Quoted from: https://doi.org/10.1017/CBO9780511535673.012
The Snowmelt-Runoff Model (SRM) is designed to simulate and forecast daily streamflow in mountain basins where snowmelt is a major runoff factor. Most recently, it has also been applied to evaluate the effect of a changed climate on the seasonal snow cover and runoff. SRM was developed by Martinec (1975) in small European basins. Thanks to the progress of satellite remote sensing of snow cover, SRM has been applied to larger and larger basins. The Ganges River Basin in the Himalayas, the largest basin where SRM has been applied so far, is about 917 444 km2 (Seidel et al., 2000). Runoff computations by SRM appear to be relatively easily understood. To date, the model has been applied by various agencies, institutes, and universities in over 100 basins situated in 29 different countries as listed in Table 11.1. About 20% of these applications have been performed by the model developers and 80% by independent users. Some of the localities are shown in Figure 11.1. SRM also successfully underwent tests by the World Meteorological Organization with regard to runoff simulations (WMO, 1986) and to partially simulated conditions of real-time runoff forecasts (WMO, 1992).
Below are quoted from: https://macaulay.webarchive.hutton.ac.uk/hydalp/private/demonstrator_v2.0/models/srm.html
The SRM model originated with Jaroslav Martinec, attached at the time to the Swiss Snow and Avalanche Research Institute at Davos. Martinec (1975) described a snowmelt runoff model which has come to be referred to as SRM. It has undergone substantial development since 1975, by Martinec himself in collaboration with Al Rango (US NASA, later US ARS) and Michael Baumgartner (University of Bern). The model has been amended and extended several times in the light of operational experience. The current version, 3.2, is described by Martinec et al. (1994).
SRM was developed specifically to predict snowmelt runoff, unlike HBV and other general-purpose hydrological models containing a snowmelt routine. It has been extensively applied to snowmelt modelling in mountainous terrain, and recently also to climate-change scenarios. Martinec et al. (1994) list applications of SRM or variants of it in over 60 basins in 19 countries, at latitudes 32-60°N and 33-54°S, and with basin sizes from <1 to ~120 000 km2. Many of these basins contain glaciers, but generally occupying only a few percent of the total area of the basin. As with HBV, goodness of fit has generally been measured by the Nash-Sutcliffe R2 statistic (eq. below) and the percentage error in total runoff.
The basic structure of SRM is shown schematically in Figure 1 below:
The basin is subdivided into elevation zones; typically 3 or 4 zones are used, but more in high-relief basins (e.g. Kumar et al. 1991). There is no provision for sub-basins or land cover types. Runoff from all elevation zones is added together before routing, so location is not taken into account in the model. A daily time step is used. Snowmelt in each zone is predicted from air temperature, any rainfall is added on, and the total new water is routed through a single store.
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Figure 1. The structure of the SRM.
(Click for enlarged image)
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The original version of the model can be represented by a single equation (1):
One other parameter is implicit in the equation above: a temperature lapse rate used to extrapolate Ti from temperature at a base station.
The current version of SRM is rather more complicated and contains additional parameters, though the basic structure is unchanged. It can be represented as (equation 2):
The SRM philosophy about parameter values has always been opposed to calibration; users are urged to use standard default values based on worldwide experience and physically reasonable limits. The only exception is that k must be determined for the basin concerned by analysis of recession flow.