Snowmelt Runoff Model (SRM)

Definition of Inputs for the SRM model

Model Settings - Basin Definition - Parameters - Daily Input

0. Overview

This page explains in more detail, the inputs required by the HYDALP Java implementation of the SRM model.

1. Model Settings

A number of parameters are used by the model to determine the operation of its algorithms in certain respects.

1.1 Update Stream Flow

1.2 Peak Rainfall Handling

1.3 Temporary Snow Handling

1.4 Standard Values

2. Basin Definition

The model requires information defining the characteristics of the basin being modelled, optionally divided up into a number of separate zones having distinct characteristics with respect to runoff modelling (typically divided into elevation bands).

The figure opposite shows the characteristics of two HYDALP basins in terms of their area with respect to elevation.

2.1 Area

2.2 Mean Elevation

2.3 Maximum Snow Water Equivalence (SWE)

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3. Parameters

Parameters and variables which may be available as zonal or basin wide values are always saved for all zones. In case of a basin wide definition, values for zone 1 represent the whole basin.

3.1 Critical Temperature

The temperature threshold above which precipitation is considered to fall as rain. Otherwise, snow is assumed.

3.2 Time Lag

3.3 Recession Coefficient

Parameter k in SRM formulae.

3.4 Degree-Day Factor

Parameter a in SRM formulae.

3.5 Runoff Coefficient

3.6 Rainfall Contribution

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4. Daily Input Data

The Snowmelt Runoff Model (SRM) requires a number of inputs for each day of the period modelled, defining the meteorological conditions for the basin, the amount of snow, and observations of runoff at monitoring points.

4.1 Temperature

Parameter T in SRM formulae.

Air temperature extrapolated to hypsometric mean height of each zone.

4.2 Precipitation

Parameter P in SRM formulae.

Precipitation falling as rain in each zone.

4.3 Temperature Lapse Rate

Used to extrapolate T for each zone.

4.4 Precipitation Lapse Rate

4.5 Snow Covered Area (SCA)

Parameter A in the SRM formulae.

This information is provided for HYDALP from classification of EO satellite data, or extrapolation from such classifications for dates on which insufficient EO data was available.