Changes in land use and management practices to store and sequester carbon are becoming integral to global efforts that both address climate change and alleviate poverty. Knowledge and evidence gaps nevertheless abound. This paper analyses the most pressing deficiencies in understanding carbon storage in both soils and above ground biomass and the related social and economic challenges associated with carbon sequestration projects. Focusing on the semi-arid and dry sub-humid systems of sub-Saharan Africa which are inhabited by many of the world’s poor, we identify important interdisciplinary opportunities and challenges that need to be addressed, in order for the poor to benefit from carbon storage, through both climate finance streams and the collateral ecosystem service benefits delivered by carbon-friendly land management. We emphasise that multi-stakeholder working across scales from the local to the regional is necessary to ensure that scientific advances can inform policy and practice to deliver carbon, ecosystem service and poverty alleviation benefits.
Archives: Publications
As dangerous climate change looms, decision-makers are increasingly realising that societies will need to adapt to this threat as well as mitigate against it. Green infrastructure (GI) is increasingly seen as an ideal climate change adaptation policy response. However, with this research the authors identify a number of crucial knowledge gaps within GI and, consequently, call for caution and for a concerted effort to understand the concept and what it can really deliver. GI has risen to prominence in a range of policy areas in large part due to its perceived ability to produce multiple benefits simultaneously, termed ‘multifunctionality’. This characteristic strengthens the political appeal of the policy in question at a time when environmental issues have slipped down political agendas. Multifunctionality, however, brings its own set of new challenges that should be evaluated fully before the policy is implemented. This research takes important first steps to developing a critical understanding of what is achievable within GI’s capacity. It focuses on one of GI’s single objectives, namely climate change adaptation, to focus the analysis of how current obstacles in applying GI’s multifunctionality could lead to the ineffective delivery of its objective. By drawing on expert opinion from government officials and representatives from the private, non-government organisation (NGO) and academic sectors, this research questions GI’s ability to be effectively ‘multifunctional’ with an inconsistent definition at its core, deficiencies in its understanding and conflicts within its governance. In light of these observations, the authors then reflect on the judiciousness of applying GI to achieve the other objectives it has also been charged with delivering.
Coastal vegetation has been widely recognized as a natural method to reduce the energy of tsunami waves. However, a vegetation barrier cannot completely stop a tsunami, and its effectiveness depends on the magnitude of the tsunami as well as the structure of the vegetation. For coastal rehabilitation, optimal planning of natural coastal systems, and their maintenance, we need to quantitatively elucidate the capacity of vegetation to reduce the energy of tsunami waves. The limitations of coastal forests in relation to the magnitude of a tsunami and the maintenance of forests as natural disaster buffer zones have to be understood correctly for effective coastal vegetation planning. Demerits of coastal forests have also been revealed: for example, an open gap in a forest (i.e., a road, river, difference in elevation, etc.) can channel and amplify a strong current by forcing it into the gap. Floating debris from broken trees also can damage surrounding buildings and hurt people. However, many studies have revealed that these demerits can be overcome with proper planning and management of mangroves and coastal forests, and that coastal vegetation has a significant potential to mitigate damage in constructed areas and save human lives by acting as buffer zones during extreme natural events. However, mangrove forests have been damaged by anthropogenic activities (i.e., tourism, shrimp farming, and industrial development), making coastal areas increasingly vulnerable to tsunamis and other natural disasters. The effectiveness of vegetation also changes with the age and structure of the forest. This highlights the fact that proper planning and management of vegetation are required to maintain the tsunami buffering function of coastal forests. Although many government and nongovernmental organizations have implemented coastal vegetation projects, many of them have been unsuccessful due to a lack of proper maintenance. A pilot project in Matara City, Sri Lanka, revealed that participation and support from local authorities and communities is essential to make the planting projects successful. An integrated coastal vegetation management system that includes utilization of the materials produced by the forest and a community participation and awareness program are proposed to achieve a sustainable and long-lasting vegetation bioshield.
Building land with a rising sea and a growing coastal population requires strategies that combine conventional engineering with the restoration and maintenance of wetlands and natural delta-building processes. Advances in ecosystem-based engineering may mitigate the risks associated with conventional engineering and rising energy costs. The few existing examples, however, are too recently implemented to fully evaluate their long-term success. More proof-of-concept projects with extensive monitoring are urgently needed in the search for science-based solutions to safeguard delta societies around the world.
The risk of flood disasters is increasing for many coastal societies owing to global and regional changes in climate conditions, sea-level rise, land subsidence and sediment supply. At the same time, in many locations, conventional coastal engineering solutions such as sea walls are increasingly challenged by these changes and their maintenance may become unsustainable. We argue that flood protection by Ecosystem creation and restoration can provide a more sustainable, cost-effective and ecologically sound alternative to conventional coastal engineering and that, in suitable locations, it should be implemented globally and on a large scale.
We investigated and compared management practices for dealing with uncertainty in agroecosystem dynamics in two cases of smallholder farming in different parts of the world: northeast Tanzania and east-central Sweden. Qualitative research methods were applied to map farmers’ practices related to agroecosystem management. The practices are clustered according to a framework of ecosystem services relevant for agricultural production and discussed using a theoretical model of ecosystem dynamics. Almost half of the identified practices were found to be similar in both cases, with similar approaches for adjusting to and dealing with local variability and disturbance. Practices that embraced the ecological roles of wild as well as domesticated flora and fauna and the use of qualitative biological indicators are identified as tools that built insurance capital for change and enhanced the capacity to respond to changing agroecosystem dynamics. Diversification in time and space, as well as more specific practices for mitigating pest outbreaks and temporary droughts, can limit the effects of disturbance. In both Sweden and Tanzania, we identified social mechanisms for the protection of species that served important functions in the agroecosystem. We also found examples of how old practices served as a source of adaptations for dealing with new conditions and that new knowledge was adjusted to local conditions. The study shows that comparing management practices across scales and in different cultural settings can reveal insights into the capacity of farmers to adjust, respond to, and shape ecosystem dynamics. We emphasize the importance of continuous learning for developing the sustainable management of complex agroecosystems and securing agricultural production for the future.
This special feature provides an overview on how the ecosystem service concept has been and can be incorporated into the science, practice, and policies of ecological restoration (ER) and evidence-based land-use. It includes an edited selection of eleven invited and peer-reviewed papers based on presentations given during the 9th European Conference on Ecological Restoration in 2014. The focus is on Europe, but many contributors also make appraisals and recommendations at the global scale. Based on the contributors’ papers, and our own overview of the promise of ecological restoration in the existing international treaties, coalitions, and conventions, we propose that the following actions could contribute to the positive impacts of ER on biodiversity maintenance, ecosystem functioning, progressive mainstreaming the concepts of both ER and ecosystem services, significant mitigation and offsetting of anthropogenic climate change, and lasting enhancement of both ecosystem and human health: • ER should be incorporated into land use planning, wherever needed, and the synergies and trade-offs of different land use scenarios should be assessed in terms of their impacts on ecosystem services. • The discourse of ER should be enlarged, wherever it is needed, to include multifunctional land use that simultaneously supports sustainable production systems, built environments, and the quality and quantity of diverse ecosystem services. This approach will generate ecological, social, and economic benefits in the long run. • Monitoring and evaluation of ER projects should be a continuous process involving careful selection of indicators chosen with the full range of stakeholders in mind, and a sufficiently long-term perspective to catch the progress of long-term or highly dynamic ecosystem processes. • Scientists should actively participate in policy and land management discussions in order to give their views on the potential outcomes of decisions. • Greater cooperation and exchanges are needed within the EU and globally in order to accelerate the upscaling, improvement, and mainstreaming of both large-scale ER and the science and application of the ecosystem services concept.
Rapid climate change poses complex challenges for conservation, especially in tropical developing countries where biodiversity is high while financial and technical resources are limited. The complexity is heightened by uncertainty in predicted effects, both for ecological systems and human communities that depend heavily on natural resource extraction and use. Effective conservation plans and measures must be inexpensive, fast-acting, and able to increase the resilience of both the ecosystem and the social-ecological system. We present conservation practitioners with a framework that strategically integrates climate change planning into connectivity measures for tropical mountain ecosystems in Costa Rica. We propose a strategy for doubling the amount of habitat currently protected in riparian corridors using measures that are relatively low cost and fast-acting, and will employ and expand human capital. We argue that habitat connectivity must be enhanced along latitudinal gradients, but also within the same elevational bands, via a lattice-work corridor system. This is needed to facilitate range shifts for mobile species and evolutionary adaptation for less mobile species. We think that conservation measures within the elevational bands must include conservation-friendly land uses that improve current and future human livelihoods under dynamic conditions. Key components include community involvement, habitat priority-setting, forest landscape restoration, and environmental services payments. Our approach is fundamentally adaptive in that the conservation measures employed are informed by on-the-ground successes and failures and modified accordingly, but are relatively low risk and fast-acting. Our proposal, if implemented, would satisfy tenets of climate-smart conservation, improve the resilience of human and ecological communities, and be a model for other locations facing similar challenges.
The risk that tropical storm occurrence may alter as a result of global warming presents coastal managers, particularly in vulnerable areas, with a serious challenge. Many countries are hard-pressed to protect their coastal resources against present-day hazards, let alone any increased threat in the future. Moreover, the threat posed by climate change is uncertain making the increased costs of protection difficult to justify. Here, we examine one management strategy, based on the rehabilitation of the mangrove ecosystem, which may provide a dual, ‘winwin’ benefit in improving the livelihood of local resource users as well as enhancing sea defences. The strategy, therefore, represents a precautionary approach to climate impact mitigation. This paper quantifies the economic benefits of mangrove rehabilitation undertaken, inter alia, to enhance sea defence systems in three coastal Districts of northern Vietnam. The results of the analysis show that mangrove rehabilitation can be desirable from an economic perspective based solely on the direct use benefits by local communities. Such activities have even higher benefit cost ratios with the inclusion of the indirect benefits resulting from the avoided maintenance cost for the sea dike system which the mangrove stands protect from coastal storm surges.
Ecosystems, climate change, and disaster risk reduction are among the cross-cutting issues highlighted in the Rio+20 Conference. In view of the post-2015 development agenda, the chapter discusses the important role of ecosystem-based disaster risk reduction in sustaining ecosystems and building disaster-resilient communities. It describes ecosystem management strategies that link ecosystem protection and disaster risk reduction, elucidates the challenges in advancing the use of ecosystem-based disaster risk reduction and linking it to policy, and identifies opportunities for scaling up.
It is increasingly recognized that uncertainty concerns more than statistical errors and incomplete information. Uncertainty becomes particularly important in decision-making when it influences the ability of the decision-makers to understand or solve a problem. While the literature on uncertainty and the way in which uncertainty in decision-making is conceptualized continue to evolve, the many uncertainties encountered in policy development and projects are still mostly represented as individual and separated issues. In this paper, we explore the relationship between fundamentally different uncertainties – which could be classified as unpredictability, incomplete knowledge or ambiguity – and show that uncertainties are not isolated. Based on two case studies of ecological engineering flood defence projects, we demonstrate that important ambiguities are directly related to unpredictability and incomplete knowledge in cascades of interrelated uncertainties. We argue that conceptualizing uncertainties as cascades provides new opportunities for coping with uncertainty. As the uncertainties throughout the cascade are interrelated, this suggests that coping with a particular uncertainty in the cascade will influence others related to it. Each uncertainty in a cascade is a potential node of intervention or facilitation. Thus, if a particular coping strategy fails or system conditions change, the cascades point at new directions for coping with the uncertainties encountered. Furthermore, the cascades can function as an instrument to bridge the gap between actors from science and policy, as it explicitly shows that uncertainties held relevant in different arenas are actually directly related.
Compared to traditional hard engineering, nature-based flood protection can be more cost effective, use up less raw materials, increase system adaptability and present opportunities to improve ecosystem functioning. However, high flood safety standards cause the need to combine nature-based structures with traditional civil engineered structures. This increases complexity assessing when and how ecological and engineering objectives of such flood protection systems are achieved. This study classifies the degree to which coastal designs are nature based using criteria for ecosystem-based management (EBM). For the engineering criterion the distinction between main and supporting structures is introduced. To evaluate the ecological criterion five design concepts have been introduced, ranging from completely engineered to completely nature-based. The method results in an EBM-ranking of the coast, showing where a particular flood protection design stands on the range between completely engineered (low EBM-rank) and nature-based (high EBM-rank). It thus facilitates comparison of different flood protection systems. The method was the applied on the North-Sea coast of Belgium, the Netherlands, and Germany. The results show that combinations of civil-engineered and nature-based structures are widely applied. However, due to the overall low contribution to flood protection by the nature-based structures, about 85% of the coast is dominated by engineered structures. The majority of these stretches is located in relatively sheltered areas. Improving the flood protection capacity of the nature-based structures in these areas is hard to achieve. Therefore, application of more nature-based design concepts on the main structures is the most promising way to improve the EBM-rank of many flood protection systems.
The Kyoto Protocol (KP) requires signatories to reduce CO2-equivalent emissions by an average of 5.2% from 1990 levels by the commitment period 2008–2012. This constitutes only a small proportion of global greenhouse gas emissions. Importantly, countries can attain a significant portion of their targets by sequestering carbon in terrestrial ecosystems in lieu of emission reductions. Since carbon sink activities lead to ephemeral carbon storage, forest management and other activities that enhance carbon sinks enable countries to buy time as they develop emission reduction technologies. Although many countries are interested in sink activities because of their presumed low cost, the analysis in this paper suggests otherwise. While potentially a significant proportion of required CO2 emission reductions can be addressed using carbon sinks, it turns out that, once the opportunity cost of land and the ephemeral nature of sinks are taken into account, costs of carbon uptake could be substantial. Carbon uptake via forest activities varies substantially depending on location (tropical, Great Plains, etc.), activity (forest conservation, tree planting, management, etc.), and the assumptions and methods upon which the cost estimates are based. Once one eliminates forestry projects that should be pursued because of their biodiversity and other non-market benefits, or because of their commercial profitability, there remain few projects that can be justified purely on the grounds that they provide carbon uptake benefits.
Climate change and biodiversity loss are two of the greatest challenges of the 21st century. To date, actions proposed by the international community to address these problems have largely been conducted in a piecemeal fashion. Conservation biologists advocate for low-intensity management in temperate protected areas to maintain and restore biodiversity. Low-input, high-diversity biomass from such areas has been proposed as a promising alternative bioenergy feedstock. Here, we show that there is a vast unexploited biomass-for-bioenergy potential present in Natura 2000, the European nature conservation network. Spanning 7.5 million hectares (ha), non-forest ecosystems within Natura 2000 have a biomass production of 17.9 teragrams (Tg) of dry matter annually. The conversion of this biomass to bioenergy will not lead to the displacement of food production systems, thereby avoiding 12.5 Tg of carbon dioxide equivalent greenhouse-gas emissions and circumventing between 1.2 and 2.8 million ha of indirect land-use change. The use of conservation biomass as bioenergy feedstock clearly offers the opportunity to reconcile biodiversity goals and climate-change mitigation.
Low-lying, densely populated coastal areas worldwide are under threat, requiring coastal managers to develop new strategies to cope with land subsidence, sea-level rise and the increasing risk of storm-surge-induced floods. Traditional engineering approaches optimizing for safety are often suboptimal with respect to other functions and are neither resilient nor sustainable. Densely populated deltas in particular need more resilient solutions that are robust, sustainable, adaptable, multifunctional and yet economically feasible. Innovative concepts such as ‘Building with Nature’ provide a basis for coastal protection strategies that are able to follow gradual changes in climate and other environmental conditions, while maintaining flood safety, ecological values and socio-economic functions. This paper presents a conceptual framework for Building with Nature that is used to evaluate coastal protection strategies, based on a case study of the Holland coast in the Netherlands. The added value and the limitations of these strategies are discussed.
There is extensive experience in adaptive management of exposed sandy coastlines through sand nourishment for coastal protection. However, in complex estuarine systems, coastlines are often shortened through damming estuaries to achieve desired safety levels. The Dutch Deltaworks illustrate that this approach disrupts natural sediment fluxes and harms ecosystem health, which negatively affects derived ecosystem services, such as freshwater availability and mussel and oyster farming. This heavily impacts local communities and thus requires additional maintenance and management efforts. Nevertheless, the discussion on coastline shortening keeps surfacing when dealing with complex coastal management issues throughout the world. Although adaptive delta management accompanied by innovative approaches that integrate coastal safety with ecosystem services is gaining popularity, it is not yet common practice to include adaptive pathways, a system-based view and ecosystem knowledge into coastal management projects. Here, we provide a first attempt to integrate ecosystem-based flood risk reduction measures in the standard suite of flood risk management solutions, ranging from structural to non-structural. Additionally, for dealing with the dynamic and more unpredictable nature of ecosystems, we suggest the adaptive delta management approach that consists of flexible measures, measurable targets, monitoring and intervention, as a framework for embedding ecosystem-based alternatives for flood risk mitigation in the daily practice of engineers and coastal planners.
Ecosystem destruction not only incurs large costs for restoration but also increases hydraulic forces on existing flood defence infrastructure. This realisation has made the inclusion of ecosystems and their services into flood defence schemes a rapidly growing field. However, these new solutions require different design, construction and management methods. A close collaboration between engineers, ecologists and experts in public administration is essential for adequate designs. In addition, a mutual understanding of the basic principles of each other’s field of expertise is paramount. This chapter presents some simple approaches for the integration of ecosystem-based measures into coastal engineering projects, which may be of use to experts from a range of fields. Further, it stresses the importance of ecological processes which determine the persistence and health of coastal ecosystems, a point which is rarely emphasised in coastal engineering. The main aim of this chapter is to highlight the role of ecosystem properties for flood defence to stimulate the coastal engineering community in adopting an ecosystem view. In the near future the hope is that greater awareness of ecosystem processes will lead to more sustainable and climate-robust designs. For this, engineers, ecologists and social scientists involved in coastal defence projects need to develop a common language, share the same design concepts and be willing to share the responsibility for these innovative designs.
Measures of climate change adaptation often involve modification of land use and land use planning practices. Such changes in land use affect the provision of various ecosystem goods and services. Therefore, it is likely that adaptation measures may result in synergies and trade-offs between a range of ecosystems goods and services. An integrative land use modelling approach is presented to assess such impacts for the European Union. A reference scenario accounts for current trends in global drivers and includes a number of important policy developments that correspond to on-going changes in European policies. The reference scenario is compared to a policy scenario in which a range of measures is implemented to regulate flood risk and protect soils under conditions of climate change. The impacts of the simulated land use dynamics are assessed for four key indicators of ecosystem service provision: flood risk, carbon sequestration, habitat connectivity and biodiversity. The results indicate a large spatial variation in the consequences of the adaptation measures on the provisioning of ecosystem services. Synergies are frequently observed at the location of the measures itself, whereas trade-offs are found at other locations. Reducing land use intensity in specific parts of the catchment may lead to increased pressure in other regions, resulting in trade-offs. Consequently, when aggregating the results to larger spatial scales the positive and negative impacts may be off-set, indicating the need for detailed spatial assessments. The modelled results indicate that for a careful planning and evaluation of adaptation measures it is needed to consider the trade-offs accounting for the negative effects of a measure at locations distant from the actual measure. Integrated land use modelling can help land use planning in such complex trade-off evaluation by providing evidence on synergies and trade-offs between ecosystem services, different policy fields and societal demands.
Cost Benefit Analysis (CBA) is underutilised in assessing Ecosystem- based Disaster Risk Reduction (Eco-DRR) interventions, the protocols used are not always rigourous and the analytical framework is unclear. However, CBAs which follow best practices could be extremely beneficial and helpful to policy makers in establishing priorities for Eco-DRR interventions. A robust and systematic economic analytical approach might be useful, if not necessary, to justify large upfront investments and promote the implementation of this type of risk reduction intervention at an even broader scale. Identifying a common core of best practices for CBA applied to Eco-DRR would also increase comparability between studies, reproducibility of assessments, and facilitate much needed external review. The purpose of this chapter is to (i) outline the fundamental principles and best practices of rigourous cost-benefit analysis (CBA) applied to ecosystem-based adaptation (EbA) and (Eco-DRR) interventions; (ii) review existing studies; and – based on this review of past work – (iii) outline the possible areas of improvement to strengthen future CBAs of Eco-DRR projects.
Despite the growing interest in Ecosystem-based Adaptation, there has been little discussion of how this approach could be used to help smallholder farmers adapt to climate change, while ensuring the continued provision of ecosystem services on which farming depends. Here we provide a framework for identifying which agricultural practices could be considered ‘Ecosystem-based Adaptation’ practices, and highlight the opportunities and constraints for using these practices to help smallholder farmers adapt to climate change. We argue that these practices are (a) based on the conservation, restoration or management of biodiversity, ecosystem processes or services, and (b) improve the ability of crops and livestock to maintain crop yields under climate change and/or by buffering biophysical impacts of extreme weather events or increased temperatures. To be appropriate for smallholder farmers, these practices must also help increase their food security, increase or diversify their sources of income generation, take advantage of local or traditional knowledge, be based on local inputs, and have low implementation and labor costs. To illustrate the application of this definition, we provide some examples from smallholders’ coffee management practices in Mesoamerica. We also highlight three key obstacles that currently constrain the use of Ecosystem-based Adaptation practices (i) the need for greater understanding of their effectiveness and the factors that drive their adoption, (ii) the development supportive and integrated agriculture and climate change policies that specifically promote them as part of a broader agricultural adaptation program; and (iii) the establishment and maintaining strong and innovative extension programs for smallholder farmers. Our framework is an important starting point for identifying which Ecosystem-based Adaptation practices are appropriate for smallholder farmers and merit attention in international and national adaptation efforts.
In developing countries where economies and livelihoods depend largely on ecosystem services, policies for adaptation to climate change should take into account the role of these services in increasing the resilience of society. This ecosystem-based approach to adaptation was the focus of an international workshop on “Adaptation to Climate Change: the role of Ecosystem Services” held in November 2008 in Costa Rica. This article presents the key messages from the workshop.
Context: Integrated conservation decision-making frameworks that help to design or adjust practices that are cognisant of environmental change and adaptation are urgently needed. Objective: We demonstrate how a landscape vulnerability framework combining sensitivity, adaptive capacity, and exposure to climate change framed along two main axes of concern can help to identify potential strategies for conservation and adaptation decision-making, using a landscape in Madagascar’s spiny forest as a case-study. Methods: To apply such a vulnerability landscape assessment, we inferred the sensitivity of habitats using temporal and spatial botanical data-sets, including the use of fossil pollen data and vegetation surveys. For understanding adaptive capacity, we analysed existing spatial maps (reflecting anthropogenic stressors) showing the degree of habitat connectivity, matrix quality and protected area coverage for the different habitats in the landscape. Lastly, for understanding exposures, we used climate change predictions in Madagascar, together with a digital elevation model. Results: The fossil pollen data showed how sensitive arid-adapted species were to past climate changes, especially the conditions between 1000 and 500 cal yr BP. The spatial analysis then helped locate habitats on the two-dimensional axes of concern integrating sensitivity, adaptive capacity and climate change exposure. By identifying resistant, resilient, susceptible, and sensitive habitats to climate change in the landscape under study, we identify very different approaches to integrate conservation and adaptation strategies in contrasting habitats. Conclusion: This framework, illustrated through a case study, provides easy guidance for identifying potential integrated conservation and adaptation strategies, taking into account aspects of climate vulnerability and conservation capacity.
Vegetated foreshores such as salt marshes, mangrove forests and reed fields can reduce wave loads on coastal dikes due to depth-induced wave breaking and wave attenuation by vegetation. Here we present field measurements of wave propagation over salt marshes during severe storm conditions, a modelling approach to describe the effect of vegetated foreshores on wave loads on the dike, and a probabilistic model to quantify the effect of vegetated foreshores on failure probabilities of the dike due to wave overtopping.
A core concept in stormwater green infrastructure (GI) design is whether a system will meet its rainfall-runoff volume capture goals within a period of time after a previous event. In GI design, it is necessary not to view storms as singular, isolated events, but rather as a series of events, some of which are occurring within short durations and are often termed back-to-back events. This paper demonstrates the statistical rarity of back-to-back rainfall events that impact GI performance and analyzes the expected impact on the design of several GI systems for the mid-Atlantic region. Twenty-four scenarios were evaluated for common design events (2.5, 3.8, and 8.1 cm), followed by a substantial subsequent event (50-100% of the original storm volume) that occurred within the period where it would be expected that the GI system would be recovering capacity (24, 48, 72, or 96 h interevent period). The results indicated that only four scenarios had an annual average occurrence greater than one time per year, and 9 of the 24 scenarios had less than 0.1 annual average occurrences. Simple, conservative models of a bioinfiltration rain garden and green roof demonstrated that system storage capacity is almost always restored by infiltration and evapotranspiration within the prescribed interevent drawdown period, thus back-to-back events are not a primary concern. This finding was further confirmed with field site evidence from three GI sites at Villanova University, which regularly captured more than the design rainfall volume and only infrequently had minimal discharges for rainfalls smaller than design. An exception to this finding was that a green roof with a drainage layer did not exceed its design capacity because the drainage layer conveyed stored water away from the GI system before evapotranspiration could contribute to volume removal. These results demonstrate that the likelihood of large back-to-back events is very low, as is the chance of the design runoff volume being exceeded. This paper provides evidence that the existing required drawdown period for GI design can be overly restrictive for a system to meet its volume control goals, which may inhibit optimal implementation. The findings support more appropriate design through the development of regionally specific required drawdown times based on storm event frequency.
To achieve global food security, we need to approximately double food production over the coming decades. Conventional agriculture is the mainstream approach to achieving this target but has also caused extensive environmental and social harms. The consensus is that we now need an agriculture that can “multi-functionally” increase food production while simultaneously enhancing social and environmental goals, as committed to in the sustainable development goals (SDGs). Farming also needs to become more resilient to multiple insecurities including climate change, soil degradation, and market unpredictability, all of which reduce sustainability and are likely to exacerbate hunger. Here, we illustrate how agroforestry systems can increase yield while also advancing multiple SDGs, especially for the small developing-world agriculturalists central to the SDG framework. Agroforestry also increases resilience of crops and farm livelihoods, especially among the most vulnerable food producers. However, conventional yield-enhancement strategies have naturally dominated the debate on food production, hindering implementation of more multifunctional alternatives. Governments and institutions now have the opportunity to rebalance agricultural policy and investment toward such multigoal approaches. In doing so, they could achieve important improvements on multiple international commitments around the interlinked themes of food security, climate change, biodiversity conservation, and social well-being.