Department of Civil Engineering Faculty of Engineering Mahidol University Lecture Notes EGEN 612 Applied Hydrology Areeya Rittima D Eng by j1jnZ0D


									Department of Civil Engineering
Faculty of Engineering, Mahidol University

      Lecture Notes
EGEN 612 Applied Hydrology

                   Areeya Rittima, D.Eng.
Department of Civil Engineering
Faculty of Engineering, Mahidol University

         Chapter 1
     Hydrologic Cycle
     Systems Concept
     Hydrologic System Model

Hydrology is the science of water.

It is the study of the occurrence, character,
and movement of water within and between
the physical and biological components of
the environment.

The practical application of hydrology is
called Applied Hydrology.
           Applied Hydrology

Applied Hydrology are found in such tasks as

     Design and operation of hydraulic
     Water supply
     Wastewater treatment and disposal
     Hydropower generation
     Flood control
     Applied Hydrology

Erosion and sediment control
Salinity control
Pollution abatement
Recreation use of water
Fish and wildlife protection
    Role of Applied Hydrology

The role of applied hydrology is

  to help these tasks
  to provide guidance for planning and
  management of water resource
                Hydrologic Cycle

 15 km   Hydrosphere
                       Water on earth exists :
  1 km   Lithosphere    in a space called Hydrosphere
                        (15 km up into the atmosphere)
     Earth              in the crust of the earth (1 km
                        down into the Lithosphere)

Water circulates in the hydrosphere through the
maze of paths constituting the Hydrologic Cycle
        Hydrologic Cycle

The hydrologic cycle is the central focus
of hydrology.
The cycle has no beginning or end.
Its processes occur continuously.
                 Hydrologic Cycle
  Hydrologic Cycle
Hydrologic cycle

                                    Atmospheric Subsystem

                                         Surface Subsystem

                                    Groundwater Subsystem
       Hydrologic Cycle

                                      96.5% of all the earth’s water is in the oceans.

                                                1.7% of all the earth’s water is in
                                                the groundwater.

                                                1.7% of all the earth’s water is in
                                                the polar ices.

0.1% of all the earth’s water is in the surface and
atmospheric water system.

                                                           Estimated world
                                                           water quantities
                   Hydrologic Cycle
Hydrologic cycle with global annual average water balance.

                                           Average Water Balance in 1978
                     Hydrologic Cycle

Average Water Balance in 2005
                Hydrologic Cycle


Global annual
water balance
                     Example 1

Estimate the residence time of global
atmospheric moisture.
         Tr = Residence time (the average duration for a water
     S         molecule to pass through a subsystem of the
Tr 
     Q         hydrologic cycle).
         S = Volume of water
         Q = Flow rate

 S  12,900 km3 Table                          km3
                           Q  458,800  119,000     Table 
                            577,000
                 S  12,900    (km3 )
             Tr                     0.033 yr  8.2 days
                 Q 577,000 (km / yr)
Systems Concept

             Global hydrologic cycle is
             represented in a simplified
             way by means of “The System

             Most hydrologic system is
             inherently random, because
             their major input is
             precipitation, a highly variable
             and unpredictable

             The statistical analysis plays a
             large role in hydrologic

                 Block diagram
              representation of the
            global hydrologic system.
                         Example 2

   Represent the storm rainfall-runoff process on
   a watershed as a hydrologic system.

                      Input            A watershed is the area of
                                       land draining into a stream
                                       at a given location.

                                       The watershed divide is a
                                       line dividing land whose
                                       drainage flows toward the
                              Output   given stream from land
                                       whose drainage flows away
                                       from that stream.

A Watershed as a Hydrologic System
  Basic Equation of Hydrologic Cycle

   Input        Process      Output
  (Rainfall)    (Basin)      (Runoff)

Simple Hydrologic System Model

Unsteady Flow Equation ; I-Q=dS/dt
     I = Input (volume/time)
    O= Output (volume/time)
    dS/dt = Time rate of change of storage
          Basic Equation of Hydrologic Cycle

                                        Region A                     P=Precipitation
                                                   Earth’s surface   E=Evaporation
R1                                                                   T=Transpiration
                        Rg   Eg         Tg
                                                                     R=Surface Runoff
                                                                     G=Groundwater Flow
     Es    Ts

                                                                     Rg=Subsurface Flow
                  Sg                                     G2

                                                                     s=Land Surface

                Level of plastic rock
     Basic Equation of Hydrologic Cycle

 Water Budget in Land Surface
   (P+R1+Rg)-(R2+Es+Ts+I)=Ss                (1)

 Water Budget in Groundwater
   (I+G1)-(G2+Rg+Eg+Tg)=Sg                  (2)

     P-(R2-R1)-(Es+Eg)-(Ts+Tg)-(G2-G1)= Ss+Sg *

R (Net Surface Flow)=R2-R1
E (Net Evaporation) =E2+E1
T (Net Transpiration)=Ts+Tg      P-R-E-T-G=S
G (Net Groundwater Flow)=G2-G1
S= Ss+Sg

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