Hydrology & Water Resources Engineering - Vol 2 | 32. Runoff by Abraham | Learn Smarter
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Knowledge
32. Runoff

Runoff plays a crucial role in the hydrological cycle and is essential for effective water resource management. The chapter outlines various components of runoff, factors affecting it, methods to estimate basin yield, and techniques for analyzing runoff data through the SCS-Curve Number method and flow duration curves. Understanding these concepts is critical for managing water resources and flood control effectively.

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Sections

  • 32

    Runoff

    Runoff is a critical element of the hydrological cycle, encompassing the portion of precipitation that flows across land towards water bodies.

    Learning Practice

  • 32.1

    Components Of Runoff

    Runoff consists of surface runoff, interflow, and base flow, each with distinct characteristics impacting land and water management.

    Learning Practice

  • 32.1.1

    Surface Runoff

    Surface runoff is a vital segment of the hydrological cycle, representing precipitation that exceeds soil infiltration capacity and flows over land.

    Learning Practice

  • 32.1.2

    Interflow (Subsurface Runoff)

    Interflow, also known as subsurface runoff, is the lateral movement of water within the upper soil layers that contributes to streamflow after precipitation events.

    Learning Practice

  • 32.1.3

    Base Flow

    Base flow is the runoff that sustains river flows during dry periods, primarily originating from groundwater seeping into stream channels.

    Learning Practice

  • 32.2

    Factors Affecting Runoff

    This section discusses the various factors that influence the generation and magnitude of runoff, categorized into climatic, physiographic, and basin characteristics.

    Learning Practice

  • 32.2.A

    Climatic Factors

    Climatic factors significantly influence runoff characteristics, affecting water resource management and hydrological studies.

    Learning Practice

  • 32.2.B

    Physiographic Factors

    Physiographic factors are significant determinants of runoff, influencing the flow of water across land surfaces.

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  • 32.2.C

    Basin Characteristics

    Basin characteristics influence the runoff behavior within watersheds, impacting hydrological cycles and water resource management.

    Learning Practice

  • 32.3

    Basin Yield

    Basin yield refers to the total volume of water that can be extracted from a river basin over a specific period under defined conditions.

    Learning Practice

  • 32.3.1

    Definition

    Basin yield refers to the total volume of water available for use from a river basin in a specific time frame under defined conditions.

    Learning Practice

  • 32.3.2

    Types Of Basin Yield

    This section outlines the definitions and types of basin yield, emphasizing safe yield and maximum yield.

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  • 32.3.3

    Assessment Of Basin Yield

    This section discusses the methods used to assess the basin yield, which quantifies the total volume of water that can be extracted from a river basin within specific conditions.

    Learning Practice

  • 32.4

    Scs-Cn Method Of Estimating Runoff

    The SCS-CN method provides a simplified approach to estimate direct runoff from rainfall events, relying on a fixed relationship between rainfall, retention, and runoff.

    Learning Practice

  • 32.4.1

    Assumptions

    This section outlines the foundational assumptions underlying the SCS-CN method for estimating runoff.

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  • 32.4.2

    Key Equations

    This section outlines key equations used in the SCS-CN method for estimating runoff, providing essential mathematical relationships for rainfall, retention, and curve number.

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  • 32.4.3

    Advantages

    The SCS-Curve Number method offers several advantages, making it a popular choice for estimating runoff.

    Learning Practice

  • 32.4.4

    Limitations

    The limitations of the SCS-CN method pertain to its applicability and sensitivity, highlighting the need for caution in its use.

    Learning Practice

  • 32.5

    Flow Duration Curves

    Flow Duration Curves (FDC) graphically represent the percentage of time a specific streamflow is equaled or exceeded, aiding in water resource management.

    Learning Practice

  • 32.5.1

    Construction Steps

    This section outlines the essential steps for constructing a Flow Duration Curve (FDC), which is crucial for hydrological analysis.

    Learning Practice

  • 32.5.2

    Uses

    This section discusses the various applications of flow duration curves (FDC) in hydrology, including hydropower assessments and reservoir designs.

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  • 32.5.3

    Types

    This section classifies the components of runoff into surface runoff, interflow, and base flow, discussing their sources and timing.

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  • 32.6

    Mass Curve Of Runoff – Analysis

    The Mass Curve is a graphical representation used in hydrology to plot cumulative runoff volume over time, which helps in determining storage requirements for water supply and reservoir planning.

    Learning Practice

  • 32.6.1

    Construction

    Learning

  • 32.6.2

    Applications

    This section discusses the various applications of mass curves for runoff analysis in water resource planning and management.

    Learning Practice

  • 32.6.3

    Advantages

    The advantages of using the Soil Conservation Service Curve Number (SCS-CN) method include its simplicity and minimal data requirements.

    Learning Practice

References

Chapter_32_Runof.pdf

Class Notes

Memorization

What we have learnt

  • Runoff consists of surface ...
  • Basin yield can be assessed...
  • The SCS-Curve Number method...

Final Test

Revision Tests