Water on the Ground: Lakes, Wetlands, Streams, and Flooding

What are the main processes that form lakes?

Glaciation, volcanism, tectonics, streamflow, natural dams, cave collapse, ice dam collapse, permafrost thaw, coastal processes, and human engineering.

What are wetlands?

Permanently or intermittently moist areas that include swamps, marshes, and bogs, characterized by high biological productivity and waterlogged soils.

What is the origin of all streams?

All streams begin from sheet flow (overland flow), glacial melt, or springs.

What are the two types of flow in streams?

Storm flow and base flow.

What defines ephemeral streams?

Streams with no base flow.

What defines perennial streams?

Streams with base flow.

How much of global precipitation becomes surface flow?

40%.

What is a watershed?

An area or ridges of land that separate waters flowing to different rivers, basins, or seas.

What are the components of a watershed?

Tributaries, drainage basins, and divides.

What is the significance of the Coosa River Basin?

It is a critical freshwater resource for the area, covering 5,500 square miles in Georgia.

What role do streams play in the hydrologic cycle?

Streams play a fundamental role in both the hydrologic cycle and the rock cycle.

What factors control the size and shape of a stream channel?

Rock erodibility, channel steepness, and water volume.

What is the gradient of a stream?

The vertical distance that a stream channel descends along its course, which decreases downstream.

What predictable changes occur in a stream from source to mouth?

Width and depth increase, gradient decreases, flow velocity and discharge increase, and turbulence decreases.

What is a meander in a stream?

A bend in a low gradient stream, where velocity is lowest along the inside and highest along the outside.

What is a point bar?

Sediment that accumulates on the inner side of a meander.

What is a cut bank?

The collapse of the stream bank that occurs on the outside of a meander.

What is an oxbow lake?

A lake formed when a stream bypasses a channel loop, cutting it off.

What is a braided channel?

A stream that cannot transport the entire sediment load, resulting in interlacing channels divided by sediment bars.

What are floodplains?

Areas where fine sediment is deposited beyond natural banks during a flood.

What are alluvial fans?

Fan-shaped bodies of sediment at the base of an upland area.

What are deltas?

Deposits formed when a stream enters standing water of a sea or lake.

What causes flooding?

When a stream's discharge exceeds the capacity of the channel.

What is the recurrence interval in flooding?

The average time interval between two floods of equal magnitude.

What are some consequences of flood prevention and channelization?

Interference with ecosystems, aggravation of pollution, potential subsidence, and invalidation of historic hydrologic data.