Introduction to Rainfall Runoff Modelling

Question 1

Mathematical representation of processes

Empirical models…

Answer 1

black box models, maths equations based on analysis of concurrent input and output time series, not from the physical processes in the catchment. e.g.:
* UH (Sherman, 1932; Nash, 1959)

Question 2

Mathematical representation of processes

Conceptual models…

Answer 2

simplified equations with a physical basis. Model parameters need to be obtained through calibration.

Question 3

Mathematical representation of processes

Physically-based models

Answer 3

rigorous numerical solution of partial differential equations governing flow through porous media, overland and channel flows.

Question 4

Types – Spatial configuration

Lumped

Semi-lumped

Semi-disturbed

Distributed

Answer 4

Lumped (catchment or basin) - The spatial and temporal variation of meteorological, hydrological, geological and hydrogeological data across the model area is described as one aggregated value for input and output.

Semi-lumped (sub-catchment or sub-basin)

Semi-distributed (landuse classes, soil types, elevation, HRU)

Distributed (gridded) - Distributed models try to account for heterogeneity at finer scales, but due to the complexity of the land surface, sub-terrain layers, and the physics of infiltration, capillarity, etc. the so-called distributed models end up performing in a‘lumped’ manner.