River linking in India is a large-scale civil engineering project that aims to link Indian rivers by a network of reservoirs and canals and so reduce persistent floods in some parts and water shortages in other parts of India. India is a big country which receives its 80% rain water in four months in monsoon period.
In general each year some part of India receives the excess rain and the area faces flood situation whereas some area receives less rain make it drought like situation. By the river linking excess water from some areas can be transferred to the deficit areas. See the following image for the detail of the connect -
Now coming to the second part of the question, its a mammoth project may the costliest infrastructure project in the Indian history (not just Independent India) and may take more then 100 years to connect all the rivers (not just shown in the image). Only time can tell if project can be successful, what would be the impact on the environment & ecology and human being can win over the nature. But yes if successful then it can solve the water crisis.