RESIDENTIAL WATER DEMAND IN LAS VEGAS, NEVADA

Transcription

1 RESIDENTIAL WATER DEMAND IN LAS VEGAS, NEVADA Christa Brelsford, Santa Fe Institute 3/31/2015

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3 population area cartogram based on 1996 population

4 population area cartogram based on 2007 population

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8 Atlanta, Denver, Long Beach, Los Angeles, Portland, and Tucson have also shown declines in per capita consumption in recent decades. Is this a general trend, or caused by factors specific to each city?

9 Conservation Policy 96 WSL program begins 99 Irrigation Clock Rebate program begins 00 Restrictions on turf in new construction 02 Water Waste citations by LVVWD legally possible 04 WSL program scales up Water Smart Homes program begins Car Wash Coupon program begins Stricter restrictions on water features Water Waste citations possible in practice More restrictions on turf in new construction Water price increase 05 Pool Cover program begins Water Waste fines increased 07 Conservation TV ads

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11 What combination of infrastructure change, population growth and policy choices drove Las Vegas decline in household consumption?

12 !!!! =!!,!!!...!!!!!" = [!"#!"$$%!$]! ln!(!!" ) =! +!! +!! +!!"! +!!"!!! 1996, 2007!!!! semi-log regression with spatial fixed effects and temporal dummy variables

13 Regressors! living area! bedrooms! plumbing fixtures! vintage! pool ownership rate! precipitation! temperature! dirt area! vegetation area! vegetation * temperature! vegetation * precipitation! dirt * temperature! dirt * precipitation! pools * temperature

14 Year FE Year FE + Controls Year FE + Controls + Tract FE Living Area (m 2 ) *** ** Plumbing Fixtures *** Bedrooms 0.154*** Pool Percentage 0.527*** 0.373* Pct Pool * Min Temp (% * C) Total June Precip (cm) *** Dirt * Min Temp (100 m 2 * C) ** Vegetation * Min Temp (100 m 2 * C) * * Area Dirt (100 m 2 ) ** *** Area Veg (100 m 2 ) 0.108*** 0.217*** Min Temp (C) Vintage 1960 to *** Vintage 1984 to *** Vintage 1994 to *** Vintage 2001 to *** Vintage 2004 to *** Year Fixed Effect (baseline) Year Fixed Effect *** 1998 Year Fixed Effect *** *** *** 1999 Year Fixed Effect *** *** 2000 Year Fixed Effect Year Fixed Effect ** *** *** 2002 Year Fixed Effect *** *** *** 2003 Year Fixed Effect *** *** *** 2004 Year Fixed Effect *** *** *** 2005 Year Fixed Effect *** *** *** 2006 Year Fixed Effect *** *** *** 2007 Year Fixed Effect *** *** *** Constant 3.291*** 3.374*** 2.875*** R-squared

15 Selected Regression Results

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19 COUNTERFACTUAL SCENARIO ESTIMATION

20 1. How did changing household infrastructure characteristics like house size, number of bedrooms or plumbing fixtures, and pool prevalence influence household water consumption? 2. How did changing vegetation area per household influence household consumption? 3. How did population growth and new construction influence household water consumption?

21 Scenario Estimation Method! In each scenario, the variable in question is held constant at the 1996 levels.!!" =!!!""#!! Using our regression results, we compare expected consumption under the scenario to true consumption.! The actual changes that occurred in x caused the difference between measured and scenario consumption.

22 Pools Example! Pool ownership rates declined by a small amount in both the periphery and core between 1996 and 2007.! The estimated coefficient on pool ownership is large and positive: in a given neighborhood, an increase in pool ownership from 0% to 100% increases average household consumption there by 52%! In the pools scenario, we estimate what household consumption would have been if pool ownership rates stayed at 1996 levels.! The decline in pool ownership caused a decline in household consumption.

23 Household Infrastructure

24 Household Infrastructure

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33 1. How did changing household infrastructure characteristics like house size, number of bedrooms or plumbing fixtures, and pool prevalence influence household water consumption? 2. How did changing vegetation area per household influence household consumption? 3. How did population growth and new construction influence household water consumption?

34 Conclusions! More water efficient new construction in conjunction with rapid population growth was the single largest driver of Las Vegas decline in household water consumption.! In the city core, the largest explainable driver of changes in household consumption is the observed decline in vegetation area.

35 THANKS