New Mexico Water Dialogue Upstream-Downstream Project Workshop #1 June 26, 2006 The physical problem, and do the regional water plans address it? S.S. Papadopulos & Associates, Inc.
The Middle Rio Grande Water Supply • For ACOE and NMISC, SSPA conducted the MRG Water Supply Study (2004) • To evaluate the water supply from Cochiti to Elephant Butte, under the limits of the Rio Grande Compact, • Considering surface water and groundwater, in a probabilistic context.
Questions addressed in the Probabilistic Water Supply Study • How much water is theoretically available for use in the Middle Rio Grande region? • Where are depletions to the supply occurring? • How will the depletions and supply change in the future, with implementation of the regional water plans? • How will Compact deliveries be impacted, both in the present and in the future, under conditions of extended drought?
The Water Supply is…... • Variable • Limited
Annual Variability: Otowi Index Supply, 1950-2002 2,500,000 2,000,000 Flow (acre-ft/year) 1,500,000 1,000,000 500,000 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year
Limits: Flow at Otowi Bridge available to NM, 1950-2002 450 400 Water avail to NM (af/year) 350 300 250 200 150 100 50 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year
Method: Evaluation of Physical Supply A simple water budget model was constructed to • represent water inflow and outflow, for surface water and groundwater in the Middle Rio Grande region. • The natural variability in the water supply was addressed by applying a probabilistic analysis to the water budget. • The water budget compares supply to demand and describes the residual as Rio Grande Compact credit/debit • Changes proposed by regional water plans were evaluated.
WATER BUDGET SCHEMATIC: STREAM SYSTEM Native Inflow Flow from Change in Storage Import Water (San Juan – Chama) Inflow Gage at OTOWI Gaged Tributary Inflow Depletion Due To Pumping/ Groundwater Interaction Wastewater Returns Irrigation Consumption Ungaged Tributary Inflow Riparian Consumption Evaporation Outflow Gage: Rio Grande Below Elephant Butte Rio Grande Compact Credit/Debit Relationship
Inflow Terms - Averages • Otowi Index Supply 945,000 af/year • San Juan Chama Water 81,005 af/year • Jemez River 44,400 af/year • Santa Fe River 9,580 af year • Galisteo Creek 4,200 af/year • AMAFCA inflow 9,500 af/year • Rio Puerco 25,800 af/year • Rio Salado 10,500 af/year • Ungaged Tributaries 28,300 af/year • Wastewater inflow 66,800 af/year • Effective Precipitation 50,200 af/year
Depletions • Agricultural Consumptive Use • Groundwater Depletions • Riparian Evapotranspiration • Open Water Evaporation
Average Base Case Modeling Results Given a typical range of climate conditions, and present levels of water use, an average debit condition is projected Note: annual depletions from groundwater storage are represented by yellow arrow
Key Steps in Probabilistic Water Supply Analysis • Using historical observations, fit a probability distribution function to water budget terms influenced by climatic variabilty • Identify dependent relationships • Use probabilistic analysis to describe the water supply
Statistical Distribution: Rio Puerco Probability plot - Rio Puerco, 1950-2002 120,000 Rio Puerco Flow 100,000 Lognormal distribution 80,000 Rio Puerco A nnual Flow (1950-2002) 60,000 40,000 120,000 Flow (acre-ft/ye 20,000 80,000 0 0 10 20 30 40 50 60 70 80 90 100 40,000 Percent less than 0 1950 1960 1970 1980 1990 2000 Y ear
Probability Distribution of Projected Compact Credit/Debit Present Development Condition, 2000 150,000 Compact Credit/Debit (af/year) 100,000 50,000 0 -50,000 -100,000 -150,000 -200,000 -250,000 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 Percentile rank within Distribution
What water budget model is not projecting: • Reproduction of historic period • Prediction of specific future events or outcomes • Flow in river channel at basin mid-points • River / reservoir operations
Summary of Mean Depletions, Grouped by Use Mean depletions to River System (acre-feet/year) Year 2000 Land Use and Groundwater Development Conditions Note: Shown are percentages of total mean river depletions of approximately 680,000 acre-feet per year 37% 9% Additional depletions of 71,000 acre- feet per year are presently occurring to aquifer storage. 25% Agriculture Riparian Open Water Reservoir Evaporation 26% 3% Urban
Summary of Mean Depletions, Grouped by Geographic Section Mean depletions to River System (acre-feet/year) Year 2000 Land Use and Groundwater Development Conditions Note: Shown are percentages of total mea river depletions of approximately 680,000 acre-feet per year. 27% Additional depletions of 71,000 acre-feet 10% per year are presently occurring to aquifer storage. Section 1, MRGPR Section 2, SSPR 26% Section 3, SSPR 38% Reservoir Evaporation
Groundwater Depletions • Groundwater depletions (impacts on river from pumping) for Cochiti to San Acacia obtained from 2002 USGS Albuquerque Groundwater Model. • Cochiti to San Acacia pumping depletions: 79,600 af/year • Santa Fe pumping depletions: 2,676 af/year • Socorro pumping depletions: 3,300 af/year
Model Derived Surface Water Depletions from Groundwater Pumping, Albuquerque Basin 140 Lagged impact on river of continued pumping at Year 120 2000 rates Acre-Ft Per Year (x 1,000) 100 80 60 Year 2000 40 depletions 20 0 1900 1925 1950 1975 2000 2025 2050 2075 2100 (USGS Albuquerque Basin Groundwater Model, 2002)
Depletion at Elephant Butte Reservoir • Average evaporative and riparian ET losses within reservoir boundaries, 1950-2002, 164,000 af/year Lake Surface Evaporation Riparian Vegetation Evapotranspiration Adjusted Elephant Butte Losses 280,000 Evaporative Losses (af/y) 240,000 200,000 160,000 120,000 80,000 40,000 0 1945 1955 1965 1975 1985 1995 2005 Year
Agricultural and Riparian Consumptive Use • Average Riparian ET: 247,000 af/year • Average Agricultural CU: 180,000 af/year
Uncertainty and Sensitivity Analyses • Uncertainty in several large water budget terms exists • Acres irrigated • Agricultural consumptive use • Riparian consumptive use • Ungaged inflow • Effective precipitation • Sensitivity analyses show that error bar in basin depletion estimates may span 5% to 10% of total
How will Compact deliveries be impacted given implementation of regional water plans? • Assess base case scenario (Year 2000 development conditions) • Evaluate alternatives posed by the Socorro-Sierra and Middle Rio Grande Planning Regions (with water use projected to 2040) • Evaluate water supply and demand conditions under the combined Jemez y Sangre/ Middle Rio Grande/ Socorro- Sierra planning alternatives • Evaluate using inflow conditions as seen historically and given extended drought
Middle Rio Grande Planning Region “Preferred Scenario” (March 2004) • Implementation of City of Albuquerque Drinking Water Plan • Municipal/Industrial conservation initiatives • Importation of 22,500 af/y of desalinated water • Retirement of 25% of agricultural lands within MRGPR boundaries (11,073 acres => 33,000 af/y reduction in CU) • Retirement of 7,500 acres of agricultural lands within SSPR boundaries (21,000 af/y reduction in CU) • Restoration of 34,500 acres of bosque (34,500 af/y reduction in CU)
Modeled MRGPR Year 2040 Municipal/ Industrial Demand City of Alb Non-City of Alb Demand (af/y) Demand (af/y) Direct diversion of surface water 89,000 N/A Increase in WW returns to river 41,351 Change in GW river depletions -315 31,556 Change in GW storage depletions -32,437 N/A Net surface water impact Increase in CU of 78,890
Rio Grande Depletions from Pumping 120 Year 2000 Pumping Depletions in River (af/year) 100 City of Alb DWP 80 60 40 20 0 1900 1920 1940 1960 1980 2000 2020 2040 2060 Year
Socorro-Sierra Planning Region (SSPR) proposed alternatives • Evaporation control • Elephant Butte Reservoir • Elsewhere in region – 1,649 af/year CU decrease (10% reduction) • Improve conveyance efficiency Combined; reduces • Improve on-farm efficiency agricultural CU by 5% (2,768 af/year) • Control brush and weeds • Remove exotic 4,060 to 20,300 af/year CU decrease vegetation (10-50% removal)
Jemez y Sangre Planning Region (JySPR) Alternatives • The JyS Regional Water Plan was reviewed; Year 2040 elements impacting the water supply below Otowi gage were identified as: • 8,730 af/y increase in depletions arising from implementation of the Buckman Direct Diversion plan; • 11,000 af/y increase in depletions arising from full utilization of allocated SJC water(between 1999 and 2003 this water was leased to the Bureau). • Additional Year 2040 regional demand assumed to be met through conservation.
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