Problem Statement

Hydrologic drought refers to a deficit of water in one or more components of the hydrosphere, resulting in abnormally low streamflow in rivers and streams and low levels in lakes, reservoirs, and groundwater. Although physical factors such as climate and weather variations are typically the primary causes of droughts, anthropogenic factors such as irrigation, land use, reservoir-building, and diversions or extractions of water can also cause or exacerbate droughts. As a result, hydrologic droughts are becoming increasingly common due to both climate change and anthropogenic stressors.

In this module, we examine droughts but focus primarily on droughts in rivers and streams. First, we give background to droughts in terms of presenting definitions of the types of droughts, what is and is not a drought through case studies, examine concepts such as magnitude, frequency, and duration of droughts and their interactions, and examine the role of anthropogenic factors and hydrologic droughts. Second, we examine a variety of drought indices used in different situations and apply real-world data to the calculation of drought metrics. Next, we use streamflow data to examine hydrologic droughts through the use of flow and dimensionless flow duration curves. Students then learn strategies to communicate information about hydrologic droughts by adapting the climate stripes method to create "streamflow stripes" and create stream-flow heat maps to show changes in long-term annual and monthly averages of streamflow. Finally, students communicate about a hydrologic drought situation using their graphics and narration through role-playing as a water manager to various stakeholders.

Module Overview

This module exposes students to quantitative and graphical analysis of hydrologic droughts with a focus on rivers and streams. We introduce students to hydrologic indices and indicators used by the federal government regarding drought or low flow conditions in streams. Students apply e-flows software and become familiar with other software useful for assessing drought including Excel and IHA (indicators of hydrologic Alteration). Then, they use flow duration curves and dimensionless flow duration curves to assess long-term change associated with river regulation or other drivers. We visualize drying streams with Excel-derived colorful graphics called stream-flow stripes and stream-flow strips or "heat maps" of annual and monthly data. Ultimately, students synthesize this information into a case study of a drying stream or streams to educate and inform stakeholders about water stewardship. These activities are relevant to students interested in careers in water monitoring, management, sustainability, and conservation.