Climate Risk and Risk Treatment

As climate change will likely result in changes to the timing, frequency, intensity, and/or duration of a range of conditions like severe storms, floods, droughts, sea level rise, and storm surge impacts on water infrastructure are anticipated that directly damage water infrastructure, affect operating and maintenance needs, impacting dam safety, negatively impact service levels, and/or reduce the service life of assets. For example, in dry climates, less hydropower than planned is produced, and the difference needs to be balanced by more expensive power sources, such as diesel generators. Climate change can have large effects on expenditure for agricultural imports. In dry scenarios, irrigation underperforms compared with the no-climate-change scenario, and countries will need to make up for the deficit in food and energy production.

The Fifth IPCC assessment report (Climate Change, 2014) introduced a concept for understanding risk of impacts from climate change. Accordingly, the IPCC defines risk as the potential for impacts where something of value, such as water infrastructure, is at stake. In the context of water infrastructure climate risk can be defined as:

“The probability of experienced or future reduction and loss of service reliability, loss and damage to the structural integrity, as well as loss of human lives and their assets in the context of climate change”.

Box 1: Main causes of dam failure rooted in patterns of vulnerability

The failure of dams as a consequence of climate change can have extreme consequences depending on the size, location and type of the dam. Dam failures can be associated with the following topics:

• First impoundment: 38% of all dam failures occurred during the initial filling of a reservoir
• Main reasons of dam failure for concrete dams are internal erosion of foundation and lack of resistance to sliding
• Main reasons for dam failure of earthen dams are piping and base failure
• The cause of failure related to spillways is due to insufficient spillway capacity (22%)
• Dam failure mostly happen as a series of incidences creating a failure path. Two examples of failure paths:
• Debris blocks part of the spillway ® water level rise beyond dam crest ® overtopping of the dam ® erosion of the downstream dam side ® dam failure
• Earthquake ® landslide into the reservoir ® overtopping of the dam ® erosion of the downstream dam side ® failure

Figure 4 Overview of reasons for dam failure

The description of impacts can relate to the following five (5) impact dimensions:

Project feasibility

• Climate changes can impact the revenue streams of investments.
• The worst-case scenario for production is when there is a reduction in inflow.
• Flood risk can also be a problem with increasing runoff.
• Increases in run-off can be good if there is capacity in the system to exploit them.
• Changes in the timing or in flow-duration curves (regardless of changes in the average amount of water) can require modifications to operation strategies. e.g., for reservoirs to deal with the changes in energy generation and new environmental threats.
• The uncertainty caused by potential climate change can affect the perceptions of risk by investors thus increasing the cost of financing. This may lead to electricity and water supply constraints.
• In areas with significant increases in precipitation and therefore run-off, the risk of flooding will increase, and the safety of dams may require re-examination to cater for the changing flood characteristics.

Flood and sediment transport characteristics

• In areas with significant increases in precipitation and therefore run-off, the risk of flooding will increase, and the safety of dams may require re-examination to cater for the changing flood characteristics.
• The increase in flood values is a threat to structures that are dimensioned for lower floods.
• An assessment of the impact of changed floods is useful to determine the extent of modifications necessary to protect existing and future infrastructure.
• Sediment yield and transport characteristics may also be affected in areas that are prone to erosion.
• Reservoir storage capacity can be reduced by increasing sediment yield and the number of operations for removal of sediments may need to be increased and the technology for sediment removal may require adaption to meet the new challenges.

Socio-economic and environmental outcomes

• Minimum environmental flows that can no longer be sustained or that are sustained at a high cost to electricity generation, water supply and the environment
• Increased flood flows that affect downstream or upstream settlements and infrastructure
• Changing Land cover that may influence the rainfall-run-off relationships of catchments
• Conflict with competing water uses

Operations

• Changes in the timing or in flow-duration curves (regardless of changes in the average amount of water) can require modifications to operation strategies. e.g., for reservoirs to deal with the changes in energy generation and new environmental threats.
• Sediment yield and transport characteristics may also be affected in areas that are prone to erosion.
• Through changes in flood and sediment transport characteristics reservoir storage capacity can be reduced by increasing sediment yield and the number of operations for removal of sediments may need to be increased and the technology for sediment removal may require adaption to meet the new challenges.

Based on the IPCC (2022), the risk of climate-related impacts on water infrastructure is rooted in several dimensions explored in this chapter, including:

• evolving climate-related hazards (including hazardous events and trends),
• the exposure of water infrastructure to these climate related hazards, as well as
• the vulnerability of exposed water infrastructure to suffer loss and damage

For infrastructure systems the causal structure of risk of loss & damage can be analysed based on the following risk causality-framework. For identifying adaptation options understanding the causal structure of risk and their root causes is essential

Figure 5 Causality of climate risk - Framework for climate risk of infrastructure (Adapted from Baumert, 2016)

Risk of loss & damage of infrastructure systems are attributed to:

1. Climate change, and its impacts on the bio-physical environment as a driver of risk on which infrastructures depend on. Climatic Change & bio-physical impacts is defined as the potential occurrence of a natural or human-induced physical event or trend or physical impact that may cause loss & damage. The term hazard usually refers to climate-related physical events or trends or their physical impacts. Extreme events can also be triggered by the lack of capacity of environmental services mitigating hazard magnitudes (e.g., up-stream deforestation increasing risk of extreme flood events posed by climate change).
2. Exposure as a driver of risk. Exposure is defined as the presence of infrastructures and its components, people, livelihoods, species or ecosystems, environmental functions, services, and resources, or economic, social, or cultural assets in places and settings that could be adversely affected by climate related hazards. Exposure is rooted in:

• The lack of exposure avoidance: anticipatory risk zoning for new investments (prohibit construction, or conditional construction), and
• The lack of exposure reduction through adequately governing retreat in cases where increasing resilience on the spot is no option anymore, or neglection of analysis revealing that the type of investment is economically not viable under climate change conditions.

3. Vulnerability as a driver of risk. Vulnerability refers to the propensity or predisposition to be adversely affected. Vulnerability encompasses a variety of concepts and elements including sensitivity or susceptibility to harm and lack of capacity to cope and adapt (IPCC Glossary, 2014, p.128). Often vulnerability is also viewed as the result of “unmanaged risk”. Therefore, vulnerability can be considered as being rooted sensitivity conditions as systems lack capacity for reducing the sensitivity and increasing the adaptive capacity of the infrastructure system. A more detailed definition of entry points for understanding drivers of vulnerability are:

• The lack of capacity for anticipating current and future risks and vulnerabilities in pursuit of reducing exposure, sensitivity and increasing adaptive capacity of the water infrastructure.
• The lack of the infrastructure systems to be adequately protected to specified climate events (e.g., degraded upstream ecosystems acting as flood buffers, inadequate spillway design, inexistence of bypassing channels, cooling of energy systems against heat stress, protection gear for staff, inadequate protection from natural hazards (e.g., landslides, erosion into the reservoir)
• The lack of water infrastructure systems to be adequately physically and operationally robust to specified climate events regarding its physical structure and functionality (sediment operations, inadequate dam materials, internal erosion of foundation, lack of resistance to sliding, piping and base failure, uncontrolled seepage, inappropriate initial filling of the storage dams)
• The lack of systems to perform adequate business continuity management to specified climate events, including:  
  • The lack of performing disaster management (Preparedness, early warning systems and response, relief contingencies and operations)
  • The lack of provision or existing redundant systems to maintain function in times of crises
  • The lack of recovery & reconstruction contingencies and operations in the course and aftermath of climate related physical extreme events

In Engineering vulnerability concepts, vulnerability can be conceptualized through “impact thresholds”. A vulnerability exists when the asset can reasonably experience loads in excess of its capacity, depending on the degree of robustness, protectiveness and capacity to provide residual risk management. In vulnerability assessment, the point where climate load exceeds capacity is called the Threshold Value.

Box 2: Impact thresholds as an indicator of vulnerability to a specific stressor

Climate change impacts on infrastructure are associated with the exceedance of different threshold values. An impact threshold defines critical climate conditions at which a system of interest in sensitive to and hence damages and losses are likely to occur. Hence, its definition and calculated value is based on the system of interest’s characteristics to experience harm. The definition of impact thresholds is key for climate risk assessment and requires the inclusion of end-users for developing climate service products. 

Thresholds can include include

• Project Goals such as expected demand, supply of the services being provided.
• Technical thresholds for safety of structures such as Design floods, design loads and design temperatures.
• Financial thresholds such as Net present value (NPV) or Internal rate of return (EIRR)
• Social and environmental indicators such as minimum downstream flow requirements

Example - Design Flood as a performance metric

An example of a performance metric is the design flood for a project. A dam may for example be designed for a T=1000-year flood (Q1000) based on its consequence class (i.e., Qdim =QT). The consequence class is usually based on safety considerations in case of a dam break. This is usually decided based on analysis of historical flood data, reservoir size, dam break analysis, potential damages, and loss of life in case of a dam break. 

Next to the need to identify threshold values as an indicator of vulnerability understanding drivers of the way thresholds are being configured is important. Especially with existing infrastructure that had been build it is necessary to understanding more in-depth the root causes of risk, often embedded in unfavorable societal, political, regulative, economic, and environmental framework conditions and contexts in which infrastructures investments are carried out or infrastructure systems are operating.

Risk treatment is specifically needed in areas where the risk assessment identified the greatest weaknesses. The following image sets out the major entry points for possible risk treatment interventions. Overall, reducing risks can be achieved via reducing vulnerabilities or reducing exposure to climate hazards, to pool or share risks where they exist, and to manage residual risks and uncertainties such as via emergency preparedness or increasing capacity to cope with disruptions.

Figure 6: Climate risk and entry points for defining risk management options

Hazard magnitude reduction:

• Investments into low carbon development
• Ecosystem service rehabilitation and Ecosystem based adaptation to new climate conditions

Exposure reduction:

• Restrict or avoid infrastructure systems located at hazardous locations
• Reduce existing exposure through abandon infrastructures in the high-risk areas

Vulnerability reduction:

• Investments into protection of infrastructure beyond identified and agreed thresholds.
• Investments into the physical and operational robustness of infrastructure assets and their single components.
• Investments into residual risk management, such as preparedness, early warning and response systems, preparedness and business continuity management that can entail creating redundant critical systems, relief and recovery mechanisms.

Go to: List of possible impacts and potential measures for physical components

Go to: List of possible impacts and potential measures for infrastructure services

Many strategies are available to climate-proof water infrastructure so that it is less susceptible to climate hazards. Some of these strategies exist along a “green-to-grey” continuum. That is, to varying degrees, they harness the benefits of biodiversity and ecosystem services to reduce climate change related impacts to water infrastructure. These strategies are referred to as nature-based solutions for climate change adaptation, or simply ecosystem-based adaptation (EbA). In the Nile Basin, the most relevant EbA options for climate-proofing water infrastructure are those that minimize the impacts of increased sedimentation due to erosion, flood damages, low flow conditions, evaporation, and concentration of pollutants, since these stressors pose the greatest risk to water infrastructure and the services they provide. Ecosystem-based adaptation is “The use of biodiversity and ecosystem services as part of an overall adaptation strategy to help people adapt to the adverse effects of climate change” (Convention on Biological Diversity, 2009). In the context of water infrastructure, EbA refers to

ecosystem services that either protect, support, replace, or supplement hard/grey water infrastructure (sources), thereby extending its lifespan and reducing operation and maintenance needs, while simultaneously providing co-benefits like habitat provision and recreation opportunities (see Figure 1). In cost-benefit analyses, EbA alternatives can outperform hard/grey solutions particularly when co-benefits are considered. EbA can also be less costly to maintain over long time horizons because it relies on the self-regulating characteristics of nature (ADB 2019).

In the context of water infrastructure, EbA refers to ecosystem services that either protect, support, replace, or supplement hard/grey water infrastructure, thereby extending its lifespan and reducing operation and maintenance needs, while simultaneously providing co-benefits like habitat provision and recreation opportunities. In cost-benefit analyses, EbA alternatives can outperform hard/grey solutions particularly when co-benefits are considered. The interactive conceptual diagram illustrates how ecosystem-based adaptation (EbA) can be harnessed as climate-proofing actions targeting water infrastructure to support more resilient provision of focal services and co-benefits.

In the Nile Basin, the most relevant EbA options for climate-proofing water infrastructure are those that minimize the impacts of increased sedimentation due to erosion, flood damages, low flow conditions, evaporation, and concentration of pollutants since these stressors pose the greatest risk to water infrastructure and the services they provide. Example EbA alternatives that can assist in managing these impacts include re-meandering of rivers, creation or restoration of side-channels, flood plain widening, installation of green embankments, riparian planting, and forest restoration, altered land use practices, wetland restoration, and the creation of bioswales for urban drainage (sources).

Figure 7 is a conceptual diagram showing how different types of EbA (Protecting, Replacing, Assisting, Accompanying) can be applied to generate ecosystem services resulting in more resilient water infrastructure that, in turn, reinforces the reliability of focal service provision by that same infrastructure (positive feedback).

Figure 7: A conceptual diagram on the role of EbA for resilient infrastructure.

As Figure 7 illustrates, several ecosystem-based adaptation actions can be applied (options 1-4), each of which supply different ecosystem services. These actions can be organized into different types (colored ovals) based on how they interact with hard/grey infrastructure projects:

• Protecting options supply ecosystem services that directly protect a hard/grey infrastructure project from climate hazards, increasing its lifespan and reducing operating/maintenance costs, while also providing co-benefits.
• Replacing options supply ecosystem services that completely replace the need for a hard/grey infrastructure project and are more resilient to climate hazards, while also providing co-benefits.
• Assisting options supply ecosystem services that complement a hard/grey infrastructure project by increasing focal service provision beyond what could be provided by the project alone, thereby improving capacity to continue service provision when impacted by climate hazards, while also providing co-benefits.
• Accompanying options provide no services that directly or indirectly improve the adaptive capacity of a hard/grey infrastructure project or its focal services but can be implemented as part of the project to provide co-benefits that increase overall adaptive capacity of society to climate hazards.

EbA might not be an optimal solution in all cases and different criteria should be used to identify and prioritize the best climate proofing options. For example, if the only management objective is to protect water infrastructure against a 10,000-year flood, many EbA alternatives would not be viable because they would have a negligible effect against such an extreme event. Decision criteria such as feasibility, relevance, costs, benefits, and many others can be applied and EbA’s contribution to cumulative benefits should be considered (World Bank 2017, ADB 2019). Cost-benefit analyses (CBA) is a particularly useful decision-support tool that is often applied to help understand the net benefits to society of different management alternatives. Doing cost-benefit analysis for EbA options can be quite different from doing the same for hard/grey infrastructure alternatives because some ecosystem services provided by EbA options are not bought and sold in markets (especially co-benefits like habitat and recreation opportunities) (NOHAA 2015). This “non-market value” to society requires special economic valuation techniques to assign monetary values to non-market goods and services so the net benefits of a project can be compared on a common scale. To learn more about how to implement cost-benefit analysis for EbA, please refer to the GIZ sourcebook called “Valuing the Benefits, Costs, and Impacts of Ecosystem-based Adaptation Measures”.

The concept of Ecosystem Based Adaptation is mainstreamed into all relevant sections of the step-by-step guidance on climate proofing infrastructure investments