groundwater recharge from mains leakage

Beatriz Garcia-FrescaNovember 2002

CE 394K.3 GIS in Water Resources

datasets:GEOLOGY

geology + city footprint

datasets:WATERMAINS

source:City of Austin GIS datasets

data processing

• reprojecting Texas Central State Plane (US ft)

• spatial analysis reclassification of geology

according to relative permeability

• calculations: CoA water usage leakage

• geoprocessing: isolating pipes by aquifer group

relative permeabilities

relative permeabilities

calculations

  Pumpage pumpage real loss daily average

Year (millions of gallons) millions m3 millions m3 m3/d

1993 39,824 151 10.57 413514.96

1994 39,806 151 10.56 413328.05

1995 39,542 150 10.49 410586.79

1996 45,835 174 12.16 475930.55

1997 42,812 162 11.36 444541.04

1998 46,438 176 12.32 482191.84

1999 46,422 176 12.32 482025.70

2000 52,193 198 13.85 541949.23

2001 50,140 190 13.30 520631.78

↑ ↑

City of Austin - Water and Wastewater Utility

calculations

• attributes: diameter & length

• calculations: – V each pipe– total V pipes– daily V of water per pipe– daily leakage (~7%)– add leakage of all pipes

summary and resultsaverage pumpage CoA 520631.78 m3/d CoA Water &

Wastewater Utility total V of pipes 672465.55 m3 from GIS project coeff. 0.774

area of Austin 271.8 sqmi City of Austin – Austin Facts703.962 Km2

annual precipitation 840 mm NOOA

total mains loss 12 % Austin American Statesman, 1998

real loss (leakage) 7 % Thornton, 200236434.2 m3/d results from GIS

project13.3 million m3/a18.89 mm/a4.80 in/a

datasets:WASTEWATE

RMAINS

source:City of Austin GIS datasets

Work in progress

a fundigression

conclusions

• the urban induced recharge in Austin is significant

• utility lines can be analyzed using ArcHydro tools

• ArcGIS presents more operational problems than ArcView

future work

• add recharge from wastewater mains– what are the qualitative implications?

• refine calculations:– include infiltration coeffs. of soils?