Part 6: Recommendations

The financial risks associated with continued dependency on hydropower development in the face of climate change are increasingly clear. There is a growing consensus, certainly in Africa, that "despite uncertainties about climate change, we know enough to act" (Walther et al. 2005) Water infrastructure and its management must be considered strategically, over scales and time periods that are relevant to climate change. By building the "wrong" (under- or over-designed) infrastructure in the future, or by not modifying existing structures and operations to reflect emerging climate constraints, we may actually limit our future options for climate adaptation.

Adaptation attempts to reduce the vulnerability of human livelihoods, economies, and natural systems to the impact of climate-induced changes. The United Nations Framework Convention on Climate Change (UNDP 2004) states: "The most effective climate change adaptation approaches for developing countries are those addressing a range of environmental stresses and factors. Strategies and programs that are more likely to succeed need to link with coordinated efforts aimed at poverty alleviation, enhancing food security and water availability, combating land degradation and reducing loss of biolog ical diversity and ecosystem services, as well as improving adaptive capacity."

Reducing the economic risks associated with climate change in hydro-dependent systems must address current as well as planned infrastructure, and must take into account the financial risks associated with hydropower schemes and the broader ecosystem services potential of rivers. We recommend the following actions:

Assess Hydropower In The Context Of Comprehensive Basin-Wide Planning

More than 15,000 MW of hydropower potential exists in the Zambezi River Basin, but development of that potential would come at significant social and economic cost to many water users in the basin and entail substantial financial risk in the face of climate change. Holistic approaches to future developments are essential to ensure the sustainability of the basin. Planners need to carefully consider how climate change will shape the supply of water in terms of future river flows (and shifts in their mean and variability) as well as the demand for power, conservation, domestic use, agriculture, industry and other water services. Basin-wide approaches to hydropower and land-use planning are increasingly adopted by decision-makers in other major river basins of the world, notably including the Mekong (King et al. 2007, ICEM 2010).

Comprehensive basin-wide planning must consider a full accounting of the values of ecosystem services supported by river flows. Community- and ecosystem-based adaptation approaches that integrate the use of biodiversity and ecosystem services into an overall strategy aimed at empowering people to adapt to climate change must be central to any comprehensive planning efforts (Girot et al. 2012). When these values are fully considered and integrated along with all other management objectives, the prospects for optimizing both dam- and ecosystem-related objectives are greatly enhanced (Krchnak et al. 2009).

Incorporate Climate Change Scenarios into Hydropower Design and Operation

The major implication of climate change for dams and reservoirs is that the future is uncertain, and can no longer be assumed to mirror the past. Until now, the design and operation of hydropower dams have been based on the best historic river discharge data obtainable. For the Zambezi River Basin, a substantial time series of monthly flow data is available dating back to 1907. These flow data provide a useful picture of the natural variability of river flows over the past century, including several cycles of wet and dry periods. These data are unreliable, however, for predicting the variance of future flows under climate change, including fundamental design criteria such as mean annual runoff and maximum probable floods. Milly et al. (2008) argue that stationarity – the idea that hydrological systems fluctuate within an unchanging envelope of variability, a foundational concept that permeates training and practice in water-resource engineering – is no longer valid, and should not serve as a central assumption in water-resource risk-assessment and planning. Hallegatte (2009) notes that new infrastructure not only will have to be able to cope with new climate states, but also a large range of changing climate conditions over time, which will make design more difficult and construction more expensive.

The reality of climate change demands more adaptive, flexible water management, which includes the use of both moderate and strong climate change scenarios for estimating future dam safety and reservoir reliability for individual and cascades of dams. The risk assessment must include the safety and operation of cascades of dams, given the heightened potential for catastrophic failure of structures under new climate realities. Uncertainty in future climate makes it impossible to directly use the output of a single climate model as an input for infrastructure design, and the needed climate information will not be available soon (Hallegatte 2009). New models must be developed to incorporate climatic uncertainty into dam design and management, combining historical records of past flow volumes and periodicities (often insufficiently known, due to poor historic records) with projections of multiple climate models using stochastic (probabilistic) elements, driven by multiple climate-forcing scenarios. Research is needed into statistical techniques for separating climate-change impacts from natural variability; improvements in regional climate models, with a stronger focus on prediction in the short- to medium-term, and the inclusion of land-use and ecosystem expertise in the prediction of hydrological impacts on hydropower and reservoirs (Harrington et al. 2007). The information base for developing these models is likely to change rapidly as climate science advances during the coming decades, and will require innovative training of hydrologists, engineers, and managers (Milly et al. 2008).

Projects should be approached with extreme caution. New developments should be subject to substantial analysis of the hydrological and financial risks, performed by expert teams including hydrologists, energy economists and climate-change scientists. As an example, HydroTasmania is already downrating their power production due to climate change.1

Hallegatte (2009) provided a useful decision-making framework for adapting uncertainty-management methods to hydropower development:

  • Selecting ''no-regret'' strategies that yield benefits even in absence of climate change;
  • Favoring reversible and flexible options;
  • Buying ''safety margins'' in new investments;
  • Promoting soft-path adaptation strategies;
  • Reducing decision time horizons and projected lifetime of investments.

Diversify the Regional Power Pool to Reduce Hydropower Dependency

Climate change adaptation requires diversified investments to "avoid putting all eggs into one basket" in a time of increasing hydrological uncertainty (Goodland 2011). The Southern African Power Pool (SAPP) was created to provide a reliable and economical electricity supply to power consumers across Southern Africa, and provides an excellent framework for diversifying power production in Southern Africa and reducing dependency on hydropower.2 The SAPP vision includes ensuring sustainable energy development through sound economic, environmental and social practices, as part of a competitive electricity market for the Southern African region. In practice, however, the SAPP has emphasized large-scale coal and hydropower development to feed the regional grid, without serious consideration of climate change impacts (Hankins 2009).

SAPP can play a key leadership role in adapting the regional power grid to the realities of climate change and water scarcity by promoting decentralized energy technologies, energy efficiency standards, demand-side management, and feed-in tariff pricing to encourage the adoption of renewable technologies. Region-wide funds are needed to develop renewable energy projects that benefit SAPP. Many SAPP countries have a huge untapped potential for solar, wind, geothermal, and other renewable energy technologies that are well-suited for both urban and rural energy development. In failing to integrate these technologies with the regional grid, Southern Africa is missing out on critical global developments in new clean sources of energy that could benefit its population; create new industry, jobs and capacities, and bring clean power to the region (Hankins 2009).

Improve Existing Hydropower Capacity Rather than Investing in New Infrastructure

Existing hydropower structures should be rehabilitated, refurbished, renovated, or upgraded prior to the construction of new hydropower facilities. Adding new turbines or replacing old turbines with more efficient or bigger ones is almost always much lower impact than building new dams. Pumped-storage hydropower is one promising alternative, using off-peak electric power to pump water from a lower elevation downstream reservoir to a higher elevation upstream reservoir for energy production during peak demand (Miller and Winters 2009). In addition, hydropower can be added to existing water supply dams and water piping systems (known as no-dam or "unconventional hydro"). For example, Andritz Hydro has estimated that South Africa alone has 63 MW of unconventional hydropower potential in its irrigation canals and industrial water-conveyance systems.3

In the Zambezi Basin, Kariba Dam was recently upgraded to increase generation capacity without further impact, and plans are underway for upgrades to Cahora Bassa Dam and new generation capacity at Itezhi-Tezhi. Increased spillway capacity at Cahora Bassa Dam to enable passage of the maximum probable flood likewise would enable increased power generation by eliminating the need to dump excess reservoir waters during the dry season according to the design-flood rule curve (Beilfuss 2010).

These and other rehabilitation measures should be considered before new dams are contemplated, just as investments in energy conservation and demand management should be prioritized before new generation is permitted. New legislation limiting the licensing time-period for new and existing hydropower dams also may serve as a tool for encouraging rehabilitation, allowing for regular reviews of safety and risk of failure as well as socioeconomic and environmental impacts (Pittock and Hartmann 2011).

Prioritize Investments that Increase Climate Resilience

An estimated 60 to 120 million people in Southern Africa face water stress in the next 50 years due to climate variability and governance issues (Arnell 2006). Climate models warn about the impact of changing rainfall and runoff patterns on grain yields, water availability, and the survival of plant and animal species that are expected to shift production seasons, alter productivity, and modify the set of feasible crops. A large part of the population is engaged in subsistence agriculture on marginal lands that are particularly vulnerable to the adverse effects of climate change (Ndaruzaniye et al. 2010). By the 2080s, a significant decrease in suitable rainfed land for agriculture is estimated due to climate change (Boko et al. 2007). Wheat production is likely to disappear from Southern Africa, and notable reductions in maize production are expected (Fischer et al. 2005; Stige et al. 2006).

In this context, it is essential that future investments in the Zambezi River Basin increase the resiliency of agriculture and water sectors to climate change. Ye t large hydropower dams threaten to decrease, rather than enhance, climate resilience – especially for the rural poor. There often are inherent incompatibilities between generation of electricity and provision of water supply during the dry season, when water is scarce but most needed. When dam operators must choose one over the other, electricity generation almost always supersedes water supply (Harrison et al. 2007). Hydropower dams diminish or eliminate the annual flood pulse downstream, reducing the productivity and extent of floodplain and riverbank agricultural systems, an important alternative to drought-prone rainfed cropping practices (Scudder 1989). Evaporative water loss from large reservoirs further decreases water availability for downstream use.

Integrated river basin development investments should be prioritized to enhance climate resilience by helping poor and vulnerable communities prepare for, withstand, and recover from the negative effects of climate change (African Development Bank et al. 2003). While more water storage will be needed (World Bank 2006), decentralized solutions that preserve river-based ecosystem services are better suited to the needs of the rural majority, who face the greatest adaptation challenges. Resilience strategies should be an integral part of research, development, planning, training, capacity building, and implementation in Zambezi Basin countries.

Implement Environmental Flows for Climate Resilience

Environmental flows are an important tool for restoring river systems and the goods and services they provide (Arthington et al., 1992; Acreman, 1996; Postel and Richter, 2003; King and Brown, 2006). Environmental flows describes the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems. Maintaining and strengthening the delivery of ecosystem goods and services is an important aspect of adaptation to climate change (Bergkamp et al. 2003; Le Quesne et al. 2010). Environmental flow requirements will be critical to help communities living downstream of dams adapt to a changing climate, and therefore should be incorporated into existing hydropower operations, as well as future infrastructure planning and design. Two recent World Bank documents provide recommendations for integrating environmental flows into hydropower dam planning, design, and operations (Krchnak et al. 2009), and support improved protection of environmental flows across projects, plans, and policies (Hirji and Davis 2009).

Reoperation of existing infrastructure to realize environmental flows may include redistributing the spillage of excessive reservoir waters to better mimic seasonal fluctuations, or setting specific targets for outflows to meet stakeholder-defined goals for ecological, social, or economic outcomes. For cascades of dams, dam operators and water managers should investigate opportunities to re-regulate flows by capturing flows in the lowest dam of the cascade and then releasing flows to mimic natural patterns. Opportunities for integrating groundwater storage with dam storage should also be investigated. Releases may be timed to coincide with periods when downstream tributaries are contributing peak flows, or "piggy-backing" water releases with water diversions for human use, to increase opportunities for overbank flow to reach floodplains and wetlands. Conversely, environmental flow strategies may target dry-season releases to enhance water security.

Future structures should be designed to ensure compatibility with environmental flow releases, including adequate outflow capacity to realize a range of target outflows; multi-level intakes to allow for water releases corresponding to a range of reservoir storage levels, to improve downstream water quality; and designing dams that enable movement of fish and other organisms and sediments around dam walls. Where possible, existing dams should be retrofitted to achieve these outcomes.

Within the Zambezi River Basin, environmental flows were first considered in the Kafue River as early as the 1960s. Itezhi-Tezhi Dam was designed to generate a flood of 300 m3/s during a four-week period in March for the maintenance of agricultural and biological productivity in the Kafue Flats (Scudder and Acreman 1996). Although the additional reservoir storage capacity increased project costs by 15%, the Ministry of Power, Transport, and Communication agreed to the plan because of the importance of the annual floods for aquifer recharge, alluvial deposition, flood recession agriculture, livestock grazing, and floodplain fisheries (Handlos and Williams 1985). The World Wide Fund for Nature (WWF) is now working with dam operators to further modify these releases to improve the timing of outflows to better restore ecosystem services downstream (Schelle and Pittock 2005).

The importance of environmental flows for restoring the Lower Zambezi Basin below Cahora Bassa Dam was first proposed to the Government of Mozambique by consultants SWECO (1983). SWECO recommended an environmental flow release (freshet) from Cahora Bassa to coincide with high flows from downstream tributaries, aimed at reducing the impact of soil salinization on natural vegetation, improving agricultural productivity and the carrying capacity of grasslands, expanding floodplain waterbodies, and reducing the growth of invasive aquatic macrophytes in river channels. In 1997, under the auspices of the Zambezi Valley Planning Authority, the operators of Cahora Bassa Dam hosted a workshop on the Sustainable Management of Cahora Bassa Dam and the Zambezi Valley (Beilfuss 1997). More than 50 participants from government agencies, academic institutions, and development NGOs concluded that environmental flow releases from Cahora Bassa Dam were necessary to restore human livelihoods and ecosystems downstream (Davies 1998).

Most recently, SADC (SWRSD 2010) recognized six objectives that can be addressed through environmental flow management in the Zambezi River Basin in addition to hydropower objectives:

  • Dam Safety: Managing releases to avoid the reservoir reaching unsafe levels. Provide adequate capacity to safely store and pass the design flood;
  • Flood management: Avoiding loss of life and reducing socio-economic impact;
  • Environmental management: Providing quantity and quality of water required to maintain ecosystems and enable them to provide sustainable services and good quality water;
  • Dry season floodplain agriculture: Accommodating the harvest period in release management;
  • Plantation irrigation: Providing adequate yield for crop production, and
  • Water supply: Setting priorities based on economic or social considerations, including poverty alleviation.

Simulation modeling of the Zambezi system dam operation (Beilfuss 2010) indicates that modest environmental flow releases from Cahora Bassa Dam can be realized without a significant reduction in hydropower production, by revising the operational rule curve to redirect the spillage of excess reservoir waters from the dry season to early wet season. Beilfuss and Brown (2010) demonstrate that the majority of Lower Zambezi water users would benefit from annual flood releases, that the trade-offs among different water users is minimal in terms of the timing, magnitude, or duration of releases, and that the economic value of releases to downstream users exceeds the value of waters used solely for hydropower production.

In practice, dams of the Zambezi basin have been operated fairly independently, without regard to economic requirements of other stakeholders in the basin. Dam operations have focused primarily on dam safety and maximizing hydropower production on a one-year operating window. New modes of operation which consider multiple-objective environmental flows over a multi-year operating window should be considered for the Zambezi River system.

A unique partnership between the Zambezi River water authorities, dam operators, and power companies, NGOs (the World Wide Fund for Nature, International Crane Foundation), and regional universities is uniquely positioned to build on these findings and implement environmental flows in the Zambezi River Basin. The partnership seeks to incorporate environmental flows into the operating rules of hydropower dams in the Zambezi Rver Basin, and ensure that essential freshwater resource areas in the Zambezi Rver Basin are well protected and properly managed. This partnership could play a vital role in facilitating climate change adaption for vulnerable Zambezi Basin communities, and illustrates the potential for environmental flows to overcome conflict in shared water resources and create opportunities for cooperation.

Ensure that Monitoring and Evaluation Systems Support Adaptive Management

Climate-change adaptation requires adoption of an iterative, risk-based approach to water management (Le Quesne et al. 2010). Monitoring and evaluation systems are an essential element of this strategy. The monitoring and evaluation system should help society understand clearly whether current water management practices are delivering on their "promised" outcomes, and enable decision-makers to apply any lessons learned to improve present and future management. Monitoring is critical to building trust and confidence among riparian states, and it is absolutely necessary for developing and implementing water allocation plans.

A system for information collection and sharing in the Zambezi Rver Basin would serve to:

  • Increase our understanding of the impacts of climate change, and help develop and implement climate change adaptation and mitigation measures;
  • Foster more efficient and effective use of the basin's water resources;
  • Allow for diversification in the use of water resources, including adding agricultural and environmental uses that are not currently factored into water allocations;
  • Support the implementation of environmental flows;
  • Increase scientific understanding of the distribution of water resources in the basin over time;
  • Make it possible for dam operations and other water management decision-making to be based on realtime, basin-scale hydrological and ecological data;
  • Enable a more complete accounting of ecosystem services and their value to society.

Monitoring and evaluation systems are most effective and informative when designed to answer clear, focused management questions (Cottingham et al. 2005). The monitoring system should be based on specific hydrological, socio-economic, and ecological indicators that will respond to water flows in a clearly discernible manner that reveals the direction of the response (e.g. increased or decreased abundance of biota or productivity) and the level of the effect (i.e., the strength of the response to flow conditions). Careful monitoring of these indicators contributes to three important actions:

  • Quantifying the benefits and costs of different water management alternatives, for dissemination to decision-makers and stakeholders;
  • Applying the monitoring results to improve the management of flows through an adaptive-management framework; and
  • Evaluating and improving the monitoring system over time.

These indicators also serve as early-warning indicators of climate-change-related shifts in important traits in systems, as adaptive management requires constant attention to new signals that conditions are changing.

Rethink Flood Management Strategies

Many hydropower projects, including Kariba and Cahora Bassa dams, are justified on the basis of providing flood control in addition to energy generation. However, providing flood control storage means the reservoir must be drawn down to provide flood capture space (according to design flood rule curves) at the very time the capacity is most needed to supply the regional energy demand. This is a direct compromise in the hydropower benefits being sought, in terms of energy production and revenue (Harrison et al. 2007). These economic and ecological conflicts suggest that alternative operating scenarios for existing dams and better approaches to flood management should be considered. Because summer (wet season) high flows and seasonal high energy demand occur simultaneously, a modified "run-of-river" (full reservoir) operation could be adopted to provide more natural flow patterns downstream of the dams and maximize water levels (hydraulic head) for energy generation.

Re-envisioning Zambezi dams for run-of-river operation near reservoir storage capacity would require a reduction in flood storage space in the reservoir. Natural or enhanced floodplain storage in the river basin could provide an important alternative to lost reservoir storage capacity. As described in Part 2, the Zambezi River Basin is characterized by numerous large floodplain systems with exceptional water-holding capacity, including the Barotse and Chobe floodplains upstream of Kariba Dam, the Lukanga Swamps above Itezhi-Tezhi Dam, and the Kafue Flats upstream of Upper Kafue Gorge Dam, as well as the Zambezi Delta below Cahora Bassa Dam. Harrison et al. (2007) suggest that the differential hydropower revenue gained from run-of-river operation could be utilized for restoring flood storage capacity and insuring against flood risks in the floodplain. A portion of the consequent higher hydropower revenues could be dedicated to reducing flood risks in the floodplain or to restoring river-floodplain connectivity to enhance the conveyance of floodwaters to floodplain systems (Opperman et al. 2009). Agencies responsible for flood control could identify opportunities for securing or rehabilitating floodplains, including the purchase of floodplain easements. Revenues also could be allocated for improved flood forecasting capacity, enforcement of existing floodplain settlement policies, and effective and well-tested flood warning systems.

Allocate Hydropower Revenues to Restore Ecosystem Services

Many dams are designed and financed on the basis of "multipurpose" operation, suggesting that in addition to generation of electricity, other benefits such as flood control, water supply, fisheries, navigation, irrigation, and other downstream benefits are operational priorities. In most cases, however, these other purposes are subsidiary to power generation, which earns the most revenue – and there is rarely a full accounting of the values of ecosystem services. The regulation of rivers for strict hydropower generation, in turn, is associated with adverse impacts to river systems and the ecosystem services they provide.

New financial mechanisms are needed to reallocate revenue from hydropower sales to directly compensate downstream water uses that are negatively affected by dam operations, and to restore ecosystem services. In the Lower Zambezi River Basin, the economic impact of river regulation by Cahora Bassa Dam has been estimated for freshwater and estuarine (prawn) fisheries, agriculture, livestock, water supply, tourism, and other concerns. Investments of hydropower revenues in these sectors would encourage ecologically sustainable livelihood activities and diversification of flow-related livelihoods and income streams. These investments also would counter regional inequities in the distribution of electricity supply – the majority of the power generated by Cahora Bassa Dam, for example, is exported to South Africa rather than serving local demand. At a basin level, hydropower revenue could be used to reduce pressures on river systems, including removal of exotic invasive species and negative impacts from land-use changes such as clear-cutting riparian forests, which directly threaten the long-term viability of hydropower schemes.

Ensure Best Social and Environmental Practices

Dams in the Zambezi Basin are being planned under a variety of standards, with very little public input, and with very little if any attention to the broad social and environmental impacts these projects bring. Given the importance of well-functioning river systems to climate adaptation efforts in Africa, standards must be improved to minimize these risks and properly evaluate all alternatives. These standards should mandate that a meaningful proportion of stakeholders are fully consulted with ample opportunity to debate controversial decisions (Bosshard 2010).

The World Commission on Dams (WCD 2000) provides best-practice guidelines for hydropower selection, planning, construction, and monitoring that are highly relevant for climate change adaptation. The WCD recommendations are based on a set of five core values for future decision-making – equity, efficiency, participation, sustainability and accountability. The WCD emphasizes a "rights and risks" approach for identifying stakeholders in negotiating development choices and agreements. Seven strategic priorities are identified for water and energy resources development, which include: gaining public acceptance; assessing all options; addressing existing dams before new dams are constructed; sustaining rivers and livelihoods through their ecosystem services; recognizing entitlements and sharing benefits; ensuring compliance based on a set of clear criteria; and sharing transboundary rivers for peace, development, and security. The WCD recommends 26 guidelines for review and approval of projects during five stages of decision-making. Best practice measures should be incorporated throughout the Environmental and Social Impact Assessment (ESIA) process – beginning with adequate pre-project demographic, environmental, health, and socio-economic baseline surveys, and continuing throughout construction, operations, and decommissioning (Goodland 2011).

Another tool that is being promoted by the dam industry, the Hydropower Sustainability Assessment Protocol (IHA 2010), provides a sustainability assessment framework for hydropower development and operation. The IHA protocols include an Early Stage tool for risk assessment and discussion prior to detailed planning, and Preparation, Implementation, and Operation tools that use a graded spectrum of practice calibrated against reference conditions for basic good practice and proven best practice. The IHA protocols were developed to serve as a certification standard for hydropower projects, but the protocols are voluntary and do not define any minimal requirements of sustainability or a bottom-line of acceptability for hydropower projects (Bosshard 2010). Both the IHA protocols and the WCD guidelines must be mandated in a more rigorous regulatory context to ensure best practice going forward.

Develop Strong Institutional Capacity for Water Resources Management

The development of strong institutional capacity may be the single most important factor in the successful adaptation of existing hydropower systems to cope with climate change. Significant technical, financial, and social capacity is required, at different scales, from strong and well-governed national water ministries and river basin operators, through regional departments and basin councils, to local river basin offices and water user associations (Matthews and Le Quesne 2009). As new risks and uncertainties arise with climate change, a water resources management style is needed that is flexible enough to adjust to ongoing change (Bergkamp et al. 2003). Those responsible for hydropower management at all levels must be trained in new modes for dam operation and equipped with models and tools for implementation, including flood forecasting systems, routing models, conjunctive management systems, and monitoring and adaptive management protocols. Substantial investment in water management institutions is essential to facilitate new perspectives and proficiencies. For example, climate-change adaptation in Rwanda includes a series of training and technical assistance activities with hydropower operators and managers to improve operation and maintenance of the stations, and with decision-makers in the Ministry of Infrastructure to facilitate the integration of climate change considerations into the management of Rwanda's hydroelectric sector.4 Training opportunities for water resource managers, authorities, and users in the Zambezi River Basin may be provided through innovations in curricula at training facilities that already service hydropower professionals, such as the International Centre for Hydropower, the Global Water Partnership, and UNESCO's Institute for Water Education.