On 13th of September 2016, AAPG UPN SC held a Hidrogeology preparation class, an agenda of RED division. This preparation class have a purpose to make all of the members of AAPG UPN SC learned hidrology more intensively. Hidrogeology preparation class was held at hidrogeology laboratory UPN Veteran Yogyakarta. This event attended by members of AAPG UPN SC, from 2015, 2014, and 2013. Preparation class started at 06.30 pm until 10.00 pm. Preparation class went smoothly. Chatarina Indah is the hidrogeology staff asistant whose also the member of AAPG UPN SC , teach about hidrology to the other members. This preparation class was very usefull for all the members, because from this preparation class, AAPG’s member become one step ahead than others.