Hydrograph and it's Interpretation

The hydrograph is a way of representing the water level over time. A hydrograph plot may display stage, streamflow, and sometimes both. Hydrographs can be a helpful way to show water level observations and forecasts visually on a single graphic. The rate of flow is typically expressed in cubic meters per second. Hydrographs often relate changes of precipitation to changes in discharge over time.

Hydrograph Terminology :

Discharge : The rate of flow passing a specific location (volume per unit time)
Approach Segment : The river flow before storm

Rising limb : Also called concentration curve, reflects a prolonged increase in discharge from a catchment area, in response to a rainfall event.
Peak discharge : The highest point on the hydrograph when the rate of discharge is greatest
Falling limb : Limb of peak flow onward
Lag time : The time interval from the maximum rainfall to the peak discharge
Base level : Base flow is the portion of the stream flow that is sustained between rainfall events

Factors affecting hydrograph : Drainage basin size and shape, ground permeability, vegetation, land-use change, base flow of the river.

Skewness of the Hydrograph :

The skewness of the hydrograph depends on the relative dominance between hillslope and channel network transport processes, where the former one makes the hydrograph positively skewed while the latter one tends to make it negatively skewed.