A man takes a selfie next to a flooded street due to the overflowing of the Mapocho river during heavy rains in Santiago on April 17, 2016. Four million people in Santiago were without tap water Sunday after unusually heavy rain pounding central Chile triggered landslides that fouled the city's water supply and forced the closure of the world's biggest copper mine, officials said. (Photo by Martin Bernetti/AFP Photo)

A Nepalese Hindu devotee bathes in the Bagmati River on her way to the Pashupatinath Temple to offer prayers to Lord Shiva, Hindu god of destruction during Shravan festivities in Sundarijal, on the outskirts of Kathmandu on August 3, 2015. According to the Nepali calendar, Shravan is considered the holiest month of the year with each Monday of the month known as Shravan Somvar when worshippers offer prayers for a happy and prosperous life. (Photo by Prakash Mathema/AFP Photo)

An employee of Paris city Hall removes padlocks clipped by lovers on the fence of the Pont des Arts over the River Seine in Paris, December 9, 2014. For years, visiting couples have hung brass padlocks on the iron grills lining the city's bridges to symbolise their undying love – they write their names on the locks, then toss the key into the Seine below. About 700,000 love locks are added every few months and Paris officials say they are damaging the bridges and threatening safety because of the added weight. (Photo by Philippe Wojazer/Reuters)

Snorkelers interact with a Florida Manatee inside of the Three Sisters Springs in Crystal River, Florida January 15, 2015. On winter days, Florida manatees flock by the hundreds to the balmy waters of Three Sisters Springs, drawing crowds of snorkelers and kayakers to the U.S. sanctuary, where people may swim with the endangered species. But as tolerant as the gentle, whiskered sea giants can be of the accidental kicks and splashes of delighted tourists, wild life regulators want to ban most canoes and paddle boards and create people-free zones to protect the wintering “sea cow”. Proposed limitations for this winter are awaiting approval by the U.S. Fish and Wildlife Service. (Photo by Scott Audette/Reuters)

A Sadhu or a Hindu holy man offers prayers while sitting inside a circle of burning “Upale” (or dried cow dung cakes) on the occasion to mark the Basant or spring festival, on the banks of river Ganga in the northern Indian city of Allahabad January 24, 2015. Basant is celebrated mainly in the northern Indian states marking the start of the spring season. (Photo by Jitendra Prakash/Reuters)

Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)

“The Victoria Falls or Mosi-oa-Tunya is a waterfall located in southern Africa on the Zambezi River between the countries of Zambia and Zimbabwe. A famous feature is a naturally formed pool known as the Devil's Pool, near the edge of the falls, accessed via Livingstone Island in Zambia. When the river flow is at a certain level, usually during the months of September to December, a rock barrier forms a pool with little current; some people swim in the pool. Occasional deaths have been reported when people slip over the edge of the rock barrier”. – Wikipedia

Photo: Devil's Pool – Victoria Falls, Zambia. (Photo by Siena College Study Abroad)

Students stand on the roof of a wooden boat as haze blankets the Musi River while they travel to school in Palembang, on Indonesia's Sumatra island, September 10, 2015. Indonesia is investigating 10 firms over worsening forest fires that have created a blanket of smog over Southeast Asia, threatening them with sanctions if they are found responsible, a government minister said on Tuesday. The thick haze from Indonesia's Sumatra and Kalimantan islands has forced the repeated cancellation of flights in the area and pushed air quality to unhealthy levels in neighbouring Singapore and Malaysia. (Photo by Reuters/Beawiharta)