An Active River Beth Roland Eighth Grade Science Jacobs Fork Middle The Birth of a River Beth Roland Eight Grade Science Jacobs Fork Middle School

It starts with a single drop! Individual drops of water are drawn together by the process of cohesion. The chemical composition of water (2 atoms of Hydrogen, bonded to one atom of Oxygen) creates a polar molecule with a positive side and a negative side. This polar opposites allow one water molecule to be attracted to another.

A drop to a stream..... A stream of water joins other streams to eventually form a tributary. From a tributary to a river and with other rivers, a larger body of water is created! Drop Stream Tributary River Lake, Gulf, Ocean

Here, there and Everywhere River systems are divided into watersheds or drainage basins. The area of land interrelated by close rivers comprise the basin.

A Day in the Life.. A river serves many purposes to wildlife, humans, and Flora (plant life), –Habitat –Necessity of Life –Food Web –Recreation –Energy (Hydrologic Plants) –Transportation

Characteristics of a River Channel~ A channel is the path that a stream follows. A channel begins narrow and steep and over time as rock and soil is transported becomes longer and wider. Gradient~ the measure of the change in elevation (height) over a certain distance. The higher the gradient, the greater the energy of the moving water. Discharge~ The amount of water that a stream or river carries in a given amount of time. This is influenced by addition of water into a waterway (melting snow, large amounts of rain).

Characteristics Continued.. Erosion~ is the process of transportation of soil and sediment from one location to another. -Wind, water (ice, snow, and rain) all agents of erosion. Load~ The materials carried by a river - size of the load is effected by the stream’s speed and will also then effect the erosion process.

Stages of a River In the early 1900’s William Morris Davis developed a model for the stages of river development Youthful River~ erodes the channel wider, is steeper in gradient, has very few tributaries

Mature River Mature River~ erodes it channel wider rather than deeper, gradient is less than a youthful river, fewer falls and rapids, fed by many tributaries. A greater discharge is found in a mature river.

Old Age Old River~ has a low gradient and little erosive energy. Instead of widening or deepening its banks, an older river deposits rock and soil along the channel. Old rivers have flat flood plains and many bends. Tributaries join together to feed into a mature river.

Rejuvenated Rivers Rejuvenated River~ found wehre the land is raised by tectonic activity. As land rises, the gradient becomes steeper, river flows more quickly, cuts more deeply into the valley floor. Terraces are often formed.