How do dams affect rivers

Army Corps of Engineers has catalogued at least 90, dams greater than six-feet tall that are blocking our rivers and streams. There are tens of thousands of additional small dams that fall through the cracks of our national inventory.

While dams can benefit society, they also cause considerable harm to rivers. Although not all dams damage rivers in exactly the same way, here are some of the most common ways they inflict harm. Dams prevent fish migration. This limits their ability to access spawning habitat, seek out food resources, and escape predation. Fish passage structures can enable a percentage of fish to pass around a dam, but their effectiveness decreases depending on the species of fish and the number of dams fish have to traverse.

Aquatic organisms, including fish such as salmon and river herring, depend on steady flows to guide them. The EIS deals only with Stage 1. About Stage 2 — odd years down the track on current plans — it says little. So Stage 2 remains an unknown: deepening the reservoir by 8. QWI acknowledges that stress, depression, social withdrawal, community disintegration and deep mistrust have resulted but says not everyone has suffered. By late , QWI had reached sale agreements for 65 per cent of the land it needs.

Many people who sold have leased back their former properties and may continue to live on them for a time. Glenda breeds cattle on 68 ha beside the Mary about 1 km upstream of the proposed dam site. Her house and land would vanish under water at Stage 1. She grew up in the area and as a child fantasised about living beside the Mary. Then I bought it off him and it was only last year that I finally paid everything off.

And sadness and tears and frustration because I believed the process of water resources planning should have involved the community and some warning.

Other anti-dam protest signs dot the Mary Valley. In Kandanga, one beside the main street shows the projected water level after Stage 2. There, an airy weatherboard shed has become the headquarters and public information centre of the Save the Mary River Coordinating Group.

At Stage 1 they would lose much of their land. Kevin is bitter but, like Glenda, he diverts his emotions into action. What irks them most is that water from the proposed reservoir would be pumped out of the area. Angela Arthington says the environmental consequences of such extraction, together with the flooding of a shallow valley, are predictable because they characterise all megadams in similar landscapes. But if darns are such a bad idea, what are the alternatives — and are they really going to cost as much as the Queensland Government claims?

In a report, the Institute of Sustainable Futures lSF at the University of Technology in Sydney outlined a suite of measures that, in combination, would make a new darn unnecessary. Many are already in use or are planned, such as desalination, recycling, domestic water tanks, water efficiency standards for water-using appliances and fixtures, and business water-saving programs. But the ISF envisages much greater and more effective use of them to both reduce demand and increase supply. Her mother, Evelyn Monkland-Olsen, was born beside the river, which her people call Mumabula.

They knew instinctively it was special. Close Menu. Facebook Twitter Instagram Instagram Adventure. Popular this week A long way from home: Antarctic penguin makes it all the way to New Zealand New Zealand conservationists have released an adelie penguin back into the sea after the Antarctic-based bird swam thousands of kilometres to make a rare visit. How climate scientists talk to their kids about the climate crisis We chat to three climate scientists from the University of New South Wales about how they talk to their kids about the climate crisis.

It is said that after construction of Hirakud dam across Mahanadi, the flood devastation has rather increased than to control flood. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.

You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. This site uses Akismet to reduce spam. Learn how your comment data is processed. We can go on like this much longer. But such is a vast network of rivers that we call Ganga. From: The River continuum Concept.

Species in India will be different, but this represents how biological entitites in a river are linked to each other through a number of processes including nutrient spiralling Oxbowriver.

Dry Baspa River downstream Baspa II Dam, Himachal Pradesh Photo: SANDRP Partners This is because these structures not only stop the flow of water to the downstream areas, they also stop flow of everything else that was flowing in the river: the silt, the nutrients, the sand, the organisms, the flora, fauna, and severe every one of the connections of rivers we described earlier And imagine when a river has to face such death every few kilometers in its journey!

The same Chenab Basin now witnesses one of the highest dam densities in Himalayas. From: WikiArt Some people will read in this a plea to go back by those years. This is true of Ganga, as any other River! Like this: Like Loading Share this: Twitter Facebook. Previous Post What do Rivers have to do with Silt?? Himanshu Thakkar Like Like. Wonderful article. Mobility is God, Mobility is life. Pingback: Rivers Greetings World. Leave a Reply Cancel reply Enter your comment here 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. 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.