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Nature-based Solutions for Leveed River Corridors
... Levees are anthropogenic embankments constructed along a water course or river for flood risk reduction to prevent overflow of the river onto adjacent lands. Most levees constructed to date were designed to confine floods within a narrow, engineered floodway that blocked river access to its natural floodplain, resulting in deepening and accelerated flow through the leveed reach and decreased groundwater recharge, increased channel erosion, and reduced native species habitat (Chambers et al., 2023;Knox et al., 2022;Opperman et al., 2017). Many of these floodplain and water cycle functions have been further impacted by climate change in recent decades as the severity of floods and droughts has increased, which also reduces the effectiveness of traditional water management (e.g., canals and reservoirs) to capture, transfer, and store these extreme flows (Cayan et al., 2005;Swain et al., 2018). ...
... While traditional flood risk reduction strategies have mainly focused on engineered control structures of river systems such as levees and reservoirs that were built based on a short streamflow record (less than 100 years), levee setbacks provide a more naturebased solution to flood risk reduction and in some ways a form of managed infrastructure retreat (Chambers et al., 2023;Klijn et al., 2018;Van Rees et al., 2024). Levees and reservoirs function best under the conditions of the design flow, but the extreme streamflows occurring today due to climate change are increasing the risk of infrastructure failure (Swain et al., 2018) and require the implementation of alternative flood management strategies such as levee setbacks. ...
Constructed levees are designed to protect anthropogenic developments from destructive flooding events, but their construction has reduced groundwater recharge, increased flood risk severity under levee failure, increased the incision of river channels, and deteriorated riparian habitat. To reverse these impacts, levee setbacks are often designed to reduce flood risk and provide the opportunity to restore ecohydrological function, while groundwater recharge is rarely considered because it may require relatively detailed groundwater system analysis. In this study, we evaluated 100 heterogeneous hydrogeology realizations to estimate recharge with high-conductivity pathways (HCPs) under varying flood flows for a range of levee setback distances to identify the trade-offs in groundwater recharge and floodplain habitat. We find that on a regional scale, total recharge potential increases with setback distance, with the largest gains up to 1,400 m where there are outcropping HCPs and sufficient flow to inundate more of the setback area. In contrast, the recharge per unit area (i.e., the average daily recharge divided by setback area) generally decreases as levee setback increases, but there are local increases in the recharge per unit area at 1,400 m where HCP recharge may sufficiently offset the larger area. There is a median 10%–40% reduction in peak streamflow with increasing setback distance, which would aid flood risk reduction, but the increased area leads to decreasing depth due to flow losses and increased spreading of flood water. Ultimately, the decision for levee setback distance will depend on local conditions and management goals, as we find that increasing recharge will reduce the floodplain depth necessary for ecosystem function. Our results highlight the opportunity to consider groundwater recharge benefits in levee setback feasibility studies in semi-arid regions impacted by floods and groundwater overdrafts so that setback distance designs can achieve integration of flood risk reduction, riparian habitat, and groundwater recharge.
... Key components include: (1) implementing biodiversity conservation actions (defined as those that seek to maintain or improve biodiversity, including restoration, protection and management; Langhammer et al. 2024) and managing agricultural, forested and urban land; (2) safeguarding ecosystems that strongly contribute to water retention, such as forests and wetlands, by substantially increasing the spatial extent of legally protected terrestrial and freshwater ecosystems (Schröter et al. 2023); (3) promoting natural and managed groundwater and aquifer recharge (Dillon and Arshad 2016;Salem et al. 2020) to retain water for longer periods and reduce surface evaporation (Salem et al. 2020); (4) using funding options such as the US Greenhouse Gas Reduction Fund (Callahan and DeShazo 2014), the European Green Deal (Fetting 2020) or the World Bank (Goodland 1987;Hickey and Pimm 2011); and (5) improving governance structures, which include local people, to overcome administrative and disciplinary barriers. Management of flood and drought risk should consider freshwaters as hybrid systems, by combining NbS with advanced conventional methods to convert conflicts between humans and ecosystems into mutual benefits (van Rees et al. 2019;Serra-Llobet et al. 2022;Chambers et al. 2023). In addition, flood and drought management measures should be designed to sustain biodiversity and promote ecosystem adaptation to climate change (van Rees et al. 2019, which requires an integrated approach that enables both people and nature to cope with increasing climatic extremes. ...
As climatic extremity intensifies, a fundamental rethink is needed to promote the sustainable use of freshwater resources. Both floods and droughts, including water scarcity, are exacerbating declines in river biodiversity and ecosystem services, with consequences for both people and nature. Although this is a global challenge, densely populated regions such as Europe, East Asia and North-America, as well as the regions most affected by climate change, are particularly vulnerable. To date mitigation measures have mainly focused on individual, local-scale targets, often neglecting hydrological connectivity within catchments and interactions among hydrology, biodiversity, climate change and human wellbeing. A comprehensive approach is needed to improve water infiltration, retention and groundwater recharge, thereby mitigating the impacts of heavy rainfall and floods as well as droughts and water scarcity. We propose a holistic catchment-scale framework that combines mitigation measures including conventional civil engineering methods, nature-based solutions and biodiversity conservation actions. This framework integrates legislation, substantial funding and a governance structure that transcends administrative and discipline boundaries, enabling coordinated actions across multiple spatial and temporal scales. It necessitates the collaboration of local and regional stakeholders including local people with scientists and practitioners. A holistic vision for the sustainable management of freshwater resources could have synergistic effects that support biodiversity and mitigate climate change within functional ecosystems that deliver benefits to people.
Among various natural hazards, those induced by hydrological and meteorological factors have emerged as the most frequent and damaging. India is at the second from the top, after Bangladesh, of flood hazard-affected countries of the world, causing immense damage to life and property every year. The Middle Ganga Plain in the country is one of the most severely affected regions due to the convergence of Himalayan rivers in the Ganga (Ganges) plain. This study focuses on optimizing novel ensemble models to enhance the mapping of flood hazard susceptibility in specific topoclimatic setting, characterized by a low-altitude-range, sub-tropical monsoonal climate, and a riverine floodplain environment of the tectonically active Middle Ganga Plain. This region forms part of the Ganga Foreland Basin prone to frequent floods. We employ a comprehensive flood inventory and twelve selected flood conditioning factors and is the first study that has developed these ensemble models in low relief riverine floodplain environmental setting with high resolution geomorphology as one of the conditioning factors. Four artificial intelligence ensemble models were employed in this work: Logistic Regression-Evidential Belief Function (LR-EBF), Logistic Regression-Frequency Ratio (LR-FR), Multi-Layer Perceptron-Evidential Belief Function (MLP-EBF), and Multi-Layer Perceptron-Frequency Ratio (MLP-FR). Results showed that LR-based ensembles outperformed MLP-based ensembles in the studied topoclimatic setting, with LR-EBF model achieving 87.2% and 84.7% success and prediction rates respectively. Our results reveal consistent performance differences between LR-based ensembles with FR and EBF models across different environmental settings. MLP-based ensembles, particularly with Frequency Ratio, displayed more significant performance variations. The findings underscore the importance of considering specific topoclimatic and altitudinal range environments when applying flood hazard susceptibility models. Our study also provides valuable insights for planning and policymaking in flood management practices in similar topoclimatic settings worldwide.
Nature‐based solutions (NbS, and related concepts like natural infrastructure, Ecosystem‐based Adaptation, and green infrastructure) are increasingly recognized as multi‐benefit strategies for addressing the critical sustainability challenges of the Anthropocene, including the climate emergency and biodiversity crisis. Mainstreaming NbS in professional practice requires strategic, landscape‐level planning integrating multiple sources of benefits and their synergies and trade‐offs. Levee setbacks (LS) are among the best‐studied riverine NbS with recognized benefits for flood risk management, drought resilience, water quality management, recreational opportunities, and ecological restoration for biodiversity. Although awareness of the multifarious benefits of LS as forms of Natural Capital is growing, implementation remains ad‐hoc and opportunistic. To address this critical implementation gap for one major example of NbS, we review and synthesize literature across diverse disciplines to provide an overview of the primary social, economic, and ecological mechanisms that affect the co‐benefit delivery of LS projects. Next, to make this information relevant to NbS practitioners, we link these mechanisms to spatial metrics that can be used to approximate the relative magnitude of project benefits and costs across these mechanisms. Finally, we highlight examples of key synergies and trade‐offs among benefits that should be considered for LS planning. This synthetic approach is intended to familiarize readers with the diverse potential benefits of LS, and provide an understanding of how to select and prioritize potential sites for further study and implementation. Synergies and trade‐offs among important benefit drivers abound, and social equity concerns will be paramount in ensuring the successful implementation of LS and other NbS in the future.
This article is categorized under: Engineering Water > Sustainable Engineering of Water
Engineering Water > Planning Water
Water and Life > Nature of Freshwater Ecosystems
Enthusiasm for and investments in nature-based solutions (NBS) as sustainable strategies for climate adaptation and infrastructure development is building among governments, the scientific community, and engineering practitioners. This is particularly true for water security and water-related risks. In a freshwater context, NBS may provide much-needed “win-wins” for society and the environment that could benefit imperiled freshwater biodiversity. Such conservation benefits are urgently needed given the ongoing freshwater biodiversity crisis, with declines in freshwater species and their habitats occurring at more than twice the rate of marine or terrestrial systems. However, for NBS to make meaningful contributions to safeguarding freshwater biodiversity, clear links must be established between NBS applications and priorities for conservation. In this paper, we link common water-related NBS to six priority actions for freshwater life established by the conservation science n community, and highlight priority research and knowledge that will be necessary to bring NBS to bear on the freshwater biodiversity crisis. In particular, we illustrate how NBS can play a direct role in restoring degraded aquatic and floodplain ecosystems, enhancing in-stream water quality, and improving hydrological connectivity among freshwater ecosystems. System-level monitoring is needed to ensure that freshwater NBS deliver on their promised benefits for ecosystems and species.
A large body of scientific research has demonstrated a changing climate, which affects river flow regimes and extreme flood frequencies and magnitudes. The magnitude and frequency of extreme events are of critical importance in the evaluation of river systems to inform flood risk reduction under current and future conditions. The global climate projections from the Coupled Model Intercomparison Project, Phase 5 (CMIP5) datasets were used by the Variable Infiltration Capacity (VIC) land surface model to produce a runoff dataset, implementing a Bias-Correction Spatial Disaggregation (BCSD) approach. The resulting runoff was then used as input to the Routing Application for Parallel computatIon of Discharge (RAPID) river routing model to simulate daily flows within all 1.2 million Mississippi River Basin river reaches for years 1950 through 2099. This research effort analyzed the performance of the models for the historical time period, comparing with the observations at 64 gage locations for 16 different climate models. A recurrence interval analysis was performed to determine the 2-, 5-, 10-, 50-, 100-, 500-, and 1000-year events within both the historical and projected time periods, highlighting the relative changes predicted into the future. Anticipated seasonal changes are demonstrated by comparing monthly average streamflows for three different time periods (1951–2005, 2006–2049, and 2050–2099). Results indicate that the hydrologic conditions of the Lower Mississippi River are not stationary. Based on all 16 models considered in this study, the median of the model projections shows an 8% increase in the 100-year return period discharge at Vicksburg, Mississippi, into the future time period, although the full range of 16 models varies widely from − 11 to + 85% change in the 100-year discharge in the future.
Artificial levees are a major human modification of river corridors, but we still do not have a clear understanding of how artificial levees affect floodplain extent at regional and larger scales. We estimated changes in river-floodplain connectivity due to artificial levees in the contiguous United States (CONUS) using a combination of artificial levee databases, delineations of floodplain areas, and deletion of artificial levees from topography. Our results indicate that artificial levees do not only decrease floodplain extent but also alter locations of floodplain connectivity. Anthropogenically connected and disconnected locations are similar in land cover and are predominantly, in decreasing order of extent, cultivated, wetland, forested, and developed land cover types, with more than 30% of the entire floodplain area in the CONUS cultivated or developed. This study indicates that artificial levees cause complex changes in river-floodplain connectivity and can increase flooded areas in some rivers.
Floodplains of large rivers are exploited for agricultural production, industrial and municipal development, and transportation infrastructure. Recently, increased frequency of costly floods has prompted consideration of whether offsetting benefits might accrue from management of floodplains for ecosystem services. We employed a simple inundation model for 800 km of the Lower Missouri River, USA, to evaluate spatial and temporal distributions of ecological floodplain inundation metrics and how those distributions might vary with levee removal and climatic change. The model evaluates inundation at 30 × 30 m resolution on a daily basis over 82 years of record. We quantified provisioning of waterfowl habitat and potential denitrification. Spatial variability is affected by ongoing geomorphic adjustments that affect floodplain connectivity. Statistical models indicate that available floodplain area and recent aggradation are predictive of most inundation metrics. Connectivity is sensitive to climate‐change scenarios that predict increased floodplain inundation during spring waterfowl migrations; the greatest sensitivity to future climate exists where channel‐floodplain geomorphology presently enhances floodplain connectivity. Evaluation of floodplain denitrification indicates that on average, the nonleveed part of the floodplain could denitrify 0.05%–1.7% of the mean annual nitrogen load of the river. Levee removal could increase this rate to only 3.6% of the nitrogen load. The capacity of floodplain connectivity to influence certain ecosystem services is highly variable in space along the Lower Missouri River and may be appreciably influenced by climate change. Hence, decisions to optimize management of large‐river floodplains are likely to be highly location dependent.
Vulnerable locations, such as coastlines, are at a high risk of loss and
damage. Such places will suffer deleterious impacts as climate change
impacts are increasingly realized. As societies try to adapt to these impacts,
managed or planned retreat—aimed at moving people and assets away from
vulnerable locations—is gaining increased attention. Despite this increased
attention, systematic literature reviews of the retreat literature remain
scarce. This paper undertakes such review and uncovers a marked increase
in retreat scholarly research papers in the past 5 years. An analysis of 135
managed and planned retreat journal articles is completed. Findings include
a strong emphasis on regional or local case studies exploring governance,
policy or institutional settings and levers across a range of geographies.
Property rights and market interventions, such as compensation schemes,
evidence the prevalence of neoliberal predilections. This emphasizes the
importance of renewed engagement with political economy scholarship
vis-à-vis climate change adaptation, also supported by the sharp increase
in the evidenced social and environmental justice impacts.
Artificial levees are anthropogenic structures designed to hydrologically disconnect rivers from floodplains. The extent of artificial levees in the contiguous United States (CONUS) is unknown. To better estimate the distribution of artificial levees, we tested several different geomorphic, land cover, and spatial variables developed from the National Elevation Dataset, the National Land Cover database, and the National Hydrology Dataset HR Plus. We used known levee locations from the National Levee Database as training data. We tested machine learning and general logistic models’ ability to detect artificial levees in a 100‐year hydrogeomorphic floodplain of seven geographically diverse 8‐digit HUC basins. Random forest models outperformed other models in predicting the location of levees using variables representing geomorphic attributes, land cover, and distance from streams ranging in size between stream order one through six. To demonstrate the ability of our approach to detect unknown levees, we conducted a leave‐one‐out cross‐validation in the lower Mississippi Basin using approximately 1,100 artificial levees. This approach detected known levees constituting 94% of the total levee length in the basin. Scaling up to the CONUS, we applied a high performing (overall accuracy of 97%) random forest model using land cover and stream order variables. We detected 182,213 km of potential levees, mostly along streams of order 2–6 in the Mississippi and Missouri River Basins, indicating that the national levee database contains 20.4% of levee length. Potential levees and those documented in the national levee database modify 2% of the total length of streams in the contiguous United States.
Conventional flood control has emphasized structural measures such as levees, reservoirs, and engineered channels—measures that typically simplify river channels and cut them off from their floodplain, both with adverse environmental consequences. Structural measures tend to be rigid and not easily adapted to increased flooding regimes resulting from environmental change. Such actions also limit the natural hydrologic benefits of floodplains such as storing floodwaters, improving water quality, providing habitat for invertebrates and fish during periods of inundation, and supporting a multitude of cultural services. As these benefits are more widely recognized, policies are being adopted to encourage projects that reduce flood risks and restore floodplain ecosystems, while acknowledging the social-ecological context. The number of such projects, however, remains small. We assessed four multi-benefit floodplain projects (two in California, United States, and two in Germany) and characterized their drivers, history, and measures implemented. In both United States cases, the dominant driver behind the project was flood risk reduction, and ecosystem restoration followed, in one case inadvertently, in the other as a requirement to receive a subsidy for a flood risk reduction project. One German case was motivated by ecosystem restoration, but it was more widely accepted because it also offered flood management benefits. The fourth case was conceived in terms of balanced goals of flood risk reduction, ecosystem restoration, and recreation. We conclude that projects that both reduce flood risk and restore ecosystems are clearly possible and often cost-effective, and that they could be more widely implemented. The principal barriers are often institutional and regulatory, rather than technical.
Although hydraulic infrastructure such as levees remain important for flood risk management in the USA, France, and Quebec (Canada), there is increasing emphasis on nonstructural measures, such as regulatory flood maps, to reduce exposure and vulnerability, for example, preventing people from building in high hazard areas. One key concept related to areas protected by levees is that of “residual risk”, that is, the risk from floods greater than the design standard of the levees (levee overtopping) and from levee breach. In this article, we review the legislative framework for regulatory flood maps in the USA, France, and Quebec (Canada) and compare how residual risk behind protective structures is taken into account (or not) in regulatory flood maps. We find big differences in how the USA, France and Canada manage residual risk behind the levees. While in France the area behind levees is part of the regulatory flood prone area, and land use restrictions, building codes, emergency measures and risk communication are mandatory, in the USA the area behind levees is only shown as part of the regulatory flood prone area if the levee is not accredited. In Quebec, regulatory flood maps in general follow the French approach with a few exceptions.
Lateral Hydrological Connectivity (LHC) has been extensively fragmented in river–floodplain ecosystems of the world. Uncertainties about how LHC affects fishes are great, impeding the design of effective rehabilitation strategies. Existing conceptual frameworks do not provide sufficient mechanistic detail to support the novel decision problems river managers face. We offer a framework of how LHC affects fishes in river–floodplain ecosystems that is, process‐based, integrates all life‐stages and is spatial; these features, we argue, are required to assess risks and opportunities associated with different LHC rehabilitation strategies. Within river–floodplain segments, LHC affects population processes through five ‘effect‐classes’: effects of floodplain habitat (1) and channel habitat (2); effects of material subsidies from the floodplain to the channel (3) and vice versa (4); and effects of connectivity on lateral dispersal (5). The relative influence of these effect‐classes on processes varies among species and life‐stages. At the scale of the drainage basin, inter‐segment variation in geomorphology generates a longitudinal source‐sink structure to habitat quality and quantity, pointing to a need to better understand fish metapopulation dynamics in river–floodplain ecosystems. Given the significant investment in trying to restore river–floodplain ecosystems, we highlight potentially costly and ineffective LHC management decisions. These include certain heavily engineered LHC rehabilitation strategies that do not promote critical population processes at a local scale, and at basin scales implementing strategies that do not facilitate the metapopulation processes that promote species’ persistence.
Due to the effects of climate change, coastal areas and communities around the world will be increasingly impacted by diverse hazards including sea-level rise, flooding and eroding shorelines, leading to increasing displacement of people. Managed retreat is one potential adaptation strategy to proactively plan for large-scale climate-related displacements. There is, however, evidence that in many cases managed retreat has had problematic social impacts and that it has frequently been implemented through top-down models of planning. In response, this article reviews the literature on managed retreat to identify the limitations of current practices and the challenges for a more environmentally just approach. Based on this review, the article argues that a coproduction approach would provide a means to help address key planning challenges in this field. This involves collecting local knowledge of the risks posed by climate hazards and/or retreat, creating a connection between local knowledge and institutional mechanisms for supported relocation and facilitating community-led processes of retreat and redevelopment. The key contribution of the article is its analysis of the value of a coproduction approach from the perspective of achieving a more environmentally just approach to managed retreat.
Abstract
The Lower Mississippi River flows from the confluence of the Ohio River and Mississippi River at Cairo, Illinois into the Gulf of Mexico. Mississippi River and Ohio River pathway shifts have shaped and re-shaped the landscapes through which they flow and where their sediment-laden tributary waters co-mingle at the confluence on the voyage to the Gulf of Mexico. For much of their history, the lands adjacent to the Lower Mississippi River were bottomlands that flooded with the seasons unconstrained by human river training structures. Since 1717 European nations have fought over strategic navigational control of the Mississippi River. After the Louisiana Purchase in 1803, the United States took controlled the Lower Mississippi River. During the Civil War, from 1861-1865, the Union and Confederate forces battled for navigational control of the Lower Mississippi River. The primary objective of this paper was to highlight how the strategic navigational and flooding control of the Lower Mississippi River and geological and landscape resources were responsible for the successful economic development of this rich historical region of North America.
Floodplains perform diverse functions, including attenuation of fluxes of water, solutes, and particulate material. Critical details of floodplain storage including magnitude, duration, and spatial distribution are strongly influenced by floodplain biogeochemical processes and biotic communities. Floodplain storage of diverse materials can be conceptualized in the form of a budget that quantifies inputs, outputs, and storage within the floodplain control volume. The floodplain control volume is here defined as bounded on the inner edges by the banks of the active channel(s), on the outer edges by the limit of periodic flooding and the deposition of fluvially transported sediment, on the underside by the extent of hyporheic exchange flows and the floodplain aquifer, and on the upper side by the upper elevation of living vegetation. Fluxes within the floodplain control volume can also change the location, characteristics, and residence time of material in storage. Fluxes, residence time, and quantities of material stored in floodplains can be measured directly; inferred from diverse types of remotely sensed data; or quantitatively estimated using numerical models. Human activities can modify floodplain storage by: hydrologically and/or geomorphically disconnecting channels and floodplains; altering fluxes of water and sediment to the river corridor; and obliterating floodplains through alluvial mining or urbanization. Floodplain restoration can focus on enlarging the functional floodplain, reconnecting the channel and floodplain, restoring natural regimes of water, sediment, and/or large wood, or enhancing the spatial heterogeneity of the channel and floodplain. Each form of floodplain restoration can increase floodplain storage and resilience to disturbances.
Nature‐based solutions (NbS)—solutions to societal challenges that involve working with nature—have recently gained popularity as an integrated approach that can address climate change and biodiversity loss, while supporting sustainable development. Although well‐designed NbS can deliver multiple benefits for people and nature, much of the recent limelight has been on tree planting for carbon sequestration. There are serious concerns that this is distracting from the need to rapidly phase out use of fossil fuels and protect existing intact ecosystems. There are also concerns that the expansion of forestry framed as a climate change mitigation solution is coming at the cost of carbon rich and biodiverse native ecosystems and local resource rights. Here, we discuss the promise and pitfalls of the NbS framing and its current political traction, and we present recommendations on how to get the message right. We urge policymakers, practitioners and researchers to consider the synergies and trade‐offs associated with NbS and to follow four guiding principles to enable NbS to provide sustainable benefits to society: (1) NbS are not a substitute for the rapid phase out of fossil fuels; (2) NbS involve a wide range of ecosystems on land and in the sea, not just forests; (3) NbS are implemented with the full engagement and consent of Indigenous Peoples and local communities in a way that respects their cultural and ecological rights; and (4) NbS should be explicitly designed to provide measurable benefits for biodiversity. Only by following these guidelines will we design robust and resilient NbS that address the urgent challenges of climate change and biodiversity loss, sustaining nature and people together, now and into the future.
This paper critically reviews the outcomes of internationally-funded interventions aimed at climate change adaptation and vulnerability reduction. It highlights how some interventions inadvertently reinforce, redistribute or create new sources of vulnerability. Four mechanisms drive these maladaptive outcomes: (i) shallow understanding of the vulnerability context; (ii) inequitable stakeholder participation in both design and implementation; (iii) a retrofitting of adaptation into existing development agendas; and (iv) a lack of critical engagement with how ‘adaptation success’ is defined. Emerging literature shows potential avenues for overcoming the current failure of adaptation interventions to reduce vulnerability: first, shifting the terms of engagement between adaptation practitioners and the local populations participating in adaptation interventions; and second, expanding the understanding of ‘local’ vulnerability to encompass global contexts and drivers of vulnerability. An important lesson from past adaptation interventions is that within current adaptation cum development paradigms, inequitable terms of engagement with ‘vulnerable’ populations are reproduced and the multi-scalar processes driving vulnerability remain largely ignored. In particular, instead of designing projects to change the practices of marginalised populations, learning processes within organisations and with marginalised populations must be placed at the centre of adaptation objectives. We pose the question of whether scholarship and practice need to take a post-adaptation turn akin to post-development, by seeking a pluralism of ideas about adaptation while critically interrogating how these ideas form part of the politics of adaptation and potentially the processes (re)producing vulnerability. We caution that unless the politics of framing and of scale are explicitly tackled, transformational interventions risk having even more adverse effects on marginalised populations than current adaptation.
Publisher's Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Abstract: The perception of the impact of climate change on the environment is becoming a lived experience for more and more people. Several new terms for climate change-induced distress have been introduced to describe the long-term emotional consequences of anticipated or actual environmental changes, with ecological grief as a prime example. The mourning of the loss of ecosystems, landscapes, species and ways of life is likely to become a more frequent experience around the world. However, there is a lack of conceptual clarity and systematic research efforts with regard to such ecological grief. This perspective article introduces the concept of ecological grief and contextualizes it within the field of bereavement. We provide a case description of a mountaineer in Central Europe dealing with ecological grief. We introduce ways by which ecological grief may pose a mental health risk and/or motivate environmental behavior and delineate aspects by which it can be differentiated from related concepts of solastalgia and eco-anxiety. In conclusion, we offer a systematic agenda for future research that is embedded in the context of disaster mental health and bereavement research.
Nutrient loads in fresh and coastal waters continue to lead to harmful algal blooms across the globe. Historically, floodplains—low-lying areas adjacent to streams and rivers that become inundated during high-flow events—would have been nutrient deposition and/or removal sites within riparian corridors, but many floodplains have been developed and/or disconnected. This review synthesizes literature and data available from field studies quantifying nitrogen (N) and phosphorus (P) removal within floodplains across North America and Europe to determine how effective floodplain restoration is at removing nutrients. The mean removal of nitrate-N (NO3−-N), the primary form of N in floodplain studies, was 200 (SD = 198) kg-N ha−1 year−1, and of total or particulate P was 21.0 (SD = 31.4) kg-P ha−1 year−1. Based on the literature, more effective designs of restored floodplains should include optimal hydraulic load, permanent wetlands, geomorphic diversity, and dense vegetation. Floodplain restorations along waterways with higher nutrient concentrations could lead to a more effective investment for nutrient removal. Overall, restoring and reconnecting floodplains throughout watersheds is a viable and effective means of removing nutrients while also restoring the many other benefits that floodplains provide.
Non-technical summary
Ecosystems across the globe are vulnerable to the effects of climate change, as are the communities that depend on them. However, ecosystems can also protect people from climate change impacts. As the evidence base strengthens, nature-based solutions (NbS) are increasingly prominent in climate change policy, especially in developing nations. Yet intentions rarely translate into measurable, evidence-based targets. As Paris Agreement signatories revise their Nationally Determined Contributions, we argue that NbS are key to meeting global goals for climate and biodiversity, and we urge researchers to work more closely with policy-makers to identify targets that benefit both people and ecosystems.
Freshwater ecosystems provide irreplaceable services for both nature and society. The quality and quantity of freshwater affect biogeochemical processes and ecological dynamics that determine biodiversity, ecosystem productivity, and human health and welfare at local, regional and global scales. Freshwater ecosystems and their associated riparian habitats are amongst the most biologically diverse on Earth, and have inestimable economic, health, cultural, scientific and educational values. Yet human impacts to lakes, rivers, streams, wetlands and groundwater are dramatically reducing biodiversity and robbing critical natural resources and services from current and future generations. Freshwater biodiversity is declining rapidly on every continent and in every major river basin on Earth, and this degradation is occurring more rapidly than in terrestrial ecosystems. Currently, about one third of all global freshwater discharges pass through human agricultural, industrial or urban infrastructure. About one fifth of the Earth’s arable land is now already equipped for irrigation, including all the most productive lands, and this proportion is projected to surpass one third by midcentury to feed the rapidly expanding populations of humans and commensal species, especially poultry and ruminant livestock. Less than one fifth of the world’s preindustrial freshwater wetlands remain, and this proportion is projected to decline to under one tenth by midcentury, with imminent threats from water transfer megaprojects in Brazil and India, and coastal wetland drainage megaprojects in China. The Living Planet Index for freshwater vertebrate populations has declined to just one third that of 1970, and is projected to sink below one fifth by midcentury. A linear model of global economic expansion yields the chilling prediction that human utilization of critical freshwater resources will approach one half of the Earth’s total capacity by midcentury. Although the magnitude and growth of the human freshwater footprint are greater than is generally understood by policy makers, the news media, or the general public, slowing and reversing dramatic losses of freshwater species and ecosystems is still possible. We recommend a set of urgent policy actions that promote clean water, conserve watershed services, and restore freshwater ecosystems and their vital services. Effective management of freshwater resources and ecosystems must be ranked amongst humanity’s highest priorities.
There is growing awareness that ‘nature-based solutions' (NbS) can help to protect us from climate change impacts while slowing further warming, supporting biodiversity and securing ecosystem services. However, the potential of NbS to provide the intended benefits has not been rigorously assessed. There are concerns over their reliability and cost-effectiveness compared to engineered alternatives, and their resilience to climate change. Trade-offs can arise if climate mitigation policy encourages NbS with low biodiversity value, such as afforestation with non-native monocultures. This can result in maladaptation, especially in a rapidly changing world where biodiversity-based resilience and multi-functional landscapes are key. Here, we highlight the rise of NbS in climate policy—focusing on their potential for climate change adaptation as well as mitigation—and discuss barriers to their evidence-based implementation. We outline the major financial and governance challenges to implementing NbS at scale, highlighting avenues for further research. As climate policy turns increasingly towards greenhouse gas removal approaches such as afforestation, we stress the urgent need for natural and social scientists to engage with policy makers. They must ensure that NbS can achieve their potential to tackle both the climate and biodiversity crisis while also contributing to sustainable development. This will require systemic change in the way we conduct research and run our institutions.
This article is part of the theme issue ‘Climate change and ecosystems: threats, opportunities and solutions’.
A growing number of cities are incorporating resilience into their plans and policies to respond to shocks, stresses, and uncertainties. While some scholars advocate for the potential of resilience research and practice, others argue that it promotes an inherently conservative and neoliberal agenda, prevents systemic transformations, and pays insufficient attention to power, politics, and justice. Notably, critics of the urban resilience agenda argue that policies fail to adequately address social equity issues. This study seeks to inform these debates by providing a cross-sectional analysis of how issues of equity are incorporated into urban resilience planning. We develop a tripartite framework of equity that includes distributional, recognitional, and procedural dimensions and use it to analyse the goals, priorities, and strategies of formal resilience plans created by member cities of the Rockefeller Foundation’s 100 Resilient Cities programme. Our analysis reveals considerable variation in the extent to which cities focus on equity, implying that resilience may be more nuanced than some critics suggest. There are, however, clear areas for improvement. Dominant conceptions of equity are generally tied to a distributional orientation, with less focus on the recognitional and procedural dimensions. We hope our conceptual framework and lessons learned from this study can inform more just resilience planning and provide a foundation for future research on the equity implications of resilience.
Despite substantial increases in the scope and magnitude of biodiversity conservation and ecological restoration, there remains ongoing degradation of natural resources that adversely affects both biodiversity and human well-being. Nature-based Solutions (NbS) can be an effective framework for reversing this trend, by increasing the alignment between conservation and sustainable development objectives. However, unless there is clarity on its evolution, definition and principles, and relationship with related approaches, it will not be possible to develop evidence-based standards and guidelines, or to implement, assess, improve and upscale NbS interventions globally. In order to address this gap, we present the definition and principles underpinning the NbS framework, recently adopted by the International Union for Conservation of Nature, and compare it to (1) the Ecosystem Approach that was the foundation for developing the NbS definitional framework, and (2) four specific ecosystem based approaches (Forest Landscape Restoration, Ecosystem-based Adaptation, Ecological Restoration and Protected Areas) that can be considered as falling under the NbS framework. Although we found substantial alignment between NbS principles and the principles of the other frameworks, three of the eight NbS principles stand out from other approaches: NbS can be implemented alone or in an integrated manner with other solutions ; NbS should be applied at a landscape scale; and, NbS are integral to the overall design of policies, measures and actions, to address societal challenges. Reversely, concepts such as adaptive management/governance, effectiveness , uncertainty, multi-stakeholder participation, and temporal scale are present in other frameworks but not captured at all or detailed enough in the NbS principles. This critical analysis of the strengths and weaknesses of the NbS principles can inform the review and revision of principles supporting specific types of NbS (such as the approaches reviewed here), as well as serve as the foundation for the development of standards for the successful implementation of NbS.
The natural wood regime forms the third leg of a tripod of physical processes that supports river science and management, along with the natural flow and sediment regimes. The wood regime consists of wood recruitment, transport, and storage in river corridors. Each of these components can be characterized in terms of magnitude, frequency, rate, timing, duration, and mode. We distinguish the natural wood regime, which occurs where human activities do not significantly alter the wood regime, and a target wood regime, in which management emphasizes wood recruitment, transport, and storage that balance desired geomorphic and ecological characteristics with mitigation of wood-related hazards. Wood regimes vary across space and through time but can be inferred and quantified via direct measurements, reference sites, historical information, and numerical modeling. Classifying wood regimes with respect to wood process domains and quantifying the wood budget are valuable tools for assessing and managing rivers
Researchers, stakeholders and funding organizations have embraced co-production of knowledge to solve sustainability problems. Research focusing on the practice of co-production can help us understand what works in what contexts and how to avoid potentially undesirable outcomes.
Global climate change poses significant risks to coastal and riverine communities. Managed retreat, the purposeful movement of people and infrastructure out of vulnerable floodplains, is one possible adaptation strategy. The USA has already engaged in a limited amount of retreat by providing federal funds to purchase and demolish or relocate vulnerable properties. As retreat programs are expected to expand in size and frequency to address the increased risks posed by climate change, a review of how such property acquisition programs have been implemented is timely. Specifically, decisions made by government officials regarding where to acquire properties have significant potential social justice implications, as buyouts could promote or reduce existing social inequities, but it is unclear how such decisions are being made. A review of eight US buyout programs suggests that buyouts, as practiced, lack transparency, which may increase public distrust of the process and reduce participation. Moreover, decisions often involve political motivations and rely on cost-benefit logic that may promote disproportionate retreat in low-income or minority communities, continuing historic patterns of social inequity. However, as low-income communities in the USA also tend to be highly vulnerable to climate-exacerbated hazards, a decision not to relocate may also promote disproportionate harm. The buyout programs reviewed provide examples of how to mitigate these concerns through increased transparency, emphasis on relocation, explicit focus on social inequality, longer-term and larger-scale holistic approaches, and participatory pre-disaster planning. Further research on past programs is needed to evaluate outcomes and processes to improve future adaptation efforts.
The Netherlands has just finished implementing the Room for the Rivers program along the Rhine and Meuse Rivers in response to increasing river discharges. Recently, making more room for the river is, however, being challenged for future application because the flood defenses are assessed to be too weak and will need reinforcement anyway. To be able to decide on the most desirable policy for the remainder of the century, we require knowledge of all benefits and costs of individual interventions and strategic alternatives for flood mitigation. In this paper, we quantify some benefits of making more room for the rivers. We recognize and quantify two risk-reducing effects and provide results of analyses for the Rhine and Meuse Rivers in The Netherlands. Making room for rivers was originally advocated because it (1) reduces the consequences of flooding, as well as (2) reduces the probability of failure of the embankments. We have now quantified these effects allowing translation into risk reduction proper. Moreover, larger floodplain surface area may influence the relationship between discharge and flood level, which implies that rivers with widened floodplains are less sensitive to uncertainties about future river discharges. This does not reduce risk proper, but makes the river system more robust, as we shall argue in the discussion where we present risk reduction and robustness as complementary perspectives for assessing strategic alternatives for flood risk management.
Resilience has attracted criticism for its failure to address social vulnerability and to engage with issues of equity and power. Here, we ask: what is equitable resilience? Our focus is on what resilience does on the ground in relation to development, adaptation and disaster management, and on identifying critical issues for engaging with equity in resilience practice. Using techniques from systematic reviews, with variants of equitable resilience as our key search terms, we carried out an analytical literature review which reveals four interconnected themes: subjectivities, inclusion, cross-scale interactions, and transformation. Drawing on this analysis, we find that ‘equitable resilience’ is increasingly likely when resilience practice takes into account issues of social vulnerability and differential access to power, knowledge, and resources; it requires starting from people’s own perception of their position within their human-environmental system, and it accounts for their realities and for their need for a change of circumstance to avoid imbalances of power into the future. Our approach moves beyond debates that focus on the ontological disconnect between resilience and social theory, to provide a definition that can be used in practice alongside resilience indicators to drive ground level interventions towards equitable outcomes. Defined in this way, equitable resilience is able to support the development of social-ecological systems that are contextually rooted, responsive to change and socially just, and thus relevant to global sustainability challenges.
This paper explores place disruption, where transformative adaptation was proposed for flood risk management, by examining: a) the relationships between place attachment, place-related symbolic meanings, place-protective interpretative responses and attitudinal responses, and b) evaluation of governance processes. Questionnaires were administered to residents in Clontarf, County Dublin, Ireland in 2014 (n = 280) in the aftermath of community resistance to perceived transformative flood defences. Results highlight the dilemmas for individuals who recognise adaptation as necessary but who ascribe significant importance to valued places. Contrary to previous studies, our analysis shows place attachment to be strongest in individuals who perceive governance processes as inadequate, and finds that neither flood experience nor flood risk affect strength of place attachment and support for flood defences. We suggest that where transformative adaptation disrupts place and threatens place attachment, considering the views of both those affected and unaffected by hazardous events is paramount.
Nutrient pollution is a pervasive water quality problem. Stream restoration has been proposed as a novel approach to reduce loading and increase nutrient processing within streams. We summarize evidence from the literature on the efficacy of stream restoration for reducing nutrient loading and increasing nutrient removal in stream ecosystems. We also analyze published data on streambank phosphorus concentrations and riparian and stream denitrification rates to improve understanding of the potential benefits of stream restoration for phosphorus retention and nitrogen removal. Finally, we discuss the role of stream restoration in nutrient management and provide recommendations for practice and future research.
Revised discharge frequency relationships were developed for the Missouri River below Gavins Point Dam. Daily flow hydrographs were developed for both natural and regulated flow conditions over a 100-year period by means of model studies, developing a homogenous record for both flow conditions. Natural (or unregulated) flows were estimated by adjusting the observed flow record to reflect water resource development impacts such as irrigation depletions, reservoir regulation and evaporation, and other consumptive water uses. Mean annual, monthly and daily flows were derived from the flow record, as well as peak annual flows. Results of the study show significant differences in the natural flow regime over several periods of time. Results also show differences in the natural flow hydrograph along the river due to watershed and climatic effects. Period of record regulated flow hydrographs were estimated by adjusting all water resource development in the basin to current levels of development. A relationship was determined between the unregulated and regulated annual peaks and used to develop a discharge-frequency relationship at each gage location. The application of flow-frequency results to address environmental issues including the evaluation of endangered species flow regime for current and historical flow is discussed.
Poster Presented at Restore America’s Estuaries (RAE) 2016
In this paper, we reflect on the implications for science, policy and practice of the recently introduced concept of Nature-Based Solutions (NBS), with a focus on the European context. First, we analyse NBS in relation to similar concepts, and reflect on its relationship to sustainability as an overarching framework. From this, we derive a set of questions to be addressed and propose a general framework for how these might be addressed in NBS projects by funders, researchers, policy-makers and practitioners. We conclude that:
The threats of old are still the dominant drivers of current species loss, indicates an analysis of IUCN Red List data by Sean Maxwell and colleagues.
ABSTRACT. Nature-based solutions promoting green and blue urban areas have significant potential to decrease the vulnerability and enhance the resilience of cities in light of climatic change. They can thereby help to mitigate climate change-induced impacts and serve as proactive adaptation options for municipalities. We explore the various contexts in which nature-based solutions are relevant for climate mitigation and adaptation in urban areas, identify indicators for assessing the effectiveness of nature-based solutions and related knowledge gaps. In addition, we explore existing barriers and potential opportunities for increasing the scale and effectiveness of nature-based solution implementation. The results were derived from an inter-and transdisciplinary workshop with experts from research, municipalities, policy, and society. As an outcome of the workshop discussions and building on existing evidence, we highlight three main needs for future science and policy agendas when dealing with nature-based solutions: (i) produce stronger evidence on nature-based solutions for climate change adaptation and mitigation and raise awareness by increasing implementation; (ii) adapt for governance challenges in implementing nature-based solutions by using reflexive approaches, which implies bringing together new networks of society, nature-based solution ambassadors, and practitioners; (iii) consider socio-environmental justice and social cohesion when implementing nature-based solutions by using integrated governance approaches that take into account an integrative and transdisciplinary participation of diverse actors. Taking these needs into account, nature-based solutions can serve as climate mitigation and adaptation tools that produce additional cobenefits for societal well-being, thereby serving as strong investment options for sustainable urban planning.
The 2019 Missouri River flood caused billions of dollars in damage to businesses, homes, and public infrastructure. Yet little is known about the farm-level effects of this event and farmers' perceptions of its causes. This study reports on the operational and financial setbacks farmers sustained because of the 2019 floods, as well as on their beliefs on the causes of these floods. It further explores farmers' willingness to pay (WTP) to avoid flood risks and the factors that condition it. The empirical application focuses on a sample of approximately 700 Missouri farmers operating near the Missouri River. Results show that yield loss, loss of growing crops, and inability to plant crops were the three most important consequences of flooding. Nearly 40% of the flood-affected farmers reported financial losses of 3 per $10,000 value of agricultural land. Subjective but not objective risk exposure influences WTP for flood risk reduction. Other important determinants of WTP are risk aversion, disutility from flood risks, and respondents' age, income, and education. Directions for policy to improve flood risk management in the Missouri River Basin are discussed.
Nature-based solutions (NbS); working with and enhancing nature to address societal challenges, increasingly feature in climate change adaptation strategies. Despite growing evidence that NbS can reduce vulnerability to climate change impacts in general, understanding of the mechanisms through which this is achieved, particularly in the Global South, is lacking. To address this, we analyse 85 nature-based interventions across the rural Global South, and factors mediating their effectiveness, based on a systematic map of peer-reviewed studies encompassing a wide diversity of ecosystems, climate impacts, and intervention types. We apply an analytical framework of people's social-ecological vulnerability to climate change, in terms of six pathways of vulnerability reduction: social and ecological exposure, sensitivity, and adaptive capacity. Most cases (95%) report a reduction in vulnerability, primarily by lowering ecosystem sensitivity to climate impacts (73% of interventions), followed by reducing social sensitivity (52%), reducing ecological exposure (36%), increasing social adaptive capacity (31%), increasing ecological adaptive capacity (19%) and/or reducing social exposure (14%). Our analysis shows that social dimensions of NBS are important mediating factors for equity and effectiveness. This study highlights how understanding the distinct social and ecological pathways by which vulnerability to climate change is reduced can help harness the multiple benefits of working with nature in a warming world.
Advancing social equity has been implicitly and explicitly central to water resources policy for decades. Yet, equity remains largely outside of standard water resources planning and management practices. Inclusion of equity within water resources infrastructure is inhibited by barriers including an incomplete conceptual understanding of equity, a perceived lack of quantitative and qualitative equity metrics, unclear connections between equity and standard project planning frameworks, and the absence of concrete examples. To facilitate greater practical inclusion of social equity in water resources practices, we describe equity relative to dimensions of distribution, procedure, and recognition and identify metrics associated with each. We then map these dimensions of equity onto different stages of a water resources project life cycle. We discuss how inequities are often perpetuated by current approaches and highlight case studies that promote one or more of the facets of equity. Rather than providing a prescriptive solution to “achieve” equity within water resources practices, we emphasize the need for contextualized approaches that include pragmatic steps toward more equitable practices and outcomes.
Social-ecological systems underpinning nature-based solutions (NbS) must be resilient to changing conditions if they are to contribute to long-term climate change adaptation. We develop a two-part conceptual framework linking social-ecological resilience to adaptation outcomes in NbS. Part one determines the potential of NbS to support resilience based on assessing whether NbS affect key mechanisms known to enable resilience. Examples include social-ecological diversity, connectivity, and inclusive decision-making. Part two includes adaptation outcomes that building social-ecological resilience can sustain, known as nature's contributions to adaptation (NCAs). We apply the framework to a global dataset of NbS in forests. We find evidence that NbS may be supporting resilience by influencing many enabling mechanisms. NbS also deliver many NCAs such as flood and drought mitigation. However, there is less evidence for some mechanisms and NCAs critical for resilience to long-term uncertainty. We present future research questions to ensure NbS can continue to support people and nature in a changing world.
Expected final online publication date for the Annual Review of Environment and Resources, Volume 47 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Despite the recognition of floodplain importance in the scientific community, floodplains are not afforded the same legal protection as river channels. In the United States alone, flood-related economic losses were much higher in the second half of the 20th century than the first half despite the expenditure of billions of dollars on flood defenses. Partially to blame are the low appraisal and understanding of human impacts to floodplain functions. Here, we explore the impacts of levees on floodplain functions and analyze case studies of floodplain restoration through levee removal. Floodplain functions include (1) fluxes of water, solutes, and particulate materials; (2) enhanced spatial heterogeneity of hydrology and biogeochemistry; (3) enhanced habitat abundance and diversity; (4) enhanced biomass and biodiversity; and (5) hazard mitigation. Case studies of floodplain restoration involving artificial levee adjustment are heavily concentrated in North America, Europe, and Japan, and those case studies assess floodplain functions within 30 years of restoration. In the United States, restoration through levee removal comprises less than 1% of artificial levee length and 1–2% of disconnected floodplains. In Europe, restoration effectiveness was severely limited by upstream flow regulation. Most case studies were impacted by stressors outside the study site and took place in lowland alluvial rivers. Reconfiguration was successful at achieving limited aims while reconnection set floodplains on a trajectory to more fully restore floodplain functions. Case studies illustrated the tension between restoration scale and study resolution in time and space as well as the role of site-specific characteristics in determining restoration outcomes. Numerous knowledge gaps surrounding the integrative relationships between floodplain functions must be addressed in future studies. The ubiquity of flow regulation demands that future floodplain restoration occur in a whole-of-basin manner. Monitoring of restoration must take place for longer periods of time and include multiple functions.
Benefit–cost analysis (BCA) is often viewed as measuring the efficiency of a policy independent of the distribution of its consequences. The role of distributional effects on policy choice is disputed; either: ( a ) the policy that maximizes net benefits should be selected and distributional concerns should be addressed through other measures, such as tax and transfer programs or ( b ) BCA should be supplemented with distributional analysis and decision-makers should weigh efficiency and distribution in policy choice. The separation of efficiency and distribution is misleading. The measure of efficiency depends on the numéraire chosen for the analysis, whether monetary values or some other good (unless individuals have the same rates of substitution between them). The choice of numéraire is not neutral; it can affect the ranking of policies by calculated net benefits. Alternative evaluation methods, such as BCA using a different numéraire , weighted BCA, or a social welfare function (SWF), may better integrate concerns about distribution and efficiency. The most appropriate numéraire , distributional weights, or SWFs cannot be measured or statistically estimated; it is a normative choice.
Globally, rising seas, coastal erosion, extended dry periods, and flooding contribute to decreased water security and increased disaster incidence. Nature-Based Solutions (NBS) are increasingly advanced as innovative responses to promote adaptation and build resilience, and they are arguably more sustainable than traditional gray infrastructure. There is a growing body of information regarding the material, social, and technological advances that constitute NBS and the ways in which nature can complement traditional built infrastructure. However, critical gaps remain. Promoting a coupled systems approach, we explore fundamental challenges, including issues of participation and equity, economic valuation, scalar mismatches, the integration of natural and built infrastructure, and governance. NBS do not entail quick solutions, and to reach their full potential NBS require a fundamental rethinking of society's relationship with nature. Addresses
Levee construction results in the systematic replumbing of river systems and reduces the frequency of floodplain inundation, which impacts nutrient delivery and transformations in floodplains. Floodplain restoration via levee removal affects downstream water quality by restoring soil microbial metabolic pathways such as denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA). Although these metabolisms are important for the nitrogen cycle, few studies have quantified the contribution of all three pathways to nitrate retention or loss in restored floodplains. The objectives of this study were to quantify the relevance of denitrification, anammox and DNRA to nitrogen retention, characterize the hydrologic conditions most favorable to each pathway, and estimate the potential for floodplain restoration to improve nitrogen cycling in the Cosumnes River watershed. To address these goals, we simulated flood conditions in soil mesocosms collected from two floodplains where levees were breached in 1997 and 2014 along the Lower Cosumnes River in the San Joaquin Basin of California. River water enriched with K15NO3 tracer was pumped into each mesocosm at a constant rate for a period of 3 months. Samples were collected from the surface water and soil pore water for measurements of NO3-, NO2-, and NH4+ concentrations, and δ15N of dissolved gases (N2 and N2O). To the best of our knowledge, this study reports the highest relative contribution to N2 production due to anammox for freshwater systems (41 to 84%) to date. High anammox rates were associated with heterogeneous grain size distribution across depth and high nitrification rates. We quantify the capacity of restored floodplain soils with distinct textural and chemical characteristics to retain or release nitrogen during large and small floods in a particular water year.
Climate change is increasingly understood to impact mental health through multiple pathways of risk, including intense feelings of grief as people suffer climate-related losses to valued species, ecosystems and landscapes. Despite growing research interest, ecologically driven grief, or 'ecological grief', remains an underdeveloped area of inquiry. We argue that grief is a natural and legitimate response to ecological loss, and one that may become more common as climate impacts worsen. Drawing upon our own research in Northern Canada and the Australian Wheatbelt, combined with a synthesis of the literature, we offer future research directions for the study of ecological grief.
The coast is a highly populated environment that is under increasing risk because of sea level rise (SLR) and climate change. Social science predicts that social and political systems will habitually privilege certain communities and disadvantage others under conditions of risk and disaster. This paper tests that supposition on a particular disaster policy in the United States. Voluntary buyouts are a policy tool in the US that has the potential to help communities adapt to SLR. While buyouts have been resisted in the past, there is some indication that they are becoming more politically popular. Despite increased popularity, communities in Alaska who need to relocate because of repetitive flooding and sea level rise do not meet the basic requirements of the buyout program in a way that makes this policy applicable to their situation. We find that notions of the market, property, and individualism are ideological assumptions inherent to the buyout policies, which ultimately serve to disadvantage tribal communities as they attempt to relocate as an adaptation strategy to climate change. This analysis suggests that adaptation policies to climate change themselves, can limit the inventory of possibilities that some communities have to choose from, and re-entrench inequity in the face of risk.
The rehabilitation and restoration of land is a key strategy to recover services -goods and resources- ecosystems offer to the humankind. This paper reviews key examples to understand the superior effect of nature based solutions to enhance the sustainability of catchment systems by promoting desirable soil and landscape functions. The use of concepts such as connectivity and the theory of system thinking framework allowed to review coastal and river management as a guide to evaluate other strategies to achieve sustainability. In land management NBSs are not mainstream management. Through a set of case studies: organic farming in Spain; rewilding in Slovenia; land restoration in Iceland, sediment trapping in Ethiopia and wetland construction in Sweden, we show the potential of Nature based solutions (NBSs) as a cost-effective long term solution for hydrological risks and land degradation. NBSs can be divided into two main groups of strategies: soil solutions and landscape solutions. Soil solutions aim to enhance the soil health and soil functions through which local eco-system services will be maintained or restored. Landscape solutions mainly focus on the concept of connectivity. Making the landscape less connected, facilitating less rainfall to be transformed into runoff and therefore reducing flood risk, increasing soil moisture and reducing droughts and soil erosion we can achieve the sustainability. The enhanced eco-system services directly feed into the realization of the Sustainable Development Goals of the United Nations.
Benefit–cost analysis (BCA) evaluates policy choices by summing unweighted monetary equivalents, and is insensitive to distributional considerations. An established scholarly tradition proposes to use distributional weights in BCA—multiplying monetary equivalents by weighting factors that are inversely proportional to individuals’ incomes.
This article provides an accessible overview of the topic of distributional weights, with a special focus on environmental policy. The intellectual foundation for weights is the concept of a social welfare function (SWF). Two are considered: a utilitarian SWF and an isoelastic/Atkinson SWF, which incorporates an extra degree of inequality aversion.
The article explains the concept of an SWF, discusses in detail how to specify utilitarian and isoelastic/Atkinson weights so as to mimic the corresponding SWFs, and uses the value of statistical life (VSL) to provide an example of weighting. The article then considers two important objections to distributional weighting: that interpersonal well-being comparisons (and thus weights) are undermined by preference heterogeneity, and that distributional considerations are best handled through the tax system.
Levee setback (location) and height are important issues in flood levee system design and modification. This paper derives an economic-engineering theory of the optimal trade-off of levee setback for height both for original and redesigned flood levees, demonstrating the interconnection of levee setback, height, costs and risks, and economically optimal design. These analyses assume stationary flood hydrology and static ratios among damageable property value, unit construction cost, and land price. The economic trade-off of levee setback for height depends on economic cost and benefit and hydraulic parameters, and only indirectly on flood frequency and economic damage parameters. The redesign rules derived in this paper indicate conditions where existing levees should be raised or moved in response to changes in conditions. Numerical examples illustrate the results. This paper demonstrates several ideas and theory for economic flood levee system planning and policy rather than providing guidelines for direct design practice.
During the latter half of the 19th Century and first half of the 20th Century, the Illinois River was heavily altered through leveeing off large portions of its floodplain, draining wetlands, and the construction of dams and river-training structures that facilitated navigation. As a result of these alterations, flood stages continue to rise, increasing flood risk and threatening to overtop levees along the La Grange Segment (LGS) of the Illinois River. Over the last two decades, more emphasis has been placed on reconnecting portions of floodplains to rivers in order to solve the long-term problem of rising flood heights attributed to continual heightening of levees to provide flood protection. Multiple studies have suggested that strategically reconnecting larger portions of the LGS could result in more sustainable floodplain management. However, the true costs and benefits of reconnecting the floodplain are not known. We use a novel hydrodynamic, geospatial, economic, and habitat suitability framework to assess the tradeoffs of strategically reconnecting the Illinois River to its floodplain in order to decrease flood risk, improve floodplain habitats, and limit the costs of reconnection. Costs include building-associated losses, lost agricultural profits, and levee removal and construction costs. Tested scenarios demonstrate that while flood heights and environmental benefits are maximized through the most aggressive levee setbacks and removals, these scenarios also have the highest costs. However, the tradeoff of implementing lower-cost scenarios is that there is less flood-height reduction and less floodplain habitat available. Several individual levee districts have high potential for reconnection based on limiting potential damages as well as providing floodplain habitat. To implement large-scale strategic floodplain reconnection, costs range from 4.3 billion. As such, payments for ecosystem services will likely be necessary to compensate landowners for decreased long-term agricultural production and building losses that result in flood-reduction benefits and increased floodplain habitat.