Hydrology Exam

Is water renewable?

Is water renewable?

While water is technically a renewable resource, it is practically finite

Why is water a fugitive resource?

Water is a fugitive resource because it’s difficult to assess the stock and flow and to define boundaries of the resource

Green Water

Water held in soil and is available for plants. Important for agricultural use.

Blue Water

Water in surface and groundwater.

Consumptive Use

Water being used for consumption that results in a reduction of available water. Water will not be returned to the original source in its original form.

Consumptive Use Examples

Irrigation, Water Supply, Domestic Use

Non-Consumptive Use

Water that is being used but not for consumption. Does not significantly reduce availability. Water is returned to the environment.

Examples of Non-Consumptive Use

Navigation, Tourism, Transportation, Hydropower

Withdrawal

Total amount of water withdrawn and not returned

Highest Consumption by Industry

Agriculture (75%), Industrial Use (20%), Domestic (5%)

% of water that is freshwater on Earth

3%

Hydrology

The knowledge and study of water. Occurrence, distribution, movement and properties of water on Earth

Reasons for Hydrology

Irrigation, Drainage, Hydropower, Flood Control, Drought Forecast, Navigation, Erosion & Sediment Control, Salinity Control, Pollution Abatement, Recreational Water, Fish & Wildlife, Ecosystem Services, Cultural & Spiritual Use

Water & Lithosphere

Water is found in rocks & soil, bedrock stores groundwater, water contributes to erosion, weathering and deposition of rocks and soils

Water & Biosphere

Essential for life

Water & Atmosphere

Contributes to precipitation patterns, important part of our climate composition

Precipitation

Rain, snow etc that falls from the atmosphere into the land and oceans

Evaporation

Water becomes vaporized into the atmosphere from free water surface and land area

Transpiration

Water from the soil is absorbed by plant roots and eventually discharged into the atmosphere by the plant’s stomata

Evapotranspiration

Water that is transferred to the atmosphere from open water surfaces and vegetation

Infiltration

Movement of water from the land surface to the upper layers of the soil.

Percolation

Movement of water through the subsurface down into the water table.

Overland Flow

Portion of runoff that travels over the ground’s surface to reach a stream channel.

Surface Runoff

Includes overland flow as well as precipitation falling directly into stream channels

Convectional Precipitation

Heating of the Earth’s surface causes warm air to rise and as the air cools it condenses into clouds and precipitation

Orographic Precipitation

Warm moist air moving across the ocean is forced to rise by mountains and water condenses into clouds and precipitation. Windward side of the mountain gets precipitation

Cyclonic or Frontal Precipitation

Warm, moist air is drawn into a low-pressure cold front. This type of rainfall can cause mass destruction and soil erosion

Precision

The scatter between repeated measurements

Accuracy

The proximity of the measured value to the actual value

Bias

Also known as systematic error and usually indicates uncalibrated or incorrectly calibrated equipment.

Inferential Statistics

The process of drawing conclusions about an entire population based only on the results obtained from a small sample of that population

Descriptive Statistics

Organizing, summarizing, and describing data sets

As air in the atmosphere cools

its capacity to hold water decreases

Precipitation is

not equally distributed across the world. Because of seasonality, availability of moisture, difference in precipitation mechanisms

Precipitation Measurement Devices

Rai gauge, ground-based radar, satellite data, doppler radar

Interception

Part of the storm precipitation that occurs is intercepted by vegetation and other forms of cover

Potential Evapotranspiration (PET)

Amount of ET that would occur if unlimited water was available

Actual Evapotranspiration (AET)

Amount of transpiration that actually occurs when water is limited.

AET:PET

is low in arid areas due to water limitation

AET~PET

in humid areas due to energy limitation

Infiltration is affected by…

ground surface cover.

High Permeability

Larger sediment and soil particles and connected pore spaces

Low permeability

Smaller sediment and soil particles like clay with unconnected pore spaces

Vegetation effects infiltration because

roots create space for water to infiltrate, less plants allows more run off

Saturated Zone

Less than one inch in soil depth

Transition zone

rapid decrease in soil water content

Transmission Zone

constant soil water

Wetting Zone

Constant shape and moves downwards as it continues

Wetting Front

Boundary between advancing water and dry soil

Infiltration is hard to quantify so…

theoretical, empirical, computer simulations, models and in situ measurements are all used.

Effect of Infiltration

Reduced flood magnitude, delays time of arrival of water to the channel, reduced soil erosion, recharges groundwater

ARI - Average Reoccurrence Interval (Return Period)

average time between cases of a particular precipitation magnitude for a specific duration and at a given location.

AEP - Annual Exceedance Probability

the probability associated with exceeding a given amount in any given year once or more than once