Geology chapter 13: Water Resources

major belts of karst topography in the US are

- a region extending through Tennessee, Virginia, Maryland, and Pennsylvanisa - south-central Indiana and west-central Kentucky - the salem-springfield plateaus of Missouri - centreal Texas - central Florida

sandy soils on sandstone and well-fractured rocks....

- absorb a larger amount of precipitation and have less surface runoff and fewer streams

land-use factors that affect runoff and sediment yield

- agriculture: increases runoff and sediment yield - urban development: increase runoff because large amounts of impervious pavement

the major ecosystems of the world have evolved in response to physical conditions including:

- climate - nutrient input - soils - hydrology

vegetation factors that affect runoff and sediment yield

- decrease runoff by increasing the amount of rainfall intercepted and removed by evaporation - decrease or loss of bbegetation due to climatic change, wildfire, or land use, such as grazing will increase runoff or production of sediemtn or both - streamside vegitation reduces the stream-bank erosion because roots - in forested watersheds, large woody debris may affect the stream-channel form and processes. in steep mountain watersheds, many of the pool enviornments that are important for fish habitats may be produced by large woody debris

fine-grained, dense clay soils on shale and exposed rock types with few fractures...

- generally, allow little water to move downward and become part of the subsurface flow - runoof rapid with any streams

environmental effects of dams:

- land, with its cultural and biological resources, is lost in the area flooded by the reservoir - ecosystems are fragmented, as migrating fish are blocked from moving upstream of the dam. in reservoir, hilltop areas with adjacent valleys are transformed to more isolated islands - the reservoir traps sediment that is transported from upstream by the rivers and streams that enter the reservoir. the trapped sediment reduces the water-storage capacity of the reservoir and the sediment would normally be transported downstream, nourishing the river and coastal environment so now river erosion occurs and coastal erosion - the downstream hydrology and sediment transport system change the entire river environment, affecting the organisms that live there

advantages of virtual water

- promoting efficient use of water from a local to glabal scale - assisting countries and regions to obtain water security. virtual water can be thought of as an alternative, additional water supply that helps solve geoplotical problems between nations - knowing the virtual water content of the products we produce and where and how they are produced creates an increased awareness of waht teh water demand is and how water savings might be relaized

withdrawal of groundwater by pumping from wells can

- reduce streamflow - lower lake levels - reduce water in wetlands

geological factors affecting runoff and sediment yield

- rock and soil type - minerology - degree of weathering - structural characteristics of the soil and rock

climatic factors that affect runoff and sediment yield

- seasonal and annual patterns of precipitatoin -production of large volumes of water and sediment is associated with infrequent high-magnitude storms that occur on steep, unstable toppgraphy underlain by soil and rocks with high erosion potential

the factors that affect runoff also affect:

- sediment erosion - transport - depositoin

sink holes result from

- solutions weathering at the surface of the limestone, with water diverted to subterranean routes below the sinkhole - pits produced by collapse of surface material into part of an underground cavern system, forming spectacular collapse sinkholes

drainage density

- the length of the stream channel per unit area - determed by measruing the total length of stream channel from all streams in teh area and divingding this length by the area

factors that can influence the rate of infiltration

- topography: steeper = more water runs off = reduces infiltratoin - soil and rock type: lots of open spaces = higher infiltratoin - amount of intensity of precipitatoni: low intensity/snowmelt = infiltratoin, high-intensity precipitaion=runoff - vegitation: leaves and stems = infiltratoin - land use: pavement = reduced infiltration, agricultar = increase surface runoff and soil erosion = decrease infiltratoin, harvesting timber = reduced vegatation = increase soil erson and runoff = decrease infiltratoin

techniques to improve water conservation for agricultural irrigaton

- use lined and covered canals that reduce seepage and evaporation - computer monitoring and scheduling of water releases from canals - a more intergrated use of surface waters and groundwaters - night irrigation reduces evaporation - improved irrigation systems such as sprinklers and drip irrigation - better land preparation for water application

environmental problems caused by karst topography

- water pollution where sinkholes used for waste disposal - cavern systems prone to collapse, producing sinkholes that may form and damage buildings on the ground surface, roads, etc - many areas underlain by limestone groundwater is being mined, changes where important karst springs water emerges, less spring discharge/drying up, harmful to life there and reduction of biodiversity

Ogallala aquifer

- worlds largest aquifer - from s dakota to texas - in some areas water being used at rate 20 times its natural recharge

Darcy's Law

-Empirical relationship that states that the volumetric flow rate such as cubic meters per day is a product of hydraulic conductivity, hydraulic gradient, and cross-sectional area of flow -developed by Henry Darcy in 1856

factors affecting runoff and sediment yield

-geologic factors, -topographic factors, - climatic factors, -vegetation factors, and - land-use factors

what can be done to use water more efficiently and reduce withdrawl and consumption

-improved agricultural irrigation could reduce water withdrawls 20-30% - more efficient bathroom and sunk fixtures - nighttime watering of lawns/gardnens -drip irrigation systems for domestic plants - water removal for thermoelectricity could be recuded 25 to 30 perfect by using cooling towers dusugned to use less or no water - increase in-plant treatment and recyling water or developing new equipment and proccesses that regure less water

almost __% of the US population uses groundwater as their primary source of drinking water

50

water use globaly is __% agriculture, __% industry, __% urban and rural homes

70, 20, 10

__% of water is unavailable or unsuitable for beneficial human use

99

stalactite

A calcite deposit that hangs from the roof of a cave

stalagmite

A cone-shaped calcite deposit that builds up from the floor of a cave

desalination

A process of removing salt from ocean water - 15,000 plates around the world - high energy cost, new tecnology uses less energy than before so will be used more

karst plain

A surface containing many sinkholes

consumptive use

A type of offstream use in which the water does not return to the stream or groundwater resource after use; the water evaporates, is incorporated into crops or products, or is consumed by animals or humans.

karst topography

A type of topography characterized by the presence of sinkholes, caverns, and diversion of surface water to subterranean routes.

artesian well

A well in which water rises because of pressure within the aquifer

true or false: large drainage basins cannot be subdiveded into smaller ones

False - ex mississippe river drainage basin has many such as ohio and missorui basins

residence time

How long water stays in a reservoir

water management

Practice of managing our water resources. - based on geologic, geographic, and climatic factors as well as on the traditional economic, social, and political factors - surface water and groundwater are both subject to natural flux

zone of saturation

The lower zone where water accumilates between small rock particles. - begins with infiltratoin from the surface

porosity

The percentage of the total volume of a rock or sediment that consists of open spaces. - varies from 1% for granite with few fractures to 50% for clay

water table

The upper level of the saturated zone of groundwater

flowstone

a sheet of minerals deposited over broad areas of a wall or floor of a cave

unconfined aquifer

an aquifer with no confining layer restricting the upper surface of the zone of saturation at teh water table

drainage basin/watershed

an area of land that contributes water to a particular stream or river

groundwater recharge

any process that adds water to the aquifer - both natural and human-induced

groundwater discharge

any process that removes groundwater from an aquifer

Water Cycle (Hydrologic Cycle)

circulation of water from the oceans to the atmosphere and back to the oceans by way of precipitation, evaporation, runoff from streams and rivers, and groundwater flow

human population and water

control human population growth and conserve water - needs to be done to avoid a food crisis

whats the difference between drainage basin and drainage net

drainage basin refers to an area of land, drainage net refers to the actual river and stream channels in the drainage basin

aquifer

earth material containing sufficient groundwater that the water can be pumped out; highly fractured rocks and unconsolidated sands and gravels make good aquaifers

true or false: limestone is not susceptible to chemical weathring from acids commonly found in the natural enviornment

false

true or false: we are better prepared to handle water deficiencies than floods

false

spring

forms when water flowing in an aquifer intersects earth's surface

cone of depression

forms when water is pumped from a well - can alter the direction of groundwater movement within an area - can be from overpumping an aquifer

how are caves and caverns formed

groundwater moving through the rocks - form near watertable so when differnet number of levles shows different water tables throughout time

what type of resource is water

heterogeneous

confined aquifer

if a confining layer is present

vadose zone/unsaturated zone

includes the earth material above the water table which is the boundary between the two zones including soil, alluvium, and rock - seldom saturated - early warning area for potential pollution to groundwater rosources

perched aquifer

local zone of saturation above a regional water table

water use

more appropriate term because we seldom manage water

influent stream

often above the water table everywhere along their channel and only flow in direct response to precipitation - water moves down through teh vadose zone to teh water table, formig a recharge mount -water pollution may move downward through streambed and pollute groundwater below

void space

percentage of empy space

effluent stream

perennial stream, flow all year

sinkholes

pits formed by chemical weathering - often under karst areas

topographic factors affecting runoff and sediment yield

relief

confining layer

restricts or blocks the movement of groundwater - such as clay or shale layer

potable

suitable for drinking

artificial recharge

surface water from a river or other source is spread on recharge basins to infiltrate into the suvsurface to augment to groundwater resource

hydraulic condictivity

the ability of a particular material to allow water to move through it - expressed in m^3 - dependent upon the size of the open spaces between the grains in an aquifer and how well they are connected

virtual water

the amount of water necessary to produce a product, such as a home appliance or a crop - measured at the place where product is produced or plant is grown

drainage divide

the boundary between drainage basins

relief

the difference in elevation between the highest and lowest parts of any landform of interest - the greater the releif of a drainage basin, teh more likely the streams in teh basin are to have a steep gradient and a high percentage of steep, sloping land adjeacent to teh channel - relief and slope affect the velociry of waterin a stream, the rate at which water infiltrates the soil or raock and the rate of overland flow - affect the rate at wich surace and subsurace runoff enters a stream

drainage net

the set of channels that makes up a drainage basin

hydraulic gradient

the slope of the water table

why is it called virtual water

the water content in the product or crop is very small relative to teh amount of water used to produce teh commodity - useful for water resource planning

true or false: all stages in the contiguous US have some karst features

true

true or false: nearly all natural surface water environments have strong linkages with groundwater

true

true or false: water is moved large distances to reach demand

true - causes environmental issues, should start developing near water sources

off stream use

water is removed or diverted from its source for use ex. water for irrigation, thermoelectric power generation, industrial processes, public supply

artesian

water moves downward and laterally and is confined and underpressure and can rise up through rock fractures to form an artesian spring

instream use

water that is not removed from its source when used ex. use of river water for navigation of vessels, hydroelectric power generation, fish and wildlife habitats, and recreation

when is groundwater considered a nonrenewable source

when it is "mined" or when the groundwater is withdrawn fasther than its inflow or recharge - groundwater overdraft