Potomac Watershed Puzzle -
Potomac Watershed Puzzle is an interactive program found on the blackboard in all of the PHWS classrooms. This activity explores the geography of watersheds.
A watershed is the area of land that drains to a river. In West Virginia, it is often easy to pick out watershed boundaries by looking for ridgetops and tracing which way water would flow down the hill. Watersheds have many parts that, together, create the environment where we live. The Potomac Watershed Puzzle provides an introduction to the many parts of the watershed
Precipitation falls onto the watershed in the form of rain, snow, hail, or sleet. Once it hits the ground it can travel to different places. It can sink deep into the ground, becoming the main source of water for an aquifer. It can also run off the surface of the ground into a stream, or sink just under the surface of the ground where it moves slowly downhill and can be taken up by plants. Precipitation hitting the ground can also loosen and carry soil away in the process called "erosion."
Animals are the living creatures that depend directly or indirectly on the vegetation for food. Animals often help plants disperse their seeds. Sometimes animals can clear the soil of vegetation by overgrazing and thus open it up to erosion.
A Stream is surface water flowing through a channel. Many streams in the Potomac watershed get most of their water from an aquifer, particularly during dry periods. Because surface water in streams is often connected to groundwater in aquifers, we can often learn about one by looking at the other. For example, if a stream dries up in the summer we can assume that the aquifer that supplies water to the stream has fallen. The stream is home to plants and animals like fish, crayfish, and aquatic insects.
Vegetation refers to the living plants of the watershed. Most plants depend on soil to hold them in place, and to provide them with nutrients and water for growth. Plant roots in turn help hold soil in place, and the above ground portion of plants can shield the soil from the impact of rainfall. This helps protect soil from erosion. The roots of vegetation can also help breakdown bedrock, and draw water and nutrients from the soil to the upper parts of the plant. Decayed vegetation helps to develop and enrich our soils.
Soil is the loose mineral matter on the earth's surface. The top layers of soil include both minerals and organic matter (decayed plants and animals). Soil is created from the weathering of bedrock, and its qualities are influenced by the type of bedrock it comes from, the climate, topography, and organisms. As water passes through this layer, it reacts with the surface of the mineral particles. During this process some of the dissolved minerals in the water stick or attach to the surface of the particles, and some of the soil minerals dissolve into the water. The soil also holds water so that it will be available for vegetation and soil organisms.
The Water Table is the top of an aquifer (the zone in the ground that is saturated with water). Water tables can be deep in the ground. They can also be right at the surface - as is the case for a swamp or a spring.
An Aquifer is a zone underground that is saturated with water. It is below the water table. Sometimes this zone includes the soil and even the surface of the ground. Aquifers deep underground in the bedrock tend to be better for many human uses like drinking and washing. Well water comes from aquifers. Modern wells are usually dug deep and cased to prevent contamination flowing in from water above. Aquifers are the main source of water in streams and rivers during dry periods.
Bedrock is the rock that appears as outcrops and underlies soil. It is made of minerals like quartz, gypsum, and apatite (a mineral component of limestone). Bedrock is often called the soilís "parent material" because the sand, silt and clay in the soil come from broken down, or "weathered" bedrock. Sometimes the parent material for a soil is the bedrock right below, and sometimes a soil's parent material comes from bedrock far upstream or uphill. Because water dissolves rock, the minerals that make up the bedrock can also influence how water in an aquifer tastes and smells, how sanitary it is, and how fast it can flow through the rock.