To help its large irrigation customers save water and money while improving their efficiency, the Contra Costa Water District is creating Landscape Water Budgets for each of its dedicated irrigation accounts.

To prepare an accurate estimate of water use for a landscape water budget, factors such as local evapotranspiration, rainfall, lawn square footage, non-lawn landscape square footage, and irrigation efficiency have been calculated.

CCWD has created one of the most accurate large-scale water budget programs in the state to give its customers the tools to save water save money, and keep landscapes vibrant.

Your Landscape Water Budget Site Report compares your actual water use to an accurate estimate of the water demand for your site.

Creating the Landscape Water Budget

A water budget is an estimate of the water demand a landscape needs over a specific time period. The water budget is determined by a combination of two key factors: 1) landscape square footage area, and 2) evapotranspiration (ETo). The landscape area is determined by measuring the site; the ETo is measured daily at a local weather station.

Measuring Landscape Square Footage
With a grant from the United States Bureau of Reclamation, CCWD measured the landscape areas of each of its 1,277 commercial, institutional and multifamily dedicated irrigation accounts.

To do this, the District uses aerial multi-spectral images. These images provide estimates of landscape area using a multiple-band digital camera system.

This image is 'classified' into several key surface types including: lawn, shrub/tree, water, bare soil, and hardscape/roof. Next, parcel polygons acre overlaid onto the image, producing area measurements for each parcel.

Using GIS software, the image is linked to individual property parcels and water account numbers. Polygons were then reviewed and adjustments made to ensure accuracy of site boundaries. The final result is an image that displays individual sites and square footage measurements for turf, non-turf landscape, water features and bare soil.

CIMIS Station Number 170 is located at the Diablo Creek Golf Course. It measures solar radiation, air temperatures, wind speed, humidity and rainfall. For more on CIMIS, click here.

Weather Data
A remote weather station at the Diablo Creek Golf Course measures solar radiation, air temperature, soil temperature, wind speed and humidity, as well as rainfall.

The data is then entered into an equation; the result is the ETo, which is provided in inches per period. Accurate weather data is essential in creating useful water budgets.

In early 2001, with a grant from the United States Bureau of Reclamation, CCWD worked with the state Department of Water Resources and the city of Concord to install CIMIS Station Number 170.

The station ensures local water users and the CCWD Water Budget Program have accurate weather data for the area. For more on CIMIS, and to register to read CIMIS data from Station 170, click here

Calculating The Water Budget Equation
A water budget is created by multiplying the landscape area by the ETo - Rain, which results in a volume of water demand for a given period.

The CCWD water budgets incorporate turf, other plant materials and water features areas, landscape coefficients, current local Eto, and rainfall. The water consumption at a site is then compared to the water budget to create your individual Landscape Water Budget Site Report.

Click here for more on the Water Budget Equation.