Rivers

Why important? Flooding has tormented civilization for a long time.

But… we continue to occupy low-lying regions adjacent to rivers.

Must understand ENTIRE river system… not just the region occupied by water on most days.

Drainage Basins: Where the water comes from.

Drainage Patterns

Basic Terminology: Flood plain -area adjacent to river channel Streams and Rivers Runoff-portion of moving across the surface Drainage basin -area drained by single stream Slope-gradient of a stream (drop/unit of length) Longitudinal profile -plot of elev. vs. length Cross-section- profile across a stream valley Plan view- two dimensions, map view Base level- lowest level that a stream can erode its bed Stream power = discharge X slope X unit weight of water

Measuring and Calculating Discharge Continuity Equation Discharge Q= V x A or V x W x D  blackboard example of conservation of discharge Reach -river area under study

Channel Patterns Channel Patterns Braided Meandering Point bars Riffles and pools Oxbows Anastomosing Multiple channels Gulf Coast (Fl, La) Riverine environment--the river and adjacent floodplain

Channel Patterns – Braided Rivers Nizina river, Alaska

Channel Patterns – Meandering River (forms & processes)

Avulsion – “permanent” change in a river’s course 1952 1988 McMurdo Basin, Columbia River, B.C.

Sediments in Rivers Streams and Rivers Transport of rock cycle Erosion and sediments Total load Suspended load Bed load Dissolved load Competence-largest particle a stream can transport Capacity-total load a stream can carry

Competence Diagram

Velocity/Shear Stress, Erosion, and Deposits Alluvial fan-change in slope Bajada -coalescing alluvial fans Delta -form at the mouth of some rivers Distributaries -streams that flow on deltas

Effects of Land Use Change Change in stream profiles Development Dam construction Modification of Continuity Equation Q = C x i x A (C = Coefficient of infiltration; i =intensity of rainfall; A-area)

Florida Rivers

Florida Rivers