Fluvial Geomorphology GRG 338-C Streamflow (Discharge)

Importance geomorphic significance (performs “work”)! hydrology water resources ecological

Big Thompson River, CO

Rio Pánuco, San Luis Potosi

Rio Tamuin, San Luis Potosi

Mississippi River bank erosion, upstream of New Orleans

Rio Moctezuma, San Luis Potosi

Importance geomorphic significance (performs “work”)! hydrology water resources ecological

Lower Rio Panuco, Veracruz

Importance geomorphic significance (performs “work”)! hydrology water resources ecological

Importance geomorphic significance (performs “work”)! hydrology water resources ecological

Channel bar / aquatic habitat Oxbow lake / riparian wetlands Delta / coastal wetlands

Flow Paths to Stream Channel

Runoff Ground water (base flow) Sources of streamflow (discharge) have different travel times Runoff (throughflow) Ground water

Hydrographs express the relationship between discharge and time single event hydrograph

Discharge (m 3 /s) Time (hours, days, weeks) Single event hydrograph shape a function of runoff and base flow

Runoff Ground water (base flow) Source of streamflow determines the hydrograph shape

Discharge (m 3 /s) Rising Limb Base flow Runoff Falling limb Peak Time (hours, days, weeks) Elements of a single event hydrograph

Depth (D) Width (W) Velocity (V) Continuity equation for discharge (Q): Q (m 3 /s) = V (m) * A (m 2 )

q i = w i (d i 1 + d i 2 ) (v i v i 0.8 ) 2 2 Q =  q i w d d v 0.2 v 0.8

v = velocity (m/sec) d = depth (m) w = width (m) Q, q = discharge (m 3 /sec) v i 0.2 v i 0.8 q i = w i (d i 1 + d i 2 ) (v i v i 0.8 ) m 6.5 m 3.0 m 1.7 m 0.0 m 5.0 m q 1 = 0.64 m 3 /sec : (5.0 * 0.85 * 0.15) q 2 = 7.64 m 3 /sec : (5.0 * 2.35 * 0.65) q 3 = 30.9 m 3 /sec : (5.0 * 4.75 * 1.3) q 4 = 46.0 m 3 /sec : (5.0 * 5.75 * 1.6) q 5 = 6.88 m 3 /sec : (5.0 * 2.5 * 0.55) Q = 92.1 m 3 /sec

Q (cms) Q – stage rating curve standard procedure for estimating Q Stage (m)

Q (cms) Q – stage rating curve uniform x-sec. geometry Q bf Stage (m) Q bf floodplain

Discharge (m 3 /s) Ground water Runoff Time a. b. c. a.b. c. Channel scour and deposition during a single event

Q – stage rating curve non-uniform x-sec. low – high channel Q (cms) Stage (m) Low flow High flow

Q – stage rating curve non-uniform x-sec. low floodplain Q (cms) Stage (m) Low floodplain High (older) floodplain

Guadalupe Valley at Cuero, TX

Guadalupe Cuero, TX (06/27/ /31/02) Discharge (cfs) Gage Height (ft)

Guadalupe valley at Cuero

Q – stage rating curve single line assumes scour = deposition during flood event Q (cms) Stage (m) Q (cms) Stage (m)

Channel scour (erosion) and deposition (infilling) during Q event influences rating curve Max. scour

Discharge (m 3 /s) Base-flow Runoff Time a.a. b.b. c.c. a.a. b.b. c.c. Scour = deposition Q (cms) Stage (m) b.b. a.a. c.c.

Scour < deposition c.c. b.b. a.a.

Q (cms) Stage (m) Scour < deposition c.c. b.b. a.a. b.b. a.a. c.c.

Guadalupe Cuero, TX (06/27/ /31/02) Discharge (cfs) Gage Height (ft)

Rising stage Falling stage

Factors influencing the shape of hydrographs a.Precipitation characteristics b.Surface characteristics c.Basin characteristics

Factors influencing the shape of hydrographs a.Precipitation characteristics distribution intensity duration seasonality

distribution

Factors influencing the shape of hydrographs a.Precipitation characteristics distribution intensity duration seasonality

Factors influencing the shape of hydrographs a.Precipitation characteristics b.Surface characteristics influence on runoff and baseflow!! c.Basin characteristics

b. Surface coverage Consider how influences infiltration and runoff!!! land use soils vegetation

Urbanization results in higher rates of runoff due to a reduction in infiltration influence on hydrograph?? influence on hydrograph?? Impervious cover 2.5 cm/hr

Runoff… high rates! Ground water… much lower! Urban hydrology…

Rising Limb Base flow Falling limb Peak Discharge (m 3 /s) Time (hours, days, weeks) Runoff New Hydrograph… due to increased impervious cover higher highs… and lower lows steeper rising limb higher peak discharge steeper falling limb low base flow Ground water

Infiltration capacity (cm/hr) Time after onset of rainfall (hours) Coarse-textured (gravel, sand) Fine-textured (high clay content) soils

clay soil/geology Discharge (m 3 /s) Time (hours, days, weeks) Sandy/gravel

Infiltration capacity (cm/hr) Time after onset of rainfall (hours) Forest (original vegetation) Corn field land use

agricultural (corn field) Discharge (m 3 /s) Time (hours, days, weeks) forest

Factors influencing the shape of hydrographs a.Precipitation characteristics b.Surface characteristics c.Basin characteristics

area shape slope drainage density c. Influence of basin characteristics on streamflow * Assumes all other factors are constant Smooth vs. Flashy

Streamflow Regimes discharge conditions over a year water year in U.S. (Oct 1. - Sept. 30th)Dec. Oct. Feb. Apr. June Aug. Discharge (m 3 /s)

1. Perennial streamflow regime humid regions… flow all year long humid regions… flow all year long streamflow sustained by base flow between rainfall events streamflow sustained by base flow between rainfall events

Streamflow Regimes 1. Perennial Supplied by base flow Supplied by precip. events Dec. Oct. Feb. Apr. June Aug. Discharge (m 3 /s)

2. Intermittent streamflow regime semi-arid… seasonal flow base flow sustains streamflow during wet season Canadian River, TX Panhandle

2. Intermittent Discharge (m 3 /s) Supplied by precip. events Supplied by base flow Dry season… no base flow Dec. Oct. Feb. Apr. June Aug.

3. Ephemeral arid… flow only after a rainfall event arid… flow only after a rainfall event Monterrey, NL

Streamflow Regimes 3. Ephemeral Discharge (m 3 /s) No base flow! Individual precip. events Dec. Oct. Feb. Apr. June Aug.

Flood Recurrence Interval (RI) Avg. # years between floods of equal or greater magnitude Annual peak Q: RI = (n + 1 / N) n = # years of record N = rank of a particular flood event

Flood Recurrence Interval (RI) Avg. # years between floods of equal or greater magnitude Annual peak Q: RI = (n + 1 / N) n = # years of record N = rank of a particular flood event

Guadalupe River Cuero July 3 rd … July 7 th

2002… 1998 flood

2002