2. River HydrologyRivers are part of the global hydrologic cycle

Contributions to streamflow

Charlton 2008, Fundamentals of Fluvial Geomorphology

Hortonian overland flow (surface runoff)

Saturation overland flow (surface runoff)

Through flow (sub-surface runoff)

Groundwater flow

Measuring Streamflowdischarge: volume of water [cubic metres] passing through a cross-section of a river per unit time [seconds]:

discharge [m3/s or cms] = mean flow velocity [m/s] times cross-sectional area [m2]

Charlton 2008, Fundamentals of Fluvial Geomorphology

modern measurements of discharge use acoustic Doppler current profilers (aDcp)

https://youtu.be/3SPwz3VYnbM

Hydrographs

hydrograph: a plot of discharge over time

Dis

char

ge (

cms)

• quick flow: water that enters the channel quickly by overland flow and through flow

• base flow: water that enters the channel slowly by groundwater flow

Charlton 2008, Fundamentals of Fluvial Geomorphology

Floods

causes: rain storms and/or snowmelt, ice-jams, dam failures

importance: control sediment movement and channel morphology, damage infrastructure, cause fatalities

Nadi

Tom River

Ob

Rive

r

Tomsk

10 km

Global Discharge

river ranking by average daily discharge