Water Resource Sustainability of the Palouse Region: A Systems Approach

Transcription

1 Water Resource Sustainability of the Palouse Region: A Systems Approach M.S. Thesis Defense Ramesh Dhungel Department of Civil Engineering Date: November 12, 2007 Committee: Dr. Fritz Fiedler Dr. Chuck Harris Dr. Erik Coats

2 Acknowledgement Special thanks to Dr. Fritz Fiedler for his generous support I want to thank Prof. Chalk Harris and Dr. Erik Coats for their continuing support I want to thank Erin Brooks, John Bush, Jennifer Hinds and Ashley Lyman I want to thank Water of West (WOW) for providing me funding I want to thank Department of Civil Engineering for its continuing support I want to thank Writing Centre and Department of Statistics of UI I want to thank City of Pullman, City of Moscow, WSU and UI

3 Background and Objectives Outline Major Considerations of Sustainability of Water Resources System Dynamics Approach Characteristics of the Palouse Basin Watershed Data Collection and Generation Model Development Simple Economics of Water Demand Water Utilization Scenarios Results from Stella Model of Palouse System

4 Background Water level of the Grande Ronde aquifer of the Palouse Basin is declining 1.5 ft each year The apparent depletion of groundwater level has the potential to create a scarcity of high quality drinking water Study of groundwater in these aquifers and manage in a sustainable manner according to the future need

5 Objectives To estimate the quantity of surface and groundwater of the Palouse Basin at particular temporal and spatial scales using available data and common calculation methods; To develop a water balance using these estimates and a systems model to simulate the balance; To link the developed water balance with estimates of demand, using population growth and simple economics using systems modeling; To use the model to explore sustainability and select management approaches; and To conduct limited sensitivity analyses of the model to select parameters and various future water use scenarios in the Palouse Basin.

6 Major Considerations of Sustainability of Water Resources Environmental Legal Hydrologic Social Economic Included Considerations in this Study

7 System Dynamics Approach Stella Software is used for modeling and simulating System Dynamics Understanding of complex systems change over time Components of Stella Source Cloud Connecter Inflow Stock Outflow Sink Cloud Source cloud is infinite source of inflow and sink cloud is infinite sink for outflow Converter Stock is something that accumulates- Can be compared to surface water and Groundwater Reservoir Converters - Define and changes the relationship of stocks and flows. Flow is activity that changes the magnitude of a stock - Can be compared to recharge and water extraction Connectors - Medium for information to be passed between variables.

8 Palouse Basin Watershed

9 Characteristics Palouse Basin is a semi-arid area USGS Gauging Station ( ) at Colfax is downstream point for delineating watershed Major Cities within the basin are Moscow, Pullman, Colfax, Viola and Potlatch Two Groundwater Systems exist in the Basin Upper Aquifer -Wanapum Lower Aquifer -Grande Ronde Six Surface Water Sub-watersheds

10 Characteristics Contd. Six groundwater regions Both the Wanapum and Grande Ronde are confined aquifer systems 32% of the total Moscow water demand is fulfilled by the Wanapum and rest by the Grande Ronde 100% of the Pullman demand is fulfilled by the Grande Ronde

11 Palouse Basin Information Parameters Values References Surface Area of Watershed 2044 km 2 USGS Gauging Stations, GIS maps Groundwater Area 769 km 2 Overlay (Designated Groundwater Area) Precipitation 70.9 cm PRISM maps ( ) Evapotranspiration 49.0 cm Thonthwaite-Mather, PRISM (Brooks) Runoff 17.2 cm USGS gauge data analysis ( ) Deep Percolation 4.7 cm Water Balance Grande Ronde Volume of Water Moscow Wanapum Volume of Water 43 Billion Gallons (Bottom of Wells) 1.6 Billion Gallons Geology: Bush and Hinds; Storativity: Osiensky (Storativity 0.001) Geology: Bush and Hinds; Storativity: Osiensky Population 51,197 US Census of Bureau, Cities Population Growth Rate 0.01 Palouse Basin Aquifer Committee

12 Potential Drawdown Depth Confined Aquifer System Well Aquitard Static Level V = S * A* H Pumping Level Current Drawdown V=Volume of Groundwater S= Storativity A= Area of Groundwater H=Drawdown Depth Bottom of Pump Present Infrastructures- Drawdown Maximum Drawdown Bottom of well Future Infrastructures Drawdown Aquitard

13 Key Assumptions Hydrological Model Analysis is carried out for coming 100 years Recharge to Wanapum: water balance values applicable Recharge to Grande Ronde: 0-2cm / Year (Reports) Potential Draw Down: University of Idaho, Washington State University Present Infrastructures Moscow Wanapum: 30m, Moscow Grande Ronde: 34m Pullman Grande Ronde: 51m Future Infrastructures Moscow Wanapum: 74 m, Moscow Grande Ronde : 271m Pullman Grande Ronde: 161m Storativity: (Osiensky J., 2005)

14 Key Assumptions Contd. Economic Model: Analysis carried out for 20 years Data for price elasticity of water demand: monthly basis Precipitation: City of Pullman Quantity of Water Use: City of Pullman Price of Water: City of Pullman Median House Hold Income: US Census of Bureau Average Household population: US Census of Bureau Population Model: Analysis carried out for coming 100 years Exponential Growth Model Per capita Per Day Water Use 160 gallons: PBAC

15 Interactions Among Models Groundwater M odel Population M odel Demand M odel Surface Water M odule Economic M odule Pullman Groundwater & Recharge Estimate Population Forecast Water Demand Forecast Surface Water Estimate Water Demand Forecast with Economics Per Capita Per Day Water Use Population Model forecast population With the per capita per day water use and forecasted population, Demand Model forecast total demand Water demand is fulfilled by groundwater and surface water model Economic model forecast the water demand with economics

16 Surface Water Watershed (SM) 6 surface water sub-watersheds

17 Groundwater Regions 6 groundwater Regions Uniontown groundwater regions is outside the overlay Five groundwater regions considered

18 Surface Water Groundwater Overlay

19 Overlay (3D)

20 Population Module Population Growth Rate dt= time increment t = time Total Population Total Growth Population ( t) = Total Population ( t dt) + ( Growth )* dt Growth = Total Population * Population Growth Rate Projected Population of the Palouse Basin at year 2100: 139,073 people Projected Water Demand at year 2100: 7.63 Billion Gallons

21 Water Balance Approach P ET Q = s R P = Precipitation ET = Evapotraspiration Q s = Surface water R = Recharge

22 Hydrology Palouse Basin Water Balance Site Name USGS Gauging Stations Precipitation ET (Brooks, 2006) Runoff (Fiedler, 2006) Recharge (cm) (cm) (cm) (cm) Entire Basin Palouse river at Colfax, WA (North Fork) South Fork above Colfax (local) Palouse river near Potlatch ID Palouse river at Palouse, WA Paradise Creek at University of Idaho at Moscow ID South Fork Palouse river at Pullman, WA N/A (Lowest) 15.2 (Highest)

23 Schematic of Simplified Model (SM) Surface Water Watershed Recharge by Water Balance Recharge Water 22 BG Upper Aquifer Wanapum 1.6 BG Initial Volume Leakage by Assumption Lower Aquifer Grande Ronde 43 BG

24 Stella Simplified Model Simplified Model Concept Entire Palouse Basin as a single unit Ground Water Separated Into Upper and Lower Reservoirs Precipitation Depth Total Surface Area About precipitation 22 Soil Deep Percolation Wanapum Evapotraspiration Depth 383 Simplified Model Evapotraspiration Runoff 2 Total Surface Area Runoff Depth Total Surface Area Surface Water Collection Ground Water Area Total Wanapum Upper Pumpage Precipitation Water Balance - SM Evapotranspiration Billion Gallons Runoff Deep Percolation Deep Percolated Water Deep Percolation Grand Ronde Total Grand Ronde Lower Pumpage Total Demand

25 Hydrologically Separated Model (HSM) Palouse Basin above Colfax USGS USGS N/A South Fork USGS USGS USGS Wanapum Colfax Wanapum Viola Wanapum Moscow 1.6 BG Wanapum Pullman Wanapum Palouse Initial Volume Grande Ronde Colfax BG Grande Ronde Viola 1.37 BG Grande Ronde Moscow 4.58 BG Grande Ronde Pullman BG Grande Ronde Palouse 2.98 BG Initial Volume

26 Stella HSM (Surface Water) Surface Water Hydrology Precipitation Percipitation Precipitation Precipitation Southfork Precipitation Precipitation Runoff USGS Precep1 soil1 Potlach Ruoff USGS Evapo1 Deep Percolation 1 ET Deep1 depth Precep2 soil2 Runoff USGS Deep 2 Depth Precep3 Runoff1 Runoff2 Runoff3 Area USGS Deep Percolation 2 Palouse1 Evapo2 Area USGS soil3 Main Above Colfax MAC Runoff USGS Evapo3 Area USGS Deep 3 Depth Area Southfork Runoff Southfork 2 Runoff4 ET ET ET Southfork Deep Percolation 3 Deep 4 Depth Evapo4 Precep4 soil4 Deep Percolation 4 SF above Colfax SFAC Area USGS Runoff USGS Deep 5 depth Runoff5 Evapo5 Precep5 soil5 ET Deep Percolation 5 Paradise Creek PC Area USGS Deep 6 depth Runoff USGS Evapo6 Precep6 Runoff6 soil6 ET Deep Percolation 6 SF Pullman SFP Hydrologically Separated Model Concept 6 surface water basins and 5 geologic regions, No lateral connection between geologic regions Water is pumped from individual reservoirs Deep Percolation rates vary

27 Stella HSM (Groundwater) Deep1 depth Potlach Source Deep Percolation Palouse Wanapum Palouse source Deep Percolation Potlatch Wanapum Deep 2 Depth Potlach Section Potlach area distribution Varification Palouse Section Palouse area distribution Potlach GW Palouse GW MAC Source Deep 3 Depth MAC GW1 Palouse Subregion Deep Percolation Potlach Deep Percolation MAC Wanapum MAC Section MAC area distribution SFAC area Palouse Deep Percolated Water to GR Palouse Region MAC area Colfax MAC GW2 Deep 3 Depth Deep 4 Depth SFAC GW4 Deep Percolation Colfax Top of Model Development-3 Colfax Subregion SFAC GW1 SFC area Colfax Deep Percolation SFAC Wanapum Deep 4 Depth SFAC GW3 Deep Pullman Percolated Water Pullman Region to GR Subregion Deep Pullman area Percolated Water Pullman to GR Deep Percolation Pullman Colfax Region SFAC Source SFAC Section Deep 4 Depth Voila GW Viola area distribution SFC area Pullman Deep 6 depth Varification Deep 4 Depth SFAC GW2 SFP GW1 Viola Region Viola Subregion Deep Percolation Pullman Wanapum SFC area Moscow SFP Source Deep Percolation Viola Deep 4 Depth SFP GW2 SFP Section Pullaman area Deep Moscow Percolated Water to GR Deep Percolation Paradise Wanapum Deep 6 depth PC Source PC Section PC GW Paradise creek area Moscow Deep 5 depth

28 Volumetric Water Balance (HSM) USGS Gauging Stations N/A Site Name Palouse river near potlatch ID Palouse river at Palouse, WA Palouse river at Colfax, WA (North Fork) South Fork Palouse above Colfax Paradise Creek at UI at Moscow ID Precipitation Evapotranspiration Runoff Recharge (Billion Gallons) (Billion Gallons) (Billion Gallons) (Billion Gallons) (Lowest) South Fork Palouse river at Pullman (Highest) Total Out of 25 billion gallons of recharge water, 13 billion gallons reaches to the designated groundwater regions

29 Surface Water Model About Surface Water Utilization Assumed 80 % of surface water can be potentially utilized Moscow Demand is fulfilled by Paradise Creek ( ) Pullman Demand is fulfilled by South Fork Palouse River at Pullman( ) Runoff5 Runoff Moscow Runoff6 Runoff Pullman Moscow SW Reservoir Unused Surface Water Moscow Pullman SW Reservoir Unused Surface Water Pullman Moscow Demand Moscow SW Extraction Total Pullman Demand Pullman SW Extraction Moscow Grande Ronde'' Pullman Grande Ronde'' Minimum Volume Groundwater Minimum Volume Groundwater

30 Water Demand Economics - Data Pullman, Washington, Data Sample Year Household Water Use /100 ft 3 Fixed Price Marginal Price Household size Median Household income Precipitation (2000) $ (1 inch meter size) ($/100 ft 3 ) ($ / year) (in / month) Month Q FP MP H I P January February March April May June July August September October November December

31 Price Elasticity of Water Demand Variables of Regression Equation for Calculating Price Elasticity of Water Demand Marginal Price ($/100ft3) Fixed Price ($ for 1" meter) Years Years Median Household Income ($) 40,000 30,000 20,000 10, Average Household Size Change in water price to change in quantity of water use is price elasticity of water demand Years Years Mean Areal Precipitation (inches) Years N o. of Households 11,000 10,500 10,000 9,500 9, Years Price Elasticity is base for Economic Model 20 Years linear extrapolation in all variables except precipitation Fixed Areal mean Precipitation

32 Water Demand Economics- Model Economic Model is developed from regression equation Water Demand calculated from Economic Model Marginal Price About Fixed Price Pullman Demand by Economic Module Water Demand Economics Median Household Income Average Number of People per Household Precipitation Inch Households Q= Water Demand MP= Marginal Price FP = Fixed Price I = Median Household Income H = Household size P = Precipitation X1-X6= Unknown least square coefficients Q = MP X1 * FP Per Capita Per Day Water Use with Economics X 2 Pullman Populatin Exponential Form of Regression Equation * I X 3 * H X 4 * P X 5 * e X 6

33 Sustainability Index GSI GRANDE RONDE = TGA TGR GRANDE RONDE *100% GSI WANAPUM = TGA TGR WANAPUM *100% (UNESCO-2007) GSI = Groundwater Sustainability Index, TGA = Total Groundwater Abstraction, TGR = Total Groundwater Recharge Sustainability Index < 90% -Not fully Utilized Sustainability Index =100% -Sustainable Sustainability Index >100%-Over Exploited (Unsustainable)

34 Simple Model (SM)-Applied Conditions Scenarios According to Scenario Potential groundwater drawdown Moscow Wanapum Grande Ronde Moscow Pullman Groundwater region areas Recharge Initial Volume WP GR WP GR WP GR Storativity (m) (km 2 ) (cm yr -1 ) (BG yr -1 ) SM SM SM SM SM SM SM SM SM SM SM SM SM

35 Back Calculated Storativity S = V A* Η V= Water extracted Volume = 2.45 Billion Gallons (2005) A = Total Groundwater Area = 769 km 2 H= Water Level Decline Depth = 1.5 ft/yr Back Calculated Storativity S = 0.03

36 SM-No Recharge to Grande Ronde Unexpected High Values (Wanapum) Total W anapum (Billion Gallons) 0 Total Wanapum Total 400 Grande 200 Ronde 0 Total Grande Ronde (Billion Gallons) Total Wanapum (Billion Gallons) Total Grande Ronde (Billion Gallons) Years Years Scenario 1 Storativity Recharge 0 cm Present Infrastructure Unexpected Low Values (Grande Ronde) Scenario 2 Storativity Recharge 0 cm Present Infrastructure Total Wanapum Total Grande Ronde

37 SM- Recharge to Grande Ronde Total Wanapum (Billion Gallons) Total Grande Ronde (Billion Gallons) Total Wanapum Total Grande Ronde Years Scenario 5 Storativity Recharge 1 cm to Grande Ronde Future Infrastructure Water Level Depletion ft per year

38 SM Results Contd. Total Wanapum (Billion Gallons) Total Grande Ronde (Billion Gallons) Total Wanapum Total Grande Ronde Years Raising Trend (Grande Ronde) Scenario 6, Storativity 0.001, Recharge 2 cm, Future Infrastructure

39 SM- Back Calculated Storativity Total Wanapum (Billion Gallons) Total Grande Ronde (Billion Gallons) Total Wanapum Total Grande Ronde Total Wanapum (Billion Gallons) ,400 1,200 1, Total Grande Ronde (Billion Gallons) Total Wanapum Total Grande Ronde Years Years Scenario 9 Storativity 0.03 Present Infrastructure 1.5 feet / Year (Grande Ronde) Scenario 10 Storativity 0.03 Future Infrastructure Because of the increase in population, it is not possible to maintain constant water level depletion pattern

40 SM- Adjusted Recharge to Wanapum Total Wanapum (Billion Gallons) Total Grande Ronde (Billion Gallons) Total Wanapum Total Grande Ronde Total Wanapum (Billion Gallons) ,400 1,200 1, Total Grande Ronde (Billion Gallons) Total Wanapum Total Grande Ronde Years Scenario 12 Storativity 0.03 Present Infrastructure Constant Water Level (Wanapum) 1.5 ft water depletion (Grande Ronde) Years Scenario 13 Storativity 0.03 Future Infrastructure Adjusted Recharge Wanapum cm/yr Adjusted Recharge Wanapum cm/yr

41 SMResults (Summary) Recharge Scenario Wanapum Grande Ronde Storativity Grande Ronde Life Wanapum Life Minimum Life (cm per year) (Years) (Years) (End Trend, At Year 2100) SM > 100 Rising SM > 100 Rising SM > 100 Rising SM > 100 Rising SM > 100 Rising SM > 100 Rising Most Likely Scenario Scenario 5 & 9 SM > 100 Rising SM > 100 Rising SM > 100 Rising SM > 100 Rising SM Falling Maximum Life SM Falling SM Falling

42 Projection of Present Water Level Trend (SM) Maximum Life with Lowest Recharge Scenario Wanapum Recharge Grande Ronde (BG yr -1 (cm yr -1 ) (cm yr -1 ) Storativity Wanapum Life (Years) Grande Ronde Life SM SM SM SM Minimum Life with highest Recharge SM SM Different combinations of recharge and storativity projects similar water level depletion trend

43 Analysis by HSM Scenario Wanapum Potential groundwater drawdown Moscow Pullman Grande Ronde Recharge Grande Ronde Moscow Wanapum Initial Volume Moscow Grande Ronde Pullman Grande Ronde Storativity (m) (cm) (BG yr -1 ) HSM HSM HSM HSM HSM HSM

44 Results HSM Grande Ronde (Billion Gallons) Moscow Wanapum (Billion Gallons) Moscow Grande Ronde Pullman Grande Ronde Moscow Wanapum Grande Ronde (Billion Gallons) Moscow Wanapum (Billion Gallons) Moscow Grande Ronde Pullman Grande Ronde Moscow Wanapum 2184 Years Years Rapidly Decreasing Grande Ronde 1.5 feet / Year decline Scenario 2 Storativity Recharge 2 cm Future Infrastructure Scenario 5 Storativity Recharge 0 cm Future Infrastructure

45 Water Management with Surface water Moscow 1 (General) 2 (Critical) Pullman 1(General) 2 (Critical) Wanapum 30% 40% Grande Ronde 25% Minimum Value Grande Ronde 50% Minimum Value Surface Water 45% 60% Surface Water 50% 100% General Condition represents the condition where all sources of water are utilized If general condition is not able fulfill demand, it automatically goes to critical condition Critical Condition represents the condition after the Grande Ronde completely runs out More than 30 % of surface water is to be utilized even in general condition

46 Results of HSM (Summary) Minimum Life Maximum Life Scenario Recharge Grande Ronde (cm per year ) Storativity Moscow Grande Ronde Pullman Grande Ronde Life Moscow Wanapum Surface Water (Years) (Years) (Years) (Years) HSM >100 HSM >100 HSM-2 Pullman Surface Water Utilization HSM-3 Moscow Surface Water Utilization HSM-4 Surface Water Utilization >100 - > Instantly Minimum Level - >100 > >100 >100 HSM >100 >100 >100 Surface water is able to fulfill water demand in the applied conditions

47 Paradise Creek and South Fork Palouse Community (Water Source) Moscow (Paradise) Pullman (SF Palouse) Source Area Watershed map Daily Discharge Period of Availability 10/01/ /30/ /01/ /30/2006 Maximum Water Use 60% 100% Maximum Water Demand Fulfilled by reservoir (Billion Gallons per year) Maximum Reservoir Supply (Million gallons per day) Mean Annual Flow (cubic feet per sec) Maximum Annual Flow (cubic feet per sec) Minimum Annual Flow (cubic feet per sec) at Pullman (Summary) USGS By surface water management assumption Demand Forecasted (Year 2100) Demand Forecasted (Year 2100) WRIA WRIA WRIA-34

48 Price elasticity coefficients of Pullman (Total Residential households) Marginal Price Fixed Price Median Household income Household size Precipitation Constant Coefficient of Determination F statistics MP FP I H P C R 2 F Expected signs of the variables Marginal Price + Marginal Price Case 3 Coefficients of Price elasticity (General Case) Case 4 Without household size Price elasticity of marginal price calculated from single family and proxy of mean household water consumption are similar to the total residential households The price elasticity of water demand of marginal price has positive sign in all cases The elasticity's of other variables are also larger

49 Pullman Water Demand Trend with Economic Model Q = MP * FP * I * H * P * e billion gallons The above graph shows the decreasing water demand if the all independent variables are linearly extrapolated for coming 20 years

50 Analysis of Results of Regression Equations Relation shows price elasticity of water demand of marginal price is inelastic The price elasticity of water demand of fixed price is elastic Results shows the expected signs on fixed price, median household income and precipitation Peterson S.S., 1992 study related to price elasticity of the Palouse Basin was inconclusive due to the insignificant marginal variable (Rode, 2000).

51 Analysis of Results of Regression Equations Contd. Possible reasons of positive marginal price People not aware of water pricing and demand University town where housing and water use pattern complex Increasing block rate structures for different seasons make analysis complex Question can be raised about the data quality because of the monthly time series data are used without exact hookups

52 Groundwater Sustainability Index (GSI) Sustainability Index Grande R onde (% ) Sustainability Index (Grande Ronde) Sustainability Index W anapum (% ) Sustainability Index (Wanapum) Years Years HSM -6 SM -4 Sustainability Index of Grande Ronde is greater than 100%, it basically means, it is over exploited Sustainability Index of the Wanapum starts at 12 % and ends at 30 %, within the limit of data and water balance, it is sustainable

53 Understanding about Palouse Basin Within the range of data and analysis, Initial groundwater volume in the aquifers still uncertain If assumed no recharge to Grande Ronde, the important question is how much more year we can use Grande Ronde If assumed recharge to Grande Ronde, the Grande Ronde is unsustainable i.e. extraction is greater than recharge Recharge from the water-balance shows Wanapum to be sustainable As most of water enters to Wanapum as recharge and majority of water is extracted from Grande Ronde (literally no recharge), the issue of sustainability is always complicated in Palouse Region

54 Conclusions System dynamics approach helped to link technical and non-technical aspect of water resources with little knowledge of programming Reliability of these models depends on the quality of data Accuracy of water balance approach depends on the reliability of the components From the analysis, the best possible life of Wanapum and Grande Ronde still difficult to quantified SM 5 and 9 are the most likely scenarios for Grande Ronde

55 Conclusions Contd. SM 5 and 9 shows the Grande Ronde long last for 49 years and 84 years respectively One of the reason of constant water level increase in the Wanapum (in model) is because of no recharge and discharge conditions It is difficult to take any strong conclusions from HSM Simplified Model is easy to use and evaluate overall sustainability but difficult evaluating individual groundwater regions Within the same applied condition (scenario 6 of SM and scenario 2 of HSM, 2 cm recharge to the Grande Ronde), SM has raising trend and HSM has sharp declining trend in the Grande Ronde.

56 Conclusions Contd. Life of the confined aquifers are dominated by storativity and initial groundwater volume Within the applied condition, surface water is able to fulfill water demand Marginal price elasticity is inelastic and fixed price is elastic to water demand Because of the positive marginal price, difficulties araised to link the economic model with overall model

57 Recommendations The important task is to quantify initial groundwater volume (i.e. storativity and groundwater area) Recharge to Wanapum and Grande Ronde are important for overall sustainability of the Palouse. So efforts should be focused to minimize the discrepancies over the recharge rate For overall sustainability, all other components (legal and environment) should be introduced in future research

58 Recommendations Contd. Future model should include the recharge and discharge pattern from the Wanapum Focus on the surface water should be increased Price Inflation should used for all pricing structures The price elasticity of water demand is another challenge which should be further studied

59 Questions