Statistical Water Supply Index SWSI z Surface Water

  • Slides: 14
Download presentation
Statistical Water Supply Index (SWSI) z Surface Water Supply is the reservoir storage at

Statistical Water Supply Index (SWSI) z Surface Water Supply is the reservoir storage at the beginning of, plus the natural streamflow during, the primary snowmelt and growing season relevant to the region of interest. z Index is an appropriately scaled numeric indicator of the status of the elements used to calculate the surface water supply.

History of Statistical Water Supply Index (SWSI) z Originally developed in early 1980 s

History of Statistical Water Supply Index (SWSI) z Originally developed in early 1980 s in Colorado z Original formulation, with variations, also adopted by Montana and Oregon z Procedure reviewed by NRCS in cooperation with Colorado Climate Center in early 1990 s z Revised formulation based on water supply forecasts published in 1993 z New formulation, with variations, adopted by Idaho, New Mexico, and Colorado

Original Formulation of SWSI where: P = nonexceedance probability (%) of respective hydrologic variable

Original Formulation of SWSI where: P = nonexceedance probability (%) of respective hydrologic variable a, b, c, d = subjective weights

Limitations of Original Formulation of SWSI n n n Statistical properties of the combination

Limitations of Original Formulation of SWSI n n n Statistical properties of the combination of non-exceedance probabilities are not known Subjective weights No explicit definition of surface water supply

Revised Formulation of SWSI where: P = non-exceedance probability (%) of reservoir storage +

Revised Formulation of SWSI where: P = non-exceedance probability (%) of reservoir storage + observed or forecasted streamflow (season dependent) 50 = centers the distribution on zero 12 = scales to existing ranges for drought existing indexes

Streamflow Variable Used in Revised Formulation of SWSI z Streamflow forecast is used when

Streamflow Variable Used in Revised Formulation of SWSI z Streamflow forecast is used when available, otherwise use previous month's streamflow as alternate. z Official streamflow forecasts are available January - May or June z Forecasts during summer and fall months should be possible in areas with significant ENSO signal and/or relationship with previous month's precipitation

Example Monthly Formulation - CO z Oct-Nov: Obs. Res. Storage + Obs. Streamflow z

Example Monthly Formulation - CO z Oct-Nov: Obs. Res. Storage + Obs. Streamflow z Dec: Obs. Res. Storage + Apr-Jul / Sep volume based on Dec 1 SWE / SOI as relevant z Jan-Apr: Obs. Res. Storage + Apr-Jul /Sep volume forecasts

Example Monthly Formulation - CO z May: Obs. Res. Storage + Apr-Jul / Sep

Example Monthly Formulation - CO z May: Obs. Res. Storage + Apr-Jul / Sep volume forecasts - Apr runoff z Jun: Obs. Res. Storage + Apr-Jul / Sep volume forecasts - (Apr-May) runoff z Jul-Sep: Obs. Res. Storage + previous month’s obs. Streamflow

Current SWSI Implementation

Current SWSI Implementation

Additional Considerations z Data Sources: Precipitation, snowpack, streamflow, reservoir storage. z Centralized / De-Centralized

Additional Considerations z Data Sources: Precipitation, snowpack, streamflow, reservoir storage. z Centralized / De-Centralized computation z Actual spatial representation: Entire basin / “ribbon” along the river z Presentation: Graphic / Tabular

Proposed Initial Selections z Climate - UCAN z Streamflow - NWIS z De-Centralized -->

Proposed Initial Selections z Climate - UCAN z Streamflow - NWIS z De-Centralized --> Centralized z River-Ribbon presentation z Graphic and Tabular

Surface Water Chapter 9 Surface water movement WaterSurface Water Chapter 9 Surface water movement Water
Surface Water Surface Water Movement The water cycleSurface Water Surface Water Movement The water cycle
Surface Water Surface Water Movement Water Cycle EarthsSurface Water Surface Water Movement Water Cycle Earths
SUPPLY Definition of Supply Law of Supply SupplySUPPLY Definition of Supply Law of Supply Supply
Supply 1 Supply Defined What is supply SupplySupply 1 Supply Defined What is supply Supply
Supply Law of Supply and Supply Curve SupplySupply Law of Supply and Supply Curve Supply
Outbrief of SWSI Architecture Committee F 2 FOutbrief of SWSI Architecture Committee F 2 F
SWSI Plus Observations Phil Pasteris Supervisory Physical ScientistSWSI Plus Observations Phil Pasteris Supervisory Physical Scientist
Water Supply 1 Water Supply Components 2 WaterWater Supply 1 Water Supply Components 2 Water
Water Supply 1 Water Supply Components 2 WaterWater Supply 1 Water Supply Components 2 Water
Index table primary index one primary index forIndex table primary index one primary index for
Index Numbers Index Numbers INDEX NUMBER A numberIndex Numbers Index Numbers INDEX NUMBER A number
Organization Index u Organization index u Organization IndexOrganization Index u Organization index u Organization Index