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Aereement for TmePoint Services Exhibit D — Water Budget Methodolok <br />Variable Definition Default Values Variable <br />Type <br />Ks Species or plant factor relating to a specific plant type's water KsT or KSN or <br />requirement as a fraction of ETo. Ksw <br />KsT Turfgrass water requirement default value. 0.8 <br />KSN Non -Turf water requirement default value. 0.4 <br />Ksw Water Feature water requirement default value. 1.2 <br />ETo Reference evapotranspiration (inches) equals the depth of CIMIS Spatial <br />water evaporated and transpired from a reference crop (4 to ZIP: 94063 <br />7 inch tall fescue grass) with an abundant water supply. ETo is <br />the "standard" measure of water needs from which other <br />plant types are compared via Ks. Redwood City uses ETo from <br />CIMIS weather stations. CIMIS weather data is accessed <br />through the CIMIS Web API and REST Services more <br />information is available at http://et.water.ca.gov/ Redwood <br />City uses the CIMIS Spatial Network data source for ETo <br />collected by Zip Code. <br />ERain(d) Effective rainfall for each day (d) in inches equals the depth of <br />Constant <br />Constant <br />Constant <br />Source <br />Variable <br />Function <br />Function <br />>= 0 Function <br />Calculated, Function <br />>= 0 <br />Calculated, Function <br />>= 0 <br />1.25 Constant <br />Water Budget Methodology Page - 33 - <br />ATTYlAGR.2019.106(iruePoint TrueBill Utility Billing System <br />rain effective in offsetting ETo for each hydrozone. Effective <br />rainfall varies widely with rainfall frequency, magnitude, time <br />of year, and root zone depth. Effective Rain is calculated <br />separately for Turf and Non -Turf. <br />ERainT(d) <br />= Min(Precip(d), (MSCI+ ETo(d) - SST(d-1))) <br />ERainNT(d) <br />= Min(Precip(d), (MSCNT+ ETo(d)-SSNT(d-1))) <br />NIR(d) <br />Net Irrigation Requirement: The amount of water required in <br />a hydrozone that is not provided by rainfall. NIR is calculated <br />for each day (d), based on weather data downloaded from <br />specified weather websites. NIR is calculated for both turf <br />and non -turf surfaces, since these surfaces have different <br />water storage characteristics, and thus differing requirements <br />for irrigation. NIR is a function of daily precipitation and daily <br />reference evapotranspiration. Should any calculated NIR <br />value be a negative a value of 0 shall be used for NIR. <br />NIRT(d) <br />NIRT is calculated for Turf using the logic below and the max <br />soil constant for turf minimized to 0. <br />=Max(0, ETo(d) - ERain(d) - SST(d-1)) <br />NIRNT(d) <br />NIRNT is calculated for Non -Turf using the logic below and the <br />max soil constant for non -turf minimized to 0. <br />=Max(0, ETo(d) - ERain(d) - SSNT(d-1)) <br />NIRDF <br />A default factor to be applied to NIR when historical NIR <br />values are used to calculate water budgets. This accounts for <br />REV: 04-23-19 PR <br />Page 33 of 64 <br />Constant <br />Constant <br />Constant <br />Source <br />Variable <br />Function <br />Function <br />>= 0 Function <br />Calculated, Function <br />>= 0 <br />Calculated, Function <br />>= 0 <br />1.25 Constant <br />Water Budget Methodology Page - 33 - <br />ATTYlAGR.2019.106(iruePoint TrueBill Utility Billing System <br />