Geography, Environment, and Disaster Management play an important role to score high marks in any competitive exam. First, complete the reading of Physical geography. Then read Human and Economic Geography. Get a hold of the latest Census report to answer all demographic questions.
You do not need to read specifically for Disaster Management. It is already covered as a part of Physical Geography. However, concentrate on recently happened disasters in the state or country. Also, get a hold of a special edition of Yojana magazine on Disaster Management. It gives you a complete understanding of the subject.