Flow components

Question 1

Main flow components:

Answer 1

• Surface runoff RO:
• Interflow RI:
• Base flow RB:
• Quick flow/ direct flow RD:

Question 2

Surface runoff RO:

Answer 2

Flow from the surface of poorly permeable soils, temporarily saturated soils or permanently saturated soils.

A) Infiltration excess
Occurs if precipitation intensity PI is greater than infiltration intensity f at the soil surface
B) Saturation excess
Occurs from completely saturated soils either as immediate rainfall runoff (RR) or by return flow (RF) from subsurface runoff to the surface

Question 3

Interflow RI:

Answer 3

Rapid subsurface flow through pipes, macro-pores, and the seepage zone in soils.

A) Matrix flow
Flow trough the (homogeneous) soil matrix
B) Macropore flow
Flow through macropores (rootand animal holes, etc.) or preferential flow paths

Question 4

Base flow RB:

Answer 4

Return flow from groundwater. Base flow index (BFI): Portion of base flow from total flow.

 Base flow contribution for perennial rivers in humid climates is between 60% - >80 % of the total flow
 Base flow (groundwater flow) results from the permanent saturated zone (sedimentary and fractured aquifers) → Slowest runoff component
 In dry periods river discharge is maintained by groundwater flow; in flood periods groundwater may exfiltrate from the river into the aquifer

Question 5

Quick flow/ direct flow RD:

Answer 5

Sum of surface runoff and interflow.

Is equal to the effective rainfall or to the flood flow volume, see Chapter 10