Defining the term watershed to reflect modern uses and functions as inter- and intra-connected socio-hydrologic systems

Abstract

Despite the many programs focused on watershed education, the watershed concept is poorly understood, which can lead to a number of wide-ranging consequences from poor watershed planning and policy to inaccurate scientific studies. We argue that the definition of the term watershed, and the images that accompany the definition, contribute to these misunderstandings. The definition has remained very much the same since it was first documented in Europe in the mid-18th century. However, watershed uses and functions have evolved considerably in the past three centuries, notably in the many ways water moves within and across traditionally-defined watershed boundaries. In this study, content analyses of the definitions of the term watershed from textbooks and online sources, and the accompanying images, highlight that watersheds are nearly universally defined as an area of land that drains to a point on a river. More than half the images that accompany these definitions depict forested landscapes or high mountain relief. While over one half of online images depict human activities or developed landscapes, few textbook images do. These incomplete definitions and idealized images do not reflect the diversity of landscapes and watershed functions. The narrow description can contribute to an individual’s disconnection to their own watershed. Furthermore, the description of watersheds as lumped areas, rather than inter- and intra-connected socio-hydrologic systems, misses a fundamental element of the watershed concept: that activities at every point in a watershed impact all points downstream and are impacted by activities at all points upstream. Thus, we propose a revised definition of a watershed that better captures this connectivity: a watershed defines the boundaries of a system of hydrologically connected people, places, and things.

Introduction

Many communities face one or more water challenges, including flooding, poor surface water, lack of clean drinking water, and degraded ecosystem health, all problems that are predicted to worsen due to climate change (Pörtner et al. 2022). To combat these problems, we need citizens who better understand water and are therefore more likely to support water conservation, management, and policy solutions (Dean et al. 2016; Gunckel et al. 2012; Schueler and Holland 2000). However, water concepts such as the hydrologic cycle and watersheds are not well understood (McCarroll and Hamann 2020).

To aid in the understanding of the watershed concept, much work has been done to develop and evaluate watershed education, which has resulted in measurable gains in comprehension. Watersheds are often used for place-based inquiry and education in K-12 through higher education (ex. Endreny 2010; Peters and Spaulding 2022; Santelmann et al. 2011; Vallor et al. 2016) and there are many watershed education programs and frameworks for K-12 students (ex. Gill et al. 2014; Krauss et al. 2022; Zint et al. 2014). The watershed concept may be introduced to students as part of their regular science curriculum, as in K-12 environmental or earth science textbooks, or as part of a watershed education program (typically developed by organizations such as the Environmental Protection Agency or through federally grant-funded research programs). Yet watersheds remain particularly challenging to conceptualize for students and adults (McCarroll and Hamann 2020). When asked to draw a watershed, grade 4 through 12 students were more likely to associate a watershed with mountains and high relief and elements of the hydrologic cycle and did not include humans or human activities in their drawings (Shepardson et al. 2007). However, as (grade 5) students better understand watersheds, their drawings of them also improve (Endreny 2010). In a study of children’s drawings of watersheds,

The findings suggest that as understanding improves, the presence of ‘non-fluvial landscape features’ and ‘river bank’ features disappears from drawings to be replaced by more appropriate geographical details. The results suggest that children with a limited understanding of river basins perceive them in terms of a stretch of river bank where common features include bridges, trees and fish… In contrast, as understanding improves, children’s perspectives widen and rivers are set within the context of a river basin (Dove et al. 1999).

Despite these gains, the connectivity of natural and human-built hydrologic systems, such as stormwater networks and drinking water distribution systems, is a particularly difficult concept to comprehend. Few students, from elementary to higher ed, can trace water or water contaminants through these systems (Attari et al. 2017; Covitt et al. 2009; Gill et al. 2014). Covitt et al. (2009) argue this is because of the difficulty in understanding watershed elements that cannot easily be seen, such as underground stormwater pipes, but also the whole of a water distribution system. However, as above, as high school students’ understanding of natural and built water systems improves, so does their ability to, “trace water and substances in water along multiple pathways across visible and invisible boundaries” (Gunckel et al. 2012).

Still, even with these watershed education programs, when asked to define the term watershed, few people can correctly do so (Schueler and Holland 2000; Shepardson et al. 2007). When presented with a multiple-choice survey question, only between 24 and 44% of adult respondents could choose the correct definition of a watershed (Dean et al. 2016; Giacalone et al. 2010). Those with training in water and watershed education also find the term watershed difficult to define. Shepardson et al. (2002) showed that after teacher professional development training, where the definition of a watershed as “an area that drains water into a stream was highlighted”, only 66% of adult participants were able to correctly define a watershed in a post-program assessment compared to 31% in the pre-program assessment.

So why then, even when people receive watershed-specific training, is the watershed concept so difficult to understand and define? Some misconceptions of water concepts, such as the hydrologic cycle, have been attributed to incomplete depictions in textbooks and online (Ben-zvi Assarf & Orion 2005; Ben-zvi Assarf et al. 2012; Vinisha and Ramadas 2013). Though watershed images have not been as extensively studied as those of the water cycle, it is hypothesized that the misunderstanding of watersheds is also associated with the way they are graphically depicted on websites, textbooks, and other educational sources (Shepardson et al. 2007; Zint and Kraemer 2012). McCarroll and Hamann (2020) argue that we need visualization tools that “capture the dynamic and complex nature of water systems and are adaptable to a range of learners.” Moreover, we argue that the way the term watershed is defined equally contributes to misunderstandings.

The definition of a watershed as an area that drains to a point, overemphasizes watersheds as lumped areas with a singular geographic function, despite the growing body of literature on the interconnectedness and complexity of socio-hydrologic systems within and across watersheds. Though people have been contemplating the relationships between water and society for a long time (Wesselink et al. 2017), in the last several decades there has been an increase in studies examining human-water systems (Xu et al. 2018; Ross and Chang 2020), notably within the field of socio-hydrology, which “is aimed at understanding the dynamics and co-evolution of couple human-water systems” (Sivapalan et al. 2012), and the closely related fields of hydrosocial theory, coupled human and natural systems (CHANS), water resources systems, and earth systems science (Madani & Shafiee-Jood 2020; Ross and Chang 2020; Wesselink et al. 2017). Socio-hydrology, focused on the impact of society on hydrologic systems (Ross and Chang 2020; Wesselink et al. 2017) emerged out of, “the need to consider the two-way feedbacks between human and water systems in order to interpret and understand puzzles, paradoxes, and united consequences that arise in the context of management of human-water systems” (Pande and Sivapalan 2017).

Though increasingly interdisciplinary (Ross and Chang 2020), as a subdiscipline of hydrology, socio-hydrology is rooted in the biophysical sciences. Hydrosocial theory, on the other hand, draws from the social sciences, particularly political ecology (Ross and Chang 2020). Similar to socio-hydrology¹, hydrosocial theory advances the idea that, “The ways in which water flows over space and time is… shaped by human institutions, practices and discourses that determine modes of control, management and decision-making” (Linton and Budds 2014). But the field moves beyond just thinking about humans’ influence on water; rather, hydrosocial theory argues that water is inseparable from society (Budds et al. 2014; Meehan et al. 2023) and it is “impossible to abstract water from the social context that gives it meaning and from the socio-political processes that shape its material flows and its discursive presentation” (Budds et al. 2014).

Given these insights into the complexity and interconnectedness of human-water systems, watersheds as areas that drain to a single point, are more challenging to delineate than topography alone might suggest. Socio-hydrology recognizes that the water that drains to a point on a river channel is dynamic both in space and in time, and that understanding these connections, “becomes crucial as the world becomes increasingly globalized, and human-water systems are no longer isolated, but are highly interconnected at a hierarchy of scales, through upstream-downstream and upwind-downwind connections, interbasin transfers of real water, and interbasin, interregional and international transfer of virtual water through commodity trade” (Pande and Sivapalan 2017). Furthermore, water management agencies, influenced by existing knowledge and value systems (i.e. policy and funding priorities), can configure and reconfigure socio-hydrologic systems by building dams, stormwater management infrastructure, and irrigation systems. These decisions, in turn, can impact where and how people live and interact with the watershed and other “hydrosocial territories” (Boelens et al. 2016; Bouleau 2014; Flaminio et al. 2022). Thus human-water systems very much impact which waters and areas drain to a point. But watersheds are still described and depicted as topographically-delineated areas, rather than inter- and intra-connected socio-hydrologic bounded systems (see below for further critique).

Resource managers, NGOs, and other stakeholders increasingly utilize the watershed concept because it provides useful, mappable boundaries for integrated water management and governance. The watershed approach to water resource management and governance aims to promote public participation and empowerment, but with varying success (Cohen and Davidson 2011), and many are still excluded from the process of watershed governance (Sarna-Wojcicki et al. 2019). Solving the complex water problems of today and the future will require broad participation, inclusive communication, and interdisciplinary thinking (Vogel et al. 2015; Younos et al. 2019; 2021). Several have called on educators to do the work of training future water professionals in not only disciplinary depth, but interdisciplinary breadth and the communication skills needed to work in interdisciplinary teams that can include policy makers and the public (Konar et al. 2019; National Research Council 2012). Furthermore, the research community needs social and biophysical scientists to share a common vocabulary to discuss water-related concepts (Wesselink et al. 2017). We argue that a concept as fundamental to water management as the watershed, requires a definition that is relevant and useful across disciplines to aid interdisciplinary thinking and communication, and can support inclusive participation by diverse stakeholders in water management and governance processes.

The goal of this manuscript is to examine how the term watershed is defined in the sources the public, students, and professionals go to learn about watersheds: online dictionaries and educational websites; K-12 textbooks; and watershed, hydrology and water resource textbooks. We offer a critique of the most common definition of the term watershed. Next, we conduct a content analysis of current definitions and, where available, the associated images of watersheds to identify common themes. This provides an empirical basis from which we propose a new definition. We have come to recognize that most people are unfamiliar with how a watershed functions, sometimes unaware that they live in a watershed or the name of the one they live in. A stronger definition would reflect both the conventional conceptualization but also include the ways water, infrastructure, and people are connected by and connect different watersheds. We propose the following definition of a watershed:

A watershed defines the boundaries of a system of hydrologically connected people, places, and things; the activities at every point in a watershed impact all points downstream and are impacted by activities at all points upstream.

Critique of the definition of the term watershed

Watersheds are typically defined as the area of land that drains to a single point on a water body, such as stream, lake or ocean, or some close variation of this language. This definition reflects the basic hydrologic functions of a watershed: collecting, storing, and discharging water (Black 1997) and provides useful, mappable boundaries for analysis and governance. Though there is no universally agreed-upon definition of a watershed, we contend that the oft-used, conventional definition, the area draining to a point on a river, is outdated and inadequate, and does not reflect the many ways watersheds function particularly within urbanized landscapes. We offer the following critiques:

• (1) This definition emphasizes watersheds as lumped areas or boundaries and doesn’t capture the many ways water is connected within watersheds.

• (2) This definition does not account for the many ways water can move across topographically-delineated watershed areas.

Furthermore, as defined, the term watershed can too easily be misinterpreted and misused by both the general public and watershed professionals.

In this paper, when we discuss how a watershed is defined, we refer to how the term watershed is defined. We recognize that defining a watershed could also refer to how the boundaries of the watershed are determined and drawn on a map. To make the distinction clear, when referring to the latter, we will use the term “delineated”.

The term watershed is often used interchangeably with the terms river basin, drainage basin, and catchment. Though sometimes the area draining into a waterbody is referred to as a river basin, while the term watershed refers to the perimeter of that area, the ridgeline or boundary dividing two river basins. The US Geological Survey’s Manual of Hydrology: Part 1. General Surface-Water Techniques, General Introduction and Hydrologic Definitions, defines a watershed as,

The divide separating one drainage basin from another and in the past has been generally used to convey this meaning. However, over the years, use of the term to signify drainage basin or catchment area has come to predominate, although drainage basin is preferred. Drainage divide, or just divide, is used to denote the boundary between one drainage area and another. Used alone, the term “watershed” is ambiguous and should not be used unless the intended meaning is made clear (Langbein and Iseri 1960).

Also according to Langbein and Iseri (1960) the terms drainage basin and catchment are interchangeable and defined as:

A part of the surface of the earth that is occupied by a drainage system, which consists of a surface stream or a body of impounded surface water together with all tributary surface streams and bodies of impounded surface water (Langbein and Iseri 1960).

However, other sources make the distinction between the terms and define watershed, catchment, drainage basin, and river basin differently (see analysis below). Yet there is no agreement on what distinguishes these terms, even among the definitions analyzed as part of this study.

The earliest descriptions of a watershed, as the area of land draining to a point, have been traced back to the second half of the 18th century when French cartographer, Philippe Buache, defined a watershed as “the set of all the slopes on which fall the waters that converge to a same river or creek” (Lacoste 2003 cited in Molle 2009). But while the origin of the watershed concept is geographic in nature, and watersheds are widely used as scientific tools for hydrological, ecological, and conservation-based study, the watershed concept is also closely associated with systems of politics and power. It is not possible to separate watersheds as technical units that drain water to a point on a river, from their use by and impact on society (Linton and Budds 2014; Norman et al. 2012). Notably, the concept of a watershed has been closely associated with European and US power - electrical, political, economic, and hydraulic. Molle (2009) argues that since its conception, watersheds have “been associated with various strands of thinking and sometimes co-opted or mobilized by particular social groups or organizations to strengthen the legitimacy of their agendas.” For example, in 1921, the French Compagnie Nationale du Rhône (CNR) was established, “as part of a regional development plan to provide electricity much beyond its basin limits, up to Paris. The concept of “hydraulic region” was proposed by industrialists and urban elites in an effort to substitute the concepts of the river basin and independent/decentralized management for a wider regional/national approach that served their interest” (Molle 2009). Similarly, in the 1930s, as part of Roosevelt’s New Deal, the United States established the Tennessee Valley Authority (TVA), which organized Tennessee and its neighboring states into watersheds to aid in the design of hydroelectric dams. This model of harnessing watersheds for their power, regional planning, and economic development was exported to non-European countries including India, Iran, Afghanistan, South Africa, and others (Molle 2009). Still today, watersheds are used widely as units for water study, management and governance (Cohen & Davidson 2011).

Hydrologic and socio-hydrologic connection within watersheds

The focus of the traditional definition is on a watershed as an areal unit. However, watershed areas contain, and are delineated using connected hydrologic systems. Though a watershed area can be delineated manually by following elevation contours on a topographical map, watershed boundaries are increasingly being delineated using computer algorithms (Kayembe and Mitchell 2018; Maidment and Morehouse 2002) that trace connected flow pathways upstream of the watershed outlet using elevation data. Thus hydrologic connectivity within a watershed is foundational to determining its boundaries.

This connectivity affects a number of important hydrological and other biophysical watershed processes. In natural watersheds, structure and hydrologic connectivity impact flood characteristics (Rinaldo et al. 1995), and the structure and function of ecological communities (Doretto et al. 2020). Likewise, in urban watersheds, which are comprised of both natural and engineered flow paths (ex. street gutters, stormwater pipes) connectivity of the hydrologic network impacts a number of ecological, chemical, and biogeochemical processes (Kaushal and Belt 2012). Flooding and water quality characteristics can be impacted by patterns of development and urban infrastructure within a watershed (Meierdiercks et al. 2010, 2017; Ogden et al. 2011), location and connectivity of impervious surfaces (Mejía and Moglen 2010; Roy and Shuster 2009), and location of stormwater management infrastructure (Meierdiercks and McCloskey 2022; Smith et al. 2015).

The interactions of humans with natural and built hydrologic networks are equally as important. Recognizing watersheds as connected human-water systems (Linton and Budds 2014; Norman et al. 2012) is necessary “for participating in decision-making about environmental issues such as protecting fresh water supplies,” (Gunckel et al. 2012) and it is critically “important in order for public policy makers to more fully understand which parts of the integrated system are most at risk. When systems thinking is limited, catastrophes ensue. With respect to water, lead contamination in Flint, Michigan is a clear example of systems thinking failure” (Attari et al. 2017). The poisoning of Flint’s drinking water (2014–2016) was a result of failures in the City’s technical, financial, and managerial systems (Sokolow 2017). While lead leaching out of Flint’s pipes caused the poisoning (technical failure), the decision to switch to a new, more corrosive water source without corrosion control was made to save money (failures in the managerial and financial systems). Systems thinking can be used to better understand Flint’s and other complex water distribution systems, as well as watershed systems comprised of natural and built networks. For example, systems mapping and modeling tools can identify missing connections and impacts to aid in planning, decision-making, and anticipating outcomes (Erban and Walker 2019). Yet, despite the critical importance of understanding hydrologic, socio-hydrologic and hydrosocial systems, few people can trace water through a natural and built hydrologic network (Attari et al. 2017; Gill et al. 2014; Gunckel et al. 2012). Thus while understanding the hydrologic connectivity of watersheds is important for determining the boundaries of a watershed, and understanding the ways water flows through natural and built water systems is important for policy to protect ecosystems and humans, when watersheds are defined and depicted as lumped areas, these connections are lost.

Hydrologic and socio-hydrologic connection across watersheds

In rural or forested watersheds, tracing upstream flow pathways is based primarily on topography. However, in urban environments, the determination of these flow pathways is less straightforward (Kayembe and Mitchell 2018). Urban infrastructure such as stormwater pipes, wastewater systems, and municipal water systems can alter and reshape topographically determined flow pathways. For example, differences in watershed area of between 5 and 25% have been observed when the watersheds were delineated using topographic versus stormwater network² data (Jankowsky et al. 2013; Kayembe and Mitchell 2018). Furthermore, water regularly moves across these boundaries in a range of ways. Virtual water and interbasin water transfer are just a few examples of the permeability of conventional watershed boundaries. And with the world becoming increasingly urban - the World Bank estimates that 56% of the world’s population lives in cities, with that percentage increasing to about 70% by 2050 (World Bank 2023) - the traditional definition of a watershed will become more and more outdated and obsolete.

Interbasin water transfer (IBT) is one of the most significant ways water can move across topographically-delineated watershed areas. IBTs move water from one watershed to another using pipes, canals, or aqueducts for irrigation, public water supply, flood control, and navigation (Siddik et al. 2023). Globally, MacDonald et al. (2014) estimate 12.2% of large cities use IBTs for a portion of their water supply. In the United States, though construction of new IBT projects had ceased by the late 1960s due to environmental concerns and high social and economic costs (Ghassemi and White 2007), there are currently a total of 615 IBT projects in the US (Siddik et al. 2023), most are concentrated in cities (Dickson and Dzombak 2017), and many provide significant amounts of drinking water to those cities. For example, 90% of New York City’s drinking water is supplied by the Catskill/Delaware and Croton watersheds, located up to 125 miles away in upstate New York (New York City Department of Environmental Protection 2021).

The area that drains to a point in a river in increasingly urbanized landscapes is therefore very different than it was in 18th century France, where the term was first ‘invented’ (Molle 2009). In developed areas, where most of the world’s population now lives, the area that drains to a river can include neighboring topographically-delineated areas, as well as areas miles away. Yet all of these areas are hydrologically and socio-hydrologically connected. Therefore we suggest watershed definitions and depictions should be inclusive of both natural waterways and complex human-built systems of networks that move water between various basins throughout the world.

Misuse of the term watershed and the consequences

Given the inadequacies in the ways the term watershed is defined and depicted, and that many people do not understand the watershed concept, it is not surprising that the term watershed is not only misused by the general public but also by watershed professionals. The term watershed is regularly applied to areal units that are not true topographically-delineated watersheds, as in the publicly available and widely used Watershed Boundary Dataset. Despite its name, it is not a dataset of watershed boundaries, but Hydrologic Unit areas that can be either a watershed or a piece of a watershed, and only 40–60% of Hydrologic Units are true topographical watersheds (Omernik et al. 2017). Given the misleading title, the dataset is often used synonymously with watersheds, and Hydrologic Units can be treated as topographically-delineated watersheds, although they are not (Omernik et al. 2017). Hydrologic Unit Code (HUC) maps, first published in 1987 were described as “a set of maps depicting approved boundaries of, and numerical codes for, river-basin units of the United States” as a way to standardize and organize hydrologic data (Seaber et al. 1987). Hydrologic Unit data are available as maps and GIS data as the Watershed Boundary Dataset, defined as, “a nationally consistent watershed dataset that is subdivided into 6 levels (12-digit HUCs) and is available from the USGS and USDA-NRCS-National Cartographic and Geospatial Center’s (NCGC)” with each polygon representing all or part of a watershed (https://water.usgs.gov/GIS/huc.html). Thus two Hydrologic Units, depicted as separate polygon areas in the Watershed Boundary Dataset, may be two parts of the same hydrologically-connected watershed, though the polygons do not represent that connectivity.

As a result, Hydrologic Units and other watershed areas are misused in technical, “watershed scale” studies. Omernik et al. (2017) cite numerous peer-reviewed and government studies that have treated Hydrologic Units as traditional watersheds thereby potentially missing upstream and downstream connectivity: “hydrologic units and watersheds are commonly treated as synonymous, and this misapplication and misunderstanding can have some serious scientific and management consequences.” For example, water quality data (which is representative of the entire upstream area), if applied to a Hydrologic Unit, could misrepresent stream conditions in that region (Omernik et al. 2017). Other potential consequences include flood peaks being underestimated or failures to understand the ways aquatic species move up and down a river system. Furthermore, the Watershed Boundary Dataset is widely used to depict watersheds on public websites. By defining these as watersheds, a community might not fully understand to which watershed they belong and that they are connected to upstream and downstream Hydrologic Units.

These tools, and the way they define and depict scientific concepts, have given us a certain picture of ‘the way the world works’, but we must be critical of the situations under which these concepts were “invented” and how they’ve been used over history. Moreover, we need to evaluate whether they are the appropriate tool at all (Cohen & Davison 2011; Sarna-Wojcicki et al. 2019). The widely used “Watershed Boundary Dataset” is mapped as lumped areas and incomplete watersheds, a useful geometry and scale for a number of purposes. But these data can be treated as watershed boundaries without careful consideration of how these areas fail to depict the ways water, people, and places are connected to upstream and downstream neighbors. When municipalities and local organizations then use these data to make decisions, even though it is ‘not a true representation of the watershed’, they may mislead those trying to work within the watershed system.

Methods

Definitions of the term watershed were collected from online sources and from textbooks (from K-12 to higher education). Any images that accompanied or were associated with the definition were also collected. Definitions and images were coded and analyzed in Dedoose using a content analysis approach. Each of these steps is described in additional detail below.

Obtaining definitions of the term watershed and associated images

Online definitions were obtained through a Google search of the phrase “define watershed”. The definitions from the top result web pages were compiled for a total of 51 definitions. For the web pages that included an image of a watershed along with the text definition, the images were also compiled, for a total of 30 images from 24 sources (some websites contained multiple images associated with a single text definition). A list of all sources of definitions used in this study is provided in Appendix A.

K-12 textbooks included in the analyses were identified using the list of recommended textbooks by the Advanced Placement Board for AP Environmental Science, the National Science Teaching Association (NSTA) list of recommended earth science books, and through a Google search (15 total, Appendix B). For higher ed textbook definitions, Open Syllabus Explorer (https://opensyllabus.org/) was used to find the top 20 textbook titles with the term “watershed” in the title, 20 with “water resources” in the title, and 20 with “hydrology” in the title. These textbooks, as well as the K-12 textbooks, were obtained through Siena College’s interlibrary loan service. Duplicate titles, or textbooks for which a definition could not be identified, were removed from the sample. Whenever possible, the newest edition of the textbook was used, but in some cases, the edition of the textbook used was determined by availability through the interlibrary loan service. Three additional textbooks from the Siena College library stacks and three from the first author’s personal collection were also included, for a total of 38 higher ed textbooks analyzed (Appendix C).

Definitions were found for both K-12 and higher ed textbooks by first looking at each textbook’s glossary, if available. Then definitions were identified within the pages indicated in the subject index. If a definition of the term watershed was not identified in either a glossary or within the watershed subject index pages, the introductory chapter or any chapters on watersheds was explored for a definition. Definitions for the terms river basin, catchment, and drainage basin were identified using this same procedure. It was noted when one of these terms was used in place of, interchangeably with, or in addition to the term watershed. If a figure or image was referenced with the text definition, the associated image (7 from 7 K to 12 textbooks, and 18 from 16 higher ed textbooks) was saved along with the definition text. For six sources, no definition of a watershed was provided, but a common synonym (catchment or drainage basin) was provided. For these sources, an assumption was made that the term was used as a synonym for the term watershed.

Identifying codes

A content analysis approach was used to identify themes in the text definitions of the term watershed (Schreier 2012) and the images associated with those definitions (Banks 2014; Bell 2001). Initial coding was used on a subset of the definitions to identify major themes. These codes were then refined based on the literature describing watershed literacy, particularly studies describing conceptual models of watersheds (Shepardson et al. 2007), ideal watershed literacy standards (Endreny 2010; Gunckel et al. 2012), and common misconceptions of watersheds (Covitt et al. 2009; Dove et al. 1999; Shepardson et al. 2007). Additional codes were added during the coding process to account for themes not already captured during the initial coding process. For ease of analysis, separate codes were applied to text definitions and their associated images (Tables 1 and 2), however, there is significant overlap between the two, particularly with regard to depictions of internal or external connectivity and function.

Definitions and images were coded using Dedoose (Salmona et al. 2020). To test inter-reliability, two researchers independently coded all images and definitions, code applications were compared, and where there was disagreement in codes, they collaboratively decided on the most appropriate code to apply (Wilber and Pasricha 2017). Independent variables, called “descriptors” in Dedoose were also determined and applied. Salmona et al. (2020) define descriptors as information that describes the data and helps the researcher distinguish between data points or groups of data. For this study, descriptors were used to enable comparisons between definitions and images from online versus textbook sources.

Table 1 Codes and subcodes of text definitions of the term watershed

Table 2 Codes and subcodes of images associated with text definitions (Table 1) of the term watershed

Results

Results of the content analysis of the text definitions and associated images are shown in Tables 3 and 4, respectively. Percentages indicate the prevalence of each code for all sources, online sources, and K-12 and higher ed textbooks.

Text definitions

While the majority (96%) of text definitions describe a watershed as an area (98% of online sources, 93% of K-12 textbooks, and 89% of higher ed textbooks), there are many variations on this theme (Table 3). Most (82%) area definitions describe a watershed as the area draining to or through an outlet or point on a waterbody (82% of online sources, 67% of K-12 textbooks, and 84% of higher ed textbooks use this definition). The variations of the area definition include: area of land drained by a river (17% of all sources, 9.8% of online sources, 60% of K-12 textbooks, 7.9% of higher ed textbooks), area of land defined by topography (13% of all sources, 2.0% of online sources, 0% of K-12 textbooks, 32% of higher ed textbooks), area of land that captures rainwater or precipitation (12% of all sources, 12% of online sources, 0% of K-12 textbooks, 16% of higher ed textbooks), area of land draining to a low point (8.8% of all sources, 9.8% of online sources, 0% of K-12 textbooks, 11% of higher ed textbooks), area of land separated or surrounded by a divide (5.9% of all sources, 5.9% of online sources, 0% of K-12 textbooks, 7.9% of higher ed textbooks), area of land that captures runoff (4.9% of all sources, 3.9% of online sources, 0% of K-12 textbooks, 7.9% of higher ed textbooks), and area of land that separates two water bodies (3.9% of all sources, 5.9% of online sources, 0% of K-12 textbooks, 2.6% of higher ed textbooks). About one fifth of sources (19%) define a watershed as a divide (24% of online sources, 0% of K-12 textbooks, 18% of higher ed textbooks).

For internal processes, about one fifth of sources (22%) describe hydrologic connectivity through a natural network within the watershed (14% of online sources, 80% of K-12 textbooks, 7.9% of higher ed textbooks). Only 1.0% describe built drainage networks (0% of online sources, 0% of K-12 textbooks, 2.6% of higher ed textbooks), and 13% describe a single channel within the watershed (10% of online sources, 33% of K-12 textbooks, 7.9% of higher ed textbooks). A greater percentage (26%) describe surface runoff (18% of online sources, 40% of K-12 textbooks, 32% of higher ed textbooks); one or more elements of the water cycle, typically precipitation (17% all, 18% of online sources, 0% of K-12 textbooks, 21% of higher ed textbooks); groundwater (7.8% all, 10% of online sources, 6.7% of K-12 textbooks, 5.3% of higher ed textbooks); the flow, movement or connection to non-water biological, chemical, and/or physical elements (8.8% all, 9.8% of online sources, 20% of K-12 textbooks, 2.6% of higher ed textbooks); or runoff at the watershed divide (1.0% all, 0% of online sources, 0% of K-12 textbooks, 2.6% of higher ed textbooks).

For external forces, 7.8% describe any human activity (5.9% of online sources, 6.7% of K-12 textbooks, 11% of higher ed textbooks), and 2.0% specifically describe pollution (2.0% of online sources, 0% of K-12 textbooks, 2.6% of higher ed textbooks). None describe interbasin transfer or movement of water between topographically-delineated areas. Several different uses of watersheds are described: 10% are described as hydrological units (0% of online sources, 0% of K-12 textbooks, 26% of higher ed textbooks), 4.9% are described as planning or management units (0% of online sources, 0% of K-12 textbooks, 13% of higher ed textbooks), 2.9% are described as biophysical units (2.0% of online sources, 0% of K-12 textbooks, 5.3% of higher ed textbooks), 2.9% are described as separate or crossing political or municipal boundaries (2.0% of online sources, 0% of K-12 textbooks, 5.3% of higher ed textbooks), and 2.9% are described as technical units (0% of online sources, 0% of K-12 textbooks, 7.9% of higher ed textbooks).

Over one-third (35%) of text definitions mention that the term watershed is synonymous with one or more of the terms river basin, drainage basin, and/or catchment (5.9% of online sources, 53% of K-12 textbooks, 66% of higher ed textbooks). Much fewer (5.9%) make a distinction between these terms (0% of online sources, 0% of K-12 textbooks,16% of higher ed textbooks).

Table 3 Prevalence of codes (n/N) for all text definition sources, combined (N = 102), online (N = 51), K-12 textbook (N = 15), and higher ed textbook (N = 38). n is the number of sources for which the code was applied at least once

Associated images

For the images that are associated with these text definitions, half (50%) are an idealized or simplified drawing or diagram of a watershed with three-fourths (75%) of all online images, and one-quarter (25%) of both K-12 and higher ed textbook images are shown as a schematic (Table 4; Fig. 1). 40% of all images are shown as a geographic information systems (GIS) generated map (29% of online sources, 75% of K-12 textbooks, 38% of higher ed textbooks). Fewer (21%) include an image that depicts a technical aspect of watersheds, such as parameters included in a water balance (0% of online sources, 0% of K-12 textbooks, 63% of higher ed textbooks), while only 10% include a landscape photograph (8.3% of online sources, 13% of K-12 textbooks, 13% of higher ed textbooks). Most (67%) of the images depict a watershed in three dimensions (83% of online sources, 50% of K-12 textbooks, 50% of higher ed textbooks), and 40% depict a two-dimensional watershed (25% of online sources, 63% of K-12 textbooks, 50% of higher ed textbooks). Only 2.1% of the images are four-dimensional, depicting either the movement of water or human activities, or the dynamic nature of urbanized landscapes (0% of online sources, 0% of K-12 textbooks, 6.3% of higher ed textbooks). Code co-occurrence analysis indicates that three-dimensional schematics are the most common type of images associated with watershed definitions.

The most common geography depicted in the images is mountains or high relief (65% all, 71% of online sources, 50% of K-12 textbooks, 63% of higher ed textbooks), while forested landscapes are also common (52% all, 79% of online sources, 38% of K-12 textbooks, 19% of higher ed textbooks). Other land use types are not as well represented, including suburban (29% all, 54% of online sources, 13% of K-12 textbooks, 0% of higher ed textbooks), urban (25% all, 50% of online sources, 0% of K-12 textbooks, 0% of higher ed textbooks), and agricultural (27% all, 50% of online sources, 13% of K-12 textbooks, 0% of higher ed textbooks). Code co-occurrence analysis indicates a high occurrence of images with high relief also including forested landscapes compared to other land use types.

Compared to text definitions, the associated images are much more likely to depict internal functions or processes within the watershed. The majority (81%) show a natural hydrologic network (88% of online sources, 63% of K-12 textbooks, 81% of higher ed textbooks), 31% depict groundwater (58% of online sources, 0% of K-12 textbooks, 6.3% of higher ed textbooks), and 35% show one or more other elements of the water cycle (54% of online sources, 13% of K-12 textbooks, 19% of higher ed textbooks). Overland runoff or runoff at the watershed divide is less likely to be depicted (respectively, 19% all, 25% of online sources, 13% of K-12 textbooks, 13% of higher ed textbooks; 15% all, 25% of online sources, 13% of K-12 textbooks, 0% of higher ed textbooks). Fewer images include the built hydrologic network (10% all, 17% of online sources, 13% of K-12 textbooks, 0% of higher ed textbooks); a single stream channel (8.3% all, 4.2% of online sources, 25% of K-12 textbooks, 6.3% of higher ed textbooks); or flow, movement or connection to non-water biological, chemical, or physical elements (2.1% all, 4.2% of online sources, 0% of K-12 textbooks, 0% of higher ed textbooks). Overall, one-third of all images depict some type of human activity (33% all, 58% of online sources, 13% of K-12 textbooks, 6.3% of higher ed textbooks). Only 2.1% depict pollution (4.2% of online sources, 0% of K-12 textbooks, 0% of higher ed textbooks). One K-12 textbook image depicts interbasin transfer. Code co-occurrence analysis indicates a high occurrence of images with a natural stream network with high relief or forested landscapes, and in three-dimensions.

Table 4 Prevalence of codes (n/N) for all associated image sources, combined (N = 47), online (N = 24), K-12 textbook (N = 7), and higher ed textbook (N = 16). n is the number of sources for which the code was applied at least once

Fig. 1

Representative images associated with the text definition of the term watershed. Categories of images include GIS map (left), schematic (center), and landscape photograph (right)

Discussion

Watersheds as inter- and intra-connected socio-hydrologic systems

Results of the content analysis of the definition of the term watershed indicate a striking uniformity in the way watersheds are defined in both online sources and textbooks. About one fifth of sources define a watershed as a ridge or boundary separating two areas. However, the vast majority (96%) of definitions describe a watershed as an area (Table 3). Though there are many slight variations of this definition, most (82%) describe a watershed as an area that drains to or through a waterbody or outlet (Table 3).

Only one image and no definitions describe hydrologic connectivity across topographically-delineated watersheds. While most (81%) images do depict a surface channel network, fewer (22%) text definition sources describe the channel system. Fewer still describe (8.8%) or depict (2.1%) the flow of or connection to non-water physical, biological, or chemical elements. While one-third (33%) of images depict human activity, only 7.8% of definitions describe human activities. Notable exceptions include the following. Watersheds are,

• 1. “interconnected systems of land, water, air, and the plant and animal species they support - including humans” (Riverside-Corona Resource Conservation District, Appendix A).

• 2. “spatially explicit landscape units that contain a range of interacting physical, ecological and social attributes” (ResearchGate, Appendix A).

• 3. “that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of the community” (Watershed Discipleship, Appendix A).

This third definition is notable in that it captures both connectivity and community. The definition is often attributed to John Wesley Powell. However, Drucshe (2011) identifies its original source as an essay written by Christopher N. Brown about Powell in a 1997 edition of River Voices, a newsletter published by River Network. Brown writes, “Powell understood in the 1870s not only the geological but also the political and social significance of a watershed: that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of the ‘community’” (Brown 1997). However, this definition is still problematic. Like the personal and professional lives of many in the environmental movement’s historical (and modern) past, Powell’s contributions to the field of watershed hydrology warrants careful examination and scrutiny. As the second director of the United States Geological Survey, Powell proposed dividing the arid west into these watershed communities. However, given the views of his contemporaries, and arguably Powell himself (Pico 2019), Powell’s “communities” may have excluded many. Thus we argue that a definition of a watershed should include connections between water and people as Powell’s did, but avoid defining so narrowly what and who those connections are (Koppes 2022; Sarna-Wojcicki et al. 2019).

Understanding and mapping the socio-hydrologic connections within a watershed is critical for identifying all of the upstream people, places and things that impact a point on a stream channel and for correctly identifying the boundary of the watershed system. When watersheds are defined, depicted and treated as areas rather than inter- and intra-connected systems, connections to water sources, even those that drain to the same point on a river system, may be missed. For example, many studies aim to correlate flooding or other water quality data, collected at a point on a river channel, to other biophysical, or demographic or socioeconomic information (Hill et al. 2018; Liu et al. 2009; Meierdiercks et al. 2017; Neville et al. 2022, for example). The water quality data is a measure not only of the water quality at that point, or even the area within close proximity to the point or the surrounding civil boundary (ex. zip code, census tract), but rather, all points upstream including water transferred through interbasin water transfer or water from a neighboring Hydrologic Unit (see discussion of the misnamed Watershed Boundary Dataset above). Therefore, a factory in a neighboring Hydrologic Unit or an area miles away but connected through IBT, will impact nutrient or bacteria levels measured at a point more than a farm that is close in proximity to the point but not hydrologically connected. And water quality may be poor throughout an entire watershed system, not just at the point, census tract, municipality, or Hydrologic Unit it is measured. A definition is needed that better reflects the watershed as a system, rather than points or areas, so that connections and community are identified using upstream and downstream proximity, not just linear distances. Otherwise, a management plan or study may misattribute poor water quality to a nearby farm rather than a socio-hydrologically connected, but distant factory.

We acknowledge that an analysis of the definition of a watershed as presented here is an important, but limited in scope step toward a fuller understanding of misconceptions and misuse of the watershed concept. Many factors not fully explored as part of this study (ex. educational or cultural background) impact a person’s understanding and view of a watershed, and could be the subject of subsequent analyses. We also acknowledge that the oft-used, conventional definition of a watershed, that of a topographically-delineated area that drains to a single point, is apt and accurate in many contexts, and in these contexts, the definition proposed here introduces unnecessary complexity. Our aim is not to entirely replace the conventional definition with another, but rather to encourage those who use and teach about the watershed concept, to consider an alternative way of thinking about watersheds.

Misconceptions tied to watershed depictions online and in textbooks

The results of this study can be used to further examine the hypothesis that inaccurate or incomplete depictions of watersheds contribute to common misunderstandings of the watershed concept (McCarroll and Hamann 2020; Shepardson et al. 2007; Zint and Kraemer 2012). When students were tasked with drawing a picture of a watershed, the accuracy and detail of their drawings varied from drawing a literal shed containing water for grade 4–12 students (Shepardson et al. 2007) to relatively complex, and nearly complete, water systems including both natural and built flow pathways for undergraduate students (Attari et al. 2017). Reviews of these studies highlight several themes in elementary to higher ed students’ incomplete understanding of watersheds (Covitt et al. 2009; McCarroll and Hamann 2020; Zint and Kraemer 2012). These include:

• Drawing mountains or high relief, even when that topography does not represent the student’s own watershed (ex. Shepardson et al. 2007).

• Not including elements of watershed that are not readily visible such as groundwater (Covitt et al. 2009; Gill et al. 2014).

• Drawing a watershed in a natural setting with little or no elements of the built environment or human activity (Dove et al. 1999; Endreny 2010; Shepardson et al. 2007).

• Not depicting hydrologic connectivity such as drawing a single stream rather than a network of streams channels (Covitt et al. 2009; Dove et al. 1999; Gill et al. 2014; Gunckel et al. 2012; Shepardson et al. 2007).

Place-based education can help students build a sense of place and connection to an area, resulting in enhanced environmental stewardship of those places (Ardoin 2006; Santelmann et al. 2011; Vallor et al. 2016), and can improve students’ understanding of the watershed concept (Endreny 2010). Yet, place-based watershed education is not feasible in all contexts and many students and adults, alike, must learn about watersheds from online sources and through textbooks. There is some evidence to suggest that students’ limited or incomplete understanding of watersheds is associated with the way they are graphically depicted on websites, textbooks, and other educational sources where students are learning about water (Shepardson et al. 2007; Zint and Kraemer 2012). Good visuals can contribute to learning by allowing readers to “interpret and integrate information with minimum cognitive processing, and should accompany text definitions” because, according to the dual processing theory and conjoint retention hypothesis, “the presence of graphics along with text has additive effects on learning because visual information is represented separately from verbal information in long-term memory” and can support students with diverse learning styles and preferences (Vekiri 2002). These visuals are among the many factors that may influence and shape the way people think about a concept (Fandel et al. 2018), which makes it particularly alarming when the visuals do not accurately depict these concepts. For example, Abbott et al. (2019) found that four flaws in the water cycle diagrams, “correspond directly with current failings in water management”, though they note that the inaccuracies could also reflect current misconceptions rather than, or in addition to, leading directly to them.

However, the results of this study suggest that the relationship between the depictions of watersheds and common misunderstandings about the watershed concept is not so direct.

• 1. Mountains and high relief. As suggested by Shepardson et al. (2007), most images of watersheds do depict high relief or mountains. This includes 65% of all images (71% of online images, 50% of K-12 textbook images, and 63% of higher ed textbook images).

• 2. Groundwater. Many students were not able to draw the invisible elements of a watershed such as groundwater (Covitt et al. 2009; Gill et al. 2014). Nearly one-third (31%) of all image sources depict groundwater. However, while 58% of online sources depict groundwater, 0% of K-12 textbooks, and 6.3% of higher ed textbooks do.

• 3. Natural setting/no human activity. Students tend to draw watersheds in a natural setting. One third (33%) of the images of watersheds analyzed in this study show some evidence of human activity. However, while 58% of online sources show some evidence of human activity, only 13% of K-12 textbooks, and 6.3% of higher ed textbooks do. Our results show that while forested land use dominates all three categories of sources of watersheds (52% of all images, 79% of online images, 38% of K-12 textbooks, and 19% of higher ed textbooks show forested landscapes), other land uses are also present, but more so in online images. 29% (54% of online sources, 13% of K-12 textbooks, 0% higher ed textbooks) show town and suburban land uses, 25% (50% of online sources, 0% of K-12 textbooks, 0% higher ed textbooks) show urban, city, or industrial land uses, and 27% (50% of online sources, 13% of K-12 textbooks, 0% higher ed textbooks) show agricultural land uses. 10% of all images (17% of online images, 13% of K-12 textbooks, 0% higher ed textbooks) show some elements of the built water networks such as wastewater treatment discharges or irrigation channels.

• 4. Hydrologic connectivity. Several studies point to students’ inability to describe or depict hydrologic connectivity within watersheds. However, of the images analyzed in this study, 81% (88% online, 63% K-12 textbook, 81% higher ed textbook) depict a drainage network with tributary streams emptying into larger water bodies, and 19% (25% online, 13% of K-12 textbook, and 13% higher ed textbook) depict overland flow.

Thus the hypothesis that suggests watershed images contribute to common misunderstandings about watersheds, is both supported and contradicted by the empirical evidence from this study. Of the images analyzed in this study, most, across all three categories of sources, do show hydrologic connectivity of the natural stream network. However, while many online images also depict groundwater and human activities and land uses, fewer K-12 and higher ed textbooks do, supporting the hypothesis that images in these sources can lead to incomplete understandings of the watershed concept, particularly for these elements. One explanation for the inconsistency between online and textbook images may be that the more modern online images have been updated to reflect common misunderstandings of watersheds. Online images were collected in 2022, while K-12 textbooks range in publication date from 2009 to 2023 (mean 2017) and the higher ed textbooks range in publication date from 1988 to 2019 (mean 2004). Yet, in content analyses of images of the water cycle, Abbott et al. (2019) found no significant gain in the number of images depicting human activity in the time period before 2006 and after 2005. We argue that another plausible explanation is that inadequate text definitions of the term watershed - particularly definitions that do not describe socio-hydrologic connectivity - equally contribute to misunderstandings of the watershed concept.

However, most images, across all three categories of sources, depict mountainous regions with forested land uses. This landscape is typical of a temperate deciduous forest climate located in the Northern hemisphere and does not reflect the many other biomes that exist globally. The over-representation of a single watershed landscape may contribute to an individual’s inability to connect the images of the watersheds to their own watershed. Many people don’t know they live in a watershed and don’t know the name of their watershed (McCarroll and Hamann 2020) and most students drew watersheds in mountains although that landscape did not reflect their local topography (Shepardson et al. 2007). Furthermore, half of the images (50%) are simplified schematic drawings. While 40% of images are GIS maps, only one of these was drawn at a scale so viewers could identify distinguishable features such as roadways. The lack of a representation of real-life, distinguishable features may also hinder a person’s connection to their local watershed.

Conclusion

The term watershed is widely misused and misunderstood by the general public, researchers, practitioners, and policymakers. The consequences are wide-ranging from technical mistakes in watershed studies to not fully understanding how a community’s water is impacted by upstream neighbors. Moreover, these definitions can lead to policies and decisions made about a watershed that are misleading, and at worst, catastrophic as in the Flint Michigan water crisis. Some may argue that, given all of these inadequacies, we should jettison the word completely. Yet, we argue that instead, a critical examination of the definition and use of the term watershed is needed, and requires both a critique of the traditional, oft-used definition, and a content analysis of the definition. Furthermore, an updated version is well overdue that incorporates the diverse uses of and within modern watersheds, better reflects one’s personal connection to their own watershed, and is inclusive of the many sociocultural understandings of hydrologic connectivity.

Content analyses of definitions of the term watershed from online sources and from textbooks (K-12 to higher ed), highlight the uniformity of how watersheds are defined and depicted. The majority of definitions are close variations of: the area of land that drains to a single point. Watersheds are depicted as a simplified schematic with mountainous and forested landscapes, and are not representative of the watersheds in which most people live. Though many include river networks in these images, few describe other forms of connectivity within a watershed. A notable exception is Brown’s interpretation of John Wesley Powell’s understanding of watersheds as: “that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of the community” (Brown 1997). We build on Brown’s definition, the understanding of watersheds as inter- and intra-connected socio-hydrologic systems and propose the following definition of a watershed:

A watershed defines the boundaries of a system of hydrologically connected people, places, and things; the activities at every point in a watershed impact all points downstream and are impacted by activities at all points upstream.

The image that accompanies this definition, in contrast to the definition, which is necessarily broad and inclusive, should be precise and specific. When possible, the image should be of the watershed to which the viewer belongs and include the land use types in that watershed, both the natural and built water systems, IBTs, and culturally-important elements (parks, restaurants, roadways, etc.) that would help the viewer place themselves within and to the watershed. Though Hydrologic Units are more convenient to map, when a watershed community or classroom requires such a map they could partner with groups offering technical assistance such as a local college or university or mapping software such as USGS Streamstats could be modified to show IBTs, land use, and user-generated features. These images should be used as tools to connect communities to the watersheds they occupy and manage.

While place-based watershed education and hydrosocial and socio-hydrological research can deepen our understanding of the connections between people and water within watersheds, those who participate in these endeavors are limited. The definition and associated images of a watershed are likely the first, or only, exposure many have to the watershed concept, despite its importance for an environmentally literate and civically engaged population. Results from this study demonstrate that the most-often used definition of the watershed concept is inadequate and there is an opportunity to present the watershed concept in a better, and more holistic, relatable, and inclusive way.

Appendix

Appendix A. sources for online definitions and images used in this study (accessed, July 2022)

Alabama ACES, What Is A Watershed? - Alabama Cooperative Extension System, https://www.aces.edu/blog/topics/watershed-stewardship/what-is-watershed/.

AMRclearinghouse.org, WHAT IS A WATERSHED, http://www.amrclearinghouse.org/Sub/WATERSHEDbasics/WhatIsAWatershed.htm.

Britannica Dictionary, Watershed Definition & Meaning | Britannica Dictionary, https://www.britannica.com/dictionary/watershed.

ByJus, Watershed Definition - Discover the meaning of watershed, its implications and FAQs, https://byjus.com/biology/watershed-definition/.

Cambridge Dictionary, WATERSHED | definition in the Cambridge English Dictionary, https://dictionary.cambridge.org/us/dictionary/english/watershed.

City of Lincoln Nebraska, What is a Watershed? – City of Lincoln, NE, https://www.lincoln.ne.gov/City/Departments/LTU/Utilities/Watershed-Management/What-is-a-Watershed.

Collins Dictionary, Watershed definition and meaning | Collins English Dictionary, https://www.collinsdictionary.com/us/dictionary/english/watershed.

Connecticut Department of Energy and Environmental Protection, Watershed Management - Overview, https://portal.ct.gov/DEEP/Water/Watershed-Management/Watershed-Management---Overview.

Dictionary.com, Watershed Definition & Meaning | Dictionary.com, https://www.dictionary.com/browse/watershed.

Earth.com, What is a Watershed? Am I In One? • Earth.com, https://www.earth.com/earthpedia-articles/what-is-a-watershed-am-i-in-one/.

EPA, Basic Information and Answers to Frequent Questions | US EPA, https://www.epa.gov/hwp/basic-information-and-answers-frequent-questions.

Erie.gov, What is a Watershed? | Environment & Planning, https://www3.erie.gov/environment/what-watershed.

Extension Utah State University, What is a Watershed, https://extension.usu.edu/waterquality/learnaboutsurfacewater/watersheds/whatisawatershed.

Freie Universtat Berlin, What is a watershed?, https://www.geo.fu-berlin.de/en/v/iwm-network/learning_content/introduction_iwm/definition-watershed/index.html.

Georgia Aquarium, What is a Watershed? | Georgia Aquarium, https://www.georgiaaquarium.org/wp-content/uploads/2018/10/What-is-a-Watershed.pdf.

H2OC, What Is A Watershed? - H2OC Stormwater Program, https://h2oc.org/resources/runoff-101/what-is-a-watershed/.

Indiana Department of Environmental Management, IDEM: Nonpoint Source: What is a Watershed, https://www.in.gov/idem/nps/what-is-a-watershed/.

Learning to Give, https://www.learningtogive.org/units/watershed-sos-saving-our-sources/what-watershed.

Lee County, SW Florida, What is a Watershed Basin?, https://www.leegov.com/naturalresources/WaterQuality/watersheds.

Lexico, Dictionary.com, https://www.lexico.com/en/definition/watershed.

Long Tom Watershed Council, What Is A Watershed?, https://www.longtom.org/about-ltwc/watershed-diagram/.

MacMillan Dictionary, WATERSHED (noun) definition and synonyms | Macmillan Dictionary, https://www.macmillandictionary.com/us/dictionary/american/watershed.

Merriam-Webster, Watershed Definition & Meaning - Merriam-Webster, https://www.merriam-webster.com/dictionary/watershed.

Michigan Environmental Education Curriculum, http://techalive.mtu.edu/meec/module01/whatiswatershed.htm.

Milwaukee River Keeper, What’s a River Basin? What’s a Watershed? | Milwaukee Riverkeeper, https://milwaukeeriverkeeper.org/whats-a-river-basin-whats-a-watershed/.

Minnesota Department of Natural Resources, What is a Watershed? | Minnesota DNR, https://www.dnr.state.mn.us/whaf/key-concepts/ws_def.html.

Minnesota Pollution Control Agency, Watershed approach to water quality | Minnesota Pollution Control Agency, https://www.pca.state.mn.us/water/what-watershed.

Mississippi Watershed Management Organization, What is a Watershed? - MWMO, https://www.mwmo.org/learn/watershed-and-stormwater-basics/what-is-a-watershed/.

NatGeo, Watershed, https://education.nationalgeographic.org/resource/watershed.

National Park Service Lesson Plan, LESSON 2: WHAT IS A WATERSHED?, https://www.nps.gov/common/uploads/teachers/lessonplans/What-is-a-Watershed-pdf.pdf.

New Jersey Gov, https://www.nj.gov/dep/watershedrestoration/docs/shedbrochure.pdf.

NSRWA, What is a Watershed?, https://www.nsrwa.org/what-we-care-about/what-is-a-watershed/.

Ocean Service, What is a watershed?, https://oceanservice.noaa.gov/facts/watershed.html.

Onondaga Environmental Institute, Definition of Watershed - Onondaga Environmental Institute, https://www.oei2.org/our-watershed/definition-of-watershed/.

Oxford, https://www.google.com/search?q=define+watershed.

Plansponsor, TRIVIAL PURSUITS: Meaning and Origin of the Idiom “Watershed Moment?” | PLANSPONSOR, https://www.plansponsor.com/trivial-pursuits-meaning-origin-idiom-watershed-moment/.

Quick and Dirty Tips, https://www.quickanddirtytips.com/education/grammar/what-is-a-watershed-moment.

Riverside-Corona Resource Conservation District, What is a Watershed? - Riverside-Corona Resource Conservation District, https://www.rcrcd.org/what-is-a-watershed.

Roanoke VA, What is a Watershed? | Roanoke, VA, https://www.roanokeva.gov/2152/What-is-a-Watershed.

Rocky Mountain Research Station, https://www.fs.fed.us/rm/boise/research/techtrans/projects/scienceforkids/watersheds.shtml.

Science How Stuff Works, What Is a Watershed? | HowStuffWorks, https://science.howstuffworks.com/environmental/conservation/issues/watershed1.htm.

Stroud Water Research Center, What is a Watershed? - Leaf Pack Network, https://leafpacknetwork.org/learn/watersheds/.

Study.com, Watershed Facts & Examples | What Is a Watershed? | Study.com, https://study.com/academy/lesson/what-is-a-watershed-definition-facts-protection.html.

The Free Dictionary, definition of watershed by The Free Dictionary, https://www.thefreedictionary.com/watershed.

The Watershed Institute, What Is A Watershed? | thewatershed.org, https://thewatershed.org/what-is-a-watershed/.

University of Minnesota Extension, What is a watershed? | UMN Extension, https://extension.umn.edu/watersheds/what-watershed.

urban dictionary, Urban Dictionary: watershed, https://www.urbandictionary.com/define.php?term=watershed.

USGS, Watersheds and Drainage Basins | U.S. Geological Survey, https://www.usgs.gov/special-topics/water-science-school/science/watersheds-and-drainage-basins.

Virginia Cooperative Extension, What Is a Watershed?, https://www.hanovercounty.gov/DocumentCenter/View/4746/What-is-a-Watershed-PDF.

Vocabulary.com, Watershed - Definition, Meaning & Synonyms | Vocabulary.com, https://www.vocabulary.com/dictionary/watershed.

Wake County North Carolina, What is a Watershed? | Wake County Government, https://www.wakegov.com/departments-government/water-quality-programs/watershed-management-erosion-sedimentation-control-floodplain-and-stormwater-management/stormwater-and-environment/what-watershed.

Watershed Discipleship, What is a Watershed?, https://watersheddiscipleship.org/what-is-a-watershed/.

Wiktionary, watershed - Wiktionary, https://en.wiktionary.org/wiki/watershed.

Wiley Online Library, A Watershed Integrity Definition and Assessment Approach to Support Strategic Management of Watersheds - Flotemersch − 2016 - River Research and Applications - Wiley Online Library, https://onlinelibrary.wiley.com/doi/full/https://doi.org/10.1002/rra.2978.

WVCA, WVCA - WHAT IS A WATERSHED?, https://www.wvca.us/envirothon/a5.cfm.

Appendix B. sources for K-12 textbook and resource definitions and images used in this study

Berg, Environment, John Wiley and Sons, 2018.

Chiras, Environmental Science, Jones and Barlett, 2016.

CK-12 Foundation, CK-12 Earth Science for Middle School, 2012.

Cunningham, Principles of Environmental Science: Inquiry and Applications, McGraw-Hill Higher Education, 2023.

Friedland, Environmental Science for the AP® Course, Bedford, Freeman, and Worth, 2023.

Hassenzahl, Visualizing Environmental Science, John Wiley and Sons, 2016.

Inspire Science: Earth G9-12, McGraw Hill Education, 2020.

Keeley, Uncovering student ideas in earth and environmental science: 32 new formative assessment probes. NTA Press/National Science Teachers Association, 2016.

McKinney, Environmental Science: Systems and Solutions, Jones and Bartlett Learning, 2019.

Mead, Earth Science, Holt McDougal, 2009.

Miller, Exploring Environmental Science for AP, Cengage Learning, 2021.

Miller, Living in the Environment, Cengage Learning, 2021.

Sampson, Student Lab Manual for Argument-driven Inquiry in Earth and Space Science: Lab Investigations for Grades 6–10. National Science Teachers Association, 2018.

Withgott, Environment: The Science Behind the Stories, AP Edition, Pearson Education, 2021.

Wright, Environmental Science: Toward A Sustainable Future, Pearson Education, 2017.

Appendix C. sources for higher ed textbook definitions and images used in this study

Asawa, Irrigation and Water Resources Engineering, New Age International Ltd, 2015.

Bedient, Hydrology and Floodplain Analysis, Pearson, 2019.

Black, Watershed Hydrology, Ann Arbor Press, 1996.

Brooks, Hydrology and the Management of Watersheds, Wiley-Blackwell, 2013.

Cech, Principles of Water Resources: History, Development, Management, and Policy, Wiley, 2003.

Chin, Water-Resources Engineering, Pearson / Prentice Hall, 2013.

Chow, Applied Hydrology, McGraw-Hill,1988.

Davie, Fundamentals of Hydrology, Routledge, 2019.

DeBarry, Watersheds: Processes, Assessment, and Management, Wiley, 2004.

Dingman, Physical Hydrology, Waveland, 2008.

Gordon, Stream Hydrology: An Introduction for Ecologists, Wiley, 2004.

Heathcote, Integrated Watershed Management: Principles and Practice, Wiley,1998.

Holden, Water Resources An Integrated Approach, Routledge, 2014.

Hornberger, Elements of Physical Hydrology, Johns Hopkins University Press,1998.

Jones, Global Hydrology, Routledge, 1997.

Linsley, Water-Resources Engineering, McGraw-Hill, 1992.

Maidment, Handbook of Hydrology, McGraw-Hill,1993.

Mays, Water Resources Engineering, Wiley, 2001.

Murty, Watershed Management, New Age International, 2004.

Raghunath, Hydrology: Principles, Analysis, and Design, New Age International, 2006.

Rajora, Integrated Watershed Management: A Field Manual for Equitable, Productive and Sustainable Development, Rawat Publications,1998.

Roni, Stream and Watershed Restoration: A Guide to Restoring Riverine Processes and Habitats, Wiley, 2013.

Rose, An Introduction to the Environmental Physics of Soil, Water, and Watersheds, Cambridge University Press, 2004.

Satterlund, Wildland Watershed Management, Wiley, 1992.

Singh, Watershed Planning and Management, Yash Publising House, 2000.

Singh, Handbook of Applied Hydrology, McGraw-Hill, 2017.

Singh, Computer Models of Watershed Hydrology, Water Resources Publications,1995.

Subramanya, Engineering Hydrology, Tata McGraw-Hill Publishing Company Limited, 2009.

Tideman, Watershed Management Guidelines for Indian Conditions, Omega Scientific, 1996.

Viessman, Introduction to Hydrology, Pearson, 2008.

Ward, Environmental Hydrology, CRC Press, 2004.

Wurbs, Water Resources Engineering, Pearson / Prentice Hall, 2002.