I have an idea about how to manage water on that area, which have plenty of water to maintain.
Well, it's my raw idea,
1. Map the terrain and create artificial water reservoir and irrigation system.
2. Put the hydroelectricity also on the gate of the water reservoir.
3. Save the electricity for the people of Bihar.
If we use this idea, what can be gained?
1. Raising the tourism and create protein source also. The water reservoir can attract tourist also. You can put fish there, and create a fish restaurant or you can create fishing activity there. It's depend on the people's habit.
2. Raising the vegetables production. If we managed the water appropriately the production will not see weather or "season". Means you can still produce vegetables within a year.
3. Productivity of bihar peoples raising when electricity "touch" them, so they can use it for lamp at night time and use the hydropump at day time. So they still can productive even at night time.
Well, it's still rough. Hope you guys catch the idea. :)