3.1 Scenario-Based Multi-Criteria Decision Analysis
When considering infrastructure development decisions in a resource-constrained environment, decision makers must consider multiple, often competing, factors when evaluating candidate assets for investment – affordability, sustainability, carbon mitigation, social equity, and more (Thorisson et al. 2017). Further, evaluation and quantification of the risk to development priorities of changing future conditions is a critical component of robust decision making (Hamilton et al. 2013).
Effective decision analytic techniques combine risk analysis, modeling tools, and stakeholder viewpoints to evaluate the performance of alternatives against criteria (Palma-Oliveira et al. 2018; Linkov et al. 2020). This paper applies theory from multi-criteria decision analysis (MCDA) and scenario analysis to establish infrastructure development priorities and quantify the disruption of climate and other downstream scenarios to those priorities. MCDA is an established framework in systems analysis and decision making which synthesizes data and the value set of the stakeholder to prioritize amongst a set of potential decisions (Linkov et al. 2020). Generally, MCDA begins with the gathering of the set of alternatives or possible decisions, the set of criteria by which alternatives will be evaluated and compared, and criteria weights representing the relative importance of each criterion to the stakeholders. Alternatives are scored against each criterion and scaled by criteria weights. These scores define a prioritization of alternatives and provide an easily interpretable decision-making roadmap for stakeholders of all backgrounds (Hassler et al. 2020; Jenkins and Keisler 2022; Lambert et al. 2022).
MCDA provides valuable insights into system priorities for current conditions, however as a standalone framework it can fail to account for the risk of future stressors’ shuffling of system priorities (Linkov et al. 2012). By introducing scenario-based methods, we can evaluate risk to an infrastructure system as the influence of scenarios on priorities (Karvetski et al. 2011; Lambert et al. 2013; Thorisson et al. 2017; Thorisson and Lambert 2021). In evaluating risk to infrastructure development in regions vulnerable to climate change effects, stakeholders must consider how climate change, and the cascading social, economic, technological, and political conditions, disrupt development priorities. Extending MCDA with scenario analysis allows for consideration of scenario-specific criteria and weights to define scenario-specific system priority orders (Schroeder and Lambert 2011). This scenario-based MCDA framework delivers a risk-informed analysis which evaluates how disruptive scenarios impact a system order, thereby identifying robust decision alternatives and determining the most and least disruptive scenarios to system priorities (Hassler et al. 2020).
Scenario-based MCDA methods are broadly applicable across industries and have been used in enterprise risk analysis to evaluate emerging technological and health stressors in correctional facilities (Andrews et al. 2023), cybersecurity investments (Moghadasi et al. 2022), emerging technologies (Trump et al. 2020), public health intervention strategies (Talantsev et al. 2022), green energy investment strategies for energy services firms (Jenkins and Keisler 2022), and early initiatives for biofuel development (Connelly et al. 2015). Bonato et al. (2022) used scenario-based MCDA to evaluate informational and physical flood resilience measures in Venice. They assessed the risk management and resilience initiatives against community critical functions across four scenarios developed from expert climate projections. They noted the crucial step of considering multiple-hazard scenarios due to the unpredictable nature of event co-occurrence, a step which this paper adopts in the case study presented later in this paper. Karvetski et al. (2011) considered physical infrastructure investment portfolios to increase coastal community resilience to rising sea levels. They constructed scenarios from conditions related to global sea-level rise forecasts, population shifts, extreme temperatures, wear and tear, and changes in fossil fuel reliance. Lambert et al. (2012) focused scenario-based MCDA methods on major infrastructure projects in a volatile region of Afghanistan. Decision alternatives were grouped into high-level projects, including energy and electricity development initiatives, and were scored for drought and other political and social scenarios. Projects were classified by their baseline ranking as high, medium, or low, and by their threat level, indicated by a significant decrease in scenario ranking relative to baseline.
While Bonato et al. (2022), Karvetski et al. (2011), and Lambert et al (2012). give consideration to climate change forecasts in their development of scenarios impacting infrastructure systems, they do not account for recent climate trends in their evaluation of alternatives against system criteria such as sustainability and natural resource availability. Analysis of these climate trends for each alternative enhances scenario-based MCDA methods as governments and agencies place a heightened focus on climate resilient infrastructure planning.
3.2 Hydrological Monitoring and Analysis
This paper advances previous methods of scenario-based MCDA by including hydrology and climate data not only for development of risk scenarios, but as a metric for evaluation and prioritization of resilient infrastructure facility investments. These data are incorporated into the model as system order criteria and are used to evaluate candidates for infrastructure investment alongside other social, political, and economic criteria.
The transboundary nature of Iraq’s water supply presents unique challenges to the collection and analysis of water resource data. In many regions, field-collected data may be missing, incomplete, or inaccessible. It may be difficult for stakeholders to obtain a holistic water resources picture and predict future water supply (Voss et al. 2013). However, modern remote sensing techniques for hydrological data collection, including satellite imaging, are unconstrained by political boundaries and provide the necessary spatial and temporal resolution for hydrological analysis (Duan et al. 2021). Many of these datasets, including those referenced in this study, are publicly available and fill data gaps in regions where field data are either not collected or shared (Albarakat et al. 2022). In cases where in-situ data are available alongside satellite data, additional calibration steps can be taken to reduce bias (Waheed et al. 2020); these steps are outside the scope of this study.
Several recent remote sensing hydrology case studies have focused specifically on Iraq and surrounding regions due to the unique need for transboundary monitoring. Albarakat et al. (2022) used satellite imagery to monitor drought and surface reservoir area in three transboundary river basins of Iraq – Mosul, Qadisiyah, and Dukan – over four timescales varying in length. Their findings confirmed the capability of satellite imagery to effectively observe drought events, and they suggested the use of longer timescales for transboundary region drought monitoring. Ethaib, Zubaidi, and Al-Ansari (2022) performed a change detection analysis using satellite images in the Thi-Qar governorate which identified dramatic decreases in marshlands surface water. In particular, studies have upheld the accuracy and quality of NASA satellite data for these regions. Albarakat and Lakshmi (2019) evaluated vegetative cover and health of the Mesopotamian marshes post-2002 with data from three NASA sensors varying in spatial and temporal resolution. They found consistent trends and high correlation across the three datasets, including NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) which we utilize in this paper. Amini et al. (2023) compared NASA Global Land Data Assimilation System (GLDAS) soil moisture data with ground-collected observations in the dry Kermanshah province of Iran. They verified through statistical measures that the GLDAS soil moisture estimation aligned with the ground-collected observations, and thus GLDAS was an appropriate measure for the region.
These studies support the suitability of remote sensing data collection for hydrological analysis of domestic and transboundary basins in Iraq. In this paper, normalized difference vegetation index (NDVI) is developed from the MODIS dataset, and air temperature and soil moisture are gathered from the GLDAS dataset. In addition, precipitation data is sourced from NASA’s Integrated Multi-satellitE Retrievals for GPM (IMERG) dataset. The specific use and analysis of satellite hydrology observations in this study are outlined in detail in Section 3.3.1.
3.3 Risk Register Evaluation
This paper aims to close the gap between traditional methods for climate-informed risk and decision analysis and modern methods for hydrologic and climate scenario analysis. The risk register tool introduced by this paper synthesizes qualitative stakeholder criteria and quantitative hydrological observations to assist decision makers in infrastructure development decisions and quantify the disruption of climate and related scenarios to an infrastructure system. The methodology is adapted from Hassler et al. (2020) and Loose et al. (2022) and is extended by the incorporation of hydrologic criteria and data analysis. First, the core model inputs of criteria, initiatives, emergent conditions, and scenarios are gathered. We then outline the methods for scoring initiatives against criteria across the set of scenarios. The baseline system order and scenario-based system orders are compared to identify the most and least disruptive scenarios to infrastructure investment priorities, as well as the most robust individual initiatives.
The risk register tool is built upon four sets: criteria, initiatives, emergent conditions, and scenarios. We first define the set of criteria, \(C={\{c}_{1},{c}_{2}\dots ,{c}_{m}\}\), which represent stakeholder goals or values. These criteria can be sourced from stakeholders and literature reviews. This paper extends previous definitions of criteria by including hydrological metrics to represent hydrological health and level of water security in the location of a particular initiative. These hydrologic criteria are explained in further detail in Section 3.3.1. The set of initiatives, \(X={\{x}_{1},{x}_{2},\dots ,{x}_{n}\}\), includes the assets, projects, technologies, or policies being considered for selection, investment, or prioritization. Initiatives are identified through stakeholder interviews and agency reports. The set of emergent conditions, \(E=\{{e}_{1},{e}_{2},\dots ,{e}_{q}\}\), is defined as future events, policies, or conditions which may affect the value of initiatives within the system. These conditions are sourced from stakeholders, historical events, and recent trends. Scenarios, \(S=\{{s}_{1},{s}_{2},\dots ,{s}_{r}\}\), are developed by grouping one or more emergent conditions into the most critical higher-level threats to the system. Each scenario is a subset of \(E\).
After defining the sets of criteria, initiatives, and scenarios, we establish methods for scoring initiatives against criteria. These scores are calculated for a baseline and each scenario, establishing a system ranking or order of initiatives for each scenario. The baseline system order serves as the comparison point for evaluating the disruptiveness level of the various scenarios.
In consultation with stakeholders, each criterion \({c}_{j}\) is assigned a baseline weight, \({w}_{jb}\), reflecting its relative importance or value to stakeholders in the baseline scenario. Next, we assess how the relevance (and thus, weights) of each criterion changes in the case of each scenario. For each scenario, the criteria are determined to either increase in relevance, increase slightly, decrease slightly, decrease, or have no change. This incremental change determination, as opposed to a complete re-weighting, simplifies the process for stakeholders who often carry intuitive judgements about how system goals evolve in changing conditions (Karvetski et al. 2011). These changes in relevance scale the baseline weights up or down, defining new scenario-specific weights, \({w}_{jk}\), for each criterion \({c}_{j}\) and scenario \({s}_{k}\).
Having defined the baseline and scenario-specific criteria weights, we next assess the relationship between the criteria and the initiatives. This assessment is completed by considering how well each initiative achieves each criterion – very well, well, somewhat, or none. The four assessment levels correspond to numerical scores, \({x}_{ij}\), the numerical score of initiative \({x}_{i}\) for criterion \({c}_{j}\). For the more subjective criteria, the criteria-initiative assessment level is determined by stakeholder and expert perspectives in combination with agency reports and supporting data. Data-based criteria (e.g., hydrology criteria) are assigned their assessment level based on the observed data. The criteria-initiative assessment process for hydrological criteria is discussed in detail in Section 3.2.
Initiative scores are calculated for each scenario (the baseline and all disruptive scenarios) by computing the criteria-weighted sum of scores, as shown in Eq. 1. The score for an initiative \({x}_{i}\) and scenario \({s}_{k}\) is denoted as \(V{\left({x}_{i}\right)}_{k}\).
$$\begin{array}{c}V{\left({x}_{i}\right)}_{k}=\sum _{j=1}^{m}{w}_{jk}{x}_{ij},\forall i\in X,\forall k\in S\#\left(1\right)\end{array}$$
The system order or ranking of initiatives for scenario \({s}_{k}\) is determined by Eq. 2, where \(\succ\) indicates a higher position in the order. The ranking of an initiative \({x}_{i}\) (a number from 1 to n) in scenario \({s}_{k}\)is denoted as \(R{\left({x}_{i}\right)}_{k}\).
$$\begin{array}{c}IF V{\left({x}_{i}\right)}_{k}>V{\left({x}_{j}\right)}_{k} THEN{ x}_{i}\succ {x}_{j},\forall i,j\in X\#\left(2\right)\end{array}$$
Finally, a scenario disruptiveness score is calculated for each scenario. The disruptiveness score for a scenario \({s}_{k}\), \(D\left({s}_{k}\right)\), is calculated by a sum of squared differences method as shown in Eq. 3. The disruptiveness score can also be normalized for ease of comparison.
$$\begin{array}{c}D\left({s}_{k}\right)=\sum _{i=1}^{n}{\left(R{\left({x}_{i}\right)}_{b}-R{\left({x}_{i}\right)}_{k}\right)}^{2}\#\left(3\right)\end{array}$$
The methods outlined above can be an iterative process amongst analysts and stakeholder groups. Stakeholders can be divided into groups based on job function or experience to account for the different values and goals held by each group. Criteria, initiatives, and emergent conditions can be reassessed over time and updated to reflect resulting changes in system prioritization and scenario disruptiveness.
3.3.1 Hydrologic Data and Criteria Scoring
The introduction of hydrologic metrics as evaluation criteria requires methods for connecting individual infrastructure facilities or assets to hydrologic data sets. This study utilizes the HydroBASINS1 dataset of the World Wildlife Fund to map initiatives to the hydrological sub-basin in which they are located (Lehner and Grill 2013). HydroBASINS are available at 12 levels of spatial resolution. The Level 05 (L05) granularity was chosen for this analysis to provide a sub governorate-level evaluation of hydrological features while ensuring a large enough sub-basin area with adequate data coverage. Iraq fully or partially contains 31 L05 sub-basins, with an average sub-basin area of 27,564 km2. Figure 1 shows the four major river basins and the L05 hydrological sub-basins of Iraq. Eighteen sub-basins cross political boundaries and provide valuable insight into the transboundary rivers supplying most of Iraq’s water supply. The initiatives and L05 sub-basins are added to a layered ArcGIS map for visualization and mapping. Sub-basins may not be unique to one initiative; some sub-basins may contain multiple initiatives. Some initiatives, such as oil pipelines, major roadways, or nationwide policies, can cross through or apply to multiple sub-basins. Additional analysis or communication with stakeholders may be required to determine appropriate methods for hydrological analysis of these initiatives.
We consider the previous five years of available data (2018–2022) for analysis. The timeframe is limited to the most recent five-year period to accurately reflect the recent hydrological conditions in Iraq and avoid data skew from earlier observations which do not necessarily reflect current climate and hydrological realities of the region. Future studies may extend or otherwise alter the timeframe of analysis according to study and stakeholder goals. Five hydrology metrics, collected from NASA satellite datasets as described in Table 1, are studied. These five metrics were chosen for their ability to assess the natural water supply from precipitation in a sub-basin, as well as the impacts of water supply and water usage on soil moisture and vegetative health. Four of the metrics, annual precipitation, annual root zone soil moisture (RZSM), annual air temperature, and annual NDVI are recorded as the average of the individual annual averages within the 2018–2022 study period. The final metric, minimum monthly precipitation, records the precipitation level of the month within the study period (restricted to the rainy months of December through April) with the lowest precipitation. This metric captures a previous five-year worst case month during Iraq’s rainy season (Ethaib et al. 2022).
Table 1
Hydrology metrics used in ordering energy assets
Metric | Measurement Units | Spatial Resolution | Temporal Resolution | Satellite/Sensor/Model |
---|
Average Annual Precipitation | mm | 0.1° x 0.1° | 1 Month | NASA IMERG |
Average Annual RZSM | m3/m3 | 0.25° x 0.25° | 1 Month | NASA GLDAS |
Average Annual Air Temperature | °C | 0.25° x 0.25° | 1 Month | NASA GLDAS |
Average Annual NDVI | 0–1 Index | 250m x 250m | 16 Days | NASA MODIS |
Minimum Monthly Precipitation (December – April, only) | | 0.1° x 0.1° | 1 Month | NASA IMERG |
To compare hydrological observations across the set of initiatives being studied, a normalized metric index (NMI) between 0 and 100 is calculated for each initiative and metric. Eq. 4 shows the calculation of the NMI for the annual precipitation metric for an initiative \({x}_{i}\), where \({AP}_{i}\) is the 2018–2022 average of annual average precipitation for initiative \({x}_{i}\) and \(X\) is the set of initiatives.
$$\begin{array}{c}NM{I}_{i}^{AP}=100 \times \frac{{AP}_{i}-\text{m}\text{i}\text{n}\{A{{P}_{j}\}}_{j=1}^{n}}{\text{m}\text{a}\text{x}\{A{{P}_{k}\}}_{k=1}^{n}-\text{m}\text{i}\text{n}\{A{{P}_{j}\}}_{j=1}^{n}}, \forall i\in X\#\left(4\right) \end{array}$$
The NMI formulas for RZSM, NDVI, and minimum monthly precipitation follow the structure of Eq. 4 for each respective data set. The NMI formula is constructed such that initiatives located in basins with higher observed values have higher NMI, and initiatives located in basins with lower observed values have lower NMI. For the air temperature metric, a slight variation is made to Eq. 4 to reflect that higher observed values for this metric reflect a negative climate feature. Eq. 5 shows the calculation of the NMI for the air temperature metric for an initiative \({x}_{i}\), where \({AT}_{i}\) is the 2018–2022 average of average annual air temperature for initiative \({x}_{i}\) and \(X\) is the set of initiatives.
$$\begin{array}{c}{NMI}_{i}^{AT}=100 \times \frac{\text{m}\text{a}\text{x}\{A{{T}_{j}\}}_{j=1}^{n}-{AT}_{i}}{\text{m}\text{a}\text{x}\{A{{T}_{j}\}}_{j=1}^{n}-\text{m}\text{i}\text{n}\{A{{T}_{k}\}}_{k=1}^{n}}, \forall i\in X\#\left(5\right)\end{array}$$
In the case of air temperature only, initiatives located in basins with lower observed air temperatures have higher NMI, and initiatives located in basins with higher air temperatures have lower NMI.
For each of the five metrics, initiatives are classified into one of four bins based on the value of their NMI. Bins are constructed as follows: bin 1 = [0, 25), bin 2 = [25, 50), bin 3 = [51, 75), bin 4 = [76, 100]. These bins represent the relative hydrological health of the initiatives. For example, an initiative whose NMI values fall in bin 4 for all five metrics would be considered to have healthier hydrological features than an initiative whose NMI values fall in bin 2 for all five metrics. These bins inform the criteria-initiative assessment as described in Section 3.1.2, with bin 1 assessed as none, bin 2 assessed as somewhat, bin 3 assessed as well, and bin 4 assessed as very well. In other words, initiatives with NMI values in bin 4 are considered to perform very well (in risk register terminology) against hydrological criteria.