following nine use categories: aquaculture (AQU), self-supplied commercial facilities (COM), self-supplied industrial facilities (IND), crop and nursery irrigation
(IRR-C), golf course irrigation (IRR-G), livestock production (LIV), mining
(MIN), thermoelectric power generation (PP), and public water supply systems
(PWS).
The withdrawal data available from the states has significant data gaps over the
time period of the study, 1985–2012. To fill these gaps, annual water use data
compiled by the USGS are used. Starting in 1985 and every 5 years thereafter, the
USGS estimates total annual water use at the county level by water use type [29]. In
addition to the eight water use categories given above, the USGS data provide
estimates of self-supplied domestic water use (SSD). For this study, values of
average annual withdrawals from the USGS datasets are interpolated to provide
time series of monthly withdrawals at the county level, and these are disaggregated
by river segment and weighted by area or in some cases by land use area to obtain
monthly time series of average withdrawals by water use type by river segment.
Return flow (discharge) data for wastewater treatment plants (WWTPs) in the
Chesapeake Bay watershed are available from the CBP. These data include monthly
flows and nutrient concentrations from municipal and county wastewater treatment
facilities and certain large industrial facilities. As described below, the CBP
discharge dataset is used in this study to determine the locations of the WWTPs
associated with public water supply systems and to estimate site-specific consumptive use coefficients for selected large industrial facilities for which paired withdrawal and discharge data are available.
3.5 Consumptive Use Estimate Methods
This study uses a variety of methods to estimate consumptive use in the upper
Potomac Basin, depending on water use type and on data availability and quality.
For selected industrial and commercial facilities for which both withdrawal and
discharge data are readily available, site-specific consumptive use coefficients are
computed from Eq. (1b). For all other cases, consumptive use is estimated from
withdrawal data and non-site-specific consumptive use coefficients: (a) for public
water supply systems, consumptive use coefficients are computed from upper
Potomac Basin withdrawal data using the “winter base rate” method; (b) for other
use types, coefficients from the published literature are used.
The relational database used in this study has been designed to facilitate the
addition of site-specific consumptive use coefficients as more data becomes available. Details of consumptive use estimate methods are provided below.
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(IRR-C), golf course irrigation (IRR-G), livestock production (LIV), mining
(MIN), thermoelectric power generation (PP), and public water supply systems
(PWS).
The withdrawal data available from the states has significant data gaps over the
time period of the study, 1985–2012. To fill these gaps, annual water use data
compiled by the USGS are used. Starting in 1985 and every 5 years thereafter, the
USGS estimates total annual water use at the county level by water use type [29]. In
addition to the eight water use categories given above, the USGS data provide
estimates of self-supplied domestic water use (SSD). For this study, values of
average annual withdrawals from the USGS datasets are interpolated to provide
time series of monthly withdrawals at the county level, and these are disaggregated
by river segment and weighted by area or in some cases by land use area to obtain
monthly time series of average withdrawals by water use type by river segment.
Return flow (discharge) data for wastewater treatment plants (WWTPs) in the
Chesapeake Bay watershed are available from the CBP. These data include monthly
flows and nutrient concentrations from municipal and county wastewater treatment
facilities and certain large industrial facilities. As described below, the CBP
discharge dataset is used in this study to determine the locations of the WWTPs
associated with public water supply systems and to estimate site-specific consumptive use coefficients for selected large industrial facilities for which paired withdrawal and discharge data are available.
3.5 Consumptive Use Estimate Methods
This study uses a variety of methods to estimate consumptive use in the upper
Potomac Basin, depending on water use type and on data availability and quality.
For selected industrial and commercial facilities for which both withdrawal and
discharge data are readily available, site-specific consumptive use coefficients are
computed from Eq. (1b). For all other cases, consumptive use is estimated from
withdrawal data and non-site-specific consumptive use coefficients: (a) for public
water supply systems, consumptive use coefficients are computed from upper
Potomac Basin withdrawal data using the “winter base rate” method; (b) for other
use types, coefficients from the published literature are used.
The relational database used in this study has been designed to facilitate the
addition of site-specific consumptive use coefficients as more data becomes available. Details of consumptive use estimate methods are provided below.
150
J. Ducnuigeen et al.