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Abstract The power performance and the wind velocity field of an onshore wind farm are predicted with machine learning models and the pseudo‐2D RANS model, then assessed against SCADA data. The wind farm under investigation is one of the sites involved with the American WAKE experimeNt (AWAKEN). The performed simulations enable predictions of the power capture at the farm and turbine levels while providing insights into the effects on power capture associated with wake interactions that operating upstream turbines induce, as well as the variability caused by atmospheric stability. The machine learning models show improved accuracy compared to the pseudo‐2D RANS model in the predictions of turbine power capture and farm power capture with roughly half the normalized error. The machine learning models also entail lower computational costs upon training. Further, the machine learning models provide predictions of the wind turbulence intensity at the turbine level for different wind and atmospheric conditions with very good accuracy, which is difficult to achieve through RANS modeling. Additionally, farm‐to‐farm interactions are noted, with adverse impacts on power predictions from both models.

Humans have always wanted to know what the future holds in store for them. In earlier centuries, people often sought clues to the future from sacred texts. Today, more secular approaches are increasingly used, although the older approaches to the future persist. Modern methods for prediction include trend extrapolation, the Delphi method, mathematical modeling, and scenario analysis, including backcasting. Extrapolation was only possible when reliable past data became available. The Delphi method relies on the judgement of experts in the subject matter. Mathematical modeling has been very successful in the physical sciences, and, in the form of integrated assessment models (IAMs), has been applied to problems such as assessing future energy use. Scenario analysis looks at a number of possible futures and develops internally consistent story lines around each. It is often used in conjunction with IAMs. Each of the four methods, including both their strengths and weaknesses, are discussed in turn. Finally, this entry looks at the future of prediction, and concludes that despite progress in each of the four approaches treated, predicting the future, never easy, is now harder than ever.

This article provides a comprehensive review of the most recent advances in the planning, execution, and analysis of inflow and wake measurements from nacelle-mounted wind Doppler lidars. Lidars installed on top of wind turbines provide a holistic view of the inflow and wake characteristics required to characterize and optimize wind turbine performance, carry out model validation and calibration, and aid in real-time control. The need to balance the enhanced capabilities and limitations of lidars compared to traditional anemometers inspired a broad variety of approaches for scan design and wind reconstruction, which we discuss in this review. We give particular emphasis to identifying common guidelines and gaps in the available literature with the aim of providing an exhaustive picture of the state-of-the-art techniques for reconstructing wind plant flow using nacelle-mounted lidars.

The arrival of the hydrogen (H2) economy has been the subject of many studies. Earlier articles were over-optimistic about the timing and extent of global H2 uptake, and predicted private vehicles as leading the way to a H2 economy. The recent strong rise in the global electric vehicle fleet has inevitably led to a reassessment of the prospects for H2, at least for transport. This review paper examines how researchers over recent decades have envisaged how the H2 economy would arrive, and why it was desirable, or even inevitable; it also looks at the future prospects for the H2 economy. The key findings are as follows: ● Among the leading energy forecasting bodies, particularly the International Energy Agency (IEA), even the most optimistic scenarios predict under 10% H2 penetration by 2050. ● IEA forecasts are very optimistic about the prospects for the introduction of carbon dioxide removal technologies and growth of dispatchable sources of low-carbon energy. ● More realistic IEA forecasts would increase the need for the growth of intermittent energy sources such as wind and solar. The subsequent requirement for energy storage would in turn help the case for H2 adoption. ● No new technologies are on the horizon to decisively tip the balance in favor of H2. ● It is concluded that a global H2 economy is still distant, but it could arise in energy-poor countries such as Japan and South Korea, and it could find a niche in freight transport.

For all of human history except the past two centuries or so, bioenergy provided nearly all the world’s primary energy. Then, fossil fuels largely replaced bioenergy, but concern about climate change and fossil fuel depletion will force a move back to renewable energy, including bioenergy. The main method used here to study the future of global bioenergy was a literature surview of relevant published papers, with emphasis both on those published after 2020, and those having a global focus. The key finding is that bioenergy is unlikely to greatly increase its share of global energy consumption, for several reasons. Liquid biofuel production for transport is likely to almost disappear as countries progressively phase out internal combustion engine vehicles. Traditional firewood use is also projected to fall. There are also doubts about the technical potential of bioenergy, not only because it must compete with the other uses for biomass—food, fodder, fibre and timber—but also because in many cases its climate change mitigation impact is less than for other approaches, including alternative renewable energy sources. The overall conclusion is that bioenergy will have a minor but still useful role in the future global energy system, but global energy reductions are likely to be more important for climate stability than bioenergy.

Many governments have supported the introduction of electric vehicles (EVs) through purchase subsidies or waiving fuel taxes. The key findings of this paper are that the benefits of EVs may have been overstated, at least for some countries, as their energy savings and climate mitigation advantages depend on such factors as annual kilometres travelled per vehicle, electricity fuel mix, vehicle size and even local conditions. Because serious climate change has already arrived in the form of increasing frequency and severity of extreme events, we do not have the decades required for electricity production to be predominantly from non-carbon sources. Further, there are a variety of other challenges facing private transport—EVs just as much as conventionally powered vehicles. These include traffic casualties, non-engine air and noise pollution, light pollution, land requirements for roads and parking, and the intrusion of roads into natural habitats. With the promotion of EVs, these other transport problems run the risk of being downplayed. If all the environmental challenges facing road vehicles are to be effectively and quickly tackled, significant reductions in road vehicular travel are needed.

Non-Alcoholic Fatty Liver Disease (NAFLD) is a common condition affecting around 10–25% of the general adult population, 15% of children, and even > 50% of individuals who have type 2 diabetes mellitus. It is a major cause of liver-related morbidity, and cardiovascular (CV) mortality is a common cause of death. In addition to being the initial step of irreversible alterations of the liver parenchyma causing cirrhosis, about 1/6 of those who develop NASH are at risk also developing CV disease (CVD). More recently the acronym MAFLD (Metabolic Associated Fatty Liver Disease) has been preferred by many European and US specialists, providing a clearer message on the metabolic etiology of the disease.The suggestions for the management of NAFLD are like those recommended by guidelines for CVD prevention. In this context, the general approach is to prescribe physical activity and dietary changes the effect weight loss. Lifestyle change in the NAFLD patient has been supplemented in some by the use of nutraceuticals, but the evidence based for these remains uncertain. The aim of this Position Paper was to summarize the clinical evidence relating to the effect of nutraceuticals on NAFLD-related parameters. Our reading of the data is that whilst many nutraceuticals have been studied in relation to NAFLD, none have sufficient evidence to recommend their routine use; robust trials are required to appropriately address efficacy and safety.

Abstract Long-term weather and climate observatories can be affected by the changing environments in their vicinity, such as the growth of urban areas or changing vegetation. Wind plants can also impact local atmospheric conditions through their wakes, characterized by reduced wind speed and increased turbulence. We explore the extent to which the wind plants near an atmospheric measurement site in the central United States have affected their long-term measurements. Both direct observations and mesoscale numerical weather prediction simulations demonstrate how the wind plants induce a wind deficit aloft, especially in stable conditions, and a wind speed acceleration near the surface, which extend $$\sim 30$$ ∼ 30 km downwind of the wind plant. Turbulence kinetic energy is significantly enhanced within the wind plant wake in stable conditions, with near-surface observations seeing an increase of more than 30% a few kilometers downwind of the plants.

Conventional methods of climate change (CC) mitigation have not ‘bent the curve’ of steadily rising annual anthropic CO2 emissions or atmospheric concentrations of greenhouse gases. This study reviews the present position and likely future of such methods, using the recently published literature with a global context. It particularly looks at how fast they could be implemented, given the limited time available for avoiding catastrophic CC (CCC). This study then critically examines solar geoengineering, an approach often viewed as complementary to conventional mitigation. Next, this review introduces equity considerations and shows how these even further shorten the available time for effective action for CC mitigation. The main findings are as follows. Conventional mitigation approaches would be implemented too slowly to be of much help in avoiding CCC, partly because some suggested technologies are infeasible, while others are either of limited technical potential or, like wind and solar energy, cannot be introduced fast enough. Due to these problems, solar geoengineering is increasingly advocated for as a quick-acting and effective solution. However, it could have serious side effects, and, given that there would be winners and losers at the international level as well as at the more regional level, political opposition may make it very difficult to implement. The conclusion is that global energy consumption itself must be rapidly reduced to avoid catastrophic climate change, which requires strong policy support.

Planet Earth is simultaneously approaching a number of ecological and resource limits. The resulting uncertainties will heavily impact future energy choices, both the level of primary energy used globally and the shares of fossil, renewable and nuclear fuels in the energy mix. This paper reviews the possible futures for the various types of renewable energy. To be viable, all potential energy sources must be assessed on their energy return on energy invested (energy return). Given that renewable energy RE growth is considered important for sustainability reasons, renewable energy must be assessed on its ecologically sustainable or 'green' energy return, which includes the energy costs of ecosystem maintenance as input energy costs. The green energy return is accordingly much lower than the conventional value, so that ecologically sustainable renewable energy is unlikely to deliver anything near existing global energy use. The paper further argues that such constraints on renewable energy growth rates mean it cannot be a timely response to global climate change. The paper concludes that energy reductions will be essential, mainly in high energy use countries.

The drinking water services sector in Uganda is in the early stages of a nationally planned transition; it aims to move from a paradigm based on community managed point sources towards one of professional utilities of piped networks. The implementation of this transition was studied in Western Uganda’s Kabarole District between 2017 and 2019; a systems approach (building blocks) was used to assess the sustainability of the different service models. The level of services was assessed using household and infrastructure surveys; these were supplemented by a management assessment, key informant interviews and stakeholder workshops. The two utility models present in Kabarole outperformed the community management model, with the existing national utility demonstrating greater maturity and performance than the newer Umbrella utility. The community management model, while relatively well defined in policy and planning frameworks, was poorly implemented, with less than 20% of community management structures operational at water points. The water sector is undergoing a process of consolidation of service delivery under a smaller number of larger providers, a trend that has been observed in other countries as they progress towards universal supply. In this paper, the prospects and risks of the current sector trajectory are discussed, as are the implications for monitoring, regulation and planning systems across the urban–rural spectrum.

Energy efficiency is, in principle, a simple idea: an output of human value, for example, vehicle-km traveled, divided by the needed input energy. Efficiency improvements are regarded as an important means of mitigating not only climate change, but also other environmental problems. Despite the vast number of articles published on energy efficiency, a few people question whether it is a useful or accurate measure in its present form; nearly all papers are either engineering studies, or address barriers to efficiency improvements. This review addresses this issue via a critical review of the literature, including not only papers on energy efficiency, but those on adjacent areas of research that can help broaden the scope, both geographically and conceptually. These shortcomings are illustrated in case studies of buildings/cities and road passenger transport. The main findings of this review are that (1) energy efficiency inevitably has an ethical dimension, as well as a technical one, in that feedbacks are more widespread than they have generally considered to be, and (2) that conventional efficiency measures omit important energy input items, particularly those concerned with the mining the materials needed for renewable energy plants. The key conclusions are that present efficiency measures are not adequate, and future research is needed to overcome these shortcomings.

A number of technical solutions have been proposed for tackling global climate change. However, global climate change is not the only serious global environmental challenge we face demanding an urgent response, even though atmospheric CO2 ppm have risen from 354 in 1990 to 416 in 2020. The rise of multiple global environmental challenges makes the search for solutions more difficult, because all technological solutions give rise to some unwanted environmental effects. Further, not only must these various problems be solved in the same short time frame, but they will need to be tackled in a time of rising international tensions, and steady global population increase. This review looks particularly at how all these environmental problems impact the future prospects for renewable energy (RE), given that RE growth must not exacerbate the other equally urgent problems, and must make a major difference in a decade or so. The key finding is that, while the world must shift to RE in the longer run, in the short term what is more important is to improve Earth’s ecological sustainability by the most effective means possible. It is shown that reducing both the global transport task and agricultural production (while still providing an adequate diet for all) can be far more effective than converting the energy used in these sectors to RE.

In 2022, the record of extreme weather events already includes deep droughts in Sichuan province, China, and California, US; floods inundating a third of Pakistan and serious and repeated flooding in Eastern Australia; heat waves and drought in Europe; and wildfires in Europe and the western US [...]

This review explores the question: should the world rely wholly or partially on solar geoengineering (SG) to mitigate climate change (CC), or on renewable energy, together with deep energy reductions? Recent thinking is for SG to only supplement more conventional climate change mitigation methods. However, we first show that conventional mitigation methods are not working., given that global annual CO2 emissions are still rising, so it is far more likely that SG will be called upon to counter most anthropogenic CC, as early research proposed. The paper next examines the various SG proposals that have been considered and their objectives. Future choices could be between an increasingly unpredictable climate, and SG, with its own risks and unknowns, or deep energy reductions and RE. The claim is that SG has far lower costs for a given climate forcing reduction compared with more conventional methods, and equally important, could be quickly implemented, producing temperature reductions in a year or so, compared with decades needed for more conventional mitigation approaches. SG implementation would affect not only the technical potential for key RE sources but also the actual uptake of RE and energy reductions. However, a fair comparison of RE and SG must recognise that the SG option also requires a solution to rising ocean acidification (OA). Because the material quantities needed annually to counter OA are orders of magnitude larger than for SG, its costs and energetic requirements will also be far higher, as will the time for implementation.

Most anthropogenic greenhouse gas emissions are the result of the combustion of fossil fuels. Proposals for mitigating climate change thus include various carbon dioxide removal technologies, replacement of fossil fuels by non-carbon alternatives (renewable and nuclear energy), and reduction in energy use overall by improving energy efficiency. We argue here that deep controversy surrounds the efficacy and likely costs of all these technical fix proposals. Optimistic conclusions are often drawn for these technical solutions partly because many of the analyses do not follow an Earth Systems Science approach. Instead, we argue that in future solutions based on non-technical solutions will need to be a key approach for mitigating climate change in the short time frame we have left.

For many millennia, humans have used biomass for three broad purposes: food for humans and fodder for farm animals; energy; and materials. Food has always been exclusively produced from biomass, and in the year 1800, biomass still accounted for about 95% of all energy. Biomass has also been a major source of materials for construction, implements, clothing, bedding and other uses, but some researchers think that total human uses of biomass will soon reach limits of sustainability. It is thus important to select those biomass uses that will maximise global climate change benefits. With a ‘food first’ policy, it is increasingly recognised that projections of food needs are important for estimating future global bioenergy potential, and that non-food uses of biomass can be increased by both food crop yield improvements and dietary changes. However, few researchers have explicitly included future biomaterials production as a factor in bioenergy potential. Although biomaterials’ share of the materials market has roughly halved over the past quarter-century, we show that per tonne of biomass, biomaterials will usually allow greater greenhouse gas reductions than directly using biomass for bioenergy. particularly since in many cases, biomaterials can be later burnt for energy after their useful life.

Because of the near-term risk of extreme weather events and other adverse consequences from climate change and, at least in the longer term, global fossil fuel depletion, there is worldwide interest in shifting to noncarbon energy sources, especially renewable energy (RE). Because of possible limitations on conventional renewable energy sources, researchers have looked for ways of overcoming these shortcomings by introducing radically new energy technologies. The largest RE source today is bioenergy, while solar energy and wind energy are regarded as having by far the largest technical potential. This paper reviews the literature on proposed new technologies for each of these three RE sources: microalgae for bioenergy, photolysis and airborne wind turbines. The main finding is that their proponents have often underestimated the difficulties they face and the time taken for their introduction on a very large scale.

Controversy exists as to whether renewable energy (RE) can provide for all the world’s energy needs. The purpose of this paper is to help resolve this vital question. Official forecasts see a resumption of a business-as-usual world after the pandemic-induced recession, with further economic growth out to at least 2050. The novel approach taken in this paper is to assume that such a world is fueled entirely with RE at global energy levels at or above those of today, and then to examine whether this scenario is feasible. Because the intermittent primary electricity sources, wind, and solar power, would have to supply nearly all this energy, a simplification made for this analysis is that they do supply 100% of all energy, including non-electrical energy needs. It is found that the energy that could be delivered by these two sources is much less than often assumed, for several reasons: The declining quality of inputs; the need for inclusion of uncounted environmental costs; the need for energy conversion and storage; and the removal of existing fossil fuel energy subsidies. It is concluded that a future world entirely fuelled by RE would necessarily be a lower-energy one.

This paper focuses on urban passenger transport eco-efficiency, which can be defined as the production of maximum benefits to society while minimising environmental impacts from urban transport’s inputs of energy and materials. Researchers have intensively studied transport’s varied environmental impacts, particularly through Life Cycle Assessment; this paper argues that primary transport energy per capita is presently the best measure of impact. Although transport’s societal benefits have generally been regarded as self-evident, access to out-of-home activities, not passenger-km, should be considered as the fundamental useful output of an urban transport system, since transport is a derived demand. We argue that access levels are roughly similar in all high-income OECD cities, so that these cities can be ranked on transport eco-efficiency simply on the basis of per capita primary transport energy.

Over the past decade, a number of Earth System scientists have advocated that we need a new geological epoch, the Anthropocene, to describe the changes to Earth that have occurred since the 1800s. The preceding epoch, the Holocene (the period from the end of Earth's last glaciation about 12 millennia ago), has offered an unusually stable physical environment for human civilisations. In the new Anthropocene epoch, however, we can no longer count on this climate stability which we have long taken for granted. Paradoxically, it is our own actions that are undermining this stability—for the first time in history, human civilisation is now capable of decisively influencing the energy and material flows of our planet. Particularly since the 1950s, under the twin drivers of growth in population and per capita income, we have seen unprecedented growth in oil use and energy use overall, vehicle numbers, air travel and so on. This unprecedented growth has resulted in us heading toward physical thresholds or tipping points in a number of areas, points that once crossed could irreversibly lead to structural change in vital Earth systems such as climate or ecosystems. We may have already passed three limits: climate change; rate of biodiversity loss; and alterations to the global nitrogen and phosphorus cycles. The solutions usually proposed for our predicament are yet more technical fixes, often relying on greater use of the Earth's ecosystems, biomass for bioenergy being one example of this, and one we explore in this paper. We argue that these are unlikely to work, and will merely replace one set of problems by another. We conclude that an important approach for achieving a more sustainable and equitable world is to reorient our future toward satisfying the basic human needs of all humanity, and at the same time minimising both our use of non-renewable resources and pollution of the Earth's soil, air and water.

For millennia, humans relied almost entirely on renewable energy (RE), largely biomass, for their energy needs. Over the past century, fossil fuels (FFs) have not only largely replaced RE, but have enabled a many-fold rise in total energy use. This FF dominance changed the way we think about and accounted for energy use. If (as at present) the world essentially continues to ignore climate change, eventual resource depletion will force conversion to RE and, perhaps, nuclear energy will once again have to provide most of the world’s energy use. However, the change is more likely to come about because of the urgent need for climate change mitigation. At present, primary RE electricity accounting is done by calculating the FF energy that would be needed to produce it. But as FFs disappear, this approach makes less sense. Instead, a new approach to energy accounting will be needed, one that allows for the intermittent nature of the two most abundant RE sources, wind and solar power. Surplus intermittent RE might be converted to H2, further complicating energy accounting. An additional complication will be the treatment of energy reductions, especially from passive solar energy, likely to be more important in the coming decades. This paper is a review of the evidence to try to determine the best approach to future energy accounting.

Given that global energy use today is still dominated by fossil fuels, there is an urgent need to rapidly reduce its use in order to avert serious climate change. However, the alternatives to fossil fuels—renewable and nuclear energy—are more expensive, and have so far done little to displace fossil fuels. Accordingly, reducing energy use must play an important part in both averting climate change and avoiding the depletion of high energy return easily recoverable fossil fuel reserves. This paper examined both the potential and barriers to the adoption of energy reduction measures, with particular attention to domestic energy and passenger transport. The main finding was that energy efficiency approaches alone are unlikely to deliver anywhere near the energy reductions needed in the limited time available. Instead, most energy reductions will have to come from energy conservation, involving less use of energy-using devices, including private vehicles. Achieving such reductions will require changes in lifestyles, especially for residents of OECD nations.

Behind headline successes in providing first-time access to water lie a number of pressing challenges to the dominant approach to rural water supply in developing countries, namely community management following a demand-responsive approach. These challenges manifest themselves in poor performance of service providers, high rates of hardware failure, and very low levels of service. The papers in this special issue argue that tackling these challenges requires a shift in emphasis in rural water supply in developing countries: away from a de-facto focus on the provision of hardware for first-time access towards the proper use of installed hardware as the basis for universal access to rural water services. The outline of the main actions required to achieve this shift are becoming clearer. Chief amongst these are the professionalisation of community management and/or provision of direct support to community service providers; adoption of a wider range of service delivery models than community management alone; and addressing the sustainable financing of all costs with a particular focus on financing capital maintenance (asset management) and direct support costs. This introductory paper provides an overview of these issues and a guide to the other articles, which demonstrate these points.

The influence of 3 MW Hywind-II wind turbine wakes from an upstream offshore floating wind turbine on a downstream turbine with a separation distance of seven rotor diameters was studied for a site in the Gulf of Maine. The turbines and the platforms were subjected to atmospheric boundary layer flows. Various sensitivity studies on fatigue loads with respect to the positions of the downstream turbine were performed and validated with a large-eddy simulation tool. In particular, the effect of various lateral positions of the downstream turbine relative to the upstream turbine were considered using time-series turbine wake data generated from the large-eddy simulation tool which served as an input to an aero-elastic wind turbine model to assess the loads. The load response from the rotor, tower, and the floating platform for the downstream turbine were sensitive to the lateral offset positions where turbines that were partially exposed to upstream turbine wakes yielded significant increases in the cyclic load range. For the given set of lateral positions for the downstream turbine, the largest damage equivalent load occurred when the turbine was one rotor diameter to the left of the centerline, when looking upstream, which is the position of the turbine fully exposed to upstream turbine wake. On the other hand, the fatigue load on the downstream turbine placed on the right side of the position fully exposed to the upstream turbine wake, yielded lower stress due to the non-symmetric shape of the turbine wake. The configuration associated with the largest damage equivalent loads was further investigated in a large-eddy simulation, modeling both the upstream and downstream turbines. It was found that the energy spectra at the blade rotational frequency were a magnitude order higher for the downstream turbine, especially for surge, heave, pitch, and yaw motion of the platform. The increase of the damage equivalent load for the flapwise blade root moment was 45% compared to the upstream turbine, which can potentially reduce the turbine service life time.

Integrated Water Resources Management (IWRM) has often been interpreted and implemented in a way that is only really suited to countries with the most developed water infrastructures and management capacities. While sympathetic to many of the criticisms levelled at the IWRM concept and recognising the often disappointing levels of adoption, this paper and the series of papers it introduces identify some alternative ways forward in a developmental context that place more emphasis on the practical in-finding solutions to water scarcity. A range of lighter, more pragmatic and context-adapted approaches, strategies and entry points are illustrated with examples from projects and initiatives in mainly 'developing' countries. The authors argue that a more service-orientated (WASH, irrigation and ecosystem services), locally rooted and balanced approach to IWRM that better matches contexts and capacities should build on such strategies, in addition to the necessary but long-term policy reforms and river basin institution-building at higher levels. Examples in this set of papers not only show that the 'lighter', more opportunistic and incremental approach has potential as well as limitations but also await wider piloting and adoption.

This paper outlines the development of an approach (and a set of tools) for 'light' integrated water resources management (IWRM): that is, IWRM that is opportunistic, adaptive and incremental in nature and clearly focused on sustainable service delivery. The approach was developed as part of the EC funded EMPOWERS project in three middle-eastern countries: Egypt, Jordan and Palestine. Developed specifically for use at the intermediate and local levels (that is, sub-national and sub-basin) it is based on a facilitated process of stakeholder dialogue for concerted action supported by a strategic planning framework. The paper describes and discusses the justification for the approach, and sets out its main elements as well as experiences gained during its application. The main lesson of the EMPOWERS project is the seemingly simple – in fact, rather complex and time-consuming – work on facilitating dialogue, taking a structured approach to examining problems, collecting and sharing context-specific information, and helping to formulate a shared vision and strategies to achieve it all of which contribute to improved decision making. However, a major limitation to effective action is lack of appropriately decentralised finance, with local authorities reliant on financing from the national level that is often earmarked and over which they had very little control.

Multiple-use services (MUS) have recently gained increased attention as an alternative form of providing rural water services in an integrated manner. This stems from the growing recognition that users anyway tend to use water systems for multiple purposes. This paper aims to characterise this practice on the basis of case evidence collected in eight countries in Africa, Asia and Latin America. The cases show that people almost universally use water for both domestic and productive activities at and around the homestead. Although seldom the main source of people’s income or food production, these activities are of considerable importance for people’s livelihoods. The extent to which people use water for multiple purposes is closely related to the level of access to water expressed in the form of a water ladder in this paper. The case studies presented demonstrate how access is created by different types and combinations of well-known technologies. Additional financial and management measures are required to ensure sustainability of services. Despite the practical feasibility of the MUS approach, it is not yet widely applied by service providers and sector agencies due to observed barriers in institutional uptake. A better characterisation of MUS, alongside a learning-driven stakeholder process was able to overcome some of these barriers and improve the consideration of multiple uses of water in policy and practice.

Lessons from integrated natural resource management (INRM) practiced at different scales are reviewed, with a focus on catchment management. INRM is complex, and many interactions have to be addressed. Consequently, the scale of investigation can restrict the generality and utility of the findings. Examples show that temporal, biophysical, and institutional scales can each be critical. Contexts and dynamics associated with particular scales, and interactions or lateral flows that become important with increasing scale, also pose serious challenges. A conceptual framework is presented for scaling issues in INRM and how to deal with them. To benefit many people over large areas within sensible time frames requires considerable political will, investment, and strategic planning from the outset. Only then will an enabling environment be created to meet a range of preconditions identified in previous studies of integrated catchment management, watershed development, common property management, and devolution. This paper focuses on the links between the organizational/human aspects and the biophysical/technical perspective of various scaling issues. In particular, there is a need to reconcile current top-down and bottom-up approaches, both of which are needed to achieve effective delivery in structured programs beyond the scale of a few villages or isolated success stories. Options for bridging this gap are discussed and recommendations are made for research that might be undertaken. Action research is recommended to enable learning-by-doing, and should focus at two levels: strategic studies to help create the political and institutional landscapes required for scaling-up; and specific studies of gaps in knowledge, in particular, programs that account for scale issues. These suggestions are illustrated using the example of groundwater management via nested scales of interdisciplinary research.