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HydroGET A web service client for ArcGIS. Ernest To PhD Candidate, University of Texas at Austin August 2008. What is HydroGET?. A web service client for ESRI‘s ArcGIS environment. Harvests time series data from web services and stores them in the Arc Hydro data model.
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HydroGETA web service client for ArcGIS Ernest To PhD Candidate, University of Texas at Austin August 2008
What is HydroGET? • A web service clientfor ESRI‘s ArcGIS environment. • Harvests time seriesdata from web services and stores them in the Arc Hydrodata model. • Default Mode: Downloads data from national data sources to describe components of the hydrological cycle. Atmospheric data from Daymet or Unidata Surface data from USGS NWIS Subsurface data from USGS NWIS Illustration courtesy of the United States Geological Survey • Custom Mode: Downloads data from any combination of CUAHSI web services to describe other properties (e.g. biological) of a study area.
HydroGET Interface Types of data and sources Main Interface User inputs GIS layer that contains points of interest. Atmospheric data from Daymet and Unidata Default Mode Geodatabase to store downloaded data Surface data from USGS NWIS List of variables (each tab holds a different set of variables) Subsurface data from USGS NWIS Data from user- specified sources for single point Custom Mode Period of interest Data from user- specified sources for multipoints
The default mode of Weather Downloader describes the hydrological history of a given location by downloading time series from public data repositories. For this demonstration, we have selected the San Marcos basin in central Texas. The basin is located between the cities of Austin, TX and San Antonio TX. It isis situated over the Edwards Aquifar, a major source of fresh water for the region. Default Mode HydroGET in action (Demo I) Legend Watershed centroids (Daymet) USGS groundwater gages (USGS NWIS) USGS streamflow gages (USGS NWIS) San Marcos basin in central Texas
Assembling data for hydrological insights Precipitation data from watershed centroids Precipitation (cm) Streamflow data from USGS gages. Streamflow (cfs) Groundwater data from USGS wells. Groundwater level (m above ground surface)
Underneath the hood What HydroGET needs to call a web service What HydroGET needs to store data in Arc Hydro
Making Arc Hydro data user-friendly with SQL queries 1. Arc Hydro data model (In Arc Hydro, time series information are stored in three separate tables: TSType, TimeSeries and a featureclass containing the monitoring sites) 2. Join (Use a query to join the TimeSeries table with TSType table and the featureclass attribute table) Join Join Pivot 3. Pivot (Pivot the joined table by Variable field to create a MultiColumn table)
Multicolumn table • All the time series data from the Arc Hydro geodatabase can be integrated into a single understandable, multicolumn table using queries. • Each record in the table contains all variables measured at the same point in space and time. Latitude, Longitude, Offset and Timeinformation are also provided within each record. • Multicolumn format is more amenable to data analysis. • Because the table is actually a query, when underlying time series data are updated with HydroGET, the multicolumn table gets updated as well.
Conclusions • HydroGET and MySelect are useful tools for harvesting from CUAHSI web services. • Semantic differences between different data sources can be mediated by MySelect. • SQL queries allow instantaneous conversion of Arc Hydro time series into a format suitable for analysis. • HydroGET is available at http://his.cuahsi.org/hydroget.html