Applied Hydrology Program

Science Center Objects

The mission of the Applied Hydrology Program of the U.S. Geological Survey (USGS) New England Water Science Center (WSC) is to support water resource managers, stakeholders, and policy makers with the hydrologic data, interpretation, and tools they need to manage and make critical decisions about water resources throughout New England. This program is divided into two broad sections: the Hydrology and Hydraulics Section and the Water Quality Networks Section.

Hydrology and Hydraulics Section

Hydrologists in the Hydrology and Hydraulics Section investigate surface-water processes, develop models and tools for estimating water quantity on rivers and streams, and provide statistical and engineering analyses to policymakers, planners, and resource managers in New England. We use our expertise in hydrology and hydraulics to perform quantitative surface water assessments, including the development of statistical streamflow equations, flood and drought documentation, and flood risk analyses.

A primary task of this section is to work with the Federal Emergency Management Agency (FEMA) to create flood insurance rate maps (FIRMs), which identify flood hazards and zones for risk premiums for communities in New England. Hydraulic modelers compute riverine flood elevations using the U.S. Army Corps of Engineers HEC-RAS (Hydrologic Engineering Center's River Analysis System) modeling software. Modelers are supported by the Surveying Unit, which provides data for the models, and the Mapping Unit, which creates the draft map products for FEMA.


Surveying Unit

USGS employee stands in the river with a prism while a point measurement is taken with a station located on the river bank.

Surface-water modeling for Federal Emergency Management Agency flood insurance rate maps.​ (Credit: Rena Kalmon, U.S. Geological Survey. Public domain.)

The Surveying Unit within the Applied Hydrology Program supports survey data acquisition efforts throughout the WSC but primarily collects data to support the creation of FEMA FIRMs. Surveyors work year-round in a range of conditions to collect and process high-precision river geometry data that are vital for the hydraulic models used to compute water surface elevations at a range of streamflows. Using global navigation satellite system real-time network surveying and trigonometric leveling techniques, field teams collect positional and elevation data for river channels, banks, and structures (such as bridges, culverts, and dams) that can affect streamflow. The surveying team continues to expand their efforts to support an array of surveying projects throughout the WSC. 



Mapping Unit

USGS Employee is checking Preliminary Flood Insurance Rate Maps before a meeting.

​U.S. Geological Survey employee is checking preliminary flood insurance rate maps before a meeting. (Credit: Rena Kalmon, U.S. Geological Survey. Public domain.)

The Mapping Unit within the Applied Hydrology Program supports mapping projects throughout the WSC but primarily works towards the creation of FEMA FIRMs. Mapping tasks include coding, analysis of floodplains, development and coordination of hydrologic models, map development, floodway editing, map redelineations based on new topography, FEMA FIRM annotations, and creation of draft risk maps. In addition, the mapping team collaborates with other sections and projects throughout the WSC by providing expert ArcGIS mapping and graphical display support.




Water Quality Networks Section

Collecting a water-quality sample

U.S. Geological Survey hydrologic technician collecting a water-quality sample at Maple Meadow Brook, Wilmington, Mass. (Credit: David Armstrong, U.S. Geological Survey. Public domain.)

The WSC Water Quality Networks Section currently has programs in Connecticut, Rhode Island, and Massachusetts. These networks focus on short- and long-term physical-chemical monitoring. Scientists collect data from a variety of locations and watershed sizes throughout the networks. Data from the networks are used to estimate nutrient and other constituent loads and assess short- and long-term trends in water quality. The networks include discrete water quality sampling and continuous water quality monitoring.

Discrete water-quality samples are collected on a routine schedule that can vary between quarterly to more than monthly but can also target specific environmental conditions, including storm sampling, baseflow conditions, or tidal conditions. Discrete water quality samples are collected, processed, then sent to the USGS National Water Quality Laboratory in Denver, Colo. to test for a variety of analytes, including major ions, nutrients, trace metals, bacteria, and chlorophyll a.

Continuous water quality data are collected using multi parameter unattended monitors. These monitors measure water quality conditions in situ and can log data between 5- and 15-minute intervals. These data are often transmitted in near-real-time to the USGS National Water Information System (NWIS) database and displayed on the NWIS water quality data web page. Continuous water quality monitors can measure water quality parameters such as water temperature, specific conductance, pH, dissolved oxygen, turbidity, chlorophyll a, UV-nitrate, and fluorescent dissolved organic matter (fDOM). These monitors are routinely serviced to ensure accurate readings. During the site visits, sensors are cleaned and calibrated to ensure the data collected are accurate. All the records are then stored, analyzed, and approved in the Aquarius data system and released to NWIS.