Dams

Advantages	Disadvantages
water supplies assured prevent floods	people are forced to move ecosystems destroyed expensive water related diseases

A dam in Argentina

Yacyretá Dam

   The Yacyretá Dam is a dam and hydroelectric power plant built over the waterfalls of Jasyretâ-Apipé in the Paraná River, between the Argentine Province of Corrientes and the Paraguayan City of Ayolas.

   The construction of the dam affected the environment of the region in three ways. Firstly, it altered aquatic habitats because of the elevation of the water level and the flooding of dry areas, which produced chemical changes in the water, including a drop in water oxygen levels. Besides, the alteration of the streams of water affected the floating vegetation that in the system Iberá is the habitat of many species. The more calm water behind the dam has also allowed the spread of waterborne diseases, such as schistosomiasis, dengue fever and malaria. Destruction of the habitat submerged by the dam caused great loss of biodiversity. Numerous protected species have been affected in one of the few spaces in which they survive in Argentina and Paraguay, including pampas deer, capybara, certain water birds and yacare caiman. The consequences for the fish population of Paraná have been very severe, causing a large drop in the volume of some species, especially when the dam was first constructed. Moreover, the lake created by the dam displaced 40,000 people.

Water-rich and water-poor countries

  The video shows the different lifestyles of a boy who lives in a water rich country and a girl who lives in a poor water country. The boy lives under very good conditions and has easy access to drinking water (he just need to open the tap to get pure and fresh water), while the little girl has to travel miles and miles to get water that can sometimes be polluted. In my opinion, the video trys to represent that water rich countries can help the poor ones, since access to drinking water is a right that everyone should have.

 

Water uses

Uses of fresh water                             Examples

DOMESTIC -          In the home (shower, wash the dishes/clothe) -          For waste disposal INDUSTRIAL -          In factories -          For power (hydroelectric) AGRCULTURAL -          For irrigation

Tropical Cyclones

Satelite image of a hurricane.

   Tropical cyclones are like giant engines that use warm, moist air as a fuel. That is why they form only over warm ocean waters near the equator. The warm, moist air over the ocean rises upward from near the surface. Since this air moves up and away from the surface, there is less air left near the surface. Another way to say the same thing is that the warm air rises, causing an area of low air pressure below.
   According to where they occur they have different names. The name "hurricane" is given to systems that develop over the Atlantic and the eastern Pacific Ocean. In the western North Pacific and Philippines this systems are called "typhoons", while in the Indian and South Pacific Ocean they are called "cyclones". There is a list in which each hurricane is named with a woman or a mens name. What is a curious coincidence is that most of the small hurricanes were named with mens names, while the most catastrophic ones have a woman name.
   Hurricanes form within the tropics, usually between the end of summer and beginning of autumn. However, there are other neccessary conditions for hurricanes to develop. For example, the humidity must be high, with high rainfall and winds. Also water temperature must be high, at least 27°C.
    The Saffer-Simpson Scale is a 1 to 5 rating, based on a hurricane's sustained wind speed. This scale estimates potential property damage. Hurricanes reaching category 3 and higher are considered mayor hurricanes because of their potential for significat loss of life and damage. While category 1 and 2 are still dangerous but the damage can be reduced with preventative measures.
    The effects can be a storm surge, which means a rise in the ocean water level as a result of extreme winds blowing over the sea's surface. Other consecuences can be floods, heavy winds, death, injured people, diseases, an impact on the economy, etc. However, there are ways to lessen these effects. Nowadays, thanks to satelite images hurricanes can be predicted and people can get ready to reduce the damage. For example, they can store water and food supplies. The government can take some preventive action, such as evacuation plans. Also, people can buy battery-operated radios to get inform after the sorm have started in case there is no electricity.