There is growing evidence that traditional response to floods and flood-related disaster is no longer achieving desirable results. Nature-Based Solutions (NBS) represent a relatively new response towards disaster risk reduction, water security, and resilience to climate change, which has a potential to be more effective and sustainable than traditional measures. However, in practice, these measures are still being applied at a slow rate while traditional grey infrastructure remains as a preferred choice. This can be attributed to several barriers which range from political and governance to social and technological/technical. More generally, there is a lack of sufficient knowledge base to accelerate their wider acceptance and uptake. The present work provides contribution in this direction and addresses the question of effectiveness of different types of NBS (i.e., small- and large-scale NBS) and their hybrid combinations with grey infrastructure. The work has been applied on the case of Ayutthaya, Thailand. The results suggest that the effectiveness of small-scale NBS is limited to smaller rainfall events whereas the larger (or extreme) events necessitate combinations of different kinds of measures with different scales of implementation (i.e., hybrid measures).
Habitat Type: RIV_L
Large rivers
Flooding is the most frequent and damaging natural hazard globally. While nature-based solutions can reduce flood risk, they are not part of mainstream risk management. We develop a probabilistic risk analysis framework to quantify these benefits that (1) accounts for frequent small events and rarer large events, (2) can be applied to large basins and data-scarce contexts, and (3) quantifies economic benefits and reduction in people affected. Measuring benefits in terms of avoided losses enables the integration of nature-based solutions in standard cost-benefit analysis of protective infrastructure. Results for the Chindwin River basin in Myanmar highlight the potential consequences of deforestation on long-term flood risk. We find that loss reduction is driven by small but frequent storms, suggesting that current practice relying on large storms may underestimate the benefits of nature-based solutions. By providing average annual losses, the framework helps mainstream nature-based solutions in infrastructure planning or insurance practice.
The formulation of management plans as required by EU environmental policies such as the Floods Directive may facilitate the uptake of nature-based solutions (NBS) into practice. Previous research has indicated that the uptake of NBS in water management plans is still low and hindered by various elements of the existing water governance system. However, research so far neglected the role of water managers as “plan-makers” of solution strategies and programs of measures, as well as their beliefs in choosing certain measures in the plan-making process. The aim of this study is to shed more light on the plan-makers’ reasoning for integrating, or not integrating, NBS into specific flood risk management plans (FRMPs). We conducted ten qualitative interviews with plan-makers from Germany and adopted a grounded theory approach to identify their beliefs that underlie the process of formulating FRMPs as well as their perceived role in this process. The analysis reveals a dominance of shared substantive and relational beliefs that are obstructive to a greater uptake of NBS in FRMPs. In particular, identified beliefs about NBS often do not align with their self-perception of their role in being the “plan-makers”. We present a differentiated portrait of water managers as key actors in the decision-making on FRMPs, illustrating that while water managers are belonging to the same distinct professional group with a similar social role in the decision-making process, they do not necessarily share the same preferences.
Adverse effects of climate change are increasing around the world and the floods are posing significant challenges for water managers. With climate projections showing increased risks of storms and extreme precipitation, the use of traditional measures alone is no longer an option. Nature-Based Solutions (NBS) offer a suitable alternative to reduce the risk of flooding and provide multiple benefits. However, planning such interventions requires careful consideration of various factors and local contexts. The present paper provides contribution in this direction and it proposes a methodology for allocation of large-scale NBS using suitability mapping. The methodology was implemented within the toolboxes of ESRI ArcMap software in order to map suitability for four types of NBS interventions: floodplain restoration, detention basins, retention ponds, and river widening. The toolboxes developed were applied to the case study area in Serbia, i.e., the Tamnava River basin. Flood maps were used to determine the volume of floodwater that needs to be stored for reducing flood risk in the basin and subsequent downstream areas. The suitability maps produced indicate the potential of the new methodology and its application as a decision-support tool for selection and allocation of large-scale NBS.
Purpose: This paper aims to advance the idea of sustainable flood reduction. Flood reduction through the use of the drainage system is considered an unsustainable approach that decreases the use of water. In contrast, the Water Sensitive City is a sustainable concept aimed at increasing the value of water for human needs and reduce flooding. Design/methodology/approach: The current approach of relying on drainage systems is ineffective and must be combined with green infrastructures to reduce flooding. Green infrastructures can increase infiltration rates or facilitate rain harvesting. The study developed four scenarios that combine green and grey infrastructures and used the Soil and Water Assessment Tool (SWAT) model to select the most effective scenario based on the remaining amount of flood volume in every scenario. Findings: Green infrastructures that are related to increased infiltration and rain-harvesting instruments reduced flooding by 22.3 and 27.7 per cent, respectively. Furthermore, a combination of the two types of green infrastructures reduced flooding up to 45.5 per cent. Conversely, applying only grey infrastructures (by increasing drainage capacity) to reduce the flooding to zero is unfeasible, as this requires more than double the current capacity. Therefore, a combination of green and grey infrastructures can significantly reduce flooding in a water sensitive and feasible manner. Originality/value: Applying a combination of green and grey infrastructures is a new and effective approach to reduce flooding in the Kedurus Catchment Area.
Climate change is projected to alter river flows and the magnitude/frequency characteristics of floods and droughts. Ecosystem-based adaptation highlights the interdependence of human and natural systems, and the potential to buffer the impacts of climate change by maintaining functioning ecosystems that continue to provide multiple societal benefits. Natural flood management (NFM), emphasising the restoration of innate hydrological pathways, provides important regulating services in relation to both runoff rates and water quality and is heralded as a potentially important climate change adaptation strategy. This paper draws together 25 NFM schemes, providing a meta-analysis of hydrological performance along with a wider consideration of their net (dis) benefits. Increasing woodland coverage, whilst positively linked to peak flow reduction (more pronounced for low magnitude events), biodiversity and carbon storage, can adversely impact other provisioning service-especially food production. Similarly, reversing historical land drainage operations appears to have mixed impacts on flood alleviation, carbon sequestration and water quality depending on landscape setting and local catchment characteristics. Wetlands and floodplain restoration strategies typically have fewer disbenefits and provide improvements for regulating and supporting services. It is concluded that future NFM proposals should be framed as ecosystem-based assessments, with trade-offs considered on a case-by-case basis.
Nature-based solutions (NBS) in river landscapes, such as restoring floodplains, can not only decrease flood risks for downstream communities but also provide co-benefits in terms of habitat creation for numerous species and enhanced delivery of diverse ecosystem services. This paper aims to explore how landscape planning and governance research can contribute to the identification, design and implementation of NBS, using the example of water-related challenges in the landscape of the Lahn river in Germany. The objectives are (i) to introduce the NBS concept and to provide a concise definition for application in planning research, (ii) to explore how landscape planning and governance research might support a targeted use and implementation of NBS, and (iii) to propose an agenda for further research and practical experimentation. Our methods include a focused literature review and conceptual framework development. We define NBS as actions that alleviate a well-defined societal challenge (challenge-orientation), employ ecosystem processes of spatial, blue and green infrastructure networks (ecosystem processes utilization), and are embedded within viable governance or business models for implementation (practical viability). Our conceptual framework illustrates the functions of NBS in social-ecological landscape systems, and highlights the complementary contributions of landscape planning and governance research in developing and implementing NBS. Finally, a research and experimentation agenda is proposed, focusing on knowledge gaps in the effectiveness of NBS, useful approaches for informed co-design of NBS, and options for implementation. Insights from this paper can guide further studies and support testing of the NBS concept in practice
While the benefits humans gain from ecosystem functions and processes are critical in natural resource-dependent societies with persistent poverty, ecosystem services as a pathway out of poverty remain an elusive goal, contingent on the ecosystem and mediated by social processes. Here, we investigate three emerging dimensions of the ecosystem service-poverty relationship: economic contribution of provisioning ecosystem services to the household livelihood mix, social-ecological systems producing different bundles of ecosystem services and material wealth versus reported life satisfaction. We analyse these relationships in Bangladesh, using data from a bespoke 1586-household survey, stratified by seven social-ecological systems in the delta coastal region. We create poverty lines to ensure comparability with traditional poverty measures that overlook environmental factors and subjective measurements of well-being. We find that any contribution of ecosystem service-based income to the livelihood mix decreases the likelihood of the incidence of poverty, and of individuals reporting dissatisfaction. We find no relationship between the incidence of material poverty and the specific social-ecological systems, from agriculture to fishery-dominated systems. However, the probability of the household head being dissatisfied was significantly associated with social-ecological system. Individuals living in areas dominated by export-oriented shrimp aquaculture reported lower levels of life satisfaction as an element of their perceived well-being. These results highlight the need for social policy on poverty that accounts for the diversity of outcomes across social-ecological systems, including subjective as well as material dimensions of well-being. National poverty reduction that degrades ecosystem services can have negative implications for the subjective wellbeing of local populations.
Nature-based solutions (NBS) in river landscapes, such as restoring floodplains, can not only decrease flood risks for downstream communities but also provide co-benefits in terms of habitat creation for numerous species and enhanced delivery of diverse ecosystem services. This paper aims to explore how landscape planning and governance research can contribute to the identification, design and implementation of NBS, using the example of water-related challenges in the landscape of the Lahn river in Germany. The objectives are (i) to introduce the NBS concept and to provide a concise definition for application in planning research, (ii) to explore how landscape planning and governance research might support a targeted use and implementation of NBS, and (iii) to propose an agenda for further research and practical experimentation. Our methods include a focused literature review and conceptual framework development. We define NBS as actions that alleviate a well-defined societal challenge (challenge-orientation), employ ecosystem processes of spatial, blue and green infrastructure networks (ecosystem processes utilization), and are embedded within viable governance or business models for implementation (practical viability). Our conceptual framework illustrates the functions of NBS in social-ecological landscape systems, and highlights the complementary contributions of landscape planning and governance research in developing and implementing NBS. Finally, a research and experimentation agenda is proposed, focusing on knowledge gaps in the effectiveness of NBS, useful approaches for informed co-design of NBS, and options for implementation. Insights from this paper can guide further studies and support testing of the NBS concept in practice.
Cities are dependent on their upstream watersheds for storage and gradual release of water into river systems. These watersheds act as important flood mitigation infrastructure, providing an essential ecosystem service. In this paper we use metrics from the WaterWorld model to examine the flood management-relevant natural infrastructure of the upstream watersheds of selected global cities. These metrics enable the characterisation of different types, magnitudes and geographical distributions of potential natural flood storage. The storages are categorised as either green (forest canopy, wetland and soil) or blue (water body and floodplain) storages and the proportion of green to blue indicates how different city upstream basin contexts provide different types and levels of storage which may buffer flood risk. We apply the WaterWorld method for examining flood risk as the ratio of accumulated modelled annual runoff volume to accumulated available green and blue water storage capacity. The aim of these metrics is to highlight areas where there is more runoff than storage capacity and thus where the maintenance or restoration of further natural infrastructure (such as canopy cover, wetlands and soil) could aid in storing more water and thus better alleviate flood risks. Such information is needed by urban planners, city authorities and governments to help prepare cities for climate change impacts.
New sustainable, cost-effective solutions are urgently needed for river management since conventional practices have posed serious ecological threats on streams, rivers and the surrounding riparian areas. Besides addressing the societal needs e.g. for flood management, river management should increasingly address the ecosystem requirements for improved water quality and biodiversity. We argue that it is not feasible to solve existing and future river management challenges with intensive restoration projects. Instead, we believe that less resource-intensive solutions using natural channel processes and features, including vegetation, should be investigated. Besides directly supporting biota, aquatic and riparian vegetation traps, takes up and helps to process nutrients and harmful substances, and thus this paper emphasizes vegetation as a tool for nature-based solutions (NBS) in river management. We synthesize findings from key literature, showing that the fate of substances in channel systems is largely controlled by abiotic and biotic processes facilitated and modified by vegetation, including flow hydrodynamics, channel morphology, and sediment transport. Subsequently, we demonstrate how vegetation can be incorporated into channel designs, focusing on a two-stage (compound) design to improve resilience to flooding, control the transport of substances, and enhance the ecological status. As a conclusion, clever use and maintenance of vegetation present an unused potential to obtain large-scale positive environmental impacts in rivers and streams experiencing anthropogenic pressures.
Water resources management requires policy enforcement in a changing environment. Climate change must be considered in major watershed river restorations in Korea. The aim of river restorations is to provide better water resource control – now and in the future. To aid in policy making in the government sector, ‘vulnerability-resilience indexes’ (VRIs) with a Delphi survey method have been adopted to provide a possible reference. The Delphi survey offers prioritized vulnerability proxy variables based on expert opinions regarding the changing environment in terms of climate change and river restorations. The VRIs of watersheds were improved after river restorations, with the exception of some locations. However, when climate change was taken into consideration in the analysis of conditions after the restorations were completed, the results showed that governments need to provide better mitigation strategies to increase vulnerability resilience in the face of climate change.
Freshwater ecosystems in many parts of the world have been severely affected by past management practices that have altered the volume, timing and quality of water flows and caused a decline in their ecological health. Some of these systems are also experiencing the negative impacts of climate change. Adaptation to climate change and the continual need to address existing ecological damage poses ongoing challenges for freshwater managers. In this paper we propose and discuss a Catchment Assessment Framework (CAF) that is used to evaluate existing and potential freshwater management actions, such as riparian revegetation and habitat connectivity, for their adaptation potential. The CAF was developed as a tool for prioritizing low risk climate change adaptation options in Australian catchment management. The CAF enables catchment managers and technical experts to assess management actions against seven inter-related criteria to provide a holistic assessment: relevance to the catchment; climate change adaptation potential, including potential for maladaptation and benefit under different climate scenarios; ecosystem service benefits; compatibility with other actions; implementation constraints; socio-economic consequences; and a risk assessment. It was developed and applied by assessing nine management options with stakeholders in three catchments within the Murray-Darling Basin in south-eastern Australia. We found that while management options are undertaken as a response to existing degradation, they can be used as building blocks for a climate change adaptation strategy that considers a range of different but complementary measures to better manage climate-related risk. The CAF enables practitioners to assess the advantages of a range of adaptation options and to subject them to their wider decision making and management planning.
Riverine input is essential for the sustainability of the estuaries, wetlands, and swamps into which they flow. An existing coastal ecosystem model was used with forested wetland and fish habitat indicators to evaluate current environmental conditions as well as future restoration projects via 50-year simulations of riverine flow with sea level rise and subsidence. The objective of this study was to utilize the Integrated Compartment Model developed for the Louisiana Coastal Protection and Restoration Authority’s 2017 Coastal Master Plan to understand how alternations of riverine flow from existing rivers and future restoration projects may influence the spatial and temporal distribution of wetland habitats and suitability of fish habitats. The model was applied to the Lake Maurepas ecosystem where the Amite River flows into the lake and supports vital fisheries for surrounding communities, as well as a unique and valuable recreational resource. Additionally, the Amite River nourishes the marshes and swamps around Lake Maurepas that are essential for storm surge protection for the broader region. Modeling results suggest that the major contributing factor to the freshwater conditions to the Lake Maurepas area is the challenge of relative sea level rise − the combination of rising seas and subsidence. Fresh forested areas comprised of bald cypress (Taxodium distichum) and tupelo gum (Nyssa aquatica) in Maurepas Swamp decrease significantly under all future climate and relative sea level rise simulations except when future restoration projects are utilized. An estimated ∼1000 km2 of fresh forested wetland could be maintained over a 50-year period when considering certain restoration projects that increase freshwater flow and under climate change-related rainfall patterns, sea level rise and subsidence. However, modeled results indicate that more than 100% of the current riverine flows into the Maurepas Swamp region are still not sufficient to fully counteract the impacts of the assumed future sea level rise scenario and maintain the current forested wetlands surrounding Lake Maurepas. The higher salinities and more estuarine open water areas provide additional habitat in the future that will likely be more suitable for spotted seatrout (Cynoscion nebulosus), and adult bay anchovy (Anchoa mitchilli) than largemouth bass (Micropterus salmoides). Modeled future conditions of this ecosystem can inform restoration agencies and organizations by helping to prioritize and plan for future decades by incorporating critical factors such as sea level rise, subsidence and precipitation patterns, including the possible need to plan and prepare for changes in the fish communities and consider how that might influence the well-being of local communities.
With the wide acceptance of forest-protection policies in the developing world comes a requirement for clear demonstrations of how deforestation may erode human well-being and economies. For centuries, it has been believed that forests provide protection against flooding. However, such claims have given rise to a heated polemic, and broad-scale quantitative evidence of the possible role of forests in flood protection has not been forthcoming. Using data collected from 1990 to 2000 from 56 developing countries, we show using generalized linear and mixed-effects models contrasted with information-theoretic measures of parsimony that flood frequency is negatively correlated with the amount of remaining natural forest and positively correlated with natural forest area loss (after controlling for rainfall, slope and degraded landscape area). The most parsimonious models accounted for over 65 % of the variation in flood frequency, of which nearly 14 % was due to forest cover variables alone. During the decade investigated, nearly 100,000 people were killed and 320 million people were displaced by floods, with total reported economic damages exceeding US$1151 billion. Extracted measures of flood severity (flood duration, people killed and displaced, and total damage) showed some weaker, albeit detectable correlations to natural forest cover and loss. Based on an arbitrary decrease in natural forest area of 10 %, the model-averaged prediction of flood frequency increased between 4 and 28 % among the countries modeled. Using the same hypothetical decline in natural forest area resulted in a 4 – 8 % increase in total flood duration. These correlations suggest that global-scale patterns in mean forest trends across countries are meaningful with respect to flood dynamics. Unabated loss of forests may increase or exacerbate the number of flood-related disasters, negatively impact millions of poor people, and inflict trillions of dollars in damage in disadvantaged economies over the coming decades. This first global-scale empirical demonstration that forests are correlated with flood risk and severity in developing countries reinforces the imperative for large-scale forest protection to protect human welfare, and suggests that reforestation may help to reduce the frequency and severity of flood-related catastrophes.
An important question for salmon restoration efforts in the western USA is ‘How should habitat restoration plans be altered to accommodate climate change effects on stream flow and temperature?’ We developed a decision support process for adapting salmon recovery plans that incorporates (1) local habitat factors limiting salmon recovery, (2) scenarios of climate change effects on stream flow and temperature, (3) the ability of restoration actions to ameliorate climate change effects, and (4) the ability of restoration actions to increase habitat diversity and salmon population resilience. To facilitate the use of this decision support framework, we mapped scenarios of future stream flow and temperature in the Pacific Northwest region and reviewed literature on habitat restoration actions to determine whether they ameliorate a climate change effect or increase life history diversity and salmon resilience. Under the climate change scenarios considered here, summer low flows decrease by 35–75% west of the Cascade Mountains, maximum monthly flows increase by 10–60% across most of the region, and stream temperatures increase between 2 and 6 C by 2070–2099. On the basis of our literature review, we found that restoring floodplain connectivity, restoring stream flow regimes, and re-aggrading incised channels are most likely to ameliorate stream flow and temperature changes and increase habitat diversity and population resilience. By contrast, most restoration actions focused on in-stream rehabilitation are unlikely to ameliorate climate change effects. Finally, we illustrate how the decision support process can be used to evaluate whether climate change should alter the types or priority of restoration actions in a salmon habitat restoration plan.
Process-based restoration aims to reestablish normative rates and magnitudes of physical, chemical, and biological processes that sustain river and floodplain ecosystems. Ecosystem conditions at any site are governed by hierarchical regional, watershed, and reach-scale processes controlling hydrologic and sediment regimes; floodplain and aquatic habitat dynamics; and riparian and aquatic biota. We outline and illustrate four process-based principles that ensure river restoration will be guided toward sustainable actions: (1) restoration actions should address the root causes of degradation, (2) actions must be consistent with the physical and biological potential of the site, (3) actions should be at a scale commensurate with environmental problems, and (4) actions should have clearly articulated expected outcomes for ecosystem dynamics. Applying these principles will help avoid common pitfalls in river restoration, such as creating habitat types that are outside of a site’s natural potential, attempting to build static habitats in dynamic environments, or constructing habitat features that are ultimately overwhelmed by unconsidered system drivers.
The Yangtze is the largest river basin in China and home to over 400 million people. In recent history, and especially during 1950s–1970s, extensive lakes and floodplains were reclaimed as polders for agriculture and rural development. Consequently, the flood retention capacity was decreased, many lakes were disconnected from the main channel of the Yangtze by embankments and sluice gates, and eutrophication was common. It is anticipated that there will be a greater frequency of extreme floods and droughts in the basin according to climate change scenarios. WWF commenced a programme in 2002 in partnership with government agencies and local communities to reconnect three lakes (Zhangdu, Hong and Tian-e-zhou) in Hubei Province to the river by opening sluice gates seasonally and improving lake management. The resilience of the lake environment to climate change and the livelihoods of local people were enhanced. The measures assessed here highlight: (a) the need for adaptation programmes to concurrently improve livelihoods and reduce exposure to physical risks; (b) the need to build the capacity of people and institutions; and (c) the value of decentralized adaptation as compared with new infrastructure investments.
Public lands and waters in the United States traditionally have been managed using frameworks and objectives that were established under an implicit assumption of stable climatic conditions. However, projected climatic changes render this assumption invalid. Here, we summarize general principles for management adaptations that have emerged from a major literature review. These general principles cover many topics including: (1) how to assess climate impacts to ecosystem processes that are key to management goals; (2) using management practices to support ecosystem resilience; (3) converting barriers that may inhibit management responses into opportunities for successful implementation; and (4) promoting flexible decision making that takes into account challenges of scale and thresholds. To date, the literature on management adaptations to climate change has mostly focused on strategies for bolstering the resilience of ecosystems to persist in their current states. Yet in the longer term, it is anticipated that climate change will push certain ecosystems and species beyond their capacity to recover. When managing to support resilience becomes infeasible, adaptation may require more than simply changing management practices—it may require changing management goals and managing transitions to new ecosystem states. After transitions have occurred, management will again support resilience—this time for a new ecosystem state. Thus, successful management of natural resources in the context of climate change will require recognition on the part of managers and decisions makers of the need to cycle between “managing for resilience” and “managing for change.”
Autonomous adaptation in the water sector is assessed to derive lessons for more successful climate change adaptation from six empirical, consistently designed river management case studies based on projects of WWF. They show that when adaptation measures are considered in the context of common problems in water management, many practical ways of building resilience to climate change through mainstream programs are evident. The cases are mainly from developing countries—India, China, Mexico, Brazil, the lower Danube basin and Tanzania—where efforts to reduce environmental degradation and enhance livelihoods have directly helped to reduce vulnerability to natural hazards and climate change. The key lessons include: the benefits of concurrent measures for improving livelihoods and reducing physical vulnerability; the need to enhance and fund local institutions to mainstream adaptation programmes; and the value in implementing ‘no and low regrets’ measures despite uncertainties.
Conflict over water allocations and the need to adapt to climate change in Australia’s Murray-Darling Basin has resulted in decision makers choosing engineering interventions to use water more efficiently for wetlands conservation. We review a range of policy and infrastructure adaptation measures implemented in the Basin by governments. The water supply and demand “environmental works and measures” adopted in the Coorong and Lower Lakes region, as well as along the River Murray, are assessed and compared with the opportunity costs for ecosystem-based adaptation. The results suggest that risks of disruption to ecological processes, desiccation of wetland areas and institutional failure with infrastructure-led adaptation measures are little appreciated. Further, ecosystem-based measures to maintain a more diverse range of ecological processes that would spread risk and conserve a more diverse range of biota have not been identified or adopted by governments. We conclude that as a primary adaptation to climate change environmental works and measures may represent overly-narrow or mal-adaptation that can reduce the resilience of wetland ecosystems.
Inland flood risks are defined by a range of environmental and social factors, including land use and floodplain management. Shifting patterns of storm intensity and precipitation, attributed to climate change, are exacerbating flood risk in regions across North America. Strategies for adapting to growing flood risks and climate change must account for a community’s specific vulnerabilities, and its local economic, environmental, and social conditions. Through a stakeholder-engaged methodology, we designed an interactive decision exercise to enable stakeholders to evaluate alternatives for addressing specific community flood vulnerabilities. We used a multicriteria framework to understand what drives stakeholder preferences for flood mitigation and adaptation alternatives, including ecosystem-based projects. Results indicated strong preferences for some ecosystem-based projects that utilize natural capital, generated a useful discussion on the role of individual values in driving decisions and a critique of local environmental and hazard planning procedure, and uncovered support for a river management alternative that had previously been considered socially infeasible. We conclude that a multicriteria decision framework may help ensure that the multiple benefit qualities of natural capital projects are considered by decision makers. Application of a utility function can demonstrate the role of individual decision-maker values in decision outcomes and help illustrate why one alternative may be a better choice than another. Although designing an efficient and accurate multicriteria exercise is quite challenging and often data intensive, we imagine that this method is applicable elsewhere. It may be especially suitable to group decisions that involve varying levels of expertise and competing values, as is often the case in planning for the ecological and human impacts of climate change.
This study proposes a novel approach for establishing adaptive environmental-flow prescriptions for rivers, channels, and floodways with substantial flow augmentation and a limited decision space using the highly altered Atchafalaya River Basin (ARB) in Louisiana as an example. Development of the ARB into the primary floodway of the Mississippi River and Tributaries Project has contributed to hydrologic changes basin-wide that have altered the river-floodplain interface threatening important ecosystems, notably the expansive baldcypress-water tupelo swamp forests. Current restoration efforts only address the spatial distribution of water in local areas of the basin; however, the timing, frequency, magnitude, and duration of ecologically-important high and low flows are determined at the basin-wide scale by the daily implementation of a federal flow mandate that limits available water management options. We used current hydrologic conditions and established flow-ecology relationships from the literature to develop an environmental flow prescription for the ARB that provides basin-wide flow targets to complement ongoing restoration efforts. Hydrologic analysis of current flows and the flow-ecology requirements for these wetland forests revealed an overlap in the range of flow variability under the current water management model, suggesting environmental flows can be complementary with the desired hydraulic and geomorphic characteristics of the floodway. The result is a first step towards an adaptive flow regime that strives to balance important flow-ecology relationships within a decision space limited by a federal flow mandate. We found high potential for success in managing water for nature while accommodating other management needs for the river.
The Three-Rivers Headwater Region (TRHR) is the headwater of the Yangtze River Basin (YARB), Yellow River Basin (YRB), and Lancang River Basin (LRB); it is known as China’s ‘Water Tower’ owing to its important supply of freshwater. In order to assess ecosystem changes in the TRHR during 2000–2012, we systematically and comprehensively evaluated a combination of model simulation results and actual observational data. The results showed the following: (1) Ecosystem pattern was relatively stable during 2000–2010, with a slight decrease in farmland and desert areas, and a slight increase in grassland and wetland/water-body areas. (2) A warmer and wetter climate, and ecological engineering, caused the vegetation cover and productivity to significantly improve. (3) Precipitation was the main controlling factor for streamflow. A significant increase in precipitation during 2000–2012 resulted in an obvious increase in annual and seasonal streamflow. Glacier melting also contributed to the streamflow increase. (4) The total amount of soil conservation increased slightly from 2000 to 2012. The increase in precipitation caused rainfall erosivity to increase, which enhanced the intensity of soil erosion. The decrease in wind speed decreased wind erosion and the frequency of sandstorms. (5) The overall habitat quality in the TRHR was stable between 2000 and 2010, and the spatial pattern exhibited obvious heterogeneity. In some counties that included nature reserves, habitat quality was slightly higher in 2010 than in 2000, which reflected the effectiveness of the ecological restoration. Overall, the aforementioned ecosystem changes are the combined results of ecological restoration and climate change, and they are likely a local and temporary improvement, rather than a comprehensive and fundamental change. Therefore, more investments and efforts are needed to preserve natural ecosystems.
Climate change is projected to alter river flows and the magnitude/frequency characteristics of floods and droughts. Ecosystem-based adaptation highlights the interdependence of human and natural systems, and the potential to buffer the impacts of climate change by maintaining functioning ecosystems that continue to provide multiple societal benefits. Natural flood management (NFM), emphasising the restoration of innate hydrological pathways, provides important regulating services in relation to both runoff rates and water quality and is heralded as a potentially important climate change adaptation strategy. This paper draws together 25 NFM schemes, providing a meta-analysis of hydrological performance along with a wider consideration of their net (dis) benefits. Increasing woodland coverage, whilst positively linked to peak flow reduction (more pronounced for low magnitude events), biodiversity and carbon storage, can adversely impact other provisioning service – especially food production. Similarly, reversing historical land drainage operations appears to have mixed impacts on flood alleviation, carbon sequestration and water quality depending on landscape setting and local catchment characteristics. Wetlands and floodplain restoration strategies typically have fewer disbenefits and provide improvements for regulating and supporting services. It is concluded that future NFM proposals should be framed as ecosystem-based assessments, with trade-offs considered on a case-by-case basis.