One approach to the introduction of computational material to the classroom is to supplement a textbook with modern computer codes. Unfortunately most codes are expensive, designed for commercial use, without source code and may require special software. Visual Hydrology provides a cheaper and simpler alternative, supplying computational exercises that can be fully assimilated by students, and allowing them to activate, understand and reproduce modern computer code. Visual Hydrology aims to: *explain the structure of modern object-oriented computer code; *provide the source code for worked examples; *numerically check the worked examples used in text; *show how worked examples can be used with alternative data; *describe and reference the underlying theory; *provide additional exercises with each worked example; *use Microsoft Excel 2000 software alone. Requiring only a basic knowledge of Microsoft Excel(tm), this primer teaches the uses of modern and readily-available computer code for engineering computation. Visual Hydrology demonstrates codes for common and practical examples used in hydrological engineering, and will be a valuable resource to students, research workers and consulting engineers in the water-related sector.