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Catchment Hydrology Overview (HUMID (Channel Morphology (Discharge &…

- - - - :rain_cloud: AF
        
        Bimodal distribution with two clear peaks during the equinoxes
        
        Only one bankfull discharge but frequently occurs
        
        Discharge ↑ downstream due to contribution by tributaries, throughflow and baseflow
        
        Exhibits channels of a single size ; proportional depth and width with high hydraulic radius (narrower & deeper)
        
        Large flood may temporarily enlarge the channel but after time, channel would revert
        
        :partly_sunny_rain: AM / AW
        
        High ppt during summer but rest are dry seasons
        
        Streamflow α rainfall
        
        Affects channel efficiency (high flow, ↑ HR, ↑ efficiency)
        
        Several, less frequent bankfull discharge levels due to rainfall seasonality (normal flows to floods in wet seasons)
        
        Thus, nested channel shape, a macrochannel consisting of other channels of different discharge levels
        
        Width many times larger than depth, so hydraulic radius varies with flood events
        EG: Auranga River
    - - Long channel length and concave profile (steeper to gentler gradient)
        
        Due to greater erosion and downstream fining where finer sediments are deposited downstream
    - - Large sediment loads due to active weathering and mass movement
        
        :rain_cloud: Finer load (silt/clay)
        
        :partly_sunny_rain: Coarser load where load transport is highest in the wet season
  - - - More frequent deposition in seasonally humid where there are regular seasonal rainfalls and high discharge
        
        Deposited load is coarser and larger due to higher settling velocities, so mostly bedload is deposited while suspended load remains in suspension due to lower settling velocities and constant discharge and river energy
        
        Deposition occurs throughout channel
        
        :rain_cloud: Inner banks of meanders as point bar deposits
        
        :partly_sunny_rain: Large mid-channel bars , especially in dry seasons where stream capacity and competence ↓
    - - Continuous frequent transport due to constant high discharge from regular high rainfalls
        
        Commonly saltation and suspension
        
        Channel load is larger in numbers and finer (fine sits/clay/fine sands) due to downstream fining and dominant CW
        
        Coarser load transported by traction during large rainstorms
        
        Sediments transported further downstream
        
        Sediment size decreases with increasing discharge downstream
        
        Af: transport is frequent and regular while Am/Aw: all load is transported during wet seasons
    - - Continuous erosion of high frequency where discharge is constantly high
        
        Abrasion more common due to large supply of available load while hydraulic action occurs mostly during a rainfall event where channel has high energy
        
        Smaller extent of erosion than arid as humid's sediment load is smaller and finer
        
        In seasonally humid, erosion and transport is dominant during wet seasons
- - - - Frequency of bankfull discharge is not more than once or twice a year
        
        Discharge decreases downstream due to high evaporation rates, absence of tributaries and large transmission losses
        
        Flood discharges of varying magnitudes due to past wetter climates :koala: , producing nested channels called wadis
        EG: Todd River
    - - Short channel length and convex profile (gentler to steeper gradient)
        
        Limited erosion and lack of downstream fining
    - - Large sediment load of mainly coarse sediments (sand/gravel) that are transported only during rainfall events
        
        Presence of large mid-channel bars and deposits outside of the channel as stable islands and ridges
  - - - Infrequent transport due to irregular discharge
        
        During rainstorm where discharge is high from large surface runoffs, channel competency and capacity ↑, and all load is suspended
        
        Load is coarser and smaller in number due to dominant PW and lack of downstream fining , transported only a short distance downstream [every fluvial process in the arid occurs upstream as due to transmission losses, there is rarely a downstream part of a channel as discharge is insufficient]
    - - Rare infrequent erosion due to irregular rainfall
        
        Erosion only occurs during episodic rainfalls, usually hydraulic action due to high stream energy and abrasion due to large calibre load
        
        Larger extent of erosion than humid because of highly erodible banks with sparse vegetation to hold them together and prevent erosion
    - - After the intense rainfall where river energy, competence and capacity falls, all load is deposited in temporary mid-channel bars
        
        Compared to frequency in humid, arid has lesser deposition as materials deposited rarely gets picked up to be deposited again
        
        Deposition occurs upstream, only in the middle of the channel as large temporary bars