Major Projects for Hydrology Group
Physically-Based Enhancements to SAC-SMA
This area of research seeks to combine physically-based algorithms with the Sacramento Soil Moisture Accounting (SAC-SMA) model. The goal is to incorporate advanced physics for processes and to reduce the amount of parameter calibration.
This area of research encompasses the calibration of hydrologic
model parameters. Included here are existing and emerging rainfall/runoff
models, snow models, and hydrologic routing models. The goal is
to develop tools to help the hydrologist derive the optimum model
parameters so as to produce forecasts of the highest possible
accuracy. In this area, we are interested in manual and automatic
methods of parameter calibration. Also, an extremely important
area is the development of new tools such as the ICP GUI as well
as an enhanced Calibration System to streamline the data collection
and analysis function.
Distributed Model Intercomparison Project (DMIP)
The goal of this project is to provide NWS/OHD/HL with an
accelerated path to advanced distributed hydrologic models for
improved river and flash flood forecasting. 12 US and international
research groups participated in this first phase of DMIP. HL provided
all data through a web site so that modelers could set up and
run their models. Simulations were analyzed to determine which
modeling approaches would best benefit the NWS forecasting mission.
Distributed Modeling Research
HL views distributed modeling as a major pathway through which
new science can be infused into NWS forecasting. This area of
research involves the idea that accounting for the spatial variability
of precipitation, temperature, and physiographic features will
lead to more accurate simulations. In addition, distributed modeling
facilitates new modeling capabilities such as flash flood forecasting
at ungaged sites and the generation of spatial output displays
of variables such as soil moisture.
Frozen Ground Modeling
The effect of frozen soil on the rainfall/runoff process can be
dramatic in many parts of the country and can severely complicate
the river forecast process. Frozen soil can act as impervious
area so that rain runs off into the stream system rather than
infiltrating into the soil. HL is actively involved in developing
a physically based method of modeling this phenomenon.
Snow accumulation and melt are the dominant hydrologic processes
in many parts of the US, especially in the inter-mountain West.
Traditionally, the NWS has used a conceptual temperature index
approach to model these processes. Current research involves the
use of energy budget approaches to more accurately model these