Answer:
When a large dam is constructed, the original landscape is changed. The trees are cut down causing deforestation. The wild animals lose their habitat. Many of them become extinct. There is a great loss of flora and fauna due to the construction of large dams. There is undue pressure on the land surface caused due to stored water columns. This may cause earthquakes. The human settlements are removed as their houses and farms are immersed underwater. In all the above ways large dams destroy the ecosystems.