WaterWare: a Water Resources
Management Information System
The Rainfall-Runoff Model RRM
The rainfall runoff model (RMM) is daily, lumped parameter
water budget and runoff model for small and medium-sized
sub catchments. It obtains its input data from the
river basin objects and their associated
time series of precipitation, temperature,
and runoff data.
The RRM rainfall-runoff model can be explored in
an interactive on-line demo
RRM is a daily, spatially aggregated water budget and runoff model for small
and medium sized catchments, for which a representative synoptic rainfall
can be defined.
The main elements and processes represented in the model are:
Interception storage, which is a function of land cover;
excess water reaches the soil (surface);
from the interception storage, evaporation (function of temperature) is
deducted;
Soil surface; depending on infiltration capacity,
(depending on land cover and soil moisture), precipitation is split
into surface runoff (Hortonian flow) and infiltration.
Depending on the air temperature (profile), which is calculated from the
basins elevation distribution, precipitation can be both in the form of
rain or snow. In the latter case, a snow pack is simulated,
from which both evaporation and melting (the latter greatly enhanced by
precipitation events above freezing) are estimated using a simple
degree-day approach.
Rootzone; this compartment represents the soil moisture in
the rootzone, which is replenished up to field capacity;
from it, evapotranspiration (a function of temperature, land cover, and
soil moisture) returns water to the atmosphere;
water in excess of field capacity reaches the next storage level, the
Virtual drainage storage. From here water is split into an
interflow component and (deep) percolation into the groundwater.
Assuming a maximum speed of deep percolation, any excess water is routed
through the soil system to the nearest channel as interflow.
Groundwater system (shallow) supplies, in a non-linear
function of storage, the baseflow contribution of the total runoff.
Again a fraction of the (shallow) groundwater can percolate into a second,
deeper layer that has no direct connection to the surface water system.
From both shallow and deep groundwater, groundwater extractions (time
series defined for specific wells or well fields) can be considered.
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