Exam 2 Water Resources

Watershed

The total land area that drains water to a common point, also called a drainage basin.

Overland Flow

Runoff water moving across land toward a stream or river.

Headwaters

The source or beginning of a river.

Tributary

A smaller stream that flows into a larger river.

Confluence

The point where two streams or rivers meet.

Thalweg

The deepest part of a stream channel.

Hyporheic Zone

Region beneath and beside a stream where groundwater and surface water mix.

River Discharge

Amount of water flowing past a point per unit time.

Formula for River Discharge

$Q = A \times V$ where $Q$ is discharge, $A$ is cross-sectional area, and $V$ is velocity.

Rainfall-Runoff Equation

$Q = K \times I \times A$ where $K$ is runoff coefficient, $I$ is rainfall intensity, and $A$ is watershed area.

Flow Meter

Instrument used to measure stream velocity.

Staff Gage

Measures water height (stage) in a river.

Hydrograph

Graph showing river discharge or water level over time.

Reservoir Storage Equation

$\text{Storage} = Q_i + G_i - Q_o - S - E$ where $Q_i$ is surface inflow, $G_i$ is groundwater inflow, $Q_o$ is surface outflow, $S$ is seepage, and $E$ is evaporation.

Laminar Flow

Water moves in smooth, parallel layers.

Turbulent Flow

Chaotic, mixed water movement.

Sediment Transport

Includes dissolved load, suspended load, and bed load.

Dissolved Load

Materials dissolved in water.

Suspended Load

Particles carried within the water.

Bed Load

Particles moving along the bottom by rolling, sliding, or saltation.

Sediment Pollution

Identified by the EPA as the most common pollutant in streams, rivers, lakes, and reservoirs.

Meandering River

A river with winding curves.

Oxbow Lake

A lake formed when a river meander is cut off.

Braided Rivers

Form when sediment load is high and gradient is low.

Influent (Losing) Stream

Water moves from stream into groundwater.

Effluent Stream

Groundwater feeds water into the stream.

Types of Lakes

Includes crater, cirque, pluvial, kettle, reservoir, oxbow, tectonic, solution, and animal-made lakes.

Lake Ecological Zones

Includes littoral zone, limnetic zone, profundal zone, and benthic zone.

Littoral Zone

The near shore area where plants grow.

Limnetic Zone

Open water area.

Profundal Zone

Dark bottom layer of a lake.

Benthic Zone

Sediment layer where decomposition occurs.

Lake Overturn

Mixing of lake water that reoxygenates deep water and brings nutrients to the surface.

Seiche

Oscillation of lake water caused by wind or pressure changes.

Flood

Causes of flooding include thunderstorms, snowmelt, glacier melt, ice jams, and monsoons.

Flash Floods

Sudden flooding occurring in less than $6 \, \text{hours}$ due to heavy rainfall.

Flood Recurrence

1-Year Flood has a $100\%$ chance, 10-Year Flood has a $10\%$ chance, and 100-Year Flood has a $1\%$ chance.

Drought vs Aridity

Drought is temporary, aridity is a permanent climate condition.

Types of Drought

Includes meteorological, hydrological, agricultural, and socioeconomic drought.

Drought Indices

Includes Percent of Normal, Palmer Drought Index, and Surface Water Supply Index (SWSI).

Groundwater

Water found in pore spaces beneath Earth's surface.

Aquifer

Permeable geologic formation that stores and yields water.

Porosity

Percentage of pore space in a material.

Permeability

Ability of material to allow fluid movement.

Hydraulic Conductivity (K)

Rate of fluid flow through porous material.

Darcy's Law

$Q = K \times i \times A$ where $Q$ is discharge, $K$ is hydraulic conductivity, $i$ is hydraulic gradient, and $A$ is area.

Ogallala Aquifer

Largest aquifer in North America.

Thermal Pollution

Human-caused changes in water temperature.

Dissolved Oxygen (DO)

Oxygen available for aquatic organisms, normal levels are $6-8 \, \text{mg/L}$ DO.

Hypoxia

Low oxygen conditions in water.

Algal Bloom

Rapid algae growth that can reduce dissolved oxygen.

pH

Measure of acidity or alkalinity, pure water has a $pH = 7$.

Turbidity

Cloudiness caused by suspended particles.

Total Dissolved Solids (TDS)

Measure related to salinity and conductivity.