National Hydrologic Model Infrastructure

Science Center Objects

The USGS National Hydrologic Model (NHM) infrastructure supports the efficient construction of local-, regional-, and national-scale hydrologic models. The NHM infrastructure consists of: 1) an underlying geospatial fabric of modeling units with an associated parameter database, 2) a model input data archive, and 3) a repository of the physical model simulation code bases. 

The USGS National Hydrologic Model (NHM) infrastructure was developed to support the efficient construction of local-, regional-, and national-scale hydrologic models for the conterminous United States (Regan and others, 2019 and 2018). The NHM is a modeling infrastructure consisting of three main parts: 1) an underlying geospatial fabric of modeling units (hydrologic response units and stream segments) with an associated parameter database, 2) a model input data archive, and 3) a repository of the physical model simulation code bases. The NHM has been used for a variety of applications since its initial development.

1. Geospatial Fabric 

The geospatial fabric was originally developed by Viger and Bock (2014) and is based on an aggregation of the spatial features associated with NHDPlus version 1. The more than two million catchments in the NHDPlus version 1 dataset were aggregated to approximately 110,000 hydrologic response units (HRUs). Model parameter values were computed for each HRU and are stored in a centralized parameter database.

2. Model Input Datasets 

Inputs of climate forcings are necessary to run the hydrologic model simulations in the NHM. Primarily, time series of maximum and minimum daily temperature and daily precipitation accumulation are needed by the simulations. Many gridded climate datasets are currently available for the conterminous United States. The three climate datasets that have been used with the NHM to this point are Daymet (Thornton and others, 2016), gridMET (Abatzoglou, 2013), and the forcings developed by Maurer and others (2002). These gridded climate forcings were transferred to the HRUs using an area-weighted averaging algorithm.

3. Physical Models 

Currently, two physical model simulation codes have been included in the NHM Infrastructure: 1) the Monthly Water Balance Model (MWBM; McCabe and Markstrom, 2007) and 2) the Precipitation-Runoff Modeling System (PRMS; Markstrom and others, 2015; Leavesley and others, 1983).

Illustration of the NHM infrastructure as applied to the PRMS model.

Illustration of the U.S. Geological Survey National Hydrologic Model infrastructure as applied to the Precipitation-Runoff Modeling System (NHM-PRMS). The NHM-PRMS includes: (1) process representation using the PRMS hydrologic simulation code; (2) a consistent geospatial structure for modeling; (3) a database of estimated parameter values; (4) climate input variables; and (5) model extraction software (Regan et al., 2018).

 

Applications using the NHM 

2019 

2018 

2017 

2016