The list of books given below can be read as an alternative to Subramanya's Engineering Hydrology:
1.A Text-Book of Hydrology by P. Jaya Rami Reddy
2.Hydrology: Principles, Analysis and Design by H M Raghunath
3.Concise Hydrology by David Han
4.Introduction to Hydrology by Warren Viessman, Gary L Lewis
5. Water-resources engineering by David A. Chin.