Both Alaknanda and Bhagirathi are glacier-fed rivers and the hydrology of these rivers is directly impacted by climate change. The rate at which the glacier is melting has to be a consideration for the running of these projects.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/climate-uncertainties
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/down-earth
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/alakananda
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/bhagirathi
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ganga
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/dams-irrigation
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/river-basin