Flow framework

Article reference Flow framework
For planning purposes For monitoring purposes

Article 6A - Acceptable minimum monthly natural flow during each month of the dry season (December - May)

Applied at all stations except Kampong Luong and Prek Kdam (in the Tonle Sap River)

Options for agreed for testing:

  • Option1: a range of the 1:4-1:5 years Annual Recurrence Interval (ARI)*
  • Option2: a range of the 80- 90% time exceedance of Flow Duration Curve (FDC)**

Actions determined in relation to:

  • 1:5 Annual Recurrence Interval (ARI)
  • 1:10 ARI
  • 1:20 ARI
 

Article 6A For Planning Purposes

Article 6A For Monitoring Purposes


Article 6B - Acceptable natural reverse flow of the Tonle Sap taking place during the wet season (June - November)

Applied at Kratie in the Mekong River and Prek Kdam (in the Tonle Sap River), but using also data from Kampong Luong (in the Tonle Sap Lake)

Probability of exceedance of total wet season flow volumes (June - November) at Kratie within the upper and lower 90% confidence interval of the Baseline

Historically observed maximum and minimum accumulated reverse flow volume at Prek Kdam

 

Article 6B For Planning Purposes

Article 6B For Monitoring Purposes


Article 6C - Preventing average daily peak flows greater than what naturally occur on the average during the flood season (July - October)

Applied at all stations except Kampong Luong (in the Tonle Sap Lake) and Prek Kdam (in the Tonle Sap River)

Average daily peak flow during the flood season (July-October)

Actions determined in relation to:

  • 1:2 ARI
  • 1:10 ARI
  • 1:20 ARI
 

Article 6C For Planning Purposes

Article 6C For Monitoring Purposes


*:  Annual Recurrence Interval (ARI) is defined as the average annual rate of occurrence of an event. In this instance, a 1:5 ARI flow is the mean monthly flow that that is NOT equalled or exceeded one year in five in the record under consideration; a lognormal distribution is used to calculate the ARIs.


**: A Flow Duration Curve (FDC) is a plot of flows ranked from highest to lowest. In this instance the 80% exceedance value is the mean monthly flow in a particular month that is exceeded for 80% of the record under consideration.