Ebook: Soil Conservation Service Curve Number (SCS-CN) Methodology

The Soil Conservation Service (SCS) curve number (CN) method is one of the most popular methods for computing the runoff volume from a rainstorm. It is popular because it is simple, easy to understand and apply, and stable, and accounts for most of the runoff producing watershed characteristics, such as soil type, land use, hydrologic condition, and antecedent moisture condition. The SCS-CN method was originally developed for its use on small agricultural watersheds and has since been extended and applied to rural, forest and urban watersheds. Since the inception of the method, it has been applied to a wide range of environments. In recent years, the method has received much attention in the hydrologic literature. The SCS-CN method was first published in 1956 in Section-4 of the National Engineering Handbook of Soil Conservation Service (now called the Natural Resources Conservation Service), U. S. Department of Agriculture. The publication has since been revised several times. However, the contents of the methodology have been nonetheless more or less the same. Being an agency methodology, the method has not passed through the process of a peer review and is, in general, accepted in the form it exists. Despite several limitations of the method and even questionable credibility at times, it has been in continuous use for the simple reason that it works fairly well at the field level.

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The book is divided into nine chapters, treating the following topics: a brief introduction of rainfall-runoff modeling and elements of catchment, precipitation, interception, surface detention and depression storage, evaporation, infiltration, runoff, and the runoff hydrograph; the factors affecting the curve number (CN), the determination of CN, the use of NEH-4 tables, sensitivity analysis, advantages and limitations of the SCS-CN method, and application to distributed watershed modeling; an analytical derivation of the SCS-CN method focusing on the Mockus and other methods; a determination of `S' using the volumetric concept encompassing an analytical derivation, verification of the existing AMC criteria, determination of S, use of NEH-4 tables and advantages and limitations of the modified model; the determination of `S' using physical principles, involving Fokker-Planck equation of infiltration, description of S, S/P relations for the modified model and determination of Ds from universal soil loss equation; simulation of infiltration and runoff hydrographs, with particular emphasis on SCS-CN-based infiltration and runoff models and application of infiltration and runoff models; long-term hydrologic simulation and hydrologic models of Williams and LaSeur, Hawkins, Pandit and Gopalkrishnan, and Mishra and others; rainfall-excess computation, soil moisture budgeting, catchment routing, and baseflow computation; transport of pollutants in urban watersheds; and sediment yield.

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The book is divided into nine chapters, treating the following topics: a brief introduction of rainfall-runoff modeling and elements of catchment, precipitation, interception, surface detention and depression storage, evaporation, infiltration, runoff, and the runoff hydrograph; the factors affecting the curve number (CN), the determination of CN, the use of NEH-4 tables, sensitivity analysis, advantages and limitations of the SCS-CN method, and application to distributed watershed modeling; an analytical derivation of the SCS-CN method focusing on the Mockus and other methods; a determination of `S' using the volumetric concept encompassing an analytical derivation, verification of the existing AMC criteria, determination of S, use of NEH-4 tables and advantages and limitations of the modified model; the determination of `S' using physical principles, involving Fokker-Planck equation of infiltration, description of S, S/P relations for the modified model and determination of Ds from universal soil loss equation; simulation of infiltration and runoff hydrographs, with particular emphasis on SCS-CN-based infiltration and runoff models and application of infiltration and runoff models; long-term hydrologic simulation and hydrologic models of Williams and LaSeur, Hawkins, Pandit and Gopalkrishnan, and Mishra and others; rainfall-excess computation, soil moisture budgeting, catchment routing, and baseflow computation; transport of pollutants in urban watersheds; and sediment yield.

Content:
Front Matter....Pages i-xx
Introduction....Pages 1-83
SCS-CN Method....Pages 84-146
Analytical Derivation of the SCS-CN Method....Pages 147-204
Determination of ‘S’ Using Volumetric Concept....Pages 205-243
Determination of ‘S’ Using Physical Principles....Pages 244-277
Infiltration and Runoff Hydrograph Simulation....Pages 278-322
Long-Term Hydrologic Simulation....Pages 323-359
Transport of Urban Pollutants....Pages 360-435
Sediment Yield....Pages 436-456
Back Matter....Pages 457-516

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The book is divided into nine chapters, treating the following topics: a brief introduction of rainfall-runoff modeling and elements of catchment, precipitation, interception, surface detention and depression storage, evaporation, infiltration, runoff, and the runoff hydrograph; the factors affecting the curve number (CN), the determination of CN, the use of NEH-4 tables, sensitivity analysis, advantages and limitations of the SCS-CN method, and application to distributed watershed modeling; an analytical derivation of the SCS-CN method focusing on the Mockus and other methods; a determination of `S' using the volumetric concept encompassing an analytical derivation, verification of the existing AMC criteria, determination of S, use of NEH-4 tables and advantages and limitations of the modified model; the determination of `S' using physical principles, involving Fokker-Planck equation of infiltration, description of S, S/P relations for the modified model and determination of Ds from universal soil loss equation; simulation of infiltration and runoff hydrographs, with particular emphasis on SCS-CN-based infiltration and runoff models and application of infiltration and runoff models; long-term hydrologic simulation and hydrologic models of Williams and LaSeur, Hawkins, Pandit and Gopalkrishnan, and Mishra and others; rainfall-excess computation, soil moisture budgeting, catchment routing, and baseflow computation; transport of pollutants in urban watersheds; and sediment yield.

Content:
Front Matter....Pages i-xx
Introduction....Pages 1-83
SCS-CN Method....Pages 84-146
Analytical Derivation of the SCS-CN Method....Pages 147-204
Determination of ‘S’ Using Volumetric Concept....Pages 205-243
Determination of ‘S’ Using Physical Principles....Pages 244-277
Infiltration and Runoff Hydrograph Simulation....Pages 278-322
Long-Term Hydrologic Simulation....Pages 323-359
Transport of Urban Pollutants....Pages 360-435
Sediment Yield....Pages 436-456
Back Matter....Pages 457-516
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