Supporting structural engineering is the field of geotechnical engineering. The importance of geotechnical engineering can hardly be overstated: buildings must be connected to the ground! Geotechnical engineering is concerned with soil properties, foundations, footings and soil dynamics. Over time, researchers have derived empirical equations that work (it is not an exact science).
[Transportation engineering]? is concerned with queueing theory and traffic flow planning. These are highly complex computational problems.
[Environmental engineering]? deals with waste treatment and hydrology.
[Construction engineering]? involves planning and execution of the designs from structural and geotechnical engineers.
Civil engineering also includes material science. Engineering materials include concrete, steel and recently, polymers and ceramics with potential engineering application.
A popular misconception is that civil engineering is far from the exciting frontiers in mathematics and computer science. In actuality, much of what is now computer science was driven by work in civil engineering, where structural analysis problems required parallel computations and development of advanced algorithms.
There are also civil engineers who work in the area of [risk and reliability]?, applying [probabilistic methods]? to structural design, safety analysis and even estimates of insurance losses due to natural and man-made hazards.