What is a hydrologic soil group?

“Hydrologic group” is a group of soils having similar runoff potential under similar storm and cover conditions. Soil properties that influence runoff potential are those that influence the minimum rate of infiltration for a bare soil after prolonged wetting and when not frozen.

How do you identify a hydrologic soil group?

The depth and hydraulic conductivity of any water im- permeable layer and the depth to any high water table are used to determine correct hydrologic soil group for the soil. The property that is most limiting to water movement generally determines the soil’s hydrologic group.

What is the tr55?

Technical Release 55 (TR-55) presents simplified procedures to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs. These procedures are applicable in small watersheds, especially urbanizing watersheds, in the United States.

What is NRCS method?

The NRCS-CN method is widely applied in the estimation of precipitation runoff. It primarily relies on soil mapping and land use data as input parameters, although land use data is not frequently updated. This corrected the runoff values and improved the estimation of runoff in the watershed.

What is hydraulic soil?

What is soil hydraulic conductivity? In scientific terms, hydraulic conductivity is defined as the ability of a porous medium (soil for instance) to transmit water under saturated or nearly saturated conditions.

How are soils grouped?

Soils are named and classified on the basis of physical and chemical properties in their horizons (layers). “Soil Taxonomy” uses color, texture, structure, and other properties of the surface two meters deep to key the soil into a classification system to help people use soil information.

What does NGK TR55 fit?

NGK TR55 Spark Plug fits the following vehicle(s): 2004 Cadillac CTS-V. 2005 Cadillac CTS-V. 2006 Cadillac CTS-V.

How do I find my CN number?

The weighted CN is calculated by taking the sum of each CN value multiplied by its fraction of the total subcatchment area. The sum is (usually) rounded to the nearest whole number, as described below.

What is the SCS method?

The SCS curve number method is a simiple, widely used and efficient method for determining the approxient amount of runoff from a rainfall even in a particular area. The curve number is based on the area’s hydrologic soil group, land use , treatment and hydrologic condition.

What is the difference between rational method and SCS method?

1. Rational Method: drainage area is less than 50 acres 2. SCS Method: drainage area is greater than 20 acres, also the SCS method should only be used when the Curve Number exceeds 50 and the time of concentration is greater than 0.1 hr and less than 10 hr.

When was TR-55 issued for small watersheds?

These procedures are applicable in small watersheds, especially urbaniz- ing watersheds, in the United States. First issued by the Soil Conservation Service (SCS) in January 1975, TR-55 incorporates current SCS procedures. This revision includes results of recent research and other changes based on experience with use of the original edition.

Where can I find the current soil survey?

Loading Tree… Current, official soil survey information is on the Web Soil Survey. The Web Soil Survey allows you to create custom reports by selecting a specific area of interest. In the table below, clicking on a survey area that is listed as “current” takes you to the Web Soil Survey.

When does the ssurgo soil survey data come out?

Updates to the official SSURGO soil survey data are now posted only once per year, on October 1. We plan to post an updated version of this hydrologic soil group spreadsheet each year, soon after October 1, in order to capture any recent changes to hydrologic soil group data in New York.

What are the soil groups in New York?

The range of depth to seasonal high water table for group D is greater than was previously used in New York, so more soils are in this group. More soils in dual groups. For soils in groups A/D, B/D, or C/D, the first letter applies to the drained condition and the second applies to the undrained condition.