hydrology 101 fundamentals_dr joe yelderman

101: Fundamentals of Hydrogeology and

review of Texas aquifers

Dr. Joe TAGD 2016

Who is Dr. Joe? Texan Land owner Well owner Grandparent

Outline What is Hydrogeology?

What is Groundwater?

How does groundwater flow?

Concepts

Terminology

How do wells work?

Texas Aquifers

Management challenges: Aquifers vs groundwater

Hydrogeology Complex and difficult Hydrology Hydrogeology Geohydrology etc.

What is Groundwater? the saturated zone

The Earth’s Water •  Oceans and Inland Seas 97.208%

•  Ice (mostly Greenland and Antarctica) 2.15 %

•  Groundwater 0.62%

•  Surface water 0.0091%

•  Other 0.00604%

The Earth’s Water •  Oceans and Inland Seas 97.208% •  Ice (mostly Greenland and Antarctica) 2.15 % •  Groundwater 0.62% 97.5% •  Surface water 0.0091% –  Lakes 0.009% –  Rivers and Streams 0.0001%

•  Other 0.00604% –  Soil water 0.005% –  Atmosphere 0.001% –  Biosphere 0.00004%

How does groundwater flow? •  the Ohio Supreme Court in Frazier v. Brown:48 (1861)

•  In the absence of express contract and a positive authorized legislation, as between proprietors of adjoining land, the law recognizes no correlative rights in respect to underground waters percolating, oozing, or filtrating through the earth; and this mainly from considerations of public policy: (1) Because the existence, origin, movement, and course of such waters, and the causes which govern and direct their movements, are so secret, occult, and concealed that an attempt to administer any set of legal rules in respect to them would be involved in hopeless uncertainty, and would, therefore, be practically impossible.

Darcy’s Law 1856

Q = KIA

Darcy’s Law

Darcy’s Law

Q = KIA Groundwater flows from higher to lower head

Groundwater contour maps and flow directions

Our activities affect our wells

Darcy’s Law 1856

Q = KIA

Groundwater concepts

•  Aquifer –  Material that can

store and transmit water easily

•  Flow system –  Recharge to

discharge

Aquifer concept

•  Aquifer - material that can store and transmit water easily

•  Aquitard – material that retards

groundwater flow (also – confining bed)

Aquifer concept

•  Aquifer - material that can store and transmit water easily

•  Aquitard – material that retards groundwater flow (also – Confining Bed)

Aquifer (sand)

Confining bed (shale)

Aquifer concept

1.  Unconfined (water table) aquifer – an aquifer that has a free water surface (water table) on the top.

2. Confined (artesian) aquifer – an

aquifer where the water rises above the top of the aquifer or above the bottom of the overlying confining bed.

Aquifer concept 1. Unconfined (water table) aquifer – an

aquifer that has a free water surface (water table) on the top.

Aquifer concept 2. Confined (artesian) aquifer – an aquifer

where the water rises above the top of the aquifer or above the bottom of the overlying confining bed.

Confined aquifer

Unconfined and Confined aquifers

Groundwater concepts

•  Aquifer –  Material that can

store and transmit water easily

•  Flow system –  Recharge to

discharge

Groundwater flow systems recharge to discharge

Groundwater divides

Local, Intermediate, and Regional flow systems

Hydrogeological terminology •  Porosity

•  Hydraulic conductivity Q=KIA – Similar to permeability

•  Transmissivity T = Kxb

Hydrogeological terminology

•  Storativity or Storage Coefficient S

•  Specific Yield Sy

Groundwater and Wells

Flow to wells

Overlapping cones of depression

Hydrogeological terminology

•  Homogeneous (Homogeneity) – The same everywhere

•  Heterogeneous (Heterogeneity)

•  Isotropic (Isotropy) – The same in all directions

•  Anisotropic (Anisotropy)

Water chemistry •  H2O

– H180 O90

•  Dipolar •  The universal solvent

Water - the universal solvent

Aqifers Trinity

Groundwater Major aquifers Trinity (sand)

Aquifer

Aquifers Ogallala

Ogallala Aeolian Fluvial

Groundwater

The Brazos River Alluvium: regional

•  1 of 21 minor aquifers in Texas

Dallas

Waco

Austin

The Brazos River Alluvium: local

Brazos River

WACO

Lake Whitney

Brazos River Alluvium

Lithology

•  Fining upward sequence •  Sands and gravels • Heterogeneity

(after Epps, 1973)

Sandy pea gravel

Black Bell series soil

Water table

Sandy coarse gravel

Poorly sorted gravel

Blue clay (Taylor Fm.)

Red sandy clay

Sand

Edward Hay Ranch gravel deposit, near Marlin

Gaining and losing streams

The Brazos River is a gaining stream

Brazos River Alluvium aquifer

Unconfined aquifer

Saturated section

•  Range: 0.25 – 60 ft •  Average: 25 ft

Models

Uncertainty

O,enquoted:“Allmodelsarewrong,butsomeareuseful”

BoxandDraper(1987)

Uncertainty

O,enquoted:“Allmodelsarewrong,butsomeareuseful”

BoxandDraper(1987)

Thesecondhalf:“...thepracHcalquesHonishowwrongdotheyhavetobetonotbeuseful.”

WellsacrossEagleFordShaleplay

Data Accessed April 2015

CLIMATE CHANGE ?

Questions?

hydrology 101 fundamentals_dr joe yelderman

Education