The course RINAT 505 is a post graduate course on applied concepts in geomorphology, hydrology, meteorology and climatology. The introductory part of this course focuses on a review of learners’ understanding of basic notions in these sub-fields. You are requested to review these notions that will enhance your understanding. This course addresses probable or real natural hazard and risk occurrences, the nature of the phenomena, control, hazard and risk zones, the importance of damages they cause or can cause, the capacity of a population to deal with those damages, etc. Natural risks deal with phenomena perceived as uncontrollable by humans or hazards which explicitly do not result from human activity.