June 2015 Stephanie Glenn, Ph.D. Groundwater is a major source of - - PowerPoint PPT Presentation

June 2015 Stephanie Glenn, Ph.D.

 Groundwater is

a major source

• f water

worldwide

 In Texas, 60%

• f 16.1 million

acre-feet of water used annually

 61% of

groundwater in Texas is used for agriculture

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 Circular connection

• River withdrawals can deplete groundwater or pumpage
• f groundwater can deplete river
• Pollution of surface water

can degrade groundwater or degraded groundwater can impact surface water quality

 Need to understand

(quantitative) linkages between groundwater and surface water

 Recharge, the rate at which water percolates

down to the aquifer and “recharges” the water supply varies widely amongst aquifers as well as in an individual aquifer

 Rates of recharge

can be impacted by:

• Precipitation

changes

• Pumping changes
• Development on

recharge zones

• Changes to soil and

lens structures

 Groundwater-tracer techniques are considered the

most reliable estimators of recharge

 Physical techniques - surface water and

unsaturated/saturated zone data provide estimates of potential recharge

 Modeling provides estimates from published data

(precipitation, vegetation, soils, aquifer zones)

 Recharge rates vary widely amongst aquifers and even

within a single aquifer (can vary spatially and temporally)

• Gulf Coast from 0.0004 in (.0101 mm) to 2 in (50.8 mm) per

year

• High Plains from 0.004 (.0101 mm) to 11 in (280 mm) per year
• Trinity and Edwards-Trinity Plateau from 0.1 in (2.54 mm) to 2

in (50.8 mm) per year

• Seymour from 1 in (25.4 mm) to 2.5 in (63.5 mm) per year

Olll i idl f 0 024 i h (0 61 ) i

 Distance between the

pumping well and the surface water body

 Rate and duration of

pumping

 Geologic and hydrologic

characteristics of the aquifer

 Vertical permeability and

thickness of the confining beds

 Difference in head

established between the artesian aquifer and the shallow water-table aquifer

 Degree of interconnection

between the lake or wetlands bottoms and the underlying unconsolidated sediments and the limestone

Cone of Depression Drawdown Unhealthy vs. Healthy Lake

Ground Water Flow in an Aquifer with a Pumping Well – note that pumping has caused water level to decrease under the lake on the left, causing decreased surface water

 Groundwater adds

complication

 Quantifying

interactions

• Water withdrawn to

irrigate, some water will be lost due to evaporation and use by crops, while some may percolate to the groundwater

 Texas Water Plan

• Proposed reservoirs are the most

expensive items in the Plan

• Reservoir permitting and construction

are lengthy and contentious

 2011 drought:

• Evaporation loss from Lakes Travis and

Buchanan > water used by City of Austin

 Instead of reservoirs

• ASR: Aquifer Storage & Recovery

 Water security in form of stored groundwater  Florida has successfully implemented ASR  Texas has done so on a smaller scale

Assi Assist sted Ground ndwater Rechar arge ge: $90- $1100 a acre-foot foot Reservoi voir Expans nsion: n: $1700-$2700 acre re-fo foot

• t

Seaw awat ater Desalin linatio ion: $1900-$3000 acre re-fo foot

• t

(Nu (Numbers rs f fro rom Stanford’s W Water r in th the West) t)

 Changing Precipitation and Snowmelt

patterns: reduced recharge

 Sea level rise: groundwater recharge by salt

water intrusion

 Reservoir construction changes groundwater

recharge patterns

• In arid lands, reservoirs often increase recharge

right by the reservoir

 Canals change groundwater recharge

patterns

 Pumping changes groundwater recharge

patterns

• USA and Mexico

share the Rio Grande/Bravo watershed of 335,000 sq miles

• Texas, New Mexico

and Colorado share US resources

• US – 75% of water is

for agriculture

• Ongoing litigation

between States over rights and usage

 During recent drought in the Lower Rio Grande,

farmers and urban water managers supplemented decreasing surface water allotments by increasing pumping of groundwater

Fro rom T The Da Dall llas M Morn rning Ne News: Sa San Angelo S Stat ate Par ark i in 2011 2011 drought

 Groundwater is

hydrologically connected to the river – borrowing from future water supply

 Groundwater pumping used as supplement

to surface water, especially in drought

• Expensive option (inaccessible for small farmers)
• Low flows in river = less recharge
• Increased groundwater pumping = lower water

levels

Fro rom: US S Dro Drought M Monit itor, Dro Drought 2 2011

• Deeper wells draw

from levels with higher salinity = decreased farm yields

• Impacts on wetlands,

riparian vegetation

 Ogallala – major aquifer in northwest Texas in

Rio Grande watershed

• Water level changes (n= 25 wells)

 From 2011 (drought) to 2012

 Ranged from 1.2 feet to -10.1 feet  Av Average ge c change ge -1.8 f 8 feet

 From 2012 to 2013

 Ranged from 1.8 to -5.2 feet  Av Average ge c change ge -1.3 f 3 feet

 Edwards-Trinity (Plateau) – major aquifer in West

Texas in Rio Grande Watershed

• Water level changes (n= 21 wells)

 From 2011 (drought) to 2012

 Ranged from 0.8 to -8.7 feet  Av Average ge c change ge -2.5 f 5 feet

 From 2012 to 2013

 Ranged from 0.6 to -6.2 feet  Av Average ge c change ge -1.2 f 2 feet

Alon

• ng th

the Rio

• Grande, i

ima mage ge c cou

• urtesy of
• f NPS

 El Paso and desalination (Kay Bailey Hutchison Plant)

• Desalination has drawbacks

 Expensive - Plant and infrastructure cost $91 million  Waste  20% of water running through it is returned to the ground in brine (extremely salty wastewater)  Pumped into 4,000 foot injection wells

• Drawdown

 Pumping brackish water in great quantities runs the risk of fouling freshwater aquifer

• Should be studied well prior to

use, and monitored regularly

Fro rom: Texas T Trib ribune, K KBH Desal al Plan ant A April 2012 2012

 New ideas for conservation both in the

municipal and agricultural areas will impact water supply

• Updates to infrastructure for water utilities and

irrigation districts

• Incentives

Water C r Conserv rvatio ion: D Drip I p Irrig rigatio ion i in a field ld

• Crop Water Use Efficiency
• Diversity of Crop Selection
• Water conservation

 El Paso efforts have resulted in per-person consumption falling by 41% since the 1970’s  El Paso demand in summer 2014 peaked at 160 mgd – close to the Plant’s capacity to pump from the ground

 Basin/Groundwater Challenges

• Texas, New Mexico, Colorado – Rio Grand Compact

 Established apportionment for some of the water from the Rio Grande for the three states

• U.S. Supreme Court case,

Texas v. New Mexico and Colorado (2013)

• Texas claims New Mexico is

violating the Compact by increased groundwater pumping, reducing flows in the Rio Grande

Rio Grande (Nuevo Progresso Bridge, 2007)

 May 2015 – Heavy precipitation

throughout Texas – 35 trillion gallons

• Popular graphic in the news (texas

trib) equated that amount to:

 Enough to cover all of Texas in 8 inches

• f water

 Enough to fill up California’s 200 largest surface reservoirs to 3X capacity  Enough to supply the entire world’s population with 10,000 days of water (eight 8-ounce glasses a day)

 Drought is “gone”

Wa Water b r budge get planning needs ds to addr address al all spect ctru rums of clim climate sce cenari rios

From T

• m Texas W

Wate ter Develo lopm pment B Board rd

Per Percen ent capac apacity of monit itore red wat water suppl pply y re reserv rvoirs irs as as o

• f J

June une 2015 2015

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• m Ocean Nati

tion

• nal

Geogr

• graphic: Seabroo
• ok p

k pos

• st-

Ike ke From: m: Huffingt gton

• n P

Post, t, AP P Photo W Wildf ldfire ires i in Te Texas as – Mar arfa, 2011 2011

Too much water from extreme weather events, such as tropical storms. Too little water during drought results in wildfires

 Resilience should be a complement to

Sustainability in planning

 Resilience is about the ability of the system to

survive a major tipping point (severe storms, droughts, climate change)

 Sustainability assumes constant change and how

the system will adapt

 Best management practices for resilience might

not necessarily benefit the sustainability (or vice versa), but should not impede

 Resilience plans will help understand

requirements for sustainability

 Planning for resilience is key to sustainability

 General resilience is the ability of natural and human

communities to recover after damaging events

 Groundwater Resilience often measured in terms of

extractable, usable amount of total groundwater storage (How quickly did the aquifer recharge back to normal levels after increased pumping during a drought? Was the water quality impacted?)

 Watershed resilience needs to be a goal for SERIDAS

• Ability of entire watershed (surface water, groundwater and

interconnections) to recover after slow-burn (drought) and swift (extreme rainfall) impacts

• Resilience = better human health, sustainable

environment, and robust economy

 More frequent and severe

storms as well as droughts

• Possible Impacts

 Increased evaporation in reservoirs = increased pumping  Decreased snowpack = less surface water = increased pumping  Decrease in groundwater supply  Decrease in groundwater quality  Possibility of fouling entire supporting aquifer

Glacier National Park - some experts predict glacial retreat as a result of climate change will occur to such an extent that that glaciers will have melted by 2020

 Current groundwater use is not sustainable

• According to a Aug 2014 study by Texas A&M AgriLife

Research Center

 1930’s median Texas groundwater level was 46 feet from the surface of the land  By 2000’s, median was 118 feet from the surface

• Colombia University study: groundwater levels around

US have declined significantly over the past 61 years

• June 2015 NASA study* using GRACE satellite imagery

showed that of the world’s largest 37 aquifers, 13 are being depleted, with little to no water re-entering them

 Geologic complexity can make it difficult to adequately characterize groundwater resources - addressing this issue should be part of any plan that includes relying on groundwater as a long term solution

(*researchers from U. of California, Cal. IT, U. of Taiwan, NCAR and NASA)

 Determine ecosystems in basin

dependent on groundwater

• Wetlands
• Riparian zones
• Spring-fed parts of the river

 Determine Agriculture,

Municipal and Industrial dependence on groundwater

• How does this change as adequate

amount of surface water changes?

• How does this change as

population increases?

• How does this change as

conservation methods are implemented?

Wetland ecosystem

 Characterize aquifer system in basin

• Determine suite of indicators and criteria for monitoring

(i.e., water quality parameters such as heavy metals for drinking water and tds/salinity for irrigation water)

Soil and Groundwater Sampling, image courtesy of USGS

• How often will wells be monitored

and for which constituents?

• Is water supply data available real-

time? Will water managers be able to see the data in a value-added, useful format? (i.e., mapping applications or chart interfaces)

• How will data across separate

states/nations/countries be shared and analyzed?

• Will satellite data (such as GRACE)

be included?

• Will there be a separate QA check?

• If groundwater availability models

do not exist, incorporate them and ensure they model surface/groundwater interconnectivity

• If recharge zones currently are

not identified and protected, plan should be developed to incorporate protection

 Groundwater supply should be part of water

budget – model feast/famine usage to account for resilience

 Determine rates of recharge, total/available

water storage and recharge zones for all aquifers connected to river. Ideally:

Edwards Aquifer in Austin, Texas has signs to promote awareness and responsibility

 If brackish groundwater is needed to supplement

supply then

• Ensure all layers of aquifer are understood and mapped

to prevent fouling of fresh water

• Review waste injection well sites to ensure they are far

enough from freshwater supplies and that clay zone is fracture-free

 Conservation efforts needs to be a tool in the

toolbox

 Crucial to have adequate monitoring system in

place

• Needs to monitor water levels as well as water quality

 Use projected water demand and total/available

water storage to determine if water budget will support groundwater extraction levels

• Project trends in groundwater and surface water usage-

Will this threaten water quality?

• Are Aquifer Storage and Recovery projects, conservation

principles, agriculture alternatives in place? Planned? How will they supplement current supply?

• Project reservoir storage and construction- How do

existing dams or new dams change recharge?

• Forecast development of groundwater desalination

projects- How will groundwater desalination projects impact surface or groundwater quality?

• Project effects of current and likely water management

policies- Texas regulates groundwater and surface water separately, but legal system could change.

• Need comprehensive tool that visualizes entire set
• f sustainability and resiliency factors for all of

river basin management: surface and groundwater

HARCresearch.org

HARC (härk), n.

an independent research hub helping people thrive and nature flourish.

 Unsaturated zone is

characterized by voids that contain both air and water. Voids are cracks in the rock or spaces between particle grains.

 Saturated zone is

characterized by voids that are completely filled with water.

 The upper surface

• f the saturated

zone is the water table.

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 Owned by the State  Managed under the

doctrine of prior appropriation (first in time are first in right)

 33 Texas river

authorities and similar surface water entities

 Water rights

• Run of the river
• Withdrawal permits

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 Rule of Capture: groundwater pumping

is an unrestricted right

 Texas Supreme Court adopted the rule

• f capture in 1904

 Whoever pumps the groundwater owns it

and pumping cannot be restricted even if

• thers are harmed. The rule of capture

protects the liability of anyone who pumps groundwater.

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Groundwater Management

• Groundwater conservation districts

(GCDs) provide limited regulation

• A few aquifers are strictly regulated,

such as the Edwards Aquifer, where the rule of capture has been replaced.

• There are 99 GCDs covering 56% of

the state’s surface area, which include 89% of the developed groundwater.

• Many GCDs are single county districts.

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Source: TWDB

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Image from: Texas State Water Plan 2002 TWDB

 En

Engin gineered watershed vers rsus riv river r only ly –

• pt

ptimi mize ze be bene nefits to bo both h sur urface wat water and and ground undwater

 Rivers created by groundwater (San

Marcos, Comal, Devils)

• Springs (circular connection to

groundwater, springs feeding rivers and rivers feeding aquifers)

• Example: the Devil’s River, one of two

major tributaries to the Rio Grande - downstream, a series of springs from the Edwards-Trinity (Plateau) aquifer provide up to 80% of the river’s baseflow (TPWD).