Streams and Rivers

I. The basics of streams and rivers?A. The primary characteristic distinguishing

Streams and rivers from other bodies of water is flowing water.

1. The term “stream” can be used to describe any naturally flowing water. 2. Stream flow is a term describing the general

water flow in streams. 3. Very large streams are referred to as “rivers”. 4. A common trait all healthy streams and rivers share is nurturing diverse ecosystems.

B. The are 15 major river basins in Texas and over 3,700 named streams. 1. All the streams and rivers in Texas collectively flow over 191,000 miles. 2. Most of the rivers in Texas begin within the state and empty into the Gulf of Mexico. 3. Rivers form the borders of Texas. a. The Red River forms the northern border. b. The Sabine River forms the eastern border with Louisiana.

C. The Rio Grande River forms the southern and western border with Mexico. It is the second longest river in the US.

C. Natural physiographic regions give each river it’s own unique characteristics as it flows through them. 1. The variations of bedrock, soil, elevation, weather, vegetation and land use can change a river. 2.The rivers’ shape, length, flow, plants, animals, water quality, and streambed composition are affected by the various regions.

D. Streams provide water to rivers in a variety of ways. 1. Springs may support streams. 2. Large amounts of water may come from city wastewater treatment facility. 3. Runoff from rain collects in watersheds a. The amount of rainfall determines the size and flow of streams and the kind of aquatic ecosystems found there. b. Periods of low rainfall may cause streams to naturally dry up during certain time of the year. These are called ephemeral streams.

II. Components of a Stream A. Channel is the deep part of the stream where water collects to flow downstream. 1. Channel water always runs down hill. 2. The main force of currents is located in the middle of a straight stretch of stream. 3. The deepest water is usually in the middle,

while the shallowest part is near the shore. 4. Sharp curves in the river create the strongest current causing the deepest water to move to the outside edge of the

curve.

5. In flowing water, there is less current near the bottom. 6. Pools are deeper, slower-moving places in the stream channel. 7. Riffles are the shallow, faster flowing places in the stream channel, identified by small waves on the surface. 8. Runs are the fast moving water between riffle areas and pools. 9. Rapids may form where the water flows downhill very fast and pushes up against underwater obstacles, often in very turbulent water flow.

http://youtu.be/OpO9xVvMcyU

B. Stream banks are the shoulder-like sides of the stream channel. 1. Stable stream banks have plants growing on them. 2. The plant roots stabilize the soil, minimizing stream bank erosion. 3. Stream bank erosion may cover the stream’s bottom with sediment, causing habitat destruction and aquatic organisms to smother.

C. The riparian zone is the transition area between the stream edge and the uplands 1. Contains trees and smaller plants extending outward on either side of the stream. 2. Zones with heavier plant growth functions as a buffer, against non-point source water pollution. 3. Tree shaded riparian zones contain cooler water, increasing the amount of dissolved oxygen the water can hold. 4. The leaves and land insects fall into the water providing organic matter for aquatic food webs.

D. The flood plain is the relatively flat land extending outward on both sides of a stream or river. 1. When flooding occurs, large amounts of additional water overflow the stream banks and spread out to cover the floodplain. 2. By nature, flooding is a common

occurrence for all streams. 3. Floodplains reduce the floodwater’s speed resulting in less damage in the stream and to areas downstream.

4. Building homes and roads in flood plains, ignoring the natural purpose of floodplains has resulted in loss of lives and property during floods. 5. Flood plains usually contain rich soils making it an ideal location for farming.

Now let’s watch the importance of floodplains!

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III. Aquatic Ecosystems A. Biodiversity in streams and rivers 1. Texas ranks second in the US for river and stream biodiversity primarily due to the diverse habitats in Texas. 2. They contain over 250 native species of fish and 25 non-native species. 3. East Texas has the greatest diversity in their streams and rivers due to the amount of rain it receives as compared to West Texas. B. Minnows, darters, suckers, sunfish, bass and catfish are the most common stream fish.

C. 50 mussels species found in Texas Rivers.D. Texas streams contain thousands of aquatic invertebrates.

DarterSunfish

Bass

Catfish