Hydrology

Flood flow

Sens technique

For a given year: it is either the highest flash flood flow rate (QIX) or the highest daily flow rate (QJX). For several years, by using a sample including the highest number possible of annual flood flows, it is the value associated with different theoretical return periods (2, 5, 10 and 50 years in Hydro), determined by a statistic study. A confidence interval is calculated based on the number of available years, their homogeneity, the…

Source

According to SCHAPI

Minimum annual mean flow

Sens technique

Minimum annual mean flow calculated for n consecutive days. The VCN3 is used to characterize a situation of severe low water over a short period (3 days). The VCN30 gives information on the minimum resource over a month. Unlike low-flow (QMNA), it is calculated over a period of any 30 consecutive days. Using a sample of values of a

Source

According to SCHAPI

Dry 5-year flow

Sens technique

Monthly flow with a 4/5 probability of being exceeded every year. It allows characterizing a calendar month with low hydraulicity.

Source

According to SCHAPI

Wet 5-year flow

Sens technique

Monthly flow with a 1/5 probability of being exceeded every year. It allows characterizing a calendar month with high hydraulicity.

Source

According to SCHAPI

Hydraulicity

Sens technique

Ratio between the monthly (or annual) flow rate and its multiannual mean. Hydraulicity can simply compare the flow rate of a given year or month to one year or a month considered "normal".

Source

According to SCHAPI

Depth of runoff

Sens commun

Amount of water measured on a level surface and expressed as height.

Source

according to IOWater

Sens technique

A flow rate value expressed in mm. The depth of runoff is obtained by dividing a runoff volume at a measuring station by the surface of the drainage basin at the station; it is most commonly expressed in mm, which allows comparing it to the rainfalls which cause it.

Source

according to SCHAPI

Specific flow

Sens technique

Flow per surface unit of the drainage basin usually expressed in litres/seconde/km2. It allows making comparison between watercourses in different river basins.

Source

According to SCHAPI

Corrected water level

Sens technique

Water level modified by the station manager using a theoretical correction curve that can correct a water level when a disturbing phenomenon occurs.

Source

According to SCHAPI

Monthly mean flow

Sens technique

Mean for a given month, of average daily flow rates.

Source

According to SCHAPI

Daily mean flow

Sens technique

Ratio between the volume of the flow for a full day (0-24 hours) and the corresponding duration. This volume is calculated by using the record of instantaneous flow rates. If the flow is expressed in m3/s, the volume is calculated in m3 and the duration in sec.

Source

According to SCHAPI