Spokane County Water Demand Forecast Model

Transcription

1 Spokane County Water Demand Forecast Model IWAC & CAMP Joint Meeting March 11, 2014 Mike Hermanson Water Resources Specialist Spokane County Resources

2 Presentation Overview Project Overview Overall Model Structure Model Development Forecast Results Comparison to Idaho Future Water Demand Study Potential Application in Idaho

3 Water Demand Project Overview Initial Model Developed (Model 1.0) January 2010 to June 2010 Project managed by Spokane County with technical consultants CDM & Tetra Tech. Included advisory committee. Model Refinement, Calibration, & Verification (Model 2.0) June 2010-January 2011 Developed new single family & multi family models Calibrated & verified the model, using water system data Developed forecast & wrote report Forecast update, Consumptive/Non-consumptive separation, & return flow routing (Model 3.0) Used updated housing & employment data that was based on new census data, new economic forecast Separated consumptive & non-consumptive, and routed return flow

4 Overall Model Structure Segregated by Water Use Sector County Forecast Public Supply Self Supply Residential Self Supply Industry Agricultural Commercial Industrial Single Family Residence & Yard Thermoelectric Power Livestock Urban Irrigation Multi-Family Small Agriculture Golf Courses Irrigated Acres Public-Supply Agriculture Non Revenue Water Large Industry

5 Overall Model Structure Commercial Industrial Public Supply Single Family Overall Model County Forecast Self Supply Residential Residence & Yard Self Supply Industry Thermoelectric Power Agricultural Livestock Forecast model is comprised of sub models that vary in complexity from unit (simple) to econometric (complex). County Urban Irrigation Multi-Family Small Agriculture Golf Courses Irrigated Acres Public-Supply Agriculture Non Revenue Water Large Industry Unit Use: gallons per day per hohold gallons per day per acre gallons per day per employee Modified Unit Use Seasonal adjustments Econometric: Water is a function of variables Income, home value, lot size, weather, etc. Statistically derived equation Commercial Industrial Urban Irrigation Public Supply Sub Models Single Family Multi-Family Self Supply Residentia Residenc & Yard Small Agricultu Public-Supply Agriculture Non Revenue Water

6 Overall Model Structure Segregated Spatially 513 separate forecast units A unique water demand calculation is done for each forecast unit Can evaluate different areas of interest Areas over the SVRP aquifer for groundwater return flow Areas served by aquifer for SVRP groundwater withdrawals

7 Overall Model Structure Segregated in monthly increments

8 CFS (cubic feet pjer second) Water Demand Model Overview Model is highly disaggregated which allows for many types of analysis, for example: Water from SVRP Self supplied water in Little Spokane River Basin Each forecast unit can have different inputs into each sub model Water demand calculation for each month County Forecast 700 SVRP Aquifer Monthly Water Demand 2010 & 2040 Public Supply Self Supply Residential Self Supply Industry Agricultural Commercial Industrial Single Family Residence & Yard Thermoelectric Power Livestock Urban Irrigation Multi-Family Small Agriculture Golf Courses Irrigated Acres 200 Public-Supply Agriculture Non Revenue Water Large Industry 100 0

9 Water Demand Model Overview Developed and runs in Excel Series of interconnected spreadsheet and formulas

10 Model Development Fundamental components of the model Water Use per unit - Unit Use - Econometric Quantity of Units (Demand Drivers) Water Demand Variables for econometric models (Demand Factors) Seasonal Adjustments Model complexity from the adaptation of this approach to each water sector and subsector

11 Model Development Water Use Per Unit Data Public Supply Model Monthly water data per connection by sector for multiple years from Water Purveyors Single family multi-family commercial industrial Irrigation Wastewater data Commercial/Industrial water data by employee Agricultural Washington State Irrigation Guide Self Supplied Residential Residential Water Use Survey Self Supplied Industrial NPDES Discharge Monitoring Reports, BiState aquifer study, Watershed Planning Data Assessments

12 Model Development Demand Factors Data Weather NOAA, Agrimet Temperature Precipitation ET Estimates Census Data Hohold size Family size Hohold income Assessor Data Single family residential assessed value Lot size GIS Spatial Analysis of Well Yield Water availability limitations USGS Land Cover Data Rural residential setting

13 Model Development Demand Drivers Data SRTC TAZ Data Single family residential housing units Multi family residential housing units Commercial & industrial employment Acres of urban irrigation Digitized from Aerial Photo Acres of crop irrigation Agricultural Census, Digitized from Aerial Photo Number of livestock Agricultural Census Large self supplied commercial/industrial Bistate aquifer study, Watershed Planning Assessments

14 Model Development Consumptive Use & Return Flow water demand for each sector/subsector is separated into consumptive and non-consumptive and routing the return flow of non-consumptive. Model Before Update Total Water Demand

15 outdoor water non-consumptive outdoor water consumptive indoor water consumptive Model Development Total Water Demand indoor water non-consumptive

16 Model Development Calibration & Verification

17 Model Development Calibration & Verification Annual Public Water System Use: Modeled vs. Reported Sector Modeled Reported RPD Total Production 41,895 41, % Single Family Residential 15,920 15, % Multi Family Residential 3,996 4, % Total Residential 19,916 19, % Commercial/Industrial 9,528 9, % Total Non Residential 10,758 10, % Non Revenue 3,433 3, % Reported in millions of gallons per year

18 Annual Average GPD Model Development Impact of weather on water compared actual to modeled with each year s weather data for model input 900 SCWD#3 WSA Actual Modeled

19 Annual Average GPD Model Development Impact of weather on water compared actual to modeled with each year s weather data for model input 900 SCWD#3 WSA Actual Modeled

20 Annual Average GPD Model Development Impact of weather on water compared actual to modeled with each year s weather data for model input 900 SCWD#3 WSA Actual Modeled

21 Annual Average GPD Model Development Impact of weather on water compared actual to modeled with each year s weather data for model input 900 SCWD#3 WSA Actual Modeled

22 Annual Average GPD Model Development Impact of weather on water compared actual to modeled with each year s weather data for model input 900 City of Spokane Actual Modeled

23 Annual Average GPD Model Development Impact of weather on water compared actual to modeled with each year s weather data for model input 900 Whitworth Water District Actual Modeled

24 Model Development Assessment of return flow quantity and routing

25 Water Demand Forecast SVRP is a subset of the Spokane County Water Demand Forecast Model

26 Water Demand Forecast SVRP is a subset of the Spokane County Water Demand Forecast Model Returns to Spokane WWTP pumped from SVRP Septic returns Landscape irrigation returns

27 Water Demand Forecast Total Water Demand from SVRP = 151,586 AF/year Consumptive Demand = 55,857 AF/year Non-Consumptive Demand = 95,730 AF/year Return to ground from outdoor irrigation = 28,838 AF/ year Return to municipal WWTP = 38,554 AF/year (53 cfs) Return to industrial WWTP = 25,315 AF/year (34 cfs) Return to septic = 3,023 AF/year 42% of water withdrawn from the SVRP Aquifer is returned to the Spokane River via surface water discharge. Consumptive 37% Returns to Industrial WWTP with surface water discharge 17% Returns to groundwater 19% Returns to Municipal WWTP with surface water discharge 25% Returns to Septic 2% SVRP Aquifer Annual Water Demand & Return Flows

28 millions of gallons per year Results & Analysis 70,000 SVRP Aquifer Water Demand & Return Flows 60,000 50,000 40,000 30,000 20,000 10, Returns to Septic Returns to groundwater Returns to Industrial WWTP with surface water discharge Returns to Municipal WWTP with surface water discharge Consumptive Year Note: Total demand is sum of all return flows 26% growth from 2010 to 2040

29 Results & Analysis 600 SVRP Aquifer Monthly Water Demand 2010 & Non Consumptive 2010 Consumptive 2040 Non Consumptive 2040 Consumptive Winter water growth 21% August water growth 28%

30 Results & Analysis Water Demand Model Comparison of return flow from septic & irrigation in SVRP Model and Water Demand Model cubic feet per day per model cell SVRP Model Model cells with a net withdrawal shown a null

31 ID & WA Forecast Spokane County Water Demand Model and Forecast now separates consumptive and non-consumptive water Estimated SVRP Water Use (acre-feet/year) Idaho Washington Consumptive 39,830 55,857 Non-consumptive 34,320 95,730 Total 74, ,587 % consumptive 54% 37%

32 ID & WA Forecast Comparison of water sectors Estimated SVRP Water Use (acre feet per year) Idaho Washington Public Water Systems 34, ,752 Self Supplied Domestic 8, Self Supplied Commercial & Industrial 4,220 26,946 Agriculture 24,700 5,770

33 Potential Application of WA model in ID Demand Driver Data available Kootenai Metropolitan Planning Organization (KMPO) Housing & Employment Need to determine how much data is available from water purveyors water by connection by sector by month Spokane County Model d many ancillary sources of water data: Spokane County Utilities wastewater Spokane County Parks irrigation Irrigation for schools Irrigation from golf courses NPDES DMR Data Misc. water data from Watershed Planning Assessments

34 The model Excel file and reports are located at Or > Water Resources > Projects > Water Demand Forecast Model

35 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence Econometric model estimated Indoor single family water based on: Hohold Income water Home Assessed Value Monthly Max Temp Monthly Precip. Lot Size Indoor consumptive Onsite septic Indoor nonconsumptive Sanitary sewer Outdoor consumptive Outdoor water % Consumptive area of irrigated landscape Water per ft 2 of irrigated landscape Single family residential model is two separate models: Indoor model based on hohold income (r 2 =0.55) Return Flow Outdoor model based on monthly average of maximum ET Rate daily temp., monthly precipitation, assessed value, & lot size (r 2 =0.74) Outdoor nonconsumptive

36 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence Indoor water Outdoor water Indoor consumptive % Consumptive area of irrigated landscape Econometric model separated water between indoor and outdoor components Indoor nonconsumptive Water per ft 2 of irrigated landscape Return Flow ET Rate Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

37 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence Indoor water Outdoor water Used literature values for % indoor water that is consumptive % Consumptive area of irrigated landscape Indoor consumptive Indoor nonconsumptive Return Flow Water per ft 2 of irrigated landscape ET Rate Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

38 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence Indoor water Outdoor water % Consumptive area of irrigated landscape Indoor consumptive Onsite septic Indoor nonconsumptive Return Flow Sanitary sewer Outdoor consumptive Water per ft 2 of irrigated landscape Used location, sewer service areas and connection data to determine ET Rate where return flow would go Outdoor nonconsumptive

39 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence Indoor consumptive Indoor water Econometric model provide outdoor water in gallons per day per residence Indoor nonconsumptive Outdoor water % Consumptive area of irrigated landscape Water per ft 2 of irrigated landscape Return Flow ET Rate Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

40 Single Family Residential To separate outdoor water into consumptive and nonconsumptive components it is necessary to know how much landscape is irrigated. Indoor water If 500 gallons per day is d on 100 sq. ft. much of it would be non consumptive it would be consumed Indoor consumptive Indoor nonconsumptive Total daily water per single family residence Outdoor water % Consumptive area of irrigated landscape If 500 gallons per day is d on 1 acre most of Water per ft 2 of irrigated landscape Return Flow ET Rate Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

41 Single Family Residential Estimating area of irrigated landscape Parcel size Building footprint Need to know how to split remaining portion of lot into landscaped and non-landscaped Took a random sample of 284 parcels to estimate percentage

42 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence ET rate in inches can be Indoor water converted to gallons per square foot: Outdoor water % Consumptive area of irrigated landscape (Total GPD per ft 2 ) (ET GPD per ft 2 )= GPD per ft 2 returned to ground Indoor consumptive Indoor nonconsumptive ET is a difficult parameter to estimate, Return Flow and varies spatially. Water per ft 2 of irrigated landscape ET Rate Agrimet stations provide estimates Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

43 Single Family Residential Separating Single Family Residential into consumptive and nonconsumptive Total daily water per single family residence Indoor water Outdoor water % Consumptive area of irrigated landscape Indoor consumptive Indoor nonconsumptive Return Flow Water per ft 2 of irrigated landscape ET Rate Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

44 Single Family Residential Single family residential separated into 4 component parts and return flows directed to appropriate location Indoor consumptive Indoor water Indoor nonconsumptive Total daily water per single family residence Outdoor water % Consumptive area of irrigated landscape Water per ft 2 of irrigated landscape Return Flow ET Rate Onsite septic Sanitary sewer Outdoor consumptive Outdoor nonconsumptive

45 Single Family Residential

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