Lotic Systems

1. Lotic Systems Flowing water

2. Rivers • 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

3. Birth a River • Headwaters: • springs • snow melt originate in the higher elevations- gravity pulls them downward following the path of least resistance. Tributaries are smaller streams or feeder streams that empty into a larger stream or river.

4. A River’s Changing Form • Rivers are dynamic, their size, shape and content changes dramatically as they move through time and space.

6. Classification of Streams 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. • 2ndorder – 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. Rangeet Concluence: Teesta(lake) & Rangeet(glacier) India

7. Regions of a River Upper Reaches: Middle Reaches: Lower Reaches:

8. Upper Reaches • 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

9. Middle 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

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

11. Lotic Ecosystem • 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

12. Instream Habitats • 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

13. Stream Banks 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 animals 2. 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 waterquality • Habitat for insects Riparian zone

14. Stream types- climate • Rivers are dependent on climate and their characteristics are closely related to the precipitation and evaporation in their drainage areas: • Perennial- • Intermittent- • Ephemeral-