OHD/HL/HSMB - Hydrology

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.

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 Modeling

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 processes.