A new look at natural recharge in Las Vegas Valley

Transcription

1 A new look at natural recharge in Las Vegas Valley by David J. Donovan and Terry Katzer Nevada Water Resources Association Lake Tahoe, Nevada. November 2-4, 1999

2 Topics Previous estimates Methods used Verification

3 Estimates based on precipitation Maxey and Jameson (1947, 1948) 30,000-35,000 acre-feet Rainshadows - concentrated precipitation Harrill (1976) 30,000 acre-feet Calibrated with model (Darcy)

4 Estimates based on Darcy Malmberg (1961,1965) 21,000-24,000 acre-feet Multiple methods Harrill (1976) 30,000 acre-feet Model Morgan and Dettinger (1994) 33,000 acre-feet Model

5 Estimates based on Geochemistry/Isotopes Dettinger (1989) 28,000 acre-feet Chloride ion Thomas et. al (1996) 32,000 acre-feet Isotopes

6 Average annual precipitation, in feet Altitude verses precipitation Precipitation Stations with Site Numbers Kyle Canyon Lee Canyon Sheep Range Western Spring Mountains and Ivanpah Valley Regression line of all data ,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12,000 Altitude, in feet 2 Adjusted r = 0.68

7 Nye County Lincoln County Clark County Sheep & Las Vegas Ranges Spring Mountains Area 3 Western Spring Mountains Lee Canyon Area 2 Kyle Canyon Las Vegas Valley East slope of Spring Mountains Area 1 Area 4 Area 3 Edge of Las Vegas Hydrographic Basin Lake Mead Las Vegas Wash River Mtns US 93 Legend Ivanpah Valley Area 3 Precipitaion gauge site Edge of Hydrographic Basin Edge of Mountain Range Colorado River Precipitation area Area 3 McCullough Range

8 Altitude-precipitation relationships for: Kyle and Lee Canyons Average annual precipitation, in feet Kyle Canyon 2 Adjusted r = ,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12,000 Altitude, in feet Lee Canyon 2 Adjusted r = 0.97

9 Altitude precipitation relationship for: Western Spring Mountains, Ivanpah Valley and Sheep Range Western Spring Mountains and Ivanpah Valley 2 Adjusted r = 0.95 Precipitation, in feet ,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12, Altitude, in feet Sheep Range 2 Adjusted r = 0.98

10 Measured values and aproximation methods for: Kyle Canyon 3.50 Average annual precipitation, in feet Measured Values Maxey and Jameson (1948) Hardman Map PRISM (Daly et al., 1994, 1997) ,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12, Altitude, in feet

11 Measured values and aproximation methods for: Kyle Canyon 3.50 Average annual precipitation, in feet Measured Values Maxey and Jameson (1948) Hardman Map PRISM (Daly et al., 1994, 1997) This study Adjusted r = ,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12, Altitude, in feet

12 Nevada precipitation stations Precipitation, in feet Stations NV General LV General Elgin Winnemucca Laughlin Boulder City Pahrump Overton Beatty Las Vegas Lowest point in Nevada Wildhorse Pioche Carlin Carson Elko Austin Ely Montello Smokey Valley Reno Tonopah Kyle Canyon Lee Canyon Mount Hamilton Trough Spring Mount Wilson Cave Mountain NW of Mount Moriah Sheep Peak Hayford Peak Potosi Peak Mount Washington Cherry Creek Range Altitude, in feet Highest point in Las Vegas Valley Highest point in Nevada

13 Nevada precipitation stations Precipitation, in feet Stations Kyle Canyon Sheep Range Elgin Winnemucca Laughlin Boulder City Pahrump Overton Beatty Las Vegas Wildhorse Pioche Carlin Carson Elko Ely Austin Montello Reno Smokey Valley Tonopah Kyle Canyon Mount Washington Lee Canyon Mount Hamilton Trough Spring Mount Wilson Cave Mountain NW of Mount Moriah Sheep Peak Hayford Peak Potosi Peak Cherry Creek Range Altitude, in feet

14 Precipitation estimates Hardman (1936, 1965, 1972) 561,000 acre-feet PRISM (1994, 1997) 613,000 acre-feet This study 708,000 acre-feet

15 Comparison of efficiency verses precipitation for different methods 0.30 Inches of precipitation All methods use an efficiency of 25% at precipitation greater than 1.67 ft (20 Inches). Efficiency percentage E = 0.05 (P) Inches 20 Inches 15 Inches Maxey and Jameson (1948) Maxey and Eakin (1949) Midpoint M-E intervals This study Inches 12 Inches Feet of precipitation

16 Natural recharge estimate East slope of Spring Mountains 38,000 acre-feet Lee Canyon 9,000 acre-feet McCullough Range 100 acre-feet Sheep and Las Vegas Ranges 3,500 acre-feet

17 Natural recharge estimate East slope of Spring Mountains 75 percent Lee Canyon 18 percent McCullough Range < 1 percent Sheep and Las Vegas Ranges 7 percent

18 Las Vegas Valley US 95 Recharge Area I-15 Las Vegas Urban Area Recharge Area Discharge Area I-15 Recharge Area US 95/93

19 Verification Precipitation Discharge estimate Darcy / Hydrogeologic Model

20 Natural discharge estimate Devitt et al. (in, prep) Evapotranspiration 40,000 acre-feet Bare-soil evaporation 7,000 acre-feet Ground-water outflow 6,000 acre-feet Total 53,000 acre-feet

21 Inflow Natural recharge 51,000 acre-feet Ground-water inflow 6,000 acre-feet Ground-water budget Outflow Evapotranspiration and Bare-soil evaporation 47,000 acre-feet Ground-water outflow 6,000 acre-feet

22 Ground-water budget Inflow 57,000 acre-feet Outflow 53,000 acre-feet Best estimate 55,000 acre-feet

23 Use in ground-water model Location Volumes

24 Implications Water resources Use in model Water level rise

25 Implications Water resources Use in model Water level rise in response to Artificial and Secondary Recharge and redistributed pumpage

26 Las Vegas Valley US 95 Recharge Area I-15 Las Vegas Urban Area Recharge Area Discharge Area I-15 Recharge Area US 95/93