Hydrologic Cycle and Watersheds

Water an extraordinary molecule Only substance present in large quantities as solid, liquid, and gas Highest heat capacity of all solids and liquids except liquid ammonia Highest heat conduction of all liquids Highest surface tension and dielectric constant of any liquid Water expands 9% when freezing -> ice floats Essential to life and climate

Condensation Precipitation Transpiration Surface Runoff Evaporation Subsurface Runoff Accumulation Accumulation Condensation Evaporation Precipitation Subsurface Runoff Surface Runoff Transpiration

Hydrologic Cycle Components Precipitation Infiltration Percolation Runoff Evapotranspiration

Ground Water Slower flow and reduced water abundance, together with higher temperature adds minerals to water at greater depths • Even water found at several km depth turns out to be meteoric (fed from the surface) • Existence of fractures can drastically change the flow speed and patterns

Watershed A basin, drainage or catchment area that is the land area that contributes runoff to an outlet point Watershed boundary Outlet point

Watersheds We all live in a watershed! Area of land from which all water drains, running downhill, to a shared destination - a river, pond, stream, lake, or estuary

3 Functions Captures precipitation – its characteristics influence how much is captured Stores water once it infiltrates into soil (important to plants) Slowly releases water into streams, rivers, oceans

Why are watersheds important? We all live in a watershed Activities within a watershed impact runoff and water quality of water leaving the watershed Must manage at a watershed level rather than other boundaries to attain goals related to runoff and water quality