I assume you are studying the rest of civil engineering as well so I have included some books that link into these areas.
For understanding
Fluid Principles : Vardy. Excellent modern metric book by a civil engineer.
Hydraulics in Civil Engineering
Hydraulic Structures : Novak : Latest editions are modern and metric
Hydraulics in Civil and Environmental Engineering : Chadwick and Morfett: Latest editions are modern and metric
Essentials of Engineering Hydraulics : Dake : Modern and metric includes coastal engineering.
Some older good books not necessarily metric
Fluid Mechanics for Hydraulic Engineers : Hunter Rouse
Hydraulics and Fluid Mechanics : Lewitt
Hydraulics : King, Wisler and Woodburn
Problem Books
Solutions to problems in Fluid Mechanics : Douglas. Not metric but excellent and clear. In two parts part I elelementary part II advanced.