HYDROLOGIC DATA

BACKGROUND

Analysis and synthesis of data is required to perform any hydrologic computation.

The engineer needs to:• Identify and define the data needed for an

application• Identify sources of data• Acquire data and review the data for accuracy

COLLECTION AND COMPILATION OF DATA

Site investigation and field Site investigation and field surveyssurveys

Field surveys are the primary sources of hydrologic data

Typical data include drainage boundaries, flow directions, high water marks, assessments of the performance of nearby drainage structures, assessments of stream stability and scour potential, significant changes in land use, etc.

Federal Data Bases

U.S. Geological Survey (USGS)U.S. Army Corps of EngineersNational Weather Service (NWS)U.S. Soil Conservation Service (SCS)Federal Emergency Management

AgencyEnvironmental Protection Agency

State and Local Agencies

Environmental Protection AgenciesState Highway DepartmentsPlanning AgenciesUniversities

Other Data Sources

Certain types of data are needed so frequently that some state agencies have compiled them into a single drainage manual.

Historical Records or accounts are recorded in newspapers, magazines, or by state historic societies or universities.

The National Water Data Exchange (NAWDEX)

Was created to assist users of water data in the identification, location, and acquisition of needed data

Maintains two major files• Water Data Sources Directory

– Organizations that collect data– Types of water data collected and availability

• Master Water Data Index

Streamflow Data

Network of StreamgagesUSGS compiles and publishes the data

in Water Supply PapersWATSTORE = Water Data Storage and

Retrieval System

Precipitation Data

Climatological data are collected by the National Weather Service

NWS Raingage Network Weather Service Forecast Offices River Forecast Centers The National Climate Data Center (NCDC)

collects and processes, and disseminates data

Soil Data

The Natural Resources Conservation Service (NRCS) formerly the SCS, publishes generalized soil maps for each state and a detailed soil map for each county.

SCS County Extension Offices can supply the soils data.

Land Use Data

Form of Data - Topographic maps, aerial photographs, zoning maps, and Landsat Images

Sources of Data - State, Regional or municipal planning organizations, U.S. Geological Survey, Natural Resource Economic Division

Adequacy of Data

How Accurate is the Data?Will it meet my purpose?Can I add to the data base?