Water Cycle and Basins Overview

Water Cycle

• Water continuously circulates in the Earth's atmosphere, changing states (solid, liquid, gas) and location.
• Evaporation: Liquid water turns to gas (water vapor) when heated by solar energy.
• Transpiration: Plants release water vapor as a byproduct of photosynthesis.
• Evapotranspiration: Combined process of evaporation and transpiration.
• Condensation: Water vapor cools or air masses mix, converting water vapor back to liquid.
• Precipitation: Water falls to Earth as rain, snow, hail, or sleet.
• Runoff: Precipitation flows over the land surface into streams, lakes, and eventually back to the oceans.
• Infiltration: Precipitation soaks into the ground, becoming groundwater.
• Surface water and groundwater systems are connected. Water can move between surface and groundwater.

Water Basins and Budgets

• Drainage basin (watershed): Area that collects precipitation and contributes runoff to a particular stream.
• Drainage divides: High points that separate one drainage basin from another.
• Water from one side of the divide goes to one stream, while water on other side goes to different stream.
• Perennial streams: Flow year-round due to sufficient rainfall and low evaporation.
• Ephemeral streams: Flow only during rain events or wet season; common in arid climates.
• Water sheds are designated as watershed protection areas to limit use in specific areas to protect their water source.

Water Use and Distribution

• The United States uses about 1,344 billion liters of ground and surface water daily.
• Agricultural use is a significant consumer of water.
• California uses about 16% of the nation's freshwater groundwater.
• Utah and Nevada are at risk for water shortages.

Water Quality and Protection

• Federal laws, like the Clean Water Act and the Safe Drinking Water Act, protect water quality.
• The Clean Water Act protects navigable waters, preventing pollution by industries.
• The Safe Drinking Water Act ensures that public water supplies are safe for drinking.
• The Superfund program addresses hazardous contamination.

Surface Water

• Streams are bodies of flowing surface water confined to channels.
• Stream factors influencing erosion and sediment transport include gradient (slope) and velocity.
• Discharge (volume of water flowing past a point per unit of time) increases downstream.
• Stream channels can be straight, braided, meandering, or entrenched, depending on various factors.
• Floodplains: Flat areas alongside streams, where floodwaters periodically spread.
• Stream terraces: Remnants of older floodplains from uplift or base level change.

Drainage Patterns

• Drainage pattern: Pattern of tributaries (smaller streams) within a region.
• Patterns depend on the bedrock type and structures.
• Common patterns include dendritic (like tree branches), trellis, rectangular, radial, and deranged.

Fluvial Processes

• Fluvial processes include sediment production, transport, and deposition.
• Sediment production happens mainly in the headwaters (upper reaches) of a stream where erosion is prominent.
• Transportation: Sediments are transported as bedload (large, coarse material along the streambed), suspended load (finer particles carried within the water column), and dissolved load (chemical components in solution).
• Deposition: Sediments settle out of transport in quieter areas (lower reaches), forming landforms like floodplains, deltas, and alluvial fans.
• Equilibrium and base level of a stream influence its shape and behavior.

Water Rights

• States manage water rights, with federal regulations for specific situations like national parks and Native American tribes.
• Prior appropriation (first in time, first in right): Senior water rights holders get priority use during shortages.
• The Colorado River Compact outlines water sharing agreements between states in the Colorado River basin which has become an important topic in modern times.