I would like to suggest to read the following papers:

1-https://www.essaytopics.com/v/237707/essay-on-effects-of-dams-on...

2-https://www.internationalrivers.org/environmental-impacts-of-dams

3-www.environment911.org › Our Environment › Observations

According to Wikipedia, the environment impact of reservoirs can be clasified as follows:

Upstream impacts

• Fragmentation of river ecosystems
• Reservoir sedimentation

Impact below dam

• Riverline and coastal erosion
• Change in water temperature
• Natural ecosystems destroyed by agriculture
• Effects on flood-dependent ecology and agriculture
• Potential for disaster in case of accident
• Flood control

Effects beyond the reservoir

• Effects on humans
• Greenhouse gases

I would kindly appreciate and revere your worthy insights into the topic of discussion, and moreover for the papers, professor Jorge Morales Pedraza. I will go through them all.

It depends on the priorities of the human being, on the one hand it allows me to obtain energy without greenhouse gases, besides having water for the dry months, but on the other hand, I can be covering cemeteries of native peoples and / or forests or species in danger of extinction. I think that ultimately, the first thing is the survival of the human being, water is the key to it. Therefore, the answer will depend on the priority of the moment, which is dynamic over time.

Many thanks for your comments. If you wish to know more about the impact of dams in the Latin American and the Caribbean and European regions read my books entitled:

1- Electrical Energy Generation in Europe. The Current Situation and Perspectives in the Use of Renewable Energy Sources and Nuclear Power for Regional Electricity Generation, Springer, ISBN 978-3-319-16082-5, 2015.

2- Energy in Latin American and the Caribbean: The Current and Future Role of Renewables and Nuclear Energy Sources in the Regional Electricity Generation; ISBN: 978-1-62257-980-8; Nova Science Publisher Inc.; 2013.

Also you can read the following chapters:

1- The Current and Future Role of Renewable Energy Sources for the Production of Electricity in Latin America and the Caribbean; IJEEE (2012) ISSN: 1054-853X, Volume 20, Number 5, Nova Science Publishers, Inc., 2012.

2- The Use of Hydropower Plants for Electricity Generation in the European Region; Chapter 2 of the book entitled “Hydroelectricity and Power Electronics: Environmental Impacts, Emerging Technologies and Challenges”; Nova Science Publisher 978-1-63321-728-7; 2014

Dear Marcelo Eduardo Rojas Vidal and Jorge Morales Pedraza ,

Many thanks for your outstanding contributions, comments and insights. Also another special thanks for the perfectly helpful references, once again.

You are welcome!

Dear Salman

Dams have a range of positive and negative impacts depending upon a range of issues. They are significant sources of GHG emissions with spillway flooding, water loss, decay based GHG emissions making significant negative contributions etc. The concrete and other materials currently used in construction mean that dam based hydro electric schemes are equivalent to gas fired generation when assessed using a life cycle approach. There are habitat losses, microclimatic changes, social and cultural impacts and both downstream and upstream implications including water quality (oxygen depletion, pollutant concentration, impacts on fish (migration / breeding/ predation)water availability and sovereignty/rights issues. I've seen severe cultural loss, economic loss and deep political divisions occur as a result of both Australia and Indian dam development. In Australia we can have spring to autumn pan evaporation rates of over 45% meaning that uncovered "turkey nest" type dams are poor at water retention.see https://www.deakin.edu.au/about-deakin/media-releases/articles/farms-dam-good-place-to-cut-carbon-emissions-world-first-study

Native wildlife can be concentrated at dams and become targeted (think of booby trapped dam access killing Bactrian camels for meat in Mongolia), migrating birds hunted or simply poisoned with bacteria or chemical concentrations. Cotton irrigation dams have devastated large parts of Australia both economically, socially and the natural systems yet they benefit local producers.

At the smaller scale, properly designed deep dams with smaller surface area to depth ratios in hotter climates can be a good adaptation measure. These tend to be smaller in scale in the range of 4-20ML and ideally have swales/infiltration basins that are planted with native ground covers, vegetation and trees and fenced off properly from stock. These can provide a haven for wildlife and humans in drought periods

There is the important aspect that there needs to be environmental flows in rivers. A working figure is about 20% of the flow in the river from mean annual runoff (MAR). It is important that there is fresh water flow into the estuary, so that the estuary provides the right environment for a fish nursery and reeds for bird life.

So dams are useful for impounding water for agriculture and domestic use, given that the environmental flows continue. What is important is the choice of the site of the dam. Ideally the dam should have depth and be in an area where there is reduced evaporation, and where the water flows are more pristine, so that the water quality remains good, thereby minimising the cost of water treatment.

Dear Prof. Sajda Taha Mahmood , Eng. Annabel Marian Horn and Eng. Gareth Johnston, many thanks for your outstanding comments, insights and contributions for the query. I do revere and simultaneously agree to all the mentioned very important and meanwhile various aspects and perspectives.

Without dam in summer no water how human and animal will servive,no water no life

Insubmergence lot of agriculture land goes under water

Of course with new technology better use of dam