"Python in Hydrology" is a free, downloadable book written by Sat Kumar Tomer and published by Green Tea Press. The concise, 127 page book book casts a wide net and reviews how Python can calculate, graph and measure precipiation, rainfall, infiltration, and determine hydrologic routing among other techniques utilizing Python and packages including NumPY. The book also delves into graphing and the often messy real world application of creating either raster or vector spatial files by importing raw data from either a .csv file or an excel spreadsheet. The writing can be a little hard to follow at some points, but overall the book is a strong starting point, if only to prod your imagination to see what can be done with Python. Download a copy, here.