Data Storage Descriptors in HEC-DSS

Last updated on August 17, 2026

HEC-DSS (Hydrologic Engineering Center - Data Storage System) is a standardized data format used to store, manage, and exchange hydrologic time-series data. DSS files are widely used in hydrologic modeling workflows to maintain consistent, accessible datasets. Data in a DSS file is organized using a structured pathname system, where each part of the pathname conveys specific information about the dataset. Understanding these pathnames is essential for accessing, analyzing, and interpreting time-series data in hydrologic models.

In CivilGEO’s software, the DSS Data File & Path dialog box allows the user to select the DSS file and the time series data records stored within it. To learn more about the DSS Data File & Path dialog box, refer to this article in our knowledge base.

HEC-DSS Pathnames

A DSS file organizes its datasets into pathnames, which may contain up to 391 characters. Each pathname is conventionally divided into six parts, with each part allowing up to 64 characters. The standard naming convention for pathname parts is listed below:

Part	Description
A	Project, river, or basin name
B	Location
C	Data parameters (e.g., FLOW, PRECIP)
D	Starting date of block, in a 9-character military format (dd/mm/yyyy)
E	Time interval
F	Additional user-defined descriptive information

Each part of the pathname has a specific purpose, such as identifying the project, location, data type, time interval, or scenario. Among these, Part C is important because it defines the type of data stored in the DSS file, such as streamflow, precipitation, losses, canopy storage, soil moisture, routing flows, and more.

What is Part C?

Part C is also known as the Descriptor.
Part C identifies the variable, parameter, or data type for both regular and irregular interval time series data. This allows the software to recognize, retrieve, process, and plot the correct data from a DSS file.
Standard Part C descriptors are predefined to maintain consistency across projects.

Note: The availability of descriptors is project-specific and depends on which hydrologic methods (such as loss, transform, routing, or reservoir) are being used.

List of HEC-DSS Part C Descriptors

HEC-DSS provides a wide range of standard Part C descriptors for different hydrologic modeling purposes. These descriptors can represent either computed data or manually entered values. The following table lists the commonly used standard HEC-DSS Part C descriptors:

Descriptor	Description
AREA	Computed area for a reservoir element.
ATI-COLD	Computed antecedent temperature index for cold content in the snowmelt method.
ATI-COLDRATE	Manually entered antecedent temperature index versus cold-rate function (paired data).
ATI-MELT	Computed antecedent temperature index for melt-rate in snowmelt.
ATI-MELTRATE	Manually entered antecedent temperature index versus melt-rate function (paired data).
COLD CONTENT	Computed cold content in snowmelt.
CROP COEFFICIENT	Manually entered cross section in the paired data manager.
ELEVATION	Computed pool elevation for a reservoir element.
ELEVATION-AREA	Manually entered elevation-area function defined in the paired data manager.
ELEVATION-OBSERVED	Observed pool elevation for a reservoir element using an optional observed elevation time-series gage.
ELEVATION-RESIDUAL	Residual elevation for a reservoir element with observed elevation. The residual is calculated as computed flow minus the observed elevation.
ELEVATION-STORAGE	Manually entered elevation-storage function defined in the paired data manager.
ET-CANOPY	Computed actual evapotranspiration from the canopy layer in the soil moisture accounting loss method.
ET-SOIL	Computed actual evapotranspiration from the soil layer in the soil moisture accounting loss method.
ET-SURFACE	Computed actual evapotranspiration from the surface depression layer in the soil moisture accounting loss method.
EXCESS-CANOPY	Computed incremental precipitation minus canopy interception in the soil moisture accounting loss method.
FLOW	Final computed flow for an element.
FLOW-AUX	Outflow from a reservoir through the auxiliary discharge.
FLOW-BASE	Computed baseflow for a subbasin element.
FLOW-COMBINE	Computed total inflow to an element.
FLOW-DIRECT	Surface flow computed by transforming excess precipitation for a subbasin element.
FLOW-DIVERSION	Computed diversion flow for a diversion element.
FLOW-IN	Total inflow to a reach element.
FLOW-LOCAL	Local flow at a junction when the basin model is set to compute local flow at junctions.
FLOW-LOCAL-SIM	Computed local flow without blending for a junction when observed flow is present, blending is used, and the basin model is set to compute local flow at junctions.
FLOW-LOSS	At a reach, the computed channel losses.
FLOW-OBSERVED	Observed flow for an element using the optional observed flow time-series gage.
FLOW-RESIDUAL	Residual flow for an element with observed flow. The residual is calculated as computed flow minus the observed flow.
FLOW-SIM	Computed flow without blending at an element when observed flow is present, and blending is used.
FLOW-UNIT GRAPH	Manually entered unit hydrograph in the paired data manager.
GROUNDMELT	Manually entered annual ground-melt pattern in the paired data manager.
INFILTRATION	Computed infiltration from the surface layer to the soil in the soil moisture accounting loss method. Also, the amount of loss attributed to infiltration in the deficit constant loss method.
LIQUID WATER	Computed liquid water in the snowpack in snowmelt.
MELTRATE	Manually entered annual melt-rate pattern in the paired data manager.
MOISTURE DEFICIT	Computed moisture deficit in the deficit constant and gridded deficit constant loss methods.
OUTFLOW-GW	Computed outflow from a groundwater layer to channel baseflow in the soil moisture accounting loss method.
PERC-SOIL	Computed percolation from the soil layer to the upper groundwater layer in the soil moisture accounting loss method.
PERC-GW	Computed percolation from the upper groundwater layer to the lower groundwater layer or from the lower groundwater layer out of the system in the soil moisture accounting loss method.
PERCENT-GRAPH	Manually entered percentage curve in the paired data manager.
PRECIP-EXCESS	At a subbasin, incremental precipitation minus losses.
PRECIP-EXCESS-CUM	At a subbasin, cumulative precipitation minus cumulative losses.
PRECIP-CUM	Cumulative precipitation for a time-series gage.
PRECIP-INC	Incremental precipitation for a time-series gage or subbasin element.
PRECIP-LOSS	At a subbasin, the incremental precipitation that was converted to loss during loss calculations.
PRECIP-LOSS-CUM	At a subbasin, the cumulative precipitation that was converted to loss during loss calculations.
PRECIP-LWASS	The liquid water available at the soil surface calculated for a subbasin by a snowmelt method.
PRECIP-LWASS-CUM	The cumulative liquid water available at the soil surface calculated for a subbasin by a snowmelt method.
PRECIP-STAND DEV	At a subbasin, the standard deviation of incremental precipitation for each time interval computed using gridded precipitation.
RECOVERED DEFICIT	Computed recovery of the deficit by evapotranspiration in the deficit constant and gridded deficit constant loss methods.
SATURATION FRACTION	The percentage of the soil layer that is saturated in the deficit and constant or soil moisture accounting loss methods.
SOLAR RADIATION	Manually entered time-series of solar radiation for a time-series gage.
STAGE	Computed stage for an element when the optional elevation-discharge curve is used. Also, manually entered time-series of stage for a time-series gage.
STAGE-CHANNEL	Stage computed in the channel at a diversion element.
STAGE-FLOW	A manually entered elevation-discharge function defined in the paired data manager.
STAGE-OBSERVED	Observed stage for an element using the optional observed stage time-series gage.
STAGE-RESIDUAL	Residual stage for an element with observed stage. The residual is calculated as computed flow minus the observed flow.
STAGE-SIM	Stage at a reach using the modified Puls or Muskingum Cunge routing methods computed using the simulated flow depth.
STAGE-TAILWATER	The computed tailwater stage at a reservoir element.
STAGE-TW-AUX	The computed tailwater stage at the auxiliary discharge from a reservoir element.
STORAGE	Computed storage for a reservoir element.
STORAGE-CANOPY	Computed storage depth of the canopy layer in the soil moisture accounting loss method.
STORAGE-ELEVATION	A storage-elevation curve defined in the reservoir element. No longer used in the current program version.
STORAGE-FLOW	A manually entered storage-discharge function defined in the paired data manager.
STORAGE-GW	Computed storage depth of a groundwater layer in the soil moisture accounting loss method.
STORAGE-SOIL	Computed storage depth of the soil layer in the soil moisture accounting loss method.
STORAGE-SURFACE	Computed storage depth of the surface layer in the soil moisture accounting loss method.
SWE	Computed snow water equivalent in snowmelt.
SWE-OBSERVED	Observed snow water equivalent for a subbasin element using the optional observed SWE time-series gage.
SWE-RESIDUAL	Residual snow water equivalent for a subbasin element with observed SWE. The residual is calculated as computed flow minus the observed SWE.
TEMPERATURE	Computed temperature for a subbasin elevation band in snowmelt. Also, manually entered time-series of temperature for a time-series gage.