Which is the best department and subject in IIT Delhi for ESE preparation for civil engineering?

IIT Delhi's Civil Engineering department has a total of 7 branches namely

1. Structural Engineering 
2. Geotechnical Engineering 
3. Transportation Engineering 
4. Environmental Engineering 
5. Water Resources Engineering 
6. Rock Engineering
7. Construction Engineering and Management 

The ones that I will recommend you not to join include - Structural, Geotechnical, Transport, and Water Resources. This is because you are planning to prepare for ESE which won’t be possible because of the demanding and rigorous curriculum of these branches.

Construction Engineering and Management is a good choice as the coursework is light in comparison to others. Rock Engineering is another good option but the future scope is limited because it’s not a major branch of Civil Engineering.

The most common choice among aspirants is Environmental Engineering with the least burden and great opportunities.