There are many problems that could be solved by using GIS techniques more easily. GIS could be useful in every aspect of science which deals with location and space. Hydrology,Transportation, historical map, urban design, and etc.
Everyone could need GIS knowledge in his graduate studies related to the aspects mentioned above. I want to introduce a free web-based book that could be useful for engineers, especially civil engineers. Geospatial Analysis - A comprehensive guide is a web-based GIS resource written by Dr. Michael de Smith and Prof. Paul Longley, University College London, and Prof. Mike Goodchild, UC Santa Barbara.
This book consists of different comprehensive GIS techniques. I would like to list the main topics that are covered by this book here. It could be called as a reference book for undergraduate or graduate students who have started using GIS or they want to refresh their knowledge on GIS.
You can access to the web-based version of this book for free and if you like you can purchase it from its website.