Rivers & Streams

From outer-space, the earth looks like it is covered with veins and arteries, similar to our bodies. The earth's arteries, however, are really a vast web of rivers and streams that channel water across the planet, from mountains to oceans. 

Although there are many rivers and streams, these sources of running water account for a very small portion of the earth's total surface, just .3%.

Watersheds

A watershed describes an area of land that contains a common set of streams and rivers that all drain into a single larger body of water, such as a larger river, a lake or an ocean. For example, the Mississippi River watershed is an enormous watershed. All the tributaries to the Mississippi that collect rainwater eventually drain into the Mississippi, which eventually drains into the Gulf of Mexico. Rainwater that falls on more than half of the United States subsequently drains into the Mississippi. 

 

A watershed can cover a small or large land area. In the St. Louis vicinity, for instance, the Meramec River is a small river draining a relatively small amount of land. Small watersheds are usually part of larger watersheds. The Meramec River watershed, which is supplied by even smaller watersheds from dozens of streams, drains into the Mississippi River. All the streams flowing into small rivers, larger rivers, and eventually into the ocean, form an interconnecting network of waterways. 

 

Not only does water run into the streams and rivers from the surface of a watershed, but water also filters through the soil, and some of this water eventually drains into the same streams and rivers.

These two processes, surface runoff and infiltration are important for a number of reasons.

For one, they affect water quality. Think about it... The water that runs off the surface of the Earth picks up water pollution and deposits the pollution in streams and rivers as it drains the watershed. Along with many different types of pollution that are carried by surface runoff, soil also becomes a water pollutant as it is eroded from farm lands. Water that filters through the soil can also become contaminated with pollution that is left over from agricultural, industrial, commercial, and other types of human activity. 

 

The network of streams and rivers that drain our watershed and carry water pollution ultimately empty into larger bodies of water, such as lakes and oceans. As the larger rivers carrying water pollution from the land flow into lakes and oceans, all of the pollution that was in the rivers now is concentrated into these other bodies of water. The oceans of the world become the final resting place for tons of pollution. Through our watersheds, pollution is distributed far away from its original source. And oviously, polluted water affects water quality.

The Science of the Watershed

Surface Runoff 

Much of the water that returns to Earth as precipitation runs off the surface of the land, flowing downhill into streams, rivers, ponds and lakes. This water eventually reaches the ocean or large lakes. 

Surface runoff is important to aquatic ecosystems, since the water running off the land eventually supplies these systems. Water, though, is not the only thing that runs off the land. Water also carries water pollutants and soil, and both are deposited into aquatic ecosystems. 

Infiltration

Not all water runs off the surface of the land. Some of the water soaks into the ground through the soil and underlying rock layers—a process known as infiltration. When infiltration occurs, some of the water ultimately returns to the surface, while the rest remains below as groundwater. The various layers of soil act as a filter to help clean water. When water is badly polluted, however, this filtering system is not nearly as effective. 

In some cases, water moving through the ground during infiltration can even pick up pollutants present in the soil. In such an instance, these pollutants are added to the streams and rivers when the water reaches the surface, or remains in the groundwater. 

Water Pollution

Anything that is added to the water of our aquatic ecosystems that is not a normal part of the systems, and that should not be there, is a type of water pollution. 

There are many sources of water pollution. Some types of pollution can be traced directly to a particular spot, such as a factory, or industrial plant. These sources of water pollution are easier to control, because the actual point where the pollution is being added to the water can be identified. 

Other types of pollution come from more widespread sources and are more difficult to control. For example, fertilizers spread on fields, runoff of livestock wastes from farming operations, soil resulting from erosion, pesticides sprayed on lawns and crops, and materials washed from streets into storm drains come from a variety of sources and are thus difficult to monitor. 

How Streams Become Rivers

The journey from stream to ocean begins in our backyards and farms.

Precipitation comes down, literally, everywhere—in various forms. It may rain, hail, snow or sleet. Whatever the form, once it reaches the ground some water is absorbed by trees and other plants. 

Water not absorbed by roots enters the ground water supply by infiltration. Most water runs off the surface, down a hill and eventually into a river. Ditches and small streams, which may be dry when it does not rain, can quickly fill up with water when it does rains.

Once the water finds its way into a stream or ditch, where does it go?

If you have ever studied a map in detail, you will notice how rivers and streams form a network of waterways across the countryside. 

Little streams come together to form small rivers. Small rivers join together and become medium-sized rivers. All these rivers may be tributaries of a large river. such as the Mississippi. Collectively, the network of rivers and streams form a watershed which drains the land of excess water.

This type of patern is repeated many places in nature. In the human circulatory system, for example, or in human lungs, like those represented to the left. When you exhale (breath out), your lungs behave just like a watershed. The air in your lungs (which is like the water in a watershed) starts out in the smallest vessels (which are like small streams), passing into larger vessels (that are like medium rivers) and finally into one large central air passage (which is like a large river). Ultimately, all the air in the lungs (which are like a large watershed) pass through this one large air passage, out your mouth, and to the atmosphere beyond, just as water in a watershed flows out the mouth of a large river and into the ocean! (Of course rivers don't breath in!)

 

It comes as no surprise that the widest rivers have the biggest watersheds. The Mississippi watershed drains about half the Midwest and eastern United States. 

Think about rivers as excess water disposal machines. Rivers transport water from wherever it is to the ocean. In places where it rains more, such as in the temperate deciduous forest and the rainforest, there are more rivers and streams to deal with the large and consistent annual rainfall. 

In the desert, however, there is significantly less rain. Logically, fewer rivers exist in the desert. When it does rain, the rains are very short and intense. Since there is no vegetation to absorb the water, almost all the water drains immediately into dry river basins that for most of the year look like flat plains. These rivers swell up very quickly and produce swift torrents. 

Rivers Running into the Ocean

Where rivers meet the ocean is called the mouth of the river. Soil and dirt carried by these rivers is deposited at the mouth, and new land is formed. The new, soil-rich land is known as a delta.

The Amazon River is the second longest river in the world. Like all large rivers, the Amazon deposits a lot of soil and sediment, forming a delta, as it enters the ocean. Its delta is located in Brazil. 

As rivers prepare to enter the ocean, they tend to get off course and branch into many directions, creating many small islands in the delta region. This is particularly true with the Amazon River, as you can see.

Scattered across the delta at the end of the Mississippi River is the city of New Orleans. By the time the mighty Mississippi winds its way south through America's center it becomes a force well over a mile wide. It's a very dramatic sight to watch as this mammouth river spills into the ocean.

Because the Mississippi watershed drains much agricultural land, it has high sediment content. The mud spilling from the river into the Gulf of Mexico is clearly visible in this picture.

The Nile River is the longest and probably the most famous river in the world. As it flows toward the Mediterranean Sea from the mountains of central Africa, it grows in size. The Nile Delta is a very large and impressive sight. It is home to some of the most productive agricultural land in the Middle East

Amazon Delta

Mississippi Delta

Nile Delta

Cross Section of River Zones

Study the below diagram carefully. Given what you have already learned, what information can you extract? 

Why is there a sharp bluff adjacent to the river? How was it created?

Is it a good or bad idea to develop land in the "gravel bar" area? Why or why not?

If you dump waste into this area, what are the two ways the water supply could be polluted? 

Why don't trees grow at the river's bank?

River                                Country          Miles        Kilometers

Nile                        Egypt           4,145            6,670

Amazon                  Brazil           4,000            6,404

Chang jiang - Yangtze        China          3,964            6,378

Mississippi-Missouri*         U.S              3,740            6,021

Yenisei-Angara*                  Russia        3,442            5,540

* River Systems

Longest Rivers in the World

Hydroelectric Power

What is a dam?

A dam is a man-made structure built across a river. Most dams are built to control river flow, improve navigation, and regulate flooding. However, some dams are built to produce hydroelectric power.

Hydroelectric power is produced as water passes through a dam, and into a river below. The more water that passes through a dam, the more energy is produced. Once a dam is built, an artificial man-made lake is created behind the dam.

Electricity is produced by a device called a turbine. Turbines contain metal coils surrounded by magnets. When the magnets spin over the metal coils, electricity is produced. Turbines are located inside dams. The falling water spins the magnets.

Dams provide clean, pollution free energy, but they can also harm the environment. Species that use rivers to spawn are often hurt by dams. In the Northwest, sockeye salmon and trout populations have dropped from 16 million to 2.5 million since hydroelectric plants were built on the Columbia River. Dams all over the world have hurt some species.

 

What are the highest dams in the                             U.S.?

The highest dam in the Unites States is located near Oroville, California. The Oroville Dam rises 754 feet (230 meters) and is more than a mile (1.6 km) wide. This dam was built in 1968, 22 years after the Hoover Dam. The Hoover Dam, on the Nevada-Arizona border controls the Colorado river. It is 726 (221 meters) feet high and stores 21.125 million acre-feet (2.6 million hectare-meters) of water in the 115 mile (192 km) long Lake Mead reservoir, behind the dam.

Where is the highest dam in the                              world?

The highest dam in the world is Nurek Dam on the Vakhsh River in Tadzikistan, a country in central Asia. This dam is 984 feet (300 meters) tall! 

Hoover Dam

Turbines

The Bonneville Dam in Oregon

Aquatic Animals

Anaconda

Class: Reptilia: Reptiles

Diet: Birds, other animals

Order: Squamata: Lizards and Snakes

Size: 9 m (29 1/2 ft)

Family: Boidae: Pythons and Boas

Conservation Status: Non-threatened

Scientific Name: Eunectes murinus

Habitat: swampy river valleys, stream banks

Range: South America, south to Argentina

One of the world's longest snakes, the anaconda spends much of its life in sluggish fresh water but also climbs small trees and bushes with the aid of its slightly prehensile tail. It does not pursue its prey but lurks in murky water, waiting for birds and animals to come to the edge to drink. It seizes its victim and then kills it by constriction. It can only remain submerged for about 10 minutes and usually glides along with the top of its head showing above the water.  In the breeding season, males court their mates by making loud booming sounds. Females produce litters of as many as 40 live young, each of which is about 66 cm (26 in) long at birth.

Arrau River Turtle

Class: Reptilia: Reptiles

Diet: Plants

Order: Chelonia: Turtles and Tortoises

Size: 961 - 76 cm (24 - 30 in)

Family: Pelomedusidae: Greaved Turtles

Conservation Status: Lower risk-Conservation dependent 

Scientific Name: Podocnemis expansa

Habitat: Orinoco and Amazon River systems

Range: Northern South America

The largest of the side-necks, the arrau turtle may weigh over 45 kg (100 lb). Females have wide, flattened shells and are larger and more numerous than males. Adults feed entirely on plant matter.  The nesting habits of these turtles are similar to those of sea turtles in that they gather in large numbers to travel to certain suitable nesting areas. They lay their eggs on sandbanks which are exposed only in the dry season, and there are relatively few such sites. The females come out onto the sandbanks at night, and each lays as many as 90 or 100 softshelled eggs. They then return to their feeding grounds. The hatchlings, which are about 5 cm (2 in) long, emerge to the attentions of many predators; even without man's activities, only about 5 percent reach adult feeding grounds.  Uncontrolled hunting of adults and excessive collecting of eggs have seriously reduced the population of this turtle. It is now an endangered species and is protected in most areas

Barbel

Class: Fishes: 4 classes

Diet: Larvae

Order: Cypriniformes: Carps

Size: 50 - 91 cm (19 3/4 - 35 3/4 in)

Family: No Fish family information

Conservation Status: Non-threatened

Scientific Name: Barbus barbus

Habitat: lowland rivers, streams

Range: Europe: Britain, south to Alps and Pyrenees, east to Hungary

A slender, long-bodied fish, the barbel has a characteristic high dorsal fin and two pairs of sensory barbels around its fleshy lips. It is a bottom-living fish, most active at night and at dusk, and feeds on insect larvae, mollusks and crustaceans. It is a member of the family Cyprinidae.  Barbels breed in late spring, often migrating upstream before spawning. They shed their eggs in shallow, gravel-bottomed water, where they lodge among the stones until they hatch from 10 to 15 days later.

Boutu

Class: Mammalia: Mammals

Diet: Fish, some crustaceans

Order: Cetacea: Whales

Size: 1.8 - 2.7 m (6 - 9 ft)

Family: Platanistidae: River Dolphins

Conservation Status: Vulnerable

Scientific Name: Inia geoffrensis

Habitat: rivers, streams

Range: Amazon basin

The boutu has a strong beak studded with short bristles and a mobile, flexible head and neck. Most boutus have a total of 100 or more teeth. Their eyes, although small, seem to be more functional than those of other river dolphins. Boutus feed mainly on small fish and some crustaceans, using echolocation clicks to find their prey. Boutus live in pairs and seem to produce young between July and September.

Central Stoneroller

Class: Fishes: 4 classes

Diet: Larvae

Order: Cypriniformes: Carps

Size: 10 - 18 cm (4 - 7 in)

Family: No Fish family information

Conservation Status: Non-threatened

Scientific Name: Campostoma anomalum

Habitat: clear creeks, streams, rivers

Range: Eastern USA, west to Minnesota and Texas

Typically, the central stoneroller lives in small streams in riffle areas (shallow water where the flow is broken by the stones and gravel on the streambed). It feeds at the bottom on tiny plants, insect larvae and mollusks.  In spring, the dorsal and anal fins of breeding males turn bright orange and black, and tubercles develop on the upper half of the body. The male makes a shallow nest in the gravel of the streambed, in which the female lays her eggs.

Common Pufferfish

Class: Fishes: 4 classes

Diet: Aquatic invertebrates

Order: Tetraodontiformes: Puffer, Triggerfishes

Size: 15 cm (6 in)

Family: No Fish family information

Conservation Status: Non-threatened

Scientific Name: Tetraodon cutcutia

Habitat: rivers

Range: India, Burma, Malaysia

One of the few freshwater puffers, the common pufferfish has a rotund body, attractively colored with green and patches of yellow. When threatened, it inflates its body with water until it is virtually globular, but it does not have skin spines. With its plump, rather rigid, body the puffer moves slowly, using undulations of its small dorsal and anal fins, but it compensates for this lack of speed by its defensive techniques. It feeds on bottom-dwelling invertebrates and on fish.  Common puffers are very popular aquarium fishes and have been bred in captivity. The female sheds her eggs on the bottom, where they are guarded by the male, who lies over them until they hatch.  Many members of the puffer family are considered good food fish, despite the fact that their internal organs -- and occasionally even the flesh -- are extremely toxic and can cause fatal poisoning. In Japan, chefs are specially trained in the cooking of puffers, known as fugu, but there are still a number of cases of poisoning.

Dipper

Class: Aves: Birds

Diet: Insect larvae, insects, other invertebrates

Order: Passeriformes: Perching birds

Size: 18 - 22 cm (7 - 8 1/2 in)

Family: Cinclidae: Dippers

Conservation Status: Non-threatened

Scientific Name: Cinclus mexicanus

Habitat: mountain streams

Range: Alaska, through Western North America to Panama

A wren-shaped bird, the dipper has a compact body, long, stout legs and a short, square-tipped tail. Its bill is hooked and is notched at the tip. Like all dippers, it frequents mountain streams and walks or dives into the water, swims underwater and even walks on the bottom, to obtain insect and invertebrate prey, especially caddis fly larvae.  A bulky, domed nest, made of moss and grass, is built by the female on a rock in a stream or beside a stream among tree roots or rocks; it has a side entrance. The female lays 3 to 6 eggs, which she incubates for 15 to 17 days.

Eurasian Otter

Class: Mammalia: Mammals

Diet: Fish, amphibians, birds, small mammals, other aquatic animals

Order: Carnivora: Carnivores

Size: 55 - 80 cm (21 1/2 - 31 1/2 in),

tail: 30 - 50 cm (12 - 19 1/2 in)

Family: Mustelidae: Mustelids

Conservation Status: Near threatened 

Scientific Name: Lutra lutra

Habitat: rivers, lakes, sheltered coasts

Range: Europe, North Africa, Asia

Although agile on land, otters have become well adapted for an aquatic life. The Eurasian otter has the slim mustelid body, but its tail is thick, fleshy and muscular for propulsion in water. All four feet are webbed, and the nostrils and ears can be closed when the otter is in water. Its fur is short and dense and keeps the skin dry by trapping a layer of air around the body. An excellent swimmer and diver, the otter moves in water by strong undulations of its body and tail and strokes of its hind feet. It feeds on fish, frogs, water birds, voles and other aquatic creatures.  Otters are solitary, elusive creatures, now rare in much of their range. They den in a riverbank in a burrow called a holt and are most active at night. Even adult otters are playful animals and enjoy sliding down a muddy bank. A litter of 2 or 3 young is born in the spring -- or at any time of year in the south of the otter's range. There are 8 species of Lutra, all with more or less similar habits and adaptations.

Gavial

Class: Reptilia: Reptiles 

Diet: Fish

Order: Crocodilia: Crocodiles, Alligators, Gavial 

Size: 7 m (23 ft)

Family: Alligatorianae: Alligators and Caimans 

Conservation Status: Endangered 

Scientific Name: Gavialis gangeticus 

Habitat: large rivers

Range: Northern India

The Indian gavial has an extremely long narrow snout, studded with about 100 small teeth -- ideal equipment for seizing fish and frogs underwater. Like all crocodilians, the gavial has been hunted for its skin, and it is now one of the rarest in Asia. Its hind limbs are paddle-like, and the gavial seems rarely to leave the water except to nest. The female lays her eggs at night in a pit dug in the riverbank.

Hellbender

Class: Amphibia: Amphibians

Diet: Crustaceans

Order: Urodela: Newts and Salamanders

Size: 30.5 - 74 cm (12 - 29 in)

Family: Cryptobranchidae: Giant Salamanders

Conservation Status: Near threatened

Scientific Name: Cryptobranchus alleganiensis

Habitat: rocky-bottomed streams

Range: East-central USA, west to Missouri

Despite the implications of its common name, this giant salamander is a harmless creature which feeds on crayfish, snails and worms. It has the flattened head characteristic of its family and loose flaps of skin along the lower sides of its body.  A nocturnal salamander, the hellbender hides under rocks in the water during the day. It depends on its senses of smell and touch, rather than on sight, to find its prey, since its eyes are set so far down the sides of its head that it cannot focus on an object with both eyes at once.  Hellbenders breed in autumn: the male makes a hollow beneath a rock or log on the stream bed, and the female lays strings of 200 to 500 eggs. As she lays the eggs, the male fertilizes them and then guards the nest until the eggs hatch 2 or 3 months later.

Red Piranha

Class: Fishes: 4 classes

Diet: Fish

Order: Cypriniformes: Carps

Size: up to 30.5 cm (12 in)

Family: No Fish family information

Conservation Status: Non-threatened

Scientific Name: Serrasalmus nattereri

Habitat: rivers

Range: Northern South America: Amazon basin

One of the carnivorous members of the family Characidae, the red piranha is not a large fish but swims in such large shoals that, together, the fishes form a formidable hunting group. They are armed with strong jaws and razor-sharp triangular teeth, which can chop pieces of flesh from a victim with alarming efficiency. Despite their very blood-thirsty reputation, carnivorous piranhas feed largely on fish and on seeds and fruit but will attack larger, usually wounded animals, which they quickly devour by their combined efforts.

Sunbittern

Class: Aves: Birds

Diet: Fish

Order: Gruiformes: Ground nesters

Size: 46 cm (18 in)

Family: Eurypygidae: Sunbittern

Conservation Status: Non-threatened

Scientific Name: Eurypyga helias

Habitat: forest streams and creeks

Range: Central America, South America to Brazil

The sunbittern is an elegant bird, with a long bill, slender neck and long legs. It frequents the well-wooded banks of streams, where it is perfectly camouflaged in the dappled sunlight by its mottled plumage. Fish, insects and crustaceans are its main foods, which it hunts from the bank or seizes with swift thrusts of its bill, while wading in the shallows.  In courtship display, the beautifully plumaged wings are fully spread, revealing patches of color, and the tips are held forward, framing the head and neck. The birds also perform a courtship dance, with tail and wings spread. Both partners help to build the large domed nest in a tree and incubate the 2 or 3 eggs for about 28 days.

Pictures & Information from www.mbgnet.net

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