Estimation of Streamflow (Chapter 7)

1
Estimation of Streamflow (Chapter 7)
2
Runoff generation

• direct runoff
• Rs, surface runoff
• Ri, interflow
• indirect runoff
• G, groundwater flow
• infiltration
• soil moisture storage
• interflow
• percolation --gt groundwater
• Effluent (perennial) vs. influent (intermittent)
  stream

surface runoff
infiltration
water table
percolation
groundwater flow
interflow
3
Runoff generation (contd)
flood
base (dry weather) flow

4
Runoff generation (contd)
streamflow direct runoff indirect runoff
(baseflow)
N-days?Ad0.2
Direct Runoff
Indirect Runoff
5
Types of Runoff Generation Mechanism
6
How do these runoff mechanisms look like?
7
Hydrographs of Catchment OutflowUnit Hydrograph
Techniques

• hydrograph that produces unit depth of direct
  runoff from a specified unit duration of excess
  rainfall
• use to predict entire stream flow hydrograph for
  any given storm
• UH derivation
• direct method
• indirect methods (synthetic UHs)

8
UH Derivation Direct Method Example

• Given
• measured stream flow hydrograph at outlet of
• 250 km2 catchment resulting from
• excess precipitation occurring in 5-hour period

• Derive
• 5-hour UH for this catchment

outlet
9
(No Transcript)
10
(No Transcript)