Streams and Rivers (Chapter 8)

Point Bar

Along the inside of a meander, water velocity is less and allows for sand or gravel to be deposited in point bar.

Trellis Drainage

An area of linear ridges and valleys develop a pattern in which streams and mostly follow the valleys, but can cut though the ridges

Rapids and Waterfalls

As a stream deepens its valley, it may encounter rocks that are resistant to erosion.

Kinetic energy

Gravity causes water in streams to flow down slope. The motion of the water is kind of energy (kinetic energy) that causes the stream to erode rock, transport and deposit sediment, and modify the shape of its valley.

Discharge Rate

Hydrologist typically quantify or rank streams by their discharge rate, defined as the total volume of water passing a point in a particular period of time.

Rejuvenation

If the broad plain undergoes uplift, a fourth distinctive stage of landscape evolution can occur.

Dendritic Drainage

If the rock is homogeneous, the pattern tends to resemble a tree in shape.

V- shape valleys

In humid areas, the effect of mass wasting and slope erosion caused by precipitation typically produces V-shaped valleys

Tributaries

In regions downstream from the headwaters, the gradient or slope of a stream decreases while its discharge increases because of the additional water being added by Tributaries.

Meanders

In the lower reaches as gradient decreases, sinuosity increases and lateral erosion will eventually develop hairpin loops know as meanders.

Natural Levee

Is a higher bank next to a stream where the stream has deposited sediments as it overflows or floods.

Sinuosity or Sinuosity index

Is a measure of how winding the course of a stream is.

Stream or River

Is any body of water that flows in a natural channel

Meander Scar

Is easy to identify on a topographic map due to the curvature of contour lines. (This is where the lake used to be)

Stream Gradient

Is important in determining certain characteristic of the stream. Stream gradient = change in elevation/ horizontal distance

Stream's Valley

Is the region directly and indirectly eroded by the stream, and it extends well beyond the stream channel.

Gravity

Many terms are used to describe streams, such as creeks, brooks, rills, rivers; but all refer to a channelized body of water that flows across the landscape in response to gravity.

Early, Middle, and Late stage

Streams and steam valleys evolve through three stages, commonly referred to as early, middle, and late stage. Streams can carve through uplands, forming canyons in the early stage; widen those canyons into broad valleys in a hilly terrain in the middle stage; and then reduce the hills to a broad plain in the late stages of landscape evolution.

Radial Drainage

Streams may radiate away from the central point

Volume and Velocity

The amount of energy of the water in the stream, and therefore the amount of work it does, depends on its volume and velocity.

Drainage Divide

The boundary that separates one drainage basin from another.

Oxbow Lake

The cut-off meander forms a crescent shaped lake

Bed load, Suspended load, and Dissolved load

The stream's kinetic energy can transport sediment by rolling, sliding, or hopping particles along the bottom (bed load), and by suspension in the water (suspended load). The chemical properties of water also permit it to carry sediment in solution (dissolved load).

Stage

The water level in a stream is called its stage, and historical stage levels and discharge rate are often used to estimate the probability of flooding in a particular area.

Rectangular Drainage

They can follow regularly fractured rock

Determining the Sinuosity index

To determine the sinuosity index, measure the length of the channel along the stream's path and divide by the straight-line distance down the valley.

Chute

When meanders become to sinuous that the thin area of land between two meanders is cut through

Flooding

When stream's velocity or its volume increases, its ability to carry sediment increases, and it will erode material from its bottom and sides.

Stream Valleys (Downcutting)

Which deepens the channel toward base level

Stream Valleys (Headward erosion)

Which extends the head of the valley upslope

Stream Valleys (Lateral erosion)

Which widens the valley walls

Cut Bank river

On the outside of the meander, the outer bank is called the cut bank, because water velocity and turbulence are greater and the abrasive energy of the water and suspended sediments erodes the stream bank

Hydrologist

People who study natural water system and the transfer of surface water from one body to the next are referred to as hydrologist

Drainage Basin

The geographical area drained by a stream