Urban Water Security Dashboard: Systems Approach to Characterizing the Water Security of Cities

Urbanization and climate change lead to an increased need for studying water management on the urban scale. While in the 1950s only 30% of the world’s inhabitants lived in cities, by 2007 this percentage had grown to over 50%. It is expected that by 2050, two-thirds of the world population will be urban dwellers (UN 2014). In many cases, the fast rate of urbanization is exceeding the capacity of governments to respond, leading to a variety of water-related problems, such as inadequate water supply, lack of sanitation, failing stormwater management, and ecosystem degradation (Narain et al. 2013; Sadoff et al. 2015; Varis et al. 2006). At the same time, climate change is exerting increasing pressure on urban water systems by, for example, aggravating flood hazards due to rising sea levels (Hallegatte et al. 2013) and increasing the frequency of prolonged dry periods (Isler et al. 2010).

The aim of this study is to characterize the water security of cities by developing and applying a new urban water security dashboard. We take a systems perspective on urban water security by developing a dashboard of indicators based on the pressure-state-impact-response (PSIR) framework (EEA 1999). We use this to develop a scoring framework to characterize, compare, and rank the water security of ten cities. We not only consider the fulfilment of the functions of a city’s water system and its proper governance but also consider what comes before: the state of the system and the challenges the system faces. Although the focus is on urban water systems, we explicitly consider the water dependency of a city on its hinterland as well.

Water security is an emerging concept that adds value to the urban water management discourse (Bakker 2012). In water management studies, the concept complements the dominant integrated water resources management (IWRM) paradigm (Bakker and Morinville 2013; Cook and Bakker 2012). Related concepts are things like sustainable, resilient, adaptive, climate proof, and robust urban water management; although these terms have much in common, they emphasize different aspects of urban water management. IWRM is concerned with the process of water management, while water security relates to an important goal of water management. IWRM emphasizes that water management is a compromise between economic development, social equity, and ecological integrity. The term security implies certain thresholds beyond which a compromise is unacceptable (Bakker and Morinville 2013). Water security is framed in different ways; for an in-depth review of different perspectives, see Hoekstra et al. (2018). Some scholars have adopted a broad understanding of water security, which resembles the scope of IWRM (e.g., GWP 2000), while others have focused on risk (Garrick and Hall 2014; Grey et al. 2013; UN-Water 2013). The latter approach defines water security as an accepted level of water risk or the other way around—the absence of intolerable water risks (Hall and Borgomeo 2013; OECD 2013). By defining risk as the combination of hazard, exposure, and vulnerability, this approach fits best in relation to urban flood risks (Hallegatte et al. 2013). Another dominant, albeit more narrow, framing defines water security as matching water demand and supply (Brears 2017; Chang et al. 2015). Although widely accepted, such an understanding of water security overlooks other security aspects, such as flood risks and the environmental status of ecosystems. Following Cook and Bakker (2012) and Zeitoun et al. (2016), we adopt a broad and integrative understanding of water security, which covers the commonplace problems of urban water management: too little, too much, or too dirty water (OECD 2016).

Many interrelated mechanisms play a role in fulfilling the functions that make a city water secure; these mechanisms can be clarified using systems thinking (Barendrecht et al. 2017; Srinivasan et al. 2017). Basic criteria, such as meeting urban water demand by adequate supply or treating wastewater to allowable levels, have to be met, while increasing pressures, changing conditions, and governance all influence a city’s water security (Bakker and Morinville 2013; Koop and van Leeuwen 2015a; Milman and Short 2008; Rijke et al. 2013; Van de Meene et al. 2011). Given this complexity, we underscore the need to adopt a systems perspective on urban water security (see also Romero-Lankao and Gnatz 2016). The PSIR scheme is a commonly used framework for systems analysis that structures indicators that describe dynamic environmental systems (OECD 1993; EEA 1999; Pires et al. 2016; Sekovski et al. 2012). The PSIR framework schematizes the urban system dynamics using four stages: pressure (P), state (S), impact (I), and response (R). System pressures change the state of the system, which in turn has an impact on system functions, which then evokes societal and governmental responses. The responses can intervene at the level of pressures, states, and impacts. The framework has been successfully applied at the urban level to study environmental problems in general (da Costa Silva 2014; Zebradast et al. 2015), water problems specifically (Chen et al. 2015; Hazarika and Nitivattananon 2016), and holistic water management challenges (Liu et al. 2012; Sun et al. 2016).

The benchmarking and ranking of cities is being seen more and more frequently, both in the scientific literature and beyond (Arribas-Bel et al. 2013; Kılkış 2016). Ranking is typically done along a number of criteria; examples include urban sustainability indices like the green city index by Siemens (2012) or the index by Phillis et al. (2017). There are a large number of water (security) indicators, although few of them specifically focus on urban water security. Examples of dedicated indicators for urban water management are the sustainable cities water index by Arcadis (2015) and the city blueprint by Van Leeuwen et al. (2016). However, these rankings either seem to lack a sound theoretical foundation (e.g., the sustainable city water index) or have a predominantly performance-oriented approach (e.g., the city blueprint). Since ranking appears to appeal to policy makers, we ranked selected cities based on their overall score on the different indicators of the PSIR framework in order to arrive at a quantitative measure for urban water security [see Yang et al. (2012) for a catastrophe theory approach and Jensen and Wu (2018) for an approach highlighting the time dimension of water security]. Yet, with indicator development and ranking always being subject to some degree of subjectivity, the richness of understanding lies behind the overall scores, that is, in the scores per indicator and indicator category.

Using the PSIR framework, we constructed a dashboard of indicators that we then applied in order to score ten selected cities. Indicator scores were aggregated to a water security (WS) index that we used to rank the cities. We then studied the coherence between indicators’ scores on different levels of aggregation (called tiers) to obtain insight into the system dynamics.

First, we developed 56 indicators, which cover all relevant aspects of the PSIR framework for urban water security and together form the dashboard. Via three steps of aggregation, the dashboard indicators (tier 1) were aggregated to a water security index score (tier 4), as outlined in Table 1. Indicators (tier 1) were grouped into categories (tier 2), which in turn made up the respective stages of pressure, state, impact, and response (tier 3), which combined into the water security index score (tier 4). Pressures (tier 3) were defined as the basic factors, root causes, and trends that influence and determine the state of the urban water system (Pires et al. 2016; citing EEA 1999; WWAP 2006). We distinguished between environmental (natural resource) and socioeconomic pressures (Hoekstra 1998; OECD 2016; Van Leeuwen and Chandy 2013). The two main environmental pressure categories (tier 2) were water scarcity and flooding (Fig. 1). Socioeconomic pressures refer to the claims a city puts on available resources. This category included indicators for the size and growth of a city and the economic development level, water consumption, and industrial activities in the city and its surroundings. State (tier 3) was defined as the current physical properties of the natural and infrastructural elements of the urban water system (Pires et al. 2016). State categories (tier 2) were: water quantity, water quality, the state of urban water supply infrastructure, the state of flood protection infrastructure, and the state of sanitation infrastructure. Impact (tier 3) was defined as the effects of the system state on functions to be fulfilled by the urban water system (Pires et al. 2016). We distinguished the following impact categories (tier 2): dependencies, water supply, flooding, sanitation, ecology, and aesthetics (see also Brown et al. 2009). Under dependencies, we accounted for the risks associated with the supply of drinking water and the supply of water-intensive goods from the hinterland of the city (Hoekstra and Mekonnen 2016; McDonald et al. 2014; Schyns et al. 2015). Response (tier 3) refers to attempts by human actors to “prevent, compensate, ameliorate, or to adapt to the impact of the changes in the state” (Pires et al. 2016). We assessed the adequacy of the response in three categories (tier 2): institutional framework, planning, and operational management. The full dashboard, with all indicators and categories, is shown in Fig. 1. A description of each of the 56 indicators can be found in the Supplemental Data, in which we also explain the rationale of the indicators and discuss their limitations.

Next, cities were scored for each indicator within the dashboard. This indicator score represented the most disaggregated level (tier 1). We assigned indicator scores on a 1–5 point scale, based on publicly available data and literature for the indicator at hand. For the response indicators, we asked experts to fill out a questionnaire on city-specific governance settings. Someone was considered an expert if he or she had either worked in the urban water sector (in a policy-related position) or had studied the city-specific governance setting. We used a minimum of three expert responses, with an average of 4.4 responses for each city. Detailed methods to assign indicator scores are described in the Supplemental Data.

After assigning scores, we aggregated the tier-1 indicator scores of the dashboard to scores per category (tier 2). We characterized cities based on similarities in these category scores, as shown in Fig. 3. We further aggregated the tier-2 scores to indices at the P, S, I, and R levels (tier 3). Finally, the four tier-3 indices were further combined into one water security index (tier 4), which determined the final ranking of the selected cities. Aggregation from each tier to the next was done by taking the arithmetic mean. The tier-3 and tier-4 indices were first normalized on a 0–100 score (Table 1). Ten major cities (in terms of economy and size) were selected to represent differences in development level, climate, and geographical location, while also considering data availability. The ten selected cities are listed in Fig. 2.

We present the results in three steps. First, the ranking obtained based on the water security index (tier 4) is given, together with the underlying city scores for the indices for P, S, I, and R (tier 3). Second, we group cities based on resemblances between the dashboard scores (tier 2 and 1) and discuss the typical dynamics per group. Third, we obtain further insight into the system dynamics that lead to a certain level of water security by looking specifically at water supply, flood protection, and water quality.

The number of investigated cities is too small to cover the whole spectrum of urban water situations worldwide. A larger sample of cities may reveal additional system-dynamic patterns, which would enable alternative or richer characterizations. Uncertainty and subjectivity in indicator scores, emerging from the qualitative interpretation of literature and uncertainty in the quantitative data, underscores the fact that our results should be interpreted with caution. Both the limited number of respondents to the questionnaires and their personal judgment, background, and beliefs about good governance make generalizations precarious. Also, for each aggregation, the underlying scores received equal weight (Table 1). In practice, some urban water functions are prioritized over other functions (Brown et al. 2009), justifying alternative weighting procedures.

The strength of the dashboard using the PSIR framework is that it gives insight into the complex cause-and-effect relations that lead to a certain level of water security. The greatest quality of the PSIR approach according to Sekovski et al. (2012) is “the ability to provide cause-consequence relationships between the anthropogenic activities and complex environmental processes in a descriptive and rather simple way.” The drawback is that the choice of indicators leaves room for subjectivity, especially in terms of what causal relations exist between different indicators (Sekovski et al. 2012; Sun et al. 2016). One could, for example, emphasize alternative aspects of water security, such as the cascading impacts of water-related disasters on critical urban infrastructures. The systems approach could be extended by including the relation of water security to energy use (Kılkış 2016), which is strongly related to the characteristics of the urban water system (Chhipi-Shrestha et al. 2017).

Despite differences in conceptual framing, the rankings obtained by our WS index resembles the rankings in the Arcadis Sustainable Cities Water Index (Table 2). This shows that, although different indices focus on different aspects of urban water management, some cities have an undisputedly better urban water system than others. The largest dissimilarity between our ranking and the Arcadis index is observed for São Paulo, for which the WS index was 19 points lower than the Arcadis index ranking. This is best explained by the low response index in our study, which, through the governance dimension, receives little attention in the Arcadis index. Our ranking overlaps with three megacities covered in the study by Li et al. (2015) (Beijing, São Paulo, and Jakarta), who qualitatively confirm our findings for these cities as outlined in sections titled “Beijing and São Paulo: Megacities in Emerging Economies” and “Nairobi, Jakarta and Lima: Developing Cities.” The overlap between our city list and the list of cities evaluated with the revised city blueprint is too small to substantially compare the two, although the similarity between scores for Amsterdam is noteworthy (Table 2). It is interesting to compare the revised city blueprint framework (CBF) and our urban water security dashboard (UWSD), which seemingly aim for the same thing but have different underlying philosophies. We observe four differences: (1) CBF is performance-oriented (Koop and van Leeuwen 2015b), while our UWSD is security-oriented; (2) CBF is primarily designed to enable city-to-city learning, while we seek to understand the nature and dynamics of urban water security; (3) CBF aims at assessing the sustainability of the urban water cycle and is dominated by IWRM terminology, whereas we take our perspective from the water security literature; and (4) the CBF performance-oriented approach ignores some aspects that are critical for urban water security but that have no direct perspective for action by local water authorities. In an earlier version of the CBF, indicators for trends and pressures were included. These were later removed, following the reasoning that it is unfair to compare the IWRM performance of cities that operate in different settings (Koop and van Leeuwen 2015b). From a systems perspective, mapping environmental and socioeconomic pressures is key to understanding overall urban water security. Also, indicators related to water footprint were removed from the CBF because there was a lack of action perspective for local water authorities; the water imports and exports of a country are highly dependent on many socioeconomic processes and national and global trends on which local water authorities have a negligible influence (Koop and van Leeuwen 2015b). From a security perspective, external water dependencies can be an important source of water-related risks (Hoekstra and Mekonnen 2016; Schyns et al. 2015), and the fact that these are beyond the control of local authorities is a reason for even more concern. However, combining the trends and pressure framework (Koop and van Leeuwen 2015a) and the recently introduced governance capacity framework (Koop et al. 2017) with the city blueprint framework enables a study of urban water management that resembles a system-dynamic approach. The value of a system-dynamic approach to water security is not merely in the resulting dashboards or rankings themselves but rather in a way of thinking that includes factors from the whole cause-and-effect chain in the assessment of water security. It can help city planners and managers gain insight into the water security of their cities compared to other cities located in similar environmental or socioeconomic conditions.

We set out to create insight into the system dynamics of urban water systems that lead to a certain level of water security. The highest level of water security was found in water-abundant and wealthy cities such as Amsterdam and Toronto. Their degree of security is mainly determined by their ability to mitigate flood hazards, although they will never be fully secure as long as the risk of flooding exists. Moreover, even such water-abundant cities are subject to an imported water risk associated with unsustainable hinterland dependencies on drinking water and water embedded in goods consumed. We further found that a desert city (such as Dubai) may reach a reasonable level of security but at the cost of energy consumption in desalinating sea water. However, before turning to unconventional sources and reducing water use, cities—especially those located in water-scarce environments—overexploit locally available resources. Megacities in emerging economies suffer from water insecurity even when located in favorable environments because their claim on the available resources is simply too large. The largest insecurities were found in cities in developing countries, for which all water system functions are inadequately fulfilled—even those that are not facing significant environmental pressures.

The essence of urban water security is an adequate response to (partly inevitable) system pressures. The response determines the degree to which pressures will alter the state and have an impact on system functions. Under an adequate response, system functions can be properly fulfilled even in high-pressure environments. However, cities facing pressures will never reach the same level of security as cities where these pressures are absent, because the risk that a pressure propagates along the cause-and-effect chain via an unexpected pathway is always present.

The urban water security dashboard provides a way to characterize different types of insecurity, recognizing the complicated causal processes that lead to a certain level of water security. We revealed hidden dimensions of water security and operationalized the concept of water security in a broad, yet practicable, way.

The indicator formalizations and all dashboards and scores are available online in the ASCE Library (www.ascelibrary.org).

This paper was developed with funding from the National University of Singapore, project R-603-000-221-490. We would like to thank Shanisse Goh (Institute of Water Policy, National University of Singapore) for assisting in data collection and Martin Stavenhagen (Institute of Water Policy, National University of Singapore), who helped with developing the questionnaire for the response section. We thank Frans van de Ven and several other colleagues at Deltares (Delft) for providing input on the framework. We thank three anonymous reviewers for their insightful comments on the paper.