Zambezi River Research Articles

Review of the southern African Leptestheriidae (Branchiopoda: Spinicaudata), II: Diagnoses and key

AbstractWe review and revise the southern African species of Leptestheria Daday, 1913 (Leptestheriidae) based on type specimens when possible as well as on new material. We recognise four species out of the six hitherto reported from the region south of the Kunene, Okavango, and Zambezi rivers. Leptestheria inermis (Barnard, 1929) is shown to be a junior synonym of L. calcarata (Wolf in Daday, 1923), L. striatoconchaBarnard, 1924, and L. rubidgei (Baird, 1862) junior synonyms of L. siliqvaSars, 1898. Leptestheria setosa (Barnard, 1935) is clearly defined with quantifiable diagnostic characters. A key to the species of Leptestheria of southern Africa is presented as an aid to additional surveys and conservation efforts.

Propagation of CMORPH rainfall errors to REW streamflow simulation mismatch in the upper Zambezi Basin

Study regionThis research is carried out in the Kabompo Basin, a headwater catchment of the Zambezi Basin which has an area of 67,261 km2. Kabompo River originates in North-Western Province of Zambia between the Zambezi and Congo River Basins. Study focusThis study focuses on error propagation of the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center-MORPHing (CMORPH) rainfall product on simulated streamflow. Assessments are based on automated multi-objective calibration of the Representative Elementary Watershed (REW) model (2006–2012). Parameters of the model were optimized using the ɛ-NSGAII algorithm. Assessments on error propagation targeted streamflow modelling for hydrograph shape and volume, specific hydrograph characteristics, and water balance composition. New hydrological insights for the regionBy use of multiple objective functions, this study shows that uncorrected CMORPH results in substantial augmentation of rainfall error to streamflow simulation mismatch whereas bias corrected estimates result in attenuation of error. Analysis for water balance composition has great potential to improve application of satellite precipitation products in water management and decision making in the Zambezi basin. This study advises optimization of model parameters for each respective rainfall input data source so to identify outcomes and effects of respective rainfall data sources on the simulated water balance composition and closure.

Modelling Multi-Species Connectivity at the Kafue-Zambezi Interface: Implications for Transboundary Carnivore Conservation

Linking wildlife areas with corridors facilitating species dispersal between core habitats is a key intervention to reduce the deleterious effects of population isolation. Large heterogeneous networks of areas managed for wildlife protection present site- and species-scale complexity underpinning the scope and performance of proposed corridors. In Southern Africa, the Kavango-Zambezi Transfrontier Conservation Area seeks to link Kafue National Park to a cluster of wildlife areas centered in Namibia and Botswana. To assess and identify potential linkages on the Zambian side, we generated a high-resolution land cover map and combined empirical occurrence data for Lions (Panthera leo), Leopards (Panthera pardus) and Spotted Hyena (Crocuta crocuta) to build habitat suitability maps. We then developed four connectivity models to map potential single and multi-species corridors between Kafue and the Zambezi River border with Namibia. Single and multi-species connectivity models selected corridors follow broadly similar pathways narrowing significantly in central-southern areas of the Kafue-Zambezi interface, indicating a potential connectivity bottleneck. Capturing the full extent of human disturbance and barriers to connectivity remains challenging, suggesting increased risk to corridor integrity than modelled here. Notwithstanding model limitations, these data provide important results for land use planners at the Kafue-Zambezi Interface, removing much speculations from existing connectivity narratives. Failure to control human disturbance and secure corridors will leave Kafue National Park, Zambia’s majority component in the Kavango-Zambezi Transfrontier Conservation Area, isolated.

Late Quaternary deep marine sediment records off southern Africa

Abstract High-resolution mapping, sampling and analysis of upper Quaternary southern African continental margin sediments recovered from beyond the Last Glacial Maximum shoreline (>130 m water depth) have expanded our understanding of how marine and terrestrial records are linked over glacial-interglacial climatic cycles. This paper synthesises data currently available from the deep seafloor around southern Africa and, specifically, core sites that demonstrate terrestrial sedimentological connectivity. Several proxies and case studies reveal the evolution of depositional systems, palaeoceanography and palaeoclimate over the last 191 kyr. Hydroacoustic mapping and investigations of submarine canyons have been carried out primarily on the eastern and southwestern margins, while palaeoceanographic productivity and microfossil assemblages have been applied most extensively on the western marine and southern Agulhas Bank. Studies on the western margin indicate that enhanced productivity, less oxygenated bottom waters and reduced marine faunal diversity in the transition to glacial periods, while glacial terminations are associated with reduced productivity and more oxygenated bottom waters. These changes, linked to palaeoceanography and late Quaternary sea-level fluctuations, influence the sedimentary record and sedimentation rates. On the eastern margin, sediment fluxes applied as proxies for rainfall offshore of the Great Kei, Umzimvubu, Limpopo and Zambezi rivers indicate that the southern African climate responds to changes in orbitally-modulated insolation and in particular, to the ~23 kyr precessional cycle, where the proxy records keep pace with this and then diverge at ~80 to 70 kyr. Since the penultimate glacial (Marine Isotope Stage/MIS 6), more humid conditions observed in southern Africa, as the Northern Hemisphere entered phases of rapid cooling, were potentially driven by a combination of warming in the Agulhas Current and shifts of the subtropical anticyclones. Broadly, the sedimentary records reviewed suggest fluctuations in climate and oceanographic circulation that are strongly correlated with the global benthic δ18O record, suggesting sensitivity to high-latitude forcing, and a strong influence of late Quaternary glacial-interglacial cycles despite these marine sites being far-removed from terrestrial environments.

Evaluation of Streamflow under Climate Change in the Zambezi River Basin of Southern Africa

The Zambezi River basin is the fourth largest basin in Africa and the largest in southern Africa, comprising 5% of the total area of the continent. The basin is extremely vulnerable to climate change effects due to its highly variable climate. The purpose of this study was to evaluate the impact of climate change on streamflow in one of the sub-basins, the Kabombo basin. The multi- global climate model projections were used as input to the Soil Water Assessment Tool (SWAT) hydrological model for simulation of streamflow under RCP 4.5 and RCP 8.5 climate scenarios. The model predicted an annual streamflow increase of 85% and 6% for high uncertainty and strong consensus, respectively, under RCP 8.5. The model predicted a slightly reduced annual streamflow of less than 3% under RCP 4.5. The majority of simulations indicated that intra-annual and inter-annual streamflow variability will increase in the future for RCP 8.5 while it will reduce for the RCP 4.5 scenario. The predicted high and moderate rise in streamflow for RCP 8.5 suggests the need for adaptation plans and mitigation strategies. In contrast, the streamflow predicted for RCP 4.5 indicates that there may be a need to review the current management strategies of the water resources in the basin.

Understanding and modelling the effects of wetland on the hydrology and water resources of large African river basins

Wetlands are important components of many large river systems. Some basin scale hydrological models do include explicit sub-models to deal with wetland impacts, but one of the key challenges is to estimate appropriate parameter values to represent the channel-wetland exchange processes. A combined modelling approach is applied in this study and involves the use of the detailed, daily time-step, LISFLOOD-FP hydraulic model to improve the understanding of channel-wetland exchange dynamics and to quantify the wetland parameters of a basin scale hydrological model. While there remain, many uncertainties associated with a lack of sufficient validation data, the LISFLOOD-FP results largely reflect the physical characteristics of the two floodplains (the Luangwa and Barotse in the Zambezi River basin). The LISFLOOD-FP results were also used to estimate the wetland parameters of the basin scale hydrological model with greater confidence and improved the downstream simulations results (albeit marginally). The results suggest that the influence of the floodplain on the monthly Luangwa flow regime is minimal, whereas the Barotse floodplain significantly attenuates the high flows and regulates the low flows of the Upper Zambezi River. The approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins, however, further work is required to refine the model setup using additional field information related to exchange dynamics as well as high quality remote sensing data.

Cahora Bassa Dam & the Delusion of Development

Abstract On December 6, 1974, two pressure-driven steel gates of the Cahora Bassa Dam, each weighing 220 tons, stopped the mighty Zambezi River in its course. After five years of toil by more than five thousand workers, the construction of Mozambique's Cahora Bassa was complete. At the time, it was the fifth-largest dam in the world. The hydroelectric dam was the last megaproject constructed in Africa during the turbulent era of decolonization. Through the voices of peasants and fishermen, displaced by the dam and the workers who built it, this essay analyzes the far-reaching social, political, and ecological consequences of Cahora Bassa. It also explores the devastating impact on riparian life downriver from the dam, which dramatically reduced the annual inundation of the floodplain that supported hundreds of thousands of farmers as well as fish, birds, and mammals.

Infrastructure investments, regional trade agreements and agricultural market integration in Mozambique

Integration of agricultural markets has been a topic of great interest in Mozambique. Numerous studies have been conducted to assess both domestic and regional integration of maize markets in the country, though with some contradictory results. In this study domestic and regional market integration in Mozambique is assessed, focusing on maize markets as the main crop in the country. In contrast to previous work, this study takes into account new investments in infrastructure as well as changes in regional trade policies, using vector autoregressive (VAR) and vector error correction (VEC) models. The main findings suggest that maize markets in Mozambique are not efficiently integrated. This is particularly true between the deficit markets in the South and the surplus markets in the Centre and North of the country. At the regional level, market integration is also inefficient in many cases. Nonetheless, investments in infrastructure, such as the Zambezi River Bridge, linking the north to the rest of the country, as well as changes in trade policies over the years are shown to be significantly impacting to maize price changes, particularly in the north. The overall results suggest there is room for improvements in the maize value chain performance, particularly there is scope for farmers to engage more in trade and for reducing food loss. Action may include investments on training programs and incentives to shift farmers from the current subsistence farming to a more commercial farming system approach.

Implications of Misleading News Reporting on Tourism at the Victoria Falls, Zimbabwe

AbstractThe tourism sector plays a major role in the economic development of a number of countries in the Global South, particularly Southern Africa. One such country is Zimbabwe, which struggles with significant economic hardships and relies heavily on the tourism sector. The Victoria Falls, a key tourism attraction of Zimbabwe on the Zambezi River was the subject of a plethora of news articles published between November 2019 and January 2020. The media suggested that the world’s largest waterfall had dried up due to climate change induced drought. These reports arose during the dry season and were thus arguably ill-founded and downplayed the natural seasonal characteristics of the Zambezi River. This paper presents content analysis of these media articles and the phenomenological qualitative data analysis of interviews conducted with tourism operators in Victoria Falls. Although some of the articles published within this period strived for accurate reporting, some articles claimed that the Victoria Falls was dry, which was inconsistent with experiences of tourism operators. This inaccurate reporting is argued by the tourism operators to have negatively affected the tourism sector and destination image of the key attraction. This paper highlights the need for accurate science-based media reporting on weather, climate, climate change and the knowledge of the local tourism stakeholders within the tourism sector.

Integrated Assessment of Groundwater Potential Using Geospatial Techniques in Southern Africa: A Case Study in the Zambezi River Basin

Groundwater resources are largely used in rural communities of river basins due to their acceptable water quality and reliability for domestic purposes where little or no treatment is required. However, groundwater resources have been affected by changes in land use, mining activities, agricultural practices, industrial effluent, and urbanisation among anthropogenic influences while climate change impacts and volcanic eruptions have affected its involvement among the natural phenomena. The purpose of the study was to assess groundwater potential in the basin with the use of Analytical Hierarchy Process (AHP), remote sensing, GIS techniques, and groundwater occurrence and movement influencing factors. These factors were used to produce seven thematic maps, which were then assigned weights and scale using an AHP tool, based on their degree of influence on groundwater occurrence and movement. A weighted groundwater potential map was produced with four zones denoted as 0.4% (317 km2) for very good potential; 27% (19,170 km2) for good potential; 61% (43,961 km2) for moderate potential and 12% (8639 km2) for poor potential. Validation, using existing boreholes, showed that 89% were overlain on moderate to very good potential zones and henceforth considered to be a novel approach which is useful for groundwater resources assessment and integrated water management in the basin.

Distribution and establishment of the alien Australian redclaw crayfish, Cherax quadricarinatus, in the Zambezi Basin

Abstract Crayfish are invasive polytrophic keystone species, which are phylogenetically unique on the African continent. The Australian redclaw crayfish Cherax quadricarinatus is invasive in southern African freshwater systems including the Zambezi River Basin. Surveys conducted across the Zambezi Basin (Botswana, Zimbabwe, Namibia and Zambia) between 2017 and 2019 showed that C. quadricarinatus is broadly distributed across the Upper and Middle Zambezi and is rapidly spreading through natural and human‐mediated means across several ecoregions. The probability of capture (Pcapture), catch per unit effort (CPUE) and population characteristics of C. quadricarinatus from the recent Barotse floodplain invasion were compared with older invasions from Lake Kariba and Kafue River. The Pcapture and CPUE of C. quadricarinatus in the recently invaded region of the Barotse floodplain were similar to those of the older invasions. Mass and carapace length of C. quadricarinatus from the Barotse floodplain were significantly lower than those of C. quadricarinatus from the older invasions. Sex ratios differed significantly between the three invasive populations. The Barotse floodplain population had a disproportionate investment in females (65.3%) and intersex individuals (8.4%). No crayfish were detected in the Zambezian Headwaters or the Okavango Floodplains ecoregions, but current spread rates are 49 km yr−1 downstream and 12 km yr−1 upstream. Investment in population management and the prevention of spread will have high conservation value across the invaded regions in order to restrict crayfish ecological impacts via direct predation and competition. In areas where crayfish are in high abundance, existing fisheries are affected through damage to nets, leading to increased net abandonment and ghost gear pollution in invaded regions. The emphasis should be on developing cohesive transboundary biosecurity policies in southern Africa to limit further spread that will threaten the integrity of freshwater ecosystems. However, long‐term monitoring is needed to gauge invasion risk to sensitive areas such as the Okavango Floodplains ecoregion and determine field‐based ecological impacts.

How Engineers Think and Implications for Public Interest Technology

Over the recent winter holidays, in a casual conversation with some engineering friends, I brought up the role of engineers in the Cahora Bassa Dam of Mozambique, a project I highlighted at the recent IEEE International Symposium on Technology and Society 2020 (ISTAS20) Conference [1]. During the construction of the dam, local knowledge of drainage and seasonal river patterns were ignored by European and American engineers, which resulted in tragic consequences for both the environment and the welfare of the indigenous villages along the wide and mountainous Zambezi River [2]. In response, one of my (anonymous) friends declared, “Well, that's not the engineer's fault. The engineers were asked to optimize the placement of the dam, so they optimized it. Those consequences are the fault of the manager who scoped out the project!”

Measuring Trade Cost Reductions Through a New Bridge in Mozambique: Who Benefits From Transport Infrastructure?

Abstract We use spatial maize prices in Mozambique to measure transport cost reductions, attribute these reductions to road distance and road quality and assess to what extent producers, traders and consumers benefit. For identification we exploit a unique natural experiment, the construction of a new road bridge over the Zambezi River, which connects the north and south of Mozambique. The applied methodology allows for potentially oligopolistic traders with spatially varying mark-ups. Estimations are based on monthly maize prices, in 22 markets, for 5 years before and after the introduction of the bridge. Estimates of transport cost reductions, averaged over routes, vary from 3% to 7%, with large heterogeneity between routes, and roughly for two-third due to road distance and for one-third due to road quality. On average benefits of trade cost reductions are equally shared between traders and consumers, but for larger distances, a larger part accrues to traders. The evidence also indicates a reduction in prices in destination markets due to the bridge. Results are supported by observed transport cost data, robust for non-random bridge placement and strict source-destination rules.

Forest biomes of Southern Africa

ABSTRACT The forests of South Africa and the neighbouring countries, including Lesotho, eSwatini, Namibia, Botswana, Zimbabwe, and Mozambique (south of the Zambezi River), were mapped and classified according to the global system of biomes. The new four-tier hierarchical biome system suggested in this paper includes zonobiome, global biome, continental biome (all recognised earlier), and regional biome – a novel biome category. The existing spatial coverages of the forests were revised and considerably improved, both in terms of forest-patch coverage and mapping precision. Southern Africa is home to three zonal forest types, namely Subtropical Forests (Zonobiome I), Tropical Dry Forest (TDF; Zonobiome II) and Afrotemperate Forests (Zonobiome X). These three biomes are characterised by unique bioclimatic envelopes. Five, two, and eight regional biomes, respectively, have been recognised within these zonal biomes. Recognition of the Zonobiome I and the global biome Tropical Dry Forests in southern Africa is novel and expands our knowledge of the biome structure of African biotic communities. The system of the azonal regional biomes is also new and comprehensively covers the variability of the azonal helobiomes (riparian woodlands and swamp forests), mangroves, and azonal coastal forests. In total, 11 azonal regional biomes have been recognised in the study area. The forest biomes in southern Africa were captured in our electronic map in the form of more than 60 000 polygons, covering 42 416 km2 (1.27% of the study area). No less than 83% of these forests occur in the territory of southern Mozambique. Abbreviations: for the abbreviation of the biome units, see Table 1; CE: centre of endemism; IOCB: Indian Ocean Coastal Belt; MBSA: the area of the Map of Biomes of Southern Africa; VegMap2006 and VegMap2018: Vegetation Map of South Africa, Lesotho and Swaziland (as released in respective years); for the meaning of the codes of the biome units see Table 1, and for the meaning of the abbreviations of climatic characteristics see Appendix S1

Use of gridded climate data for hydrological modelling in the Zambezi River Basin, Southern Africa

The Zambezi River Basin is among many basins in Southern African region with inadequate, low resolution, poorly maintained and distributed network of hydrometeorological stations. This scenario entails scarcity of hydrological data in the basin and subsequently leads to poor assessment of water resources. This paper investigates alternative technologies in the assessment of the hydrology and water resources in the basin. The high-resolution gridded climate data together with land use and soil data were used as inputs into SWAT model to simulate hydrological processes. Calibration and validation of model were performed using SWAT-CUP. Comparison of average monthly rainfall data for gridded and observed shows 97% correlation. The statistics show NS to be 0.73 while R2 was 0.73. The uncertainty analysis was determined with a P-factor at 0.75 while the R-factor was 0.75. Therefore, use of gridded climate data for hydrological modelling in data scarce regions could be a useful tool to estimate the main hydrological parameters and water resources of an area with satisfactory accuracy.

Climatic Forcing of Plio‐Pleistocene Formation of the Modern Limpopo River, South Africa

AbstractUnderstanding the evolution of river systems in southern Africa is fundamental to constrain the evolution of landscape and sediment dispersal patterns. It is widely considered that the upper Zambezi River was connected with the Limpopo River during the Cretaceous, forming what was then the largest river in Africa. Crustal flexure during the Paleogene severed the upper Zambezi drainage from the Limpopo, setting the framework of the modern Zambezi and Limpopo River systems. We present first evidence—based on heavy‐mineral assemblages from cores drilled offshore of the Limpopo River mouth and samples collected in different reaches of the modern Limpopo River, integrated with magnetic susceptibility, detrital‐zircon geochronology, and geomorphological analysis—suggesting that the current Limpopo River formed recently in the Plio‐Quaternary. Plio‐Quaternary climate change is envisaged to have controlled the recent dynamics of river drainage and consequent distribution of sediment loads, as observed in many other transcontinental rivers worldwide.

The Segmented Zambezi Sedimentary System from Source to Sink: 1. Sand Petrology and Heavy Minerals

The Zambezi River rises at the center of southern Africa, flows across the low-relief Kalahari Plateau, meets Karoo basalt, plunges into Victoria Falls, follows along Karoo rifts, and pierces through Precambrian basement to eventually deliver its load onto the Mozambican passive margin. Reflecting its polyphase evolution, the river is subdivided into segments with different geological and geomorphological character, a subdivision finally fixed by man’s construction of large reservoirs and faithfully testified by sharp changes in sediment composition. Pure quartzose sand recycled from Kalahari desert dunes in the uppermost tract is next progressively enriched in basaltic rock fragments and clinopyroxene. Sediment load is renewed first downstream of Lake Kariba and next downstream of Lake Cahora Bassa, documenting a stepwise decrease in quartz and durable heavy minerals. Composition becomes quartzo-feldspathic in the lower tract, where most sediment is supplied by high-grade basements rejuvenated by the southward propagation of the East African rift. Feldspar abundance in Lower Zambezi sand has no equivalent among big rivers on Earth and far exceeds that in sediments of the northern delta, shelf, and slope, revealing that provenance signals from the upper reaches have ceased to be transmitted across the routing system after closure of the big dams. This high-resolution petrologic study of Zambezi sand allows us to critically reconsider several dogmas, such as the supposed increase of mineralogical “maturity” during long-distance fluvial transport, and forges a key to unlock the rich information stored in sedimentary archives, with the ultimate goal to accurately reconstruct the evolution of this mighty river flowing across changing African landscapes since the late Mesozoic.

The impact of large and small dams on malaria transmission in four basins in Africa

Expansion of various types of water infrastructure is critical to water security in Africa. To date, analysis of adverse disease impacts has focused mainly on large dams. The aim of this study was to examine the effect of both small and large dams on malaria in four river basins in sub-Saharan Africa (i.e., the Limpopo, Omo-Turkana, Volta and Zambezi river basins). The European Commission’s Joint Research Center (JRC) Yearly Water Classification History v1.0 data set was used to identify water bodies in each of the basins. Annual malaria incidence data were obtained from the Malaria Atlas Project (MAP) database for the years 2000, 2005, 2010 and 2015. A total of 4907 small dams and 258 large dams in the four basins, with 14.7million people living close (< 5 km) to their reservoirs in 2015, were analysed. The annual number of malaria cases attributable to dams of either size across the four basins was 0.9–1.7 million depending on the year, of which between 77 and 85% was due to small dams. The majority of these cases occur in areas of stable transmission. Malaria incidence per kilometre of reservoir shoreline varied between years but for small dams was typically 2–7 times greater than that for large dams in the same basin. Between 2000 and 2015, the annual malaria incidence showed a broadly declining trend for both large and small dam reservoirs in areas of stable transmission in all four basins. In conclusion, the malaria impact of dams is far greater than previously recognized. Small and large dams represent hotspots of malaria transmission and, as such, should be a critical focus of future disease control efforts.

The wind-driven response of the Zambezi River plume along the Sofala Bank: A numerical model study

The Zambezi River plume constitutes a sizable feature in the horizontal distribution of both surface salinity and suspended sediments, and it spreads both downstream and upstream, influencing substantially the coastal ecosystems. Here we present the results of several numerical experiments conducted using the Regional Oceanic Modeling System, to investigate the plume’s response to impulsive wind forcing. The model uses realistic geometry and bathymetry, as well as constant discharges emanated from three point sources. Different wind directions and magnitudes were explored, including a daily oscillating wind field. In the absence of wind forcing, a modest discharge generates a plume that propagates northeastwards trapped to the coast. A constant wind field can alter the plume shape to become either a “coastal current” or a “large bulge”, depending on the predominant wind direction. The “coastal current” characterized by a northeastward (downstream) spreading of the plume reaching up to 180 km was directly related to a downwelling favorable winds. While the “large bulge” characterized by an increased upstream penetration is related to upwelling-favorable winds. Diurnal breezes were effective in transforming the trajectories of surface water particles into ellipsoids, as well as promoting additional mixing of the plume and ambient waters. The realistic wind field can transport plume waters to nearly 120 km downstream, 75 km upstream, and 65 km seaward.

Nexus vs. Silo Investment Planning Under Uncertainty

Water, energy, and agricultural infrastructure investments have important inter-relations fulfilling potentially competing objectives. When shaping investment plans, decision makers need to evaluate those interactions and the associated uncertainties. We compare planning infrastructure under uncertainty with an integrated water-energy-food nexus framework and with sector-centered (silo) frameworks. We use WHAT-IF, an open-source hydroeconomic decision support tool with a holistic representation of the power and agriculture sectors. The tool is applied to an illustrative synthetic case and to a complex planning problem in the Zambezi River Basin involving reservoirs, hydropower, irrigation, transmission lines and power plant investments. In the synthetic case, the nexus framework selects investments that generate more synergies across sectors. In sector-centered frameworks, the value of investments that impact multiple sectors (like hydropower, bioenergy, and desalinization) are under- or overestimated. Furthermore, the nexus framework identifies risks related to uncertainties that are not linked to the investments respective sectors. In the Zambezi river case, we find that most investments are mainly sensitive to parameters related to their respective sectors, and that financial parameters like discount rate, capital costs or carbon taxes are driving the feasibility of investments. However, trade-offs between water for irrigation and water for hydropower are important; ignoring trade-offs in silo frameworks increases the irrigation expansion that is perceived as beneficial by 22% compared to a nexus framework that considers irrigation and hydropower jointly. Planning in a nexus framework is expected to be particularly important when projects and uncertainties can considerably affect the current equilibrium.