What does a flow-duration curve tell us?
What does a flow-duration curve tell us?
The flow duration curve is a plot that shows the percentage of time that flow in a stream is likely to equal or exceed some specified value of interest. The basic time unit used in preparing a flow-duration curve will greatly affect its appearance. For most studies, mean daily discharges are used.
How do you calculate flow duration curves?
Steps for drawing Flow Duration Curve
- Calculate the total number of data, say N.
- Give rank to the data for the data 1,2,3,…., N; say n.
- Compute frequency(f)
- Compute the probability of exceedance(p)
- Now place the discharge in descending order.
- Draw the probability of exceedance or % of the time versus discharge.
How is FDC calculated?
For each flow value Q in the original streamflow time series, calculate its percentile P in the FDC: P = 100 * Rank / (N + 1), where N is the number of data points and Rank is the rank order (from 1-N) of Q in the flow duration curve (flows in decreasing order).
What is mass duration curve?
Mass Curve • It is a plot of cumulative volume of water that can be stored from a stream flow versus time in days, weeks or months. It shows a mass curve, Maximum intercept between line AB and mass curve is known as reservoir capacity • The unit used for storage is either cubic metre or day-second-metre.
What does a flow duration curve look like?
The flow-duration curve is a cumulative frequency curve that show the percent of time specified discharges were equaled or exceeded during a given period.
How is the duration of a flow calculated?
A flow duration curve is a plot of discharge vs. percent of time that a particular discharge was equaled or exceeded. The area under the flow duration curve (with arithmetic scales) gives the average daily flow, and the median daily flow is the 50% value.
How is discharge related to precipitation and duration?
Catchment discharge. Analysis of the relationship between precipitation intensity and duration and the response of the stream discharge are aided by the concept of the unit hydrograph, which represents the response of stream discharge over time to the application of a hypothetical “unit” amount and duration of rainfall (e.g.,…
How to calculate the flow velocity of a discharge?
Theory and calculation 1 Q {\\displaystyle Q} is the discharge ( [L 3 T −1 ]; m 3 /s or ft 3 /s) 2 A {\\displaystyle A} is the cross-sectional area of the portion of the channel occupied by the flow ( [L 2 ]; m 2 or ft 2) 3 u ¯ {\\displaystyle {\\bar {u}}} is the average flow velocity ( [LT −1 ]; m/s or ft/s)