Session 2: Stream flow Relationship

Question 1

catchment classifications

Answer 1

hydrological, geomorphological, ecological

Question 2

Water Balance equation:

Answer 2

General Water Balance Equation:
P = Q + E + deltaS
deltaS = change in storage (surface
and subsurface)
deltaS = delltaSs + deltaSsm + deltaSG

P: Precipiation
Q-streamflow
E- Evapotraspiration
dS- change in storage

Question 3

When does overland flow occur?

Answer 3

Saturated soil (After snow melt or heavy rain),
Low permeability soil (Clay)

Question 4

Overland runoff in urban area

Answer 4

High level/flooding, cos water has nowhere to go, Urbanisation increases % of impervious surfaces.

Question 5

Types of rainfall-runoff models?

Answer 5

• Physical process-type models:
– detailed representation by physically-based
mathematical equations
– most predictive power
– large data requirements
– practical application limited to small catchments
• Empirical “black-box” models:
– reproduce catchment response from observed
rainfall data and empirical catchment descriptors
– no predictive power

Question 6

key differences between lumped, semi-distributed and distributed
hydrological model types

Answer 6

1) least accurate Lumped:
• Watershed-averaged
• Lumped description
• Low maintenance
• “Black-box” approach
• Highly empirical
2) semi- distributed model: 
• Subbasin-averaged
• Lumped description
• Low maintenance
• “Black-box” approach
• Empirical
3) Distributed model
• Pixel-based data
• Distributed description
• High maintenance
• Highly physical approach
• “White-box” approach
• Spatial non-uniformity
• Data and computer
resource intensive