Saturday, April 30, 2011

How humans affect rivers


Here is a list of some things that humans can do that have a negative impact on river ecosystems:

the levels of the water. Damming can be a great renewable resource for power, but it may destroy river ecosystems downstream. Damming can also be an effective flood control measure to ensure towns and neighborhoods are safe. Dams can obstruct the path of migratory fish and disrupt the life cycle of many different

This can have a major effect on floodplains.
– Modifying a stream or river into a pattern other than what may be its natural meandering.

storm drain will flow directly into the river. Many people don’t realize this water isn’t "cleaned" before it runs right into a natural waterway.
– Discarding materials into a river. Any chemical, such as car oil or antifreeze, poured down a

riding horses, walking a dog, fishing from a boat, or simply having a picnic. All of these activities could have a negative impact to river wildlife if not done carefully.
– Activities done for relaxation or enjoyment. Examples of river recreation are driving ATVs,


Domestic Animals
- Waste from livestock can be washed into rivers, adding excessive nutrients and illness causing bacteria. Pet waste can also be a problem, but they are more likely to impact the wildlife of the river by chasing or hunting.

– Careless disposal of trash and waste.– Obstructing the flow of a river or stream for energy production, to create a lake, or to controlaquatic organisms.

Cherie and Nicole

Tuesday, April 19, 2011

The hydrologic cycle

Any river is part of a larger water cycle. The hydrologic cycle consists of:
-Surface runcoff

The hydrologic cycle is the process, powered by the sun's energy, which moves water between the oceans, the sky, and the land.
We can start our examination of the hydrologic cycle with the oceans, which hold over 97% of the planet's water. The sun causes evaporation of water on the surface of the ocean. The water vapor rises and condenses into tiny droplets which cling to dust particles. These droplets form clouds. Water vapor usually remains in the atmosphere for a short time, from a few hours to a few days until it turns into precipitation and falls to the earth as rain, snow, sleet, or hail.
Some precipitation falls onto the land and is absorbed (infiltration) or becomes surface runoff which gradually flows into gullies, streams, lakes, or rivers. Water in streams and rivers flows to the ocean, seeps into the ground, or evaporates back into the atmosphere.
Water in the soil can be absorbed by plants and is then transferred to the atmosphere by a process known as transpiration. Water from the soil is evaporated into the atmosphere. These processes are collectively known as evapotranspiration.
Some water in the soil seeps downward into a zone of porous rock which contains groundwater. A permeable underground rock layer which is capable of storing, transmitting, and supplying significant amounts of water is known as an aquifer.
More precipitation than evaporation or evapotranspiration occurs over the land but most of the earth's evaporation (86%) and precipitation (78%) take place over the oceans.
The amount of precipitation and evaporation is balanced throughout the world. While specific areas of the earth have more precipitation and less evaporation than others, and the reverse is also true, on a global scale over a few year period, everything balances out.
The locations of the water on the earth is fascinating. You can see from the list below that very little water is among us in lakes, the soil and especially rivers.
World Water Supply by Location
Oceans - 97.08%
Ice Sheets and Glaciers - 1.99%
Ground Water - 0.62%
Atmosphere - 0.29%
Lakes (Fresh) - 0.01%
Inland Seas and Salt Water Lakes - 0.005%
Soil Moisture - 0.004%
Rivers - 0.001%

Only during the ice ages are there noticeable differences in the location of water storage on the earth. During these cold cycles, there is less water stored in the oceans and more in ice sheets and glaciers.
It can take an individual molecule of water from a few days to thousands of years to complete the hydrologic cycle from ocean to atmosphere to land to ocean again as it can be trapped in ice for a long time.
For scientists, five main processes are included in the hydrologic cycle: 1) condensation, 2) precipitation, 3) infiltration, 4) runoff, and 5) evapotranspiration. The continuous circulation of water in the ocean, in the atmosphere, and on the land is fundamental to the availability of water on the planet.

Cherie and Nicole
1.2 :)

The resultant effect of volcanic eruptions

Explosive volcanic eruptions can pose both short–term and long-term effects and hazards. Lava flows can eradicate the flanks of mountainsides. Volcanic ash can cover huge amounts of land and ash clouds can disrupt air travel.
If the ash and mud from a volcanic eruption mix with rain water, it will turn rain into acid rain. If the ash mixes with rainwater or melting snow, fast moving mudflows are created. These mudflows are called lahars.
Lava flows and lahars can destroy settlements and clear areas of woodland or agriculture. The ash will also affect the atmospheric air and turn it into poisonous air, and will therefore be harmful to people’s health.
There are two ways which volcanic eruption can affect a country’s monetary development. One is the positive way, the other the negative. The positive way is that the lava and ash deposited during an eruption breaks down into sediments to provide valuable nutrients for soil. This creates very fertile soil which is good for agriculture, raising output and productivity. Farmers will be able to grow better quality crops and sell them. This will raise the country’s Gross Domestic Profit (GDP) per capita (per person), raising the country’s Human Development Index (HDI) value of the country.
GDP= The gross profit of the country
HDI= The development of the country
The negative way is that the ash or lava from the volcano will cover the farmer’s crops and the crops will die, lowering the country’s GDP per capita and reducing the HDI value of the country.
Not only are there negative impacts on the environment, there are also positive impacts. The dramatic scenery caused by volcanic eruptions attracts tourists. This brings income to an area.
The high level of heat and activity inside the Earth, close to a volcano, can provide opportunities for generating geothermal heat.

Cherie and Nicole
1.2 :)

Wednesday, April 6, 2011

The physical environment

The physical environment can be divided into four major components. These components are:
-Landforms and rocks
-Rivers, lakes and oceans
-Weather and climate
-Natural vegetation

An important and interesting concept in Geography is that everything is closely interrelated. These four components of the physical environment are also closely interrelated.As we study the physical environment,we will discover that the components do not exist on their own. Insread, they interact and affect one another. For instance, the amount of rain received in a plce affects the amount and type of natural vegetation growing there. Some types of plants grow better in a place that receives a lot of rain while other types of plants grow better in places that receives very little rain.

There are also different types of landforms. These types of landforms include:

A mountain is an area of high ground, more than 600 metres high. It often has steep slopes and a narrow peak or top.

A hill is an area of high ground, similar to that of mountains, but unlike mountains are less than 600 metres high It is usually rounded in shape and has gentle slopes.

A valley is a low area of land typically found betreen hills or mountains.

A plain is a broad, flat and low area on the Earth's surface.

A plateau is generally a raised area of land with a flat and braod top and steep slopes.

Cherie And Nicole :)