Lotic SystemsFlowing water

vitally important geologically, biologically, historically and culturally. contain only 0.001% of the total amount of the worlds water .

carry water and nutrients to areas all around the earth.

provide habitat, nourishment and a means of transport for organisms.

powerful forces create some of the most beautiful landscapes on earth.

provide travel routes for exploration, commerce and recreation.

leave valuable deposits of sediments forming flood plains.

Provide energy for hydroelectric plants- power our lives

Rivers

Headwaters:

springs snow melt

originate in the higher elevations-

gravity pulls them downward following the path of least resistance.

Birth a River

Tributaries are smaller streams or feeder streams that empty into a larger stream or river.

Rivers are dynamic, their size, shape and content changes dramatically as they move through time and space.

A River’s Changing Form

Streams are classified by size. 1st order - smallest, these are the

headwaters: they have no tributaries running into them. They begin as a spring, or an outlet from a lake, pond, or wetland.

2nd order – When two (2) 1st order streams converge to form a larger stream - confluence

3rd order- when two (2) 2nd order streams converge- and so on.

When all the streams in the watershed converge, the result is a large river that will empty ( mouth) into a lake or the ocean.

The Mississippi is a 12th order stream.

Classification of Streams

Concluence: Teesta (lake) & Rangeet (glacier) India

Rangeet

Upper Reaches:

Middle Reaches:

Lower Reaches:

Regions of a River

narrow V-shaped channel steep slopes water flow causes downward

cutting through earth- canyons and valleys

erosion Substrate is boulders, rocks,

cobble rapids and waterfalls channel is shaded by riparian

vegetation- water is cooler and temp. is consistent

few nutrients- litter from outside the stream provides most of the energy

species diversity is generally low

Upper Reaches

wider channel that are U-shaped moderate slopes more aquatic plants floodplains have developed water flow causes bank cutting more sediment more nutrients more organisms temperature are more varied

Middle Reaches

Wider channel Slower water flow Less changes in temperature Gentle gradient Wide valleys Wide flood plains Many meanders Increased depth and turbidity

Lower Reaches

A natural system provides a variety of habitats for many species of aquatic plants and animals.

The instream habitats provide areas for feeding, resting, and reproduction and generally support a great diversity of organisms.

Examples include: Rivers Streams Brooks Creeks Human made channels

Lotic Ecosystem

Pools-areas of slow moving water

Riffles-shallow areas where fast moving water forms waves

Root mats Aquatic plants Undercut banks Overhanging vegetation Leaf litter Submerged rocks and

logs

Instream Habitats

The riparian zone: the vegetated area of a stream bank which includes the flood zone.

The stream bank serves many functions including keeping the water in the channel.

1. Home to many plants and animals2. Help protect the stream from outside influences

When this zone is covered with trees, shrubs and herbaceous plants like; grasses and herbs

helps provide erosion control sediment collection

nutrient absorption.

contribute to maintain water quality

Habitat for insects

Stream Banks

Riparian zone

Rivers are dependent on climate and their characteristics are closely related to the precipitation and evaporation in their drainage areas:

Perennial- Intermittent- Ephemeral-

Stream types- climate