My advice would be to look again at your options, but from a fresh perspective.

You will find career opportunities in all fields of Civil Engineering in time, so don't let these sorts of considerations override those that are more instinctive - go with what you enjoy, find interesting and motivates you to learn more.

For me personally, it was the enthusiasm of a teacher making a sales pitch for a geology department; my interest in travel; and climbing that clinched it - not a thought about career path entered my mind, yet I find myself specialising in an area that is continually interesting and challenging.

If you really have trouble making your mind up, ask around if you can speak or preferably meet up with professionals to get a feel for what life after graduation really involves. Speak with contractors and consultants - if you are a practical type the former might suit best, if you enjoy working drawings and written documents, perhaps the latter. People will gladly give a little time.

Lastly, here's my sales pitch - Geotechnical Engineering is all about fusing the natural and built environments, understanding how natural processes influence our lives and making people and structures safe from natural hazards. It's relevance will only increase as we develop more marginal land and encroach on steep slopes, build on soft soils, live in areas susceptible to earthquakes or re-develop and remediate brownfield sites.

Geotechnical engineering is all about detective work - taking snippets of evidence from boreholes, trial excavations and tests to build a three dimensional model of the ground, then adding a forth dimension - soil and rock parameters, from which a design evolves.