__ENVE-205
Environmental Engineering Hydrology__

__CHAPTER VI__**: Hydrographs **

In this chapter, streamflow
and runoff hydrograph general properties will be discussed. Perennial, intermittent, and ephemeral stream
properties will be introduced. The deailed mathematical derivations for both rising and
falling limbs of runoff hdrographs will be
performed. The unit hydrograph formation
from a given streamflow hydrograph will be
presented. The lagging procedure for
obtaining a longer duration unit hydrograph from given two or more shorter
duration unit hydrographs will be discussed.
A convolution-superposition procedure will be presented for producing
runoff hydrographs using unit hydrographs for precipitation events with
non-uniform intensity distribution.
Synthetic hydrograph use and their various types for Rational and NRCS
models will be discussed.

__Study Plan:__

·
Learning
hydrograph properties such as rising and falling limb behavior, the concepts of
lag time, time to peak, time of concentration, recession time, and base
time. (Section 6.1).

·
Learning
the stream types (perennial, intermittent, ephemeral) according to their streamflow behavior.
(Sections 6.1.2).

·
Deriving
the mathematical formulations for rising and falling limbs of a
hydrograph. (Sections 6.2.1, 6.2.2). ** See
formula derivations in Fig. 6.2.1.A1 and Fig. 6.2.2.A1.** Example problem
6.1 (

·
Learning
the unit hydrograph formation from a given streamflow
hydrograph in four steps. Learning the
lagging procedure for obtaining a longer duration unit hydrograph from given
two or more unit hydrographs with shorter duration. (Section 6.3). ** See Fig. 6.3.A1**.

·
Learning
a convolution-superposition procedure for producing runoff hydrographs using
unit hydrographs for precipitation events with non-uniform intensity
distribution. (Section 6.3.1). ** See Fig. 6.3.1.A1**.

·
Learning
the concept of synthetic hydrographs.
Constructing synthetic hydrographs for Rational model with D=t_{c} and D> t_{c}_{
}and derivation of peak flow rates.
Constructing synthetic hydrographs for NRCS model with D=t_{c} and D< t_{P}
and derivation of peak flow rates.
(Section 6.4.1, 6.4.2).

·
Learning
the concepts of water quality such as pollutant load, event mean concentration,
and loading rate (Section 5.5).

· Homework problems 1, 2, 4, 5, 10, 11, 12.