Civil Engineering

Opportunity in both the fields are enormous and totally depend on in depth knowledge you gain in your field in the engineering time span. So don't compare, just follow your interest and you will do fine. There are plenty of jobs in both fields for people who do well, and there's a very wide array of applications in both fields. If you like working in the open and love designing and drawing choose civil. But if you want to work in an AC room sitting on a chair in front of a PC choose computer. Computer science is comfortable branch and has more scope especially onsite opportunities.
Computer Science- branch with a high scope for campus placement especially if you see yourself in Infosys, Wipro or other CS/IT company. If you love roaming around your PC and had an interest to have insider knowledge and software development then CS/IT is the right choice. The job demand for civil engineers is also a lot more spread out. Every single city is going to have building permits/inspectors, and every contractor will eventually need an engineer's report. In that regard, a civil engineers income after expenses, can actually outpace a software developers in a lot of areas. Ultimately though, it's what a person enjoys doing more. Neither is a bad plan.
Civil- Relatively easier with a high scope of government as well as private sector in India as India requires design infrastructure and civil will be in high demand so long as infrastructure exists. I should say too that sometimes these two fields intersect and likely will intersect more in the future.