Abstract
Water security is the capability of a community to have adequate access to good quality and a sufficient quantity of water as well as safeguard resources for the future generations. Understanding the spatial and temporal variabilities of water security can play a pivotal role in sustainable management of fresh water resources. In this study, a long-term water security analysis of the Grand River watershed (GRW), Ontario, Canada, was carried out using the soil and water assessment tool (SWAT). Analyses on blue and green water availability and water security were carried out by dividing the GRW into eight drainage zones. As such, both anthropogenic as well as environmental demand were considered. In particular, while calculating blue water scarcity, three different methods were used in determining the environmental flow requirement, namely, the presumptive standards method, the modified low stream-flow method, and the variable monthly flow method. Model results showed that the SWAT model could simulate streamflow dynamics of the GRW with ‘good’ to ‘very good’ accuracy with an average Nash–Sutcliffe Efficiency of 0.75, R2 value of 0.78, and percentage of bias (PBIAS) of 8.23%. Sen’s slope calculated using data from over 60 years confirmed that the blue water flow, green water flow, and storage had increasing trends. The presumptive standards method and the modified low stream-flow method, respectively, were found to be the most and least restrictive method in calculating environmental flow requirements. While both green (0.4–1.1) and blue (0.25–2.0) water scarcity values showed marked temporal and spatial variabilities, blue water scarcity was found to be the highest in urban areas on account of higher water usage and less blue water availability. Similarly, green water scarcity was found to be highest in zones with higher temperatures and intensive agricultural practices. We believe that knowledge of the green and blue water security situation would be helpful in sustainable water resources management of the GRW and help to identify hotspots that need immediate attention.
Highlights
Water security is the capability of a community to have adequate access to good quality and a sufficient quantity of water as well as safeguard resources for the future generations [1]
The seemingly implacable rise in water demand, limited water supply, demographic changes, high standards of living, and uneven distribution of water resources are some of the factors that have led to a rise in water security issues all around the world [2]
Two snow-related parameters, snowfall temperature (SFTMP) and snowmelt temperature (SMTMP), were in the top five list, which was expected as the Grand River watershed (GRW) is in a cold climate region
Summary
Water security is the capability of a community to have adequate access to good quality and a sufficient quantity of water as well as safeguard resources for the future generations [1]. The seemingly implacable rise in water demand, limited water supply, demographic changes, high standards of living, and uneven distribution of water resources are some of the factors that have led to a rise in water security issues all around the world [2]. Many rivers around the world are running dry for considerable parts of the year before merging into the sea. The surface water resources, and the ground water is being overly exploited with pumping rates faster than replenishment, increasing threats to the availability of freshwater resources for irrigation, human consumption, energy production, and environmental sustainability [3,4]. A thorough understanding of the spatial and temporal variabilities of water security is required to sustain the available fresh water resources [7]
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