Watershed Models

This book stemmed from a desire to provide a comprehensive account of some of the world's popular computer models of watershed hydrology. To achieve this objective, a variety of models that together spanned a range of characteristics were included. Some of those models represent a large class of models, some are comprehensive, some are applicable to not only civil works but also to agricultural, range and forest, and nonpoint source pollution fields; some are equipped with the GIS and remote sensing capability, and some represent a large cross-section of models from around the world. The subject matter of this book is divided into 29 chapters. Beginning with introductory remarks on watershed modeling in Chapter 1, model calibration and reliability estimation are presented in Chapters 2 and 3, respectively. The next ten chapters (4 to 13) present some of the popular models from around the world. These models are in the realm of civil engineering applications of watershed hydrology models. Some of the models are more comprehensive than others and some have the management capabilities. The next two models, presented in Chapters 14 and 15, are large-scale models and embody GIS and remote sensing technology. The models presented in Chapters 16 to 23 are more physically-based and distributed in nature, quite suited to nonpoint source pollution modeling, and to assess environmental impact of land use changes. The remaining 5 models presented in Chapters 24 to 29 are within the realm of agricultural and forestry applications. Nonpoint source pollution, erosion and impact on soil productivity, drainage design, etc., can be modeled by applying these models. Computer Models of Watershed Hydrology will be of interest to practicing hydrologists, especially to hydrologic modelers and the model users, as well as specialists in the fields of civil engineering, agricultural engineering, environmental science, forest and range science, earth science, climatology, and watershed sciences. Graduate students, teachers engaged in graduate instruction, and researchers will also find this book useful. Due to the popularity of this book and with innovations in printing, this was reprinted in 2012 with the original information. It is now part of WRP’s Classic Resource Edition.

Watershed modeling is at the heart of modern hydrology, supplying rich information that is vital to addressing resource planning, environmental, and social problems. Even in light of this important role, many books relegate the subject to a single chapter while books devoted to modeling focus only on a specific area of application. Recognizing the

Comprehensive account of some of the most popular models of small watershed hydrology and application ~~ of interest to all hydrologic modelers and model users and a welcome and timely edition to any modeling library

Comprehensive account of some of the most popular models of large watershed hydrology ~~ of interest to all hydrologic modelers and model users and a welcome and timely edition to any modeling library

Published by the American Geophysical Union as part of the Water Science and Application Series, Volume 6. During the past four decades, computer-based mathematical models of watershed hydrology have been widely used for a variety of applications including hydrologic forecasting, hydrologic design, and water resources management. These models are based on general mathematical descriptions of the watershed processes that transform natural forcing (e.g., rainfall over the landscape) into response (e.g., runoff in the rivers). The user of a watershed hydrology model must specify the model parameters before the model is able to properly simulate the watershed behavior.

The book provides a comprehensive insight into watersheds and modeling of the hydrological processes in the watersheds. It covers the concepts of watershed hydrology and watershed management in depth. The basic types, of soil erosion and its measurement and estimation of runoff and soil loss from the small and large watersheds are discussed. Recent advances in the watershed management like the application of remote sensing and GIS and hydrological models are a part of the book. The book serve as a guide for professional and competitive examinations for undergraduate students of Agriculture and Agricultural Engineering and graduate students of Soil Science, Soil and Water Engineering, Agricultural Physics, Hydrology and Watershed Management.

Prepared by the Task Committee on GIS Modules and Distributed Models of the Watershed of ASCE. This report guides professionals in selecting the most advantageous applications of geographic information system (GIS) modules and distributed models for watershed runoff. Recent advances in technology offer hydrologic engineers, watershed managers, and data collection agencies unprecedented capabilities for storing and manipulating data. With the advent of Digital Elevation Models (DEM), Triangulated Irregular Networks (TIN), Digital Line Graphs (DLG), and GIS software, the use of watershed modeling among industry professionals has increased at an incredible rate. With this growth, it is increasingly difficult for practitioners to choose the most effective use of the technology. This report identifies state-of-the-art GIS hydrology analysis software and techniques, as well as GIS types and map projections. It covers data commonly required for hydrologic analysis, limitations of available data, and the integration of watershed hydrological analysis software and GIS techniques. The appendix highlights nine examples of watershed modeling systems, including the Watershed Modeling System (WMS), the Soil and Water Assessment Tool (SWAT), and the Hydrologic Model CASC2D.