Unit 2: Physical Hydrology

Overview

This section of the course outlines the distribution of water on land and its organization into watersheds and major river systems. Rivers are one of the major concentrated sources of fresh water that can be extracted for human use for agriculture, industry, and drinking water, prior to flowing into the oceans. Another potential source of fresh water is so-called "groundwater," which consists of water held in subsurface rock units with varying potential for storage and yield. This helps us explain the distribution and dynamics of water at the surface and in the subsurface of the Earth. At times the water distribution through river systems is either subject to a deficit of water (drought) or surfeit (flood), subject to variations in climate or to unusual meteorological events. Humans attempt to control these variations by constructing dams to regulate river flow and store water for use, particularly in dry regions. However, dams, although providing water and power, have consequences for the environment.

This section provides a more detailed overview of water transport and availability and highlights issues with water storage in reservoirs and in the subsurface. In subsequent modules, we learn how water availability influences civilizations, both past and present.

Modules

Unit Goals

Upon completion of Unit 2 students will be able to:

Describe the two-way relationship between water resources and human society.
Explain the distribution and dynamics of water at the surface and in the subsurface of the Earth.
Synthesize data and information from multiple reliable sources.
Interpret graphical representations of scientific data.
Identify strategies and best practices to decrease water stress and increase water quality
Thoughtfully evaluate information and policy statements regarding water resources
Communicate scientific information in terms that can be understood by the general public

Unit Objectives

In order to reach these goals, the instructors have established the following learning objectives for student learning. In working through the modules within unit 1 students will be able to:

Explain the processes by which precipitation accumulates, moves through, and is transported out of a watershed.
Describe the physical components of a river channel and floodplain.
Define the different types of sediment transported in rivers and explain to a first-order the physical processes governing sediment transport.
Explain the various techniques by which humans attempt to restore hydrologic, geomorphic and ecological functions of rivers and watersheds.
Explain the role of ‘extreme events’ in the water cycle and distribution of water on Earth’s surface.
Explain a few basic techniques for organizing and analyzing hydrologic data, including time series plots and histograms.
Articulate the difference between a forecast and a prediction and provide examples of each.
Define the term flood, describe the factors that influence the magnitude of a flood, and explain the implications of floods for society and ecosystems.
Compute the probability that a flood or drought of a given Recurrence Interval might occur (e.g., the 100 year flood).
List the different types of droughts and be able to explain the basic implications of each for society and ecosystems.
Define the terms stationarity and non-stationarity and explain the implications for flood predictions.
Explain the reasons why dams are built, and how these differ in different locations
Weigh the advantages and drawbacks of large dams
Consider the causes of conflict and controversy across national borders associated with large dam projects
Explain the issues caused by sediment trapping behind dams
Debate the justification for building and rationale for removing dams
Identify an artesian well and predict where artesian wells will be found
Distinguish between porosity and permeability
Associate hydraulic properties with given rock types
Interpret relative permeability from a well productivity diagram