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* Metric Name: Precipitation minus Actual Evapotranspiration during Normal Conditions *  

* Tier: 1  

* Data Vintage: 09/2021  

* Unit Of Measure: Continuous, mm/y  

* Represent element and pillar: Yes  

* Type and distribution of data: Normal, left-skewed distribution representing continuous values. Raw values range from -2000 to 1013 mm/year.  

* Translation: Where is water yield the highest?  

* Translation method and outcome: Raw data values translated to range from +1 to -1 representing more favorable to less favorable conditions, respectively. **** The proposition of more favorable is based on the objective of water yield (positive linear slope). More favorable (translated to +1) set at > 561.927 mm/year, and less favorable (translated to -1) set at -252.387 mm/year. 

Figure 201. Histogram and scoring criterion of current condition of average
annual mean runoff across the Southern California

Figure 202. Histogram of translated current condition of average annual mean
runoff across the Southern California

Figure 203. Maps displaying raw metric and translated metric of current
condition of average annual mean runoff across the Southern California

  

* Metric Definition and Relevance: Runoff is a measure of the water available for storage. It is determined by both the water supply and the demand of the existing vegetation. Annual mean runoff measures the “average” vegetative demand and thus provides a comparative index on the potential available runoff. Specifically, Annual Mean Runoff is the expected surplus water that would discharge to surface or ground water flows during a series of years with average precipitation. Larger values indicate more runoff under mean conditions.  

* Credits: CECS;