Plymouth Carver Aquifer Area Water Budgets S ub b asin W ater B udget S tream flow Out S tream flo w In W ast ew a ter D isch arg e W aste w ate r L o ss, In clu din g I/I R ech arg e L o ss F ro m Im p erv io u s C over W ater S upply W ithd raw als E vap o rativ e L o ss F ro m Irrigation W a ter S u p p ly Input Nigel Pickering Senior Engineer and Modeler Charles River Watershed Association www.charlesriver.org
Plymouth Carver Aquifer Area Water Budgets. Nigel Pickering Senior Engineer and Modeler Charles River Watershed Association www.charlesriver.org. PCAA Water Budgets Project Structure. Funding & Project Management EOEEA Data Collection & Processing Fuss & O’Niell MassGIS - PowerPoint PPT Presentation
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Plymouth Carver Aquifer Area Water Budgets
S ub b as in W aterB ud get
S tr eam f lo w O u tS tr eam f lo w I n
W as tew a te r D isc h a rg e
Wastew
ater Loss,
Including I/I
Recharge L
oss From
Impervious C
over
Wat
er S
uppl
yW
ithd
raw
als
Eva
pora
tive
Los
sF
rom
Irr
igat
ion
W a te r S u p p ly In p u t
Nigel Pickering
Senior Engineer and Modeler
Charles River Watershed Association
www.charlesriver.org
PCAA Water BudgetsProject Structure
• Funding & Project Management– EOEEA
• Data Collection & Processing– Fuss & O’Niell– MassGIS
Impact = total subbasin gain or lossSD = wastewater discharge to surface waterSW = withdrawal from surface waterWS = water supply gainWW = wastewater loss including infiltration from groundwaterIRR = evaporation loss from irrigationRIA = recharge loss from impervious areaGD = wastewater discharge to ground waterGW = withdrawal from ground waterSFAC = storage factor (0.9 – 1.1)
Water Budget Examples
• PWS, septic, no IA– water in - no water out = net gain
• PWS, sewer, no IA– water in - more water out (incl. I/I) = net loss
• Water withdrawal, no PWS, no WW, no IA– no water in - water out = net loss
• Wastewater discharge, no PWS, no WW, no IA– water in – no water out = net gain
• No PWS, no WW, large IA– no water in - water out = net loss
Withdrawals and Discharges
• Monthly flows for 2000-2004– filled-in if necessary
• Average monthly flow computed
• River withdrawals & discharges directly from sub-basin
• Well withdrawals converted to stream depletion using StrmDepl (USGS)
• Well withdrawals distributed over subbasins with zone of contribution
Cranberry Bog Impacts• Reported system areas for 2000-2004
– filled-in if necessary
• System area distributed over number of number of withdrawal points
• Monthly sub-model developed for 1-ac of cranberry– monthly inputs/outputs in ac-ft of water
• Converted to monthly point volumes (mgd) using annual area and monthly factors
Cranberry Sub-Model
• Water balance of typical cranberry farm
• Assumed calendar and amounts for water-related events
• Water moved in and out for harvesting, frost-damage control, and weed control
• Water used for irrigation in the growing season--small for “average” year
• Net water use expressed relative to natural landscape i.e. wetland
Cranberry Sub-Model• Calendar
– May to Sep-growing season• crop ET coefficient = 0.66• irrigation at 1”/wk when dry
– Oct-harvest• field flooded (1.5 ft) and drained (1.5 ft)
– Nov & Dec-freeze protection• Add water (1.0 ft then further 0.7 ft)
– Mar-drain and flood• Release (2.0 ft) and add water (2.0 ft)
– early May-drain field• Release water (2.0 ft)
Cranberry Sub-Model
0
0.5
1
1.5
2
2.5
3
1 2 3 4 5 6 7 8 9 10 11 12
Month
Wat
er D
epth
(ft
)
Inflow Outflow Cranberry Level Wetland Level
Total withdrawals = 5.2 ft/yr
Cranberry Sub-Model
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
0 2 4 6 8 10 12 14
Month
Net
Wat
er O
utF
low
(ft
)
Cranberry Wetland Difference
Cranberry Sub-Model
-1
-0.5
0
0.5
1
1.5
0 2 4 6 8 10 12 14
Month
Net
Wat
er O
utF
low
(ft
)
Cranberry Wetland Difference
Wetland Net Outflow = 1.00 ft/yrCranberry Net Outflow = 1.86 ft/yr
Net Gain = 0.86 ft/yr
Water Transfers and Irrigation
Sewer SepticPublic water +WS - WW - IRR +WS - IRRPrivate well - WW - IRR - IRR
WW = wastewater including I/IIRR = irrigation
WS = public water supply
• Subbasin transfers computed using system unit flows with people and areas
• People and areas from distribution system maps and new MassGIS population density map
• Monthly irrigation loss computed as:– 75% of (monthly use - winter use)– Applied to both public/private irrigation areas
Piped Distribution
Systems
• Water supply only
• Sewer only
• Water & sewer
Effective Impervious Area (EIA)
• Loss assumed proportional to EIA– 10% EIA 10% reduction in streamflow
• Subbasin TIA from new MassGIS IA grid
• Subbasin EIA computed from TIA as:Effectiveness (%) = -0.214+1.429*TIA (0 to 100)