bir butun olarak degerlendirilmesi uzerinde durularak, kentsel akarsularin kentlerin butunlesik bir parcasi olarak nasil planlanacagi uzerinde durulmaktadir. Bir baska deyisle makale, kentsel akarsulara iliskin uygulamalarin, cevresindeki onemli kentsel odaklari icerecek bicimde genisletilmesi uzerine bir tartisma icermektedir. Bunun icin, Eskisehir kenti, iyi uygulamalardan biri olarak ayrintili olarak degerlendirilmekte ve kentsel akarsuyun mekansal butunlesmesi cercevesinde bir olcutler takimi gelistirilmektedir.

Decision support for ecological river rehabilitation using fish habitat database.

After the recent success of several river rehabilitation projects including the Cheong-gye river case, a large number of local governments have been promoting their own projects in Korea. Most of the projects are aimed at securing the soundness of aquatic ecosystems according to the guidelines presented by the Korea Ministry of Environment. However, there is no clear guidance for the management goals of water quality and quantity. In this study, we have made an attempt to construct a habitat database (DB) for each domestic freshwater fish species. The fish population, and physical and physicochemical properties of the habitat of 70 domestic freshwater fish species were investigated using field monitoring data. After the statistical processing, the inhabitable range and optimal range of each species were suggested. Furthermore, based on the DB, a decision support system for ecological river restoration and rehabilitation has been developed, and applied for field tests. It became clear that the decision support procedure based on the fish habitat DB is useful in the planning stage of river rehabilitation projects to select the flagship fish, to decide the restoration goals considering their appropriate habitat and to suggest the optimum quantitative combination of each available water resource.

Synthetic river valleys: Creating prescribed topography for form–process inquiry and river rehabilitation design

The synthesis of artificial landforms is complementary to geomorphic analysis because it affords a reflection on both the characteristics and intrinsic formative processes of real world conditions. Moreover, the applied terminus of geomorphic theory is commonly manifested in the engineering and rehabilitation of riverine landforms where the goal is to create specific processes associated with specific morphology. To date, the synthesis of river topography has been explored outside of geomorphology through artistic renderings, computer science applications, and river rehabilitation design; while within geomorphology it has been explored using morphodynamic modeling, such as one-dimensional simulation of river reach profiles, two-dimensional simulation of river networks, and three-dimensional simulation of subreach scale river morphology. To date, no approach allows geomorphologists, engineers, or river rehabilitation practitioners to create landforms of prescribed conditions. In this paper a method for creating topography of synthetic river valleys is introduced that utilizes a theoretical framework that draws from fluvial geomorphology, computer science, and geometric modeling. Such a method would be valuable to geomorphologists in understanding form–process linkages as well as to engineers and river rehabilitation practitioners in developing design surfaces that can be rapidly iterated. The method introduced herein relies on the discretization of river valley topography into geometric elements associated with overlapping and orthogonal two-dimensional planes such as the planform, profile, and cross section that are represented by mathematical functions, termed geometric element equations. Topographic surfaces can be parameterized independently or dependently using a geomorphic covariance structure between the spatial series of geometric element equations. To illustrate the approach and overall model flexibility examples are provided that are associated with mountain, lowland, and hybrid synthetic river valleys. To conclude, recommended advances such as multithread channels are discussed along with potential applications.

Demonstration reaches: Looking back whilst moving forward with river rehabilitation under the Native Fish Strategy

Summary‘Demonstration reaches’ are sections of river where multiple threats to native fish are addressed through river rehabilitation and strong community participation. They are an important way of promoting the key driving actions of the Murray‐Darling Basin Authority's Native Fish Strategy (NFS) by using on‐ground community‐driven rehabilitation. Measuring rehabilitation success against well‐defined targets and using this information to adaptively mange activities is fundamental to the demonstration reach philosophy. Seven years on from the establishment of the first demonstration reach, there are now seven throughout the Murray‐Darling Basin (MDB), all in differing states of maturation and but all applying a standardised framework for monitoring native fish outcomes. In this study, we reflect on the role that demonstration reaches have played within the NFS, synthesise some key findings from 32 monitoring and evaluation outputs, and highlight some of the successes and barriers to success. We make recommendations as to how to strengthen the demonstration reach model to ensure it remains a relevant approach for fish habitat rehabilitation beyond the NFS and MDB.