Introduction

Watershed models simulate natural processes of the flow of water, sediment, chemicals, nutrients, and microbial organisms within watersheds, as well as quantify the impact of human activities on these processes. Simulation of these processes plays a fundamental role in addressing a range of water resources, environmental, and social problems. The current generation of watershed models is quite diverse and varies significantly in sophistication and data and computational requirements. Newly emerging technologies are being increasingly integrated into watershed models. This chapter introduces some of these technologies as well as the theme of the book.