Environmental Impacts of Dams

The environmental consequences of large dams are numerous and varied, and includes direct impacts to the biological, chemical and physical properties of rivers and riparian (or “stream-side”) environments.

 

The dam wall itself blocks fish migrations, which in some cases and with some species completely separate spawning habitats from rearing habitats. The dam also traps sediments, which are critical for maintaining physical processes and habitats downstream of the dam (include the maintenance of productive deltas, barrier islands, fertile floodplains and coastal wetlands).

 

Another significant and obvious impact is the transformation upstream of the dam from a free-flowing river ecosystem to an artificial slack-water reservoir habitat. Changes in temperature, chemical composition, dissolved oxygen levels and the physical properties of a reservoir are often not suitable to the aquatic plants and animals that evolved with a given river system. Indeed, reservoirs often host non-native and invasive species (e.g. snails, algae, predatory fish) that further undermine the river’s natural communities of plants and animals.

 

The alteration of a river’s flow and sediment transport downstream of a dam often causes the greatest sustained environmental impacts. Life in and around a river evolves and is conditioned on the timing and quantities of river flow. Disrupted and altered water flows can be as severe as completely de-watering river reaches and the life they contain. Yet even subtle changes in the quantity and timing of water flows impact aquatic and riparian life, which can unravel the ecological web of a river system.

 

A dam also holds back sediments that would naturally replenish downstream ecosystems. When a river is deprived of its sediment load, it seeks to recapture it by eroding the downstream river bed and banks (which can undermine bridges and other riverbank structures, as well as riverside woodlands). Riverbeds downstream of dams are typically eroded by several meters within the decade of first closing a dam; the damage can extend for tens or even hundreds of kilometers below a dam.

 

Low flows below dams killed thousands of salmon on the Klamath in 2002

 

Riverbed deepening (or “incising”) will also lower groundwater tables along a river, lowering the water table accessible to plant roots (and to human communities drawing water from wells) . Altering the riverbed also reduces habitat for fish that spawn in river bottoms, and for invertebrates.

 

In aggregate, dammed rivers have also impacted processes in the broader biosphere. Most reservoirs, especially those in the tropics, are significant contributors to greenhouse gas emissions (a recent study pegged global greenhouse gas emissions from reservoirs on par with that of the aviation industry, about 4% of human-caused GHG emissions). Recent studies on the Congo River have demonstrated that the sediment and nutrient flow from the Congo drives biological processes far into the Atlantic Ocean, including serving as a carbon sink for atmospheric greenhouse gases.

 

Large dams have led to the extinction of many fish and other aquatic species, the disappearance of birds in floodplains, huge losses of forest, wetland and farmland, erosion of coastal deltas, and many other unmitigable impacts.

china unveils driverless train that follows painted lines instead of rails

the world’s first railless train has been unveiled in zhuzhou, in the hunan province of central china. the self-driving train, which is 30 meters in length, is part of the intelligent rail express system by chinese rail provider CRRC zhuzhou, and runs on rubber tires rather than rails. kitted out with sensors, the train can read the dimensions of roads and plan its own route. in fact, it’s much like having a virtual rail for the train. the futuristic form of public transport can move along fully autonomously at a speed of 70 km/h and can carry up to 500 passengers, offering new options for easing modern transport pressures. as it’s green coloring would suggest, the train is eco-friendly powered by electricity, yet can still travel over a distance of 40km per full charge.

 

CRRC zhuzhou’s vehicle is the first ‘railless train’ that the world has seen

the train–which has assumed the name of ART, meaning autonomous rail rapid transit–is an initiative to help medium-sized and small citie which cannot affort to lay down rails or install expensive transport systems. whilst a railway track would take too much time and workforce to build in zhuzhou, according to the city’s government, operations to paint a 6.5 km ART line will be built downtown zhuzhou will already begin in 2018. CRRC’s train is made up of three carriages, each with a capacity of 300 people. in the future, a five-carriage train can hold as many as 500 passengers.

the train is kitted out with sensors that help it determine the size of roads and plan its journey

the train runs on an electric battery and can run 40 minutes on a single charge

the vehicle is known as ART, meaning autonomous rapid rail transit

Pacific Island Contains 38 Million Pieces of Plastic

Researchers recently discovered an island in the Pacific Ocean that contains almost 38 million pieces of plastic trash. According to an article published in April in the journal “Proceedings of the National Academy of Sciences,” Henderson Island has the world’s highest known density of plastic particles

 

 

Flying water taxis coming Paris in 2017

Next year Paris will test a futuristic, prototype water taxi that will allow people to glide along the Seine River, two feet above the water.

The vessel, named Sea Bubble, can travel up to 30 kilometers per hour and can seat five people including a driver. According to the Telegraph, the vessel’s chassis will be made of fiberglass and high-density foam.

The developers also hope that Sea Bubble vessels could eventually be ordered through vehicle-hailing apps like Uber. If successful in France, they also hope to use Sea Bubble vessels in waterways in other cities such as London, Geneva and elsewhere.

 

 

Toyota Adds Solar Roof to New Japanese Prius

Toyota shifts its fuel saving technology into the next gear adding solar panels to the Priuses, newest model launched in japan. The Prius PHV pairs plugging electric car technology with solar panel roofing.

The Prius PHV works like an electric car driving of the battery until the level gets too low.

After that it switches to the gas function while the estimated range of the electric function is 22 miles the solar panels could help push that range on sunny days.

According to the company the new model will go as far as a hundred and twenty miles per gallon including mouse travel as an electric car.

For comparison older models of the previous get about 50 miles per gallon.

However strict safety rules prevent toyota from selling the solar panel model in the US and steady so-called previous prime will only feature the plug-in hybrid engine technology.