(Worksheet – Groundwater Part 2) Thursday March 1, 2018 (Worksheet – Groundwater Part 2)

The Launch Pad Thursday, 3/1/18 List two important functions of groundwater. Give an example of each. Geologically, groundwater is important as an erosional agent. The dissolving action of groundwater slowly removes soluble rock, allowing depressions known as sinkholes to form as well as creating subterranean caverns. Hydrologically, groundwater is also an equalizer of streamflow. Much of the water that flows in rivers is not direct runoff from rain and snowmelt. Rather, a large percentage of precipitation soaks in and then moves slowly underground to stream channels.

Remediation for Quiz 12 ends tomorrow! Announcements Remediation for Quiz 12 ends tomorrow!

QUIZ 12 Next Tuesday F6 2/22 N/A S3 2/23 F7 F8 F9 Assignment 2/26 2/27 Summative or Formative # Date Issued Gone Missing Day Last Day Accepted Video Worksheet – What Rivers Can Tell Us About the Earth’s History F6 2/22 N/A Save for eResearch Paper QUIZ 12 S3 2/23 Next Tuesday Worksheet - Groundwater (Part 1) F7 2/26 Worksheet -What Is Groundwater? and Groundwater Flow Part 1) F8 2/27 Video Worksheet - What Is Groundwater? Groundwater Flow – Part 1 F9 2/28

Water Tables

Features Associated with Groundwater Whenever the water table intersects the ground surface, a natural flow of groundwater results, which we call a spring. The water in hot springs is 6 - 9°C warmer than the mean annual air temperature of the locality where they occur. The heat for hot springs is provided by the cooling of igneous rock.

Features Associated with Groundwater Geysers are intermittent hot springs or fountains in which columns of water are ejected with great force at various intervals. The water turns to steam and erupts.

The stages in the eruption cycle of a geyser. A The stages in the eruption cycle of a geyser. A. Groundwater enters underground caverns and fractures in hot igneous rock, where it is heated to near its boiling point. B. Heating causes the water to expand, with some being forced out at the surface. The loss of water reduces the pressure on the remaining water, thus reducing its boiling temperature. Some of the water flashes to steam. C. The rapidly expanding steam forces the hot water out of the chambers to produce a geyser. The empty chambers fill again, and the cycle starts anew.

Features Associated with Groundwater The most common method for removing groundwater is the well, a hole bored into the zone of saturation. Pumping a well can cause a drawdown (lowering) of the water table, forming a cone of depression in the water table.

Formation of a cone of depression in the water table Figure 5.31

Features Associated with Groundwater Artesian Wells The term artesian is applied to any situation in which groundwater in a well rises higher than the initial groundwater level.

Artesian Systems Figure 5.32

Figure 5.33

Environmental Problems Associated with Groundwater Some localities are concerned with possible contamination of their groundwater supply.

Although the contaminated water has traveled more than 100 metes before reaching well 1, the water moves too rapidly through cavernous limestone to be purified. B. As the discharge from the septic tank percolates through the permeable sandstone, it is purified in a relatively short distance.

The High Plains extend from the western Dakotas south to Texas The High Plains extend from the western Dakotas south to Texas. Despite being a land of little rain, this is an important agricultural region. The reason is a vast endowment of groundwater that makes irrigation possible through most of the region. The source of most of this water is the Ogallala formation, the largest aquifer in the U.S. In some agricultural regions, water is pumped from the ground faster than it is replenished. In such instances, water is being treated as a non-renewable resource.

The green area on the map is California’s Joaquin Valley The green area on the map is California’s Joaquin Valley. The marks on the utility pole indicate the level of the surrounding land in preceding years. Between 1925 and 1975, this area subsided almost 9 meters because of the withdrawal of groundwater and the resulting compacting of sediment.

Worksheet Groundwater (Part 2) Download the Worksheet titled “Groundwater (Part 2) from the class website under today’s date. Use the notes on this PowerPoint to answer the items on the Worksheet.