Laserfiche WebLink
<br />Page 36 of 38 <br />ATTY/AGR/2017.104/SMART ENERGY SYSTEMS – CUSTOMER WATER USE PORTAL <br />REV: 05-15-17 MI <br />Water Budget Formula <br /> <br />Water Budget Definitions & Variables: <br /> <br />Variable Definition Redwood City Value <br />BUDGET <br />= <br />Volume of water budgeted for a given hydrozone <br />area for a given period. The overall water use <br />budget for a site is the sum of budgets over all <br />hydrozones. <br /> <br />AREA = Landscape area irrigated in hydrozone (square <br />feet). <br />AT or AN or AW <br />AT Turfgrass area in square feet site measurement <br />AN Non-Turf area in square feet site measurement <br />AW Water Feature area in square feet site measurement <br />KS = <br /> <br />Species or plant factor relating a specific plant <br />type’s water requirements as a fraction of ETo. <br />KST or KSN or 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 <br />the depth of water evaporated and transpired <br />from a reference crop (4 to 7 inch tall fescue <br />grass) with an abundant water supply. ETo is the <br />“standard” measure of water needs from which <br />other plant types are compared via KS. Redwood <br />City uses ETo from CIMIS weather stations. <br />CIMIS weather data is accessed through the <br />CIMIS Web API and REST Services more <br />information is available at http://et.water.ca.gov/ <br />by CIMIS <br />(period aggregate) <br />ERain = Effective rainfall (inches) equals the depth of rain <br />effective in offsetting ETo for each hydrozone. <br />Effective rainfall varies widely with rainfall <br />frequency, magnitude, time of year, and root <br />zone depth. Redwood City uses rainfall data <br />from Weather Underground (WU). WU data is <br />accessed through the WU API more information <br />is available at <br />http://www.wunderground.com/weather/api <br />by WeatherUnderground <br />(period aggregate) <br />NIR Net Irrigation Requirement: The amount of water <br />required in a hydrozone that is not provided by <br />rainfall. NIR is calculated for each day, based on <br />Function >= 0 <br />6.1.E. - Page 39