Hydro

Hydraulic conductivity, K

- A combined property of medium and fluid (takes into account fluid and media characteristics) - Ease with which fluid moves through a medium - Measures the ability of a rock or soil to transmit water; directly proportional to porosity and permeability; for k is intrinsic permeability, p is the density of water, u is the viscosity of water, and g is the acceleration due to gravity, K = k*(pg/u) -The rate at which water can move through a permeable medium. Density and kinematic viscosity are important here. -The ability of a material to transport/conduct water per unit cross-sectional area. Dependent upon the physical properties of the porous medium and the viscosity of the water and is expressed in units of length/time.

Transmissivity, Ti

- A measure of how much water can be transmitted horizontally, such as to a pumping well. -The rate of flow of water through a vertical strip of aquifer which is one unit wide and which extends the full saturated depth of the aquifer, under a unit hydraulic gradient. - It is the average permeability of a section of the entire aquifer at a given location multiplied by the thickness of the formation. - Directly proportional to (product of) horizontal conductivity and thickness. - Transmissivity (Ti) for horizontal flow of the ith soil water with a saturated thickness di and horizontal hydraulic conductivity Khi is: Ti=Khi di - Expressed in units of m^2/day.

Confined Aquifer

- Also called artesian aquifers or pressure aquifers A confined aquifer is an aquifer below the land surface that is saturated with water. Layers of impermeable material are both above and below the aquifer, causing it to be under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer. - Water enters aquifer where the confined bed reaches the surface - If (top) confining bed ends underground then the aquifer becomes unconfined - Well water levels rise and fall mainly from changes in pressure, not changes in storage volume - Becomes unconfined when the piezometric surface falls below the bottom level of the upper confining bed

Specific yield, Sy

- Also known as drainable porosity; it is the water that drains from the pores of a sediment. - A ratio, less than or equal to the effective porosity; the ratio of the volume of water a rock or soil will yield by gravity drainage to the volume of the rock or soil. -Gravity drainage may take many months to occur. - Primarily used for unconfined aquifers. - Some water always remains in the formation, even after drainage (clings to the grains of sand and clay in the formation).

Piezometric Surface

- Also known as the potentiometric surface - An imaginary surface coinciding with the hydrostatic pressure level of the aquifer - Well water levels define this surface - If the surface is above ground level, a flowing (artesian) well exists and water rises to this surface

Zone of Saturation

- Groundwater - Pores filled with only water - Water drained by gravity - Smaller pores- more surface tension - Larger pores- less surface tension

Hydraulic gradient

- Groundwater always flows in the direction of decreasing head - Is a measure of the change in hydraulic head over a distance - Can be determined like a 3-point problem with elevations representing the height of water in wells - Need data on: geographic position of wells, distance between wells, total head (groundwater level) at each well (The slope of the water table. It is determined by finding the height difference between two points on the water table and dividing by the horizontal distance between the two points.)

Zone of Aeration

- Soil water - Pores filled with air and water - Water held against gravity by surface tension

Adhesion Water

- Water bonded to minerals - Almost never removed from particles - Usually not available to plants

Gravity Water

- Water not able to be held by either cohesion or adhesion forces - Water drains freely though soil pores - Drainage depends on porosity and permeability of soil

Hydrologic Cycle

- delineating surface drainage basins - surface and subsurface hydrology - storage reservoirs for water and pathways by which water moves - recharge and discharge

Saturated Zone

- subsurface zone where pores are filled with water - pores have only water, no air - below vadose (unsaturated) zone

Vadose Zone

- subsurface zone where pores are unsaturated - pores have both air and water - also called unsaturated zone - nearest surface - contains the soil water

Surface Drainage Basins

- synonyms: catchment (area), river or water basin - basins form closed area - water moves like a funnel - all water drains down one side or another of the divide (or watershed)

Water Table

- upper surface of the saturated zone (2D: has no volume) - below this level all is saturated - perched water table occurs above the water table and is separated by a zone of unsaturated material and a zone of impermeable material

Groundwater Zones

- vadose zone - water table - saturated zone

Discharge

-The release or extraction of water from an aquifer. - infiltration, interflow - surface water moves downwards (can move chemicals downwards) -Typical mechanisms of natural discharge are evapotranspiration by phreatophytes, springs, and drains to surface water bodies. Pumping is a man-caused discharge.

Darcy law assumptions

-laminar flow -homogenous, isotropic aquifer -flow is continuous and steady -soil is fully saturated -total cross-sectional area of soil mass considered -specific temperature

What % of freshwater is available at surface?

1%

Sand Grain Size

1/16 mm- 2 mm

Silt Grain Size

1/512 mm -1/16 mm

Gravel Grain Size

2 mm-64 mm

Roughly what % of water used in the USA is groundwater?

25%

What % of the Canadian population relies on ground water?

30%

What % of fresh water is groundwater?

98.97%

Clay Grain Size

<1/512 mm

Nonhalogenated VOCs (volatile organic compound)

A VOC that does not contain one of the halogen elements located in the seventh column of the periodic table (e.g. fluorine, chlorine, bromine, or iodine)

Subsidence

A depression of the land surface as a result of groundwater being pumped. Cracks and fissures can appear in the land. Subsidence is virtually an irreversible process.

Weir

A device placed across a stream and used to measure the discharge by having the water flow over a specifically designed spillway.

Confining layer

A geologic unit having little or no intrinsic permeability. Depends on local conditions.

Aquifer

A geologic unit that can store and transmit water at rates fast enough to supply reasonable amounts to wells. Intrinsic permeability of these unit must be fairly good (10^-2 and upward).

Rating curve

A graph of the discharge of a river at a particular point as a function of the elevation of the water surface.

Storm hydrograph

A graph of the discharge of a stream over the time period when, in addition to direct precipitation, overland flow, interflow, and return flow are adding to the flow of the stream. The graph will peak owing to the addition of these flow elements. -in places with high K, the peaks will be less severe due to infiltration -in places with low K, the peaks will be steep because there is less infiltration but they will be short-lived.

Impermeable Layer

A layer of material (such as clay) in an aquifer through which water does not pass.

Permeable Layer

A layer of porous material (rock, soil, unconsolidated sediment); in an aquifer, the layer through which water freely passes as it moves though the ground.

Permeable/Permeability

A layer of porous material (rock, soil, unconsolidated sediment); in an aquifer, the layer through which water freely passes as it moves though the ground.

Equipotential line

A line in a two-dimensional ground water field such that the total hydraulic head is the same for all points along the line.

Light Non-Aqueous Phase Liquid (LNAPL)

A liquid that does not dissolve in water and has a lower density than water.

Perched Water Table

A localized zone of water that sits on top of an aquitard. Typically unconfined and at a higher elevation than the regional aquifer system. Unsaturated conditions exist below a perched unit.

Aquitard

A low K cap that restricts the movement of water. These are present in confined aquifers, in fact, they are responsible for the aquifer being under pressure, i.e. "confined." -It can store ground water and also transmit it slowly from one aquifer to another.

Porosity, n

A measure of the void or pore space within rocks and sediments (the ratio of the volume of void spaces to the total volume). - The capacity of rock or soil to hold water varies with the material. For example, saturated sand contains about 20% water; gravel, 25%; and clay, 48%. -High n does not necessarily mean high permeability. Holes must be connected and above a certain size to conduct water efficiently.

Springs

A natural source of water formed when water from an aquifer percolates up to the ground surface. Types: Contact Fracture Depression

Monitoring Well

A non-pumping well, generally of small diameter, that is used to measure the elevation of a water table or water quality.

Piezometer

A non-pumping well, generally of small diameter, that is used to measure the elevation of the water table or potentiometric surface. A piezometer generally has a short well screen through which water can enter.

Heterogenous

A porous medium which has different physical characteristics in different locations.

Homogenous

A porous medium which has uniform physical characteristics everywhere.

Wellhead Protection Area

A protected surface and subsurface zone surrounding a well or well field supplying a public water system to keep contaminants from reaching the well water.

Observation well

A well located some distance from a pumping well which is used to measure changes in water levels during an applied aquifer stress.

Alluvial Aquifer

Alluvial deposits are sediments composed of gravel, sand, silt or clay deposited in river channels or on floodplains. Alluvial aquifers are generally shallower than sedimentary and fractured rock aquifers and water levels often fluctuate due to varying recharge and pumping rates. Due to their shallow and unconfined nature, alluvial aquifers are susceptible to contamination and pollution.

Specific retention (Sr)

Also "capillary water." This is the water that remains in the pores of the sediment once all the gravity water drains. The ratio of the volume of water the rock or sediment will retain against the pull of gravity to the total volume of the rock or sediment.

Specific Discharge, q

Also called the darcy velocity or darcy flux; this is the average groundwater flow speed through the porous medium (q [length/time] = Q/A = -Ki = -K(dh/dL))

Nonhalogenated SVOCs (semi-volatile organic compound)

An SVOC that does not contain one of the halogen elements located in the seventh column of the periodic table (e.g. fluorine, chlorine, bromine, or iodine)

Unconfined aquifer

An aquifer that is not under pressure. Also known as a water table aquifer. When a well is drilled, water remains at the water table elevation. Short residence time.

Recharge zone

An area in which there are downward components of hydraulic head in the aquifer. Infiltration moves downward into the deeper parts of an aquifer in a recharge area.

Discharge zone

An area in which there are upward components of hydraulic head in the aquifer (i.e. these zones are in topographically low-lying areas). Ground water is flowing toward the surface in a discharge area and may cause escape as a spring, seep, or baseflow or by evaporation and transpiration.

Recharge Zone or Area

An area where permeable soil or rock allows water to seep into the ground to replenish an aquifer.

Adhesion

An attraction between molecules of different substances

Darcy's law

An equation that can be used to compute the quantity of water flowing through an aquifer. Permeability is a function of area, hydraulic gradient, and hydraulic conductivity. Q= -KA (dh/dl)

Water budget

An evaluation of all the sources of supply and the corresponding discharge and recharge with respect to an aquifer or a drainage basin.

Aquiclude

An impermeable body of rock or unconsolidated material that acts as a barrier to the effective (useful) flow of groundwater. A body of rock capable of absorbing water but not transmitting it. Acts as a barrier or confining unit.

Buried Channel Aquifer

Ancient stream or river channel that has been filled in with layers of sand and gravel.

Precipitation

Any form of water that falls from clouds and reaches Earth's surface.

Cohesion

Attraction between molecules of the same substance

Bedrock Aquifer

Bedrock aquifers are, as the name implies, geologic bedrock units that have porosity and permeability such that they meet the definition of an aquifer (able to release water in quantities sufficient to supply reasonable amounts to wells). Water in these units is located in the spaces between the rock grains (such as sand grains) or in the fractures within the more solid rock.

Orographic lifting

Cloud formation that occurs when warm moist air is forced to rise up the side of a mountain (i.e. rainshadow).

Well sorted

Consistent particle sizes. Contain porosities that give good permeability (if large enough). Does not fill all the gaps between particles. Usually water or wind lain (i.e. Moved by certain energy level).

Remediation

Containment, treatment or removal of contaminated groundwater. May also include containment, treatment or removal of contaminated soil above the water table.

Secondary porosity

Created later, mainly fractures Fractures from tectonic deformation Weathered limestone (karst terrain) Slumps/debris flows can move along fractures, which can act as pathways for water Stress release fractures (unloading) Spheroidal weathering

Q= -KA (dh/dl)

Darcy's law

Wilting point

Defined as the minimal point of soil moisture the plant requires not to wilt. If moisture decreases to this or any lower point a plant wilts and can no longer recover its turgidity when placed in a saturated atmosphere for 12 hours. -The water that is left is clinging too tightly to surrounding sediment. -The soil-moisture content below which plants are unable to withdraw soil moisture.

Fluid Characteristics

Density and viscosity

Permeability

Describes the ability of a porous material to pass water through it.

Local flow

Faster, cooler, shallower, fresher. Contaminates fast but can be cleaned out fast (accessible zone).

Subsurface Water

General term for all water that lies beneath Earth's surface, including soil water and groundwater.

Landslides

Groundwater controls slope failure.

Convective lifting

Heat ground, air rises. The sun heats the land surface, which heats the adjacent air, and then the heated air rises.

Poorly sorted

Holes are closed off by varied particle sizes. Glaciers and debris flows.

Hydrostratigraphy

Identification of mappable units on the basis of hydraulic properties (aquifer/aquitard/aquiclude) that have considerable lateral extent and that form a geologic framework for a reasonably distinct hydro-geologic system.

Frontal lifting

If warm and cool air collide, the warm air will be forced up.

Plume

In groundwater a plume is an underground pattern of contaminant concentrations created by the movement of groundwater beneath a contaminant source. Contaminants spread mostly laterally in the direction of groundwater movement. The source site has the highest concentration, and the concentration decreases away from the source.

In-Situ

In the natural or original place. In-situ remediation techniques take place underground where the contaminated soil or groundwater is located.

Regional flow

Increase in depth yields slower velocity, warmer water, deeper, saltier.

Primary porosity

Intrinsic to the creation of a material Volcanic ash (low K) Vesicles=high porosity but holes are not connected (low K) Columnar jointing=low porosity but good K via cracks Flow-top Breccia=stacking lava can allow interflow sediments. Insulates lava flow and, once drained, can create a cave, which has great K

K of Well-sorted gravel = ?

K = 10^-2 to 1

K of Well-sorted sands, glacial outwash = ?

K= 10 ^-3 to 10^ -1

K of Fine sand = ?

K= 10^-5 to 10^-3

K of Clay = ?

K= 10^-9 to 10^-6

K of Silt = ?

K=10^-6 to 10^-4

Hydrogen bonding

LINKS water MOLECULES close together by some sharing of electrons between oxygen atoms of one water molecule with the hydrogen atoms of another water molecule

Well Siting

Location of a well placed to best protect water quality, access adequate water quantity, and allow for inspection and maintenance of the well.

Evapotranspiration

Loss of water from a land area through transpiration of plants and evaporation from the soil and surface water.

Streams

Mainly discharge features (but some can lose flow).

Capillary draw

Makes it difficult for water to migrate past a low K zone unsaturated zone into a high K saturated zone. Once the low K boundary is hit, this effect of cohesion and adhesion hinders the continued downward movement of water.

Anisotropic

Materials that have different physical properties in different directions. The condition under which one or more of the hydraulic properties of an aquifer vary according to the direction of flow.

Isotropic

Materials that have uniform physical properties in all directions, more specifically, the condition in which hydraulic properties of an aquifer are equal in all directions.

Pore Space

Openings between geologic material found underground. Also referred to as void space or interstices.

Semi-Volatile Organic Compounds (SVOCs)

Organic compounds that have a boiling point higher than water and may vaporize when exposed to temperatures above room temperature.

Volatile Organic Compounds (VOCs)

Organic compounds that have high vapor pressure and low water solubility.

Residence time

Period of time that groundwater remains in an aquifer. Oceans: 3500 years Glaciers: 100-200 years Ice caps: 10,000-200,000 years Fresh GW: 100-200 years Lakes: 50-100 years Rivers: 2-6 months Soil: 1-2 months Atmosphere: 10 days Biosphere: hours to days

Intrinsic permeability

Pertaining to the relative ease with which a porous medium can transmit a liquid under a hydraulic or potential gradient. It is a property of the porous medium and is independent of the nature of the liquid or the potential field.

Gaining stream

Point of headline Vs are upstream (V opens downstream)

Point Source

Pollutants discharged from a single identifiable location (e.g., Landfills, gasoline storage tanks, septic tanks, spills-surface).

Soil Water

Pores not all saturated. Water held in smaller pores of the dirt.

Media Characteristics

Porosity and permeability

Pipelines of the hydrologic cycle

Precipitation Evaporation Transpiration Baseflow Streamflow Overland flow GW flow

Hydrostatic Pressure

Pressure exerted by a volume of fluid against a wall, membrane, or some other structure that encloses the fluid.

Salt Water Intrusion

Process by which an aquifer is overdrafted creating a flow imbalance within an area that results in salt water encroaching into a fresh water aquifer.

Interception

Rainfall that does not reach the ground as it collects on plants, treetops, or other structures.

Seepages

Salinity increases in arid climates due to evaporation.

Unconsolidated sediments

Sand; usually at the surface. Can transmit water.

Consolidated sediments

Sandstone; post-burial. Not as capable of transmitting water.

Hydraulic equivalence

Size-density relationship that governs the deposition of mineral particles from flowing water. Two particles of different sizes and densities are said to be hydraulically equivalent if they are deposited at the same time under a given set of conditions; the smaller particle will have the higher density. Thus, it is not uncommon to find sedimentary deposits containing coarse quartz particles together with fine particles of heavy minerals.

Natural Source

Sources of pollution that occur in the environment without human interaction.

Baseflow

Streamflow coming from groundwater seepage into a stream or river. Groundwater flows underground until the water table intersects the land surface and the flowing water becomes surface water in the form of springs, streams/rivers, lakes and wetlands. It is the continual contribution of groundwater to rivers and is an important source of flow between rainstorms. The water in a stream that comes from effluent ground water. It sustains the stream during periods of no precipitation.

Relative humidity

Take both absolute humidity and temperature into account. An indicator of the likelihood of precipitation, dew, or fog

Soil Texture

Term for soil grain size; also includes sorting and packing aspects

Capillary fringe

That part of the vadose zone that lies just above the water table, where water can be drawn upward by capillary forces.

Laminar flow

That type of flow in which the fluid particles follow paths that are smooth, straight, and parallel to the channel walls. In laminar flow, the viscosity of the fluid damps out turbulent motion, there is low energy level. Most water in groundwater flows this way.

Turbulent flow

That type of flow in which the fluid particles move along irregular paths. Momentum can be exchanged between one portion of the fluid and another. As flow increases, kinetic energy increases, and the inertial forces due to movement are more influential than the viscous forces=particles move past each other in an erratic fashion. -More energy must be put into pumping if there is turbulent flow. DRAG FACTOR. -There is a major increase in friction, more head loss, likely to go turbulent at well screens. Turbulence increases when pores are VERY small. -Most water on surface flows this way.

Specific storage, Ss

The amount of water that a portion of an aquifer releases from storage, per unit mass or volume of aquifer, per unit change in hydraulic head, while remaining fully saturated. Much greater in confined aquifers.

Safe Yeild

The annual amount of water that can be taken from a source of supply over a period of years without depleting that source beyond its ability to be replenished naturally in "wet years." Also called sustainable yield.

Unsaturated Zone

The area above the water table where openings in soil, sediment, and rock are not saturated but filled mainly with air (also called the vadose zone)

Adsorption

The attraction and adhesion of a layer of ions from an aqueous solution to the solid mineral surfaces with which it is in contact.

Baseflow recession

The declining rate of discharge of a stream fed only by baseflow for an extended period. Typically exponential.

Percolation

The downward movement of water through soil and rock due to gravity.

Head loss

The drop in the sum of pressure head, velocity head, and potential head between two points along the path of a flowing fluid, due to causes such as fluid friction.

Water table

The elevation of the water in an unconfined aquifer. Elevation changes depending on inputs and outputs.

Overland flow

The flow of water over a land surface due to direct precipitation. Overland flow generally occurs when the precipitation rate exceeds the infiltration capacity of the soil and depression/detention storage is full.

Field Capacity

The maximum amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased-- in the unsaturated zone. Varies depending on soil textures, length of time the soil has been undergoing gravity drainage.

Capillary rise

The molecular attraction between soil and water molecules (adsorption, cohesion and adhesion), that allow water to travel upwards at the capillary fringe--makes it difficult for infiltration into the water table. The finer the material, the greater the rise.

Infiltration

The movement of water from the surface into a soil or sediment. Most precipitation returns to the atmosphere via evaporation and transpiration or moves across the surface as runoff. Only a small amount moves through the soil to recharge groundwater.

Overland Flow

The movement of water over the surface of the land, usually when the ground is saturated or frozen or when precipitation is too intense for infiltration to occur.

Lithology

The physical characteristics of a rock or stratigraphic unit.

Boundary conditions

The physical conditions at the boundaries of a system. Can be hydrologic (drainage divides) or physical (impermeable layer, ridge of constant elevation) that stop flow across that zone.

Stagnation point

The point in a flow field where the local velocity of the fluid is zero. These points exist at the surface of objects in the flow field, where the fluid is brought to rest by the object.

Quickflow

The portion of streamflow that comes from either surface runoff or interflow.

Transpiration

The process by which plants give off water vapor through their leaves (stromata).

Evaporation

The process by which water passes from the liquid to the vapor state.

Well Closure

The process of sealing a well that is no longer being used to prevent groundwater contamination and harm to people and animals.

Recharge Rate

The quantity of water per unit of time that replenishes or refills an aquifer.

Infiltration Rate

The quantity of water that enters the soil surface in a specified time interval. Often expressed in volume of water per unit of soil surface area per unit of time.

Saturated thickness

The saturated depth of an aquifer. For a confined aquifer, the saturated thickness at any point in the aquifer is equal to the aquifer thickness. For an unconfined aquifer, the saturated thickness at any point is the distance from the top of the water table to the bottom of the aquifer. As aquifer recharge and discharge conditions vary in an unconfined aquifer, the saturated thickness will change.

Flow net

The set of intersecting equipotential lines and flowlines representing the two-dimensional steady flow through porous media.

Representative Elementary Volume (REV)

The smallest volume over which a measurement can be made that will yield a value representative of the whole.

Gaining stream

The stream is the water table. Groundwater recharges the stream. Wet periods can lead to gaining streams.

Hydrostratigraphic unit

The structure of subsurface porous materials in reference to the flow of groundwater. -Identifying, naming, and specifying the extents and properties of the aquifers and aquitards in a given geographical area. -A hydrostratigraphic unit is a continuous unit of the same permeability and hydraulic conductivity.

Hydrogeology

The study of groundwater - earth material interactions

Hydraulic head

The sum of the elevation head, the pressure head, and the velocity head at a given point in an aquifer. Flow from high head to low head. The greater the slope, the faster the flow.

Potentiometric surface

The two-dimensional surface which describes the elevation of the water table. In an unconfined aquifer, the potentiometric surface is at the top of the water level. In a confined aquifer, the surface is the level to which water will rise in a well cased to the aquifer. If the potentiometric surface is above the land surface, a flowing artesian will occur.--no need for a pump. A surface that represents the level to which water will rise in tightly cased wells. If the head varies significantly with depth in the aquifer, then there may be more than one potentiometric surface.

Storativity, S

The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head. It is equal to the product of specific storage and aquifer thickness. Unconfined: S=Sy Confined: S=bSs The volume of water released from storage per unit area (per unit decline in hydraulic head in the aquifer) of the aquifer - Dimensionless

Detention storage

The water that accumulated in shallow depressions on the land surface as a result of a precipitation event.

Unsaturated zone

The zone between the land surface and the water table. It includes the belt of soil water, the intermediate belt, and the capillary fringe. The pore spaces contain water at less than atmospheric pressure, as well as air and other gases. Saturated bodies, such as perched ground water, may also exist in this zone.

Saturated zone

The zone in which the voids in the rock or soil are filled with water at a pressure greater than atmospheric. The water table is the top of the saturated zone in an unconfined aquifer.

Nested flow systems

Topography can make a huge impact in terms of compartmentalizing flow systems. A large hill may have local hills within it, which represent areas of recharge that will determine local flows. These local flows will have drainage divides along the peak axis. The local systems are shallower, cooler and fresher and the flow of water will be much faster. The regional flow systems are deeper, the water has time to warm, the water flows more slowly, and they are generally saltier because the water dissolves more--it is less likely to be potable. These regional systems can underlie the local systems where some of them converge at the same discharge zone. At the discharge zone, headlines will be closer together, indicating faster flow.

GW topography

Topography of groundwater. In unconfined aquifers, this will mimic the physical topography to some degree. In confined aquifers, the topography is determined by the confining layer.

Recharge

Water added to an aquifer. For example, when rainwater seeps into the ground. Recharge may occur artificially through injection wells or by spreading water over recharge basins. Except in the case of the injection well, it is a hydrologic process where water moves downward from surface water to groundwater. This process usually occurs in the vadose zone below plant roots and is often expressed as a flux to the water table surface.

Capillary Movement

Water movement in soils through small connected pores in the capillary fringe.

Capillary Fringe

Water seeping from saturated zone to unsaturated zone.

Losing stream

Water table is below stream. Stream recharges groundwater. Losing water by seepage into the ground. High rainfall can lead to losing streams. Dry periods can lead to losing streams due to the lowering of the water table. V's point downstream.

Groundwater

Water that fills the cracks and spaces in underground soil and rock layers. Must be below the water table. It allows free flow of water.

Bank storage

Water that infiltrates the banks/levees of a channel. Can increase with locally increasing head (dam)--which leads to a losing stream zone. Also with high input.

Interflow

Water that travels laterally or horizontally through the aeration zone (above the water table) during or immediately after a precipitation event and discharges into a stream or other body of water.

Springs

Where the water table intersects the ground surface.

Surface topography

Will effect groundwater table (i.e. the elevation of the potentiometric surface) in UNCONFINED aquifers. Only also in confined aquifer if there is SOME local infiltration. Otherwise GW topography would not reflect physical topography.

Overwithdrawal

Withdrawal of groundwater over a period of time that exceeds the recharge rate of the supply aquifer. Also referred to as overdraft or mining the aquifer.

Low K

refract away from boundary

High K

refract towards boundary (more horizontal)

Cohesion Water

• Water bonded to adhesion water • Available to plants; easiest to use