1. Introduction
Water is a scarce natural resource, essential for life and to carry out the vast majority of economic activities; it is irreplaceable, non-expandable by the mere will of man, irregular in its way of presenting itself in time and space, easily vulnerable and susceptible of successive uses. Easily available water resources have already been widely exploited across most of the planet, and the pressures from development, population growth, and climate change exert additional tensions on this vital element [
1]. The widespread recognition of the impact that human activities have on ecosystems is transforming the way in which natural resources are viewed and managed. On July 28 2010, through Resolution 64/292, the General Assembly of the United Nations explicitly recognized the human right to water and sanitation, reaffirming that clean and safe water is essential for the realization of all human rights [
2].
More than 35 years have passed since the concept of “sustainable development” was introduced for the first time by the World Conservation Strategy [
3]. Sustainable development balances the exploitation of natural resources, technological development and institutional change, in order to improve the potential to meet human needs and aspirations, now and in the future [
4]. The main challenge facing today’s society is to develop sustainable management that ensures an adequate supply of quality water and at the same time prevents the overexploitation and degradation of associated aquatic ecosystems.
Integrated Water Resources Management is a process that promotes coordinated development and management of water, land and related resources, in order to maximize economic and social well-being in an equitable manner and without compromising, in the present or future, the sustainability of vital ecosystems [
5,
6,
7]. A key aim of Integrated Water Resources Management is to promote the coordination and integration as a means to achieve holistic water management and improve the sustainability of water resources [
8]. Like the concept of sustainability, it is not a final state to be achieved, but a continuous process with the aim of creating a closer link and a better understanding of human and natural needs, as well as interactions between both [
9].
The importance that everything related to sustainable management of water resources as a field of study has acquired in various areas of knowledge, has contributed to the development of extensive academic literature. Communication in science is carried out through publications, which are recognized as adequate sources to analyze the growth and impact of science, which constitute the body of the so-called scientific literature. Every new study needs to know about previous research that may affect the subject under study, based on past advances to create new discoveries [
10]. Motivated by this fact, it is necessary to stop at this point to make an inventory of the work carried out and at the same time analyze and identify new directions and challenges for the future [
11].
To achieve a good understanding of the state of the art, synthesizing existing knowledge in a reproducible way, several authors point out that bibliographic reviews are the first common step to achieve this goal [
12]. Although there are limitations in this methodology, this type of review provides a reasonably detailed description of the body of the research carried out on the subject under analysis. Thus, our main objective was to show an in-depth analysis of the current state of research related to Sustainable Water Resources Management through a bibliometric-comparative study of articles indexed in WoS and Scopus, which enables to determine which of the two bases makes a greater coverage, as well as the overlap between the two. In the same way, and as secondary objectives, by means of statistical methods, bibliometric indicators and analysis of citations, the aim is to know how much, who, what, where and how it has been investigated.
For this purpose, this article is structured into four main sections. First, after the introduction, the academic literature is reviewed in order to establish the theoretical framework of the research. Then, in
Section 3, both databases and the methodology of the calculations and the tracking strategy used to select the references that form the empirical basis of the study are described. In
Section 4, the main results obtained in the study of the basic bibliometric indicators are detailed and discussed, as well as the analysis of overlapping and singularity between the bases, and finally, in
Section 5, the final conclusions reached, and the limitations associated with the investigation are discussed.
2. Theoretical Framework
The need for water is universal, and without it, life, as we know it, would simply cease to exist. Water can be everywhere, but its use is limited in terms of availability, quantity and quality. The methodology used to measure water scarcity has evolved in the last twenty years. The initial water scarcity threshold developed by Falkenmark [
13] was the basis on which the demands for water consumption were built. By recognizing that water consumption varies among social sectors, Falkenmark [
14], and Gleick [
15] achieved to improve the water scarcity index by incorporating specific water requirements for basic human needs. Moverover, Asheesh [
16] established the link between the demand for water resources and the future growth of the population as a way to measure water availability gaps.
Water availability has been identified as an important environmental limitation for economic growth and development [
17], and conflicts in the planning and management of water resources arise when people and institutions do not agree on the quantity and quality of water that is needed or required in a specific place for a precise purpose and at a specific time [
18]. Readily available water resources have already been widely exploited in most of the planet, and pressures from development, population growth and climate change exert additional stress on this vital resource [
1]. Many water problems have become so complex and interconnected to be managed by a single institution, regardless of the authority and resources granted, the technical expertise and management capacity available, the level of political support and all the good intentions [
19]. The solution to these problems, therefore, depends not only on the availability of water, but also on its correct management and planning [
20].
Integrated Water Resources Management (IWRM) is a process that promotes the development and coordinated management of water, land and related resources in order to maximize economic outcomes and social well-being, in an equitable manner, and without compromising the sustainability of vital ecosystems [
6]. Although some authors found the roots of this “new” paradigm in the United States in the first decades of the 20th century [
7,
21], its relevance at international level began with the Silver Sea Conference in 1977 [
22] and the subsequent summits in Rio de Janeiro and the Dublin Conference in 1992. The ideas presented at these two international meetings laid the foundations for the concept and principles of IWRM, in the way they currently exist.
In general terms, IWRM can be interpreted as an approach to water development and management that seeks balanced results among the three dimensions of sustainable development: Economic efficiency, social equity and environmental sustainability [
23]. Since then, IWRM has been followed internationally as a mantra in the management of water resources in both the political and academic spheres [
24]. In the political arena, most developed and developing countries have decided to align their water development and management policy frameworks with the general principles of IWRM in order to address the challenges in a more comprehensive and consistent way, which climate change poses among other threats [
25]. Jouravlev [
26] states that integrated management should promote economic growth, equity and environmental sustainability simultaneously, through productive transformation, the provision of social services and the conservation of natural resources.
However, these three short-term objectives are very conflicting with each other, since they seek to achieve the global optimum, by each of them sacrificing their partial optimum, and this is only possible through a lot of negotiation. Despite the international recognition of IWRM, there is an increasing criticism of this paradigm [
22] focused to a great extent on the concern about its possible implementation in real life [
27], considering that it is still a predominantly theoretical concept [
28].
At academic level, the impact of the IWRM approach can be seen in the growth of specific research networks, as well as in educational programs focused mainly on creating skills for new water managers in IWRM [
29]. Although biophysical sciences such as civil engineering and hydrology have paid a lot of attention to IWRM [
30], from the point of view of the social sciences (economics, political science, public administration, etc.) it must still be strengthened [
31]. Current research has four fundamental subjects as its object of study: Institutional framework; equitable allocation of water; implementation of IWRM; and stakeholder participation [
23], offering new opportunities for research, both in theoretical-methodological and empirical applications that explain, thanks to its strong multidisciplinary nature, the subsequent advances achieved in the field of water resources management [
32].
On the other hand, and as can be seen from its definition, the concept of IWRM is closely related to the idea of sustainability, with the definition of the term sustainability in the context of water resources being an important subject in hydrological literature [
33,
34].
The application of sustainability principles requires important changes in the objectives which decisions are based on and an understanding of the interrelationships between existing ecological, economic and social factors. The general objectives to achieve sustainability are: (a) Environmental integrity; (b) economic efficiency; and (c) equity [
35]. Together, with these objectives, the challenge of time (long-term consequences) is another aspect of utmost importance for making sustainable decisions, since sustainable development requires forms of progress that meet current needs without compromising the needs of future generations [
4].
To quantify the sustainability of water resources systems, Loucks [
34] proposed the so-called Sustainability Index with the aim of facilitating the evaluation and comparison between several proposed water management policies. Indices are frequently criticized because they are seen as a sum of different items [
36] and in practice, researchers in the water sector are sometimes reluctant to use them [
37]. However, the index proposed by Loucks summarizes the essential performance parameters of water management in a meaningful way, instead of adding broad factors and they have been widely used by the scientific community [
38].
In this context, the principles of sustainability seem to be in particular, suitable for responding to the problems posed in water management. The sustainability of water resources is therefore, the ability to use water in sufficient quantity and quality, both locally and globally, to meet the needs of human beings and ecosystems, in the present and in the future, with the objective of maintaining and protecting life from the dangers caused by natural disasters and those caused by the hand of man [
39]. Or in other words “sustainable water resources systems are those designed and managed to fully contribute to the objectives of society, now and in the future, while maintaining their ecological, environmental and hydrological integrity” [
34] (p. 518).
Research regarding water resources management models that incorporate the idea of sustainability as part of the optimization objective has been limited [
40]. Cai [
41], in a holistic management model of the Syr Darya River Basin in Central Asia, defined sustainability as a guarantee of a durable, stable and flexible water supply capacity to meet the demands, as well as the environmental maintenance associated with irrigation practices. The methods for measuring sustainability included criteria such as: Reliability, reversibility, and vulnerability of the water supply system; integrity of the environmental system by considering the water quantity and quality; spatial and temporal equity or; “socioeconomic acceptability”, directly related to the comparison of the marginal costs associated with the depletion of natural capital and marginal benefits, that is, when environmental costs exceed the marginal benefits associated with the use of the resource, the system becomes unsustainable.
5. Conclusions
The analysis of scientific publications through bibliometric reviews is a key element in the research process, not only as a tool capable of examining existing information in order to show trends, but also as a measure of its impact on the environment. In this process, bibliographic databases play a key role in allowing access to most of the information. However, the existence of differences in coverage, information provided and downloading of documents makes the selection of the most appropriate basis for each area of knowledge be an essential phase. Based on the results obtained, and as a conclusion, this section provides a series of ideas on research related to the area of Sustainable Water Resources Management (its volume, evolution, visibility and structure) that may be useful for future studies, at the same time as comparing the coverage and overlap that on this particular field is made by two of the main existing databases in the market, WoS and Scopus.
After a first period of uncertainty in which there are few publications, a second phase of exponential growth began in 2008, where the area of Sustainable Water Resources Management becomes the subject of study, concentrating two thirds of the articles in the period between 2008 and 2017, which would show the interest that has been given to the need to manage water resources in a sustainable way in the last 10 years. In addition, the growth in the number of citations that publications received during these years is constant, reaching its highest level in 2017. Throughout the period, the two databases analyzed, WoS and Scopus, show a strong correlation both in the number of articles published annually and in the number of citations received. However, as with other fields of research [
83], Scopus is the base that as a whole collects a greater number of articles and receives a greater number of citations.
However, despite these and other similarities, there are also differences such as those related to the coverage of both databases by the Sustainable Water Resources Management area. With almost a third of single articles, Scopus is shown to be the base that covers overlapping the best, at the same time, to almost 90% of WoS articles. 10% in the degree of singularity of WoS is the measure of the amount of information that would be lost if Scopus were chosen as the only bibliographic base.
Based on the results obtained and following the criteria proposed by Lotka [
79] for the classification of authors based on their productivity, there are no authors considered large producers and more than 95% of them are temporary authors, having a single authorship, causing the average productivity index per author to be very close to one. The ranking of the most productive authors is led by Simonovic S.I. with four articles. Although there is a wide variety of countries with author affiliation, which shows how geographically widespread this field is, two countries stand out at the forefront of research on Sustainable Water Resources Management, the United States and China. Canada is included in the countries with the best rated authors, by obtaining the second highest h index value (8). If the authorship (collaboration index) is observed in greater detail, the articles with multiple signatures represent more than two thirds of the total. Within these, articles with five or more authors represent 20%, which places the collaboration index, expressed as the average number of authors per article, above three.
Finally, and in relation to the journals where the articles are published, seven are the core of the main journals that collect articles on Sustainable Water Resources Management (Bradford’s core), with Water International standing out, due to the number of citations received. With regard to the thematic classification of documents that the databases make according to the areas to which the journals where they are published belong, there is a common main research field for WoS and Scopus that includes the highest percentage of articles: Environmental Sciences, but given the multidisciplinary nature of water management, other areas such as Water Resources (Wos), Social Science (Scopus) or Agriculture (both) must also be mentioned.
Although bibliometric studies are instruments capable of representing the main trends in a field of study, due to the specific characteristics of this type of research, it is worth mentioning some limitations such as the one that involves, when analyzing the results, the choice of a certain database and a particular search equation. On the other hand, the aim was not to evaluate the content quality of the selected articles, objective that can be considered in a later investigation, but a descriptive-comparative analysis of the articles and citations related to Sustainable Water Resources Management present in Wos and Scopus. In order to broaden the research, it would be interesting to extend the comparative study to other databases such as Scielo, Latindex, Emerald among others, where you can get more coverage per continent of studies in relation to IWRM, and carry out a collaboration analysis such as those carried out in other areas of knowledge.