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RAD Web Mapping Services Factsheet
Overview
The EPA Office of Water has made available several Web Mapping Services that contain nearly all of the NHD-based WATERS Program data, plus other WATERS-related layers. The services are available for use from the EPA's intranet and internet environments. This purpose of this help page is to describe the contents and purpose of each of the RAD IMS Services, and to provide 'how to' information for both general users and application developers.
The RAD Services are provided as ArcIMS Feature and Image services that utilize web/xml technology to enable the display and query of spatial RAD Event data. Both types of services are accessed through the use of ESRI's Arc Extensible Markup Language (AXL). Non-developers can utilize these services using mapping applications that 'speak' AXL, such as ArcMap or ArcExplorer. Using these tools, the RAD ArcIMS Services can be used as a data source, transparently integrated with other data sources such as shapefiles or SDE layers.
For developers, custom html-based web applications can be created that use standard AXL syntax to make requests for data and process the returned AXL data string to display maps or other information. The primary function of the RAD ArcIMS Image Services is to create and return images that are defined by the AXL <GETIMAGE> request. These images (typically .jpg or .png format) can then be displayed in the web application. The feature service also utilizes AXL requests and responses, but instead of creating an image, it streams AXL feature descriptions, which can then be mapped by the client. The feature service requires the use of a Java-based client.
The RAD image and feature services are also provided as OGC WMS and WFS web mapping services. WMS and WFS allow developers to create client mapping applications using open source projects or commercial software that connects to OGC compliant sources. For more information please see http://www.opengeospatial.org.
Service Descriptions
There are 29 RAD Services: 3 main servics, 13 image services and 13 feature services. The primary product of the RAD Image Services is a .jpg image depicting the RAD data requested. A description of each service is provided below.
RADImageDetailed - this service provides a comprehensive collection of WATERS-related data, with detailed thematic symbology that aligns with EnviroMapper for Water symbology.
RADImageBasic - this service is similar in content to the RADImageDetailed service, but does not contain the level of detailed thematic layer symbology. This enhances drawing performance and provides a smaller, simpler legend. This service is appropriate for users who do not need the detailed symbology, or for developers who may be assigning their own symbology definitions.
RADFeatureDetailed - this service is identical in content to the other services, but returns streamed vector features rather than a graphic. One major benefit of this is that the RADFeature layers can be incorporated into ArcMap or ArcExplorer sessions without 'overlap' issues associated with Image services. The RADFeature layers behave similarly to other SDE or shapefile layers within ArcMap. These layers can easily be individually symbolized and classified and incorporated with the rest of the layers.
Image/Feature services have been separated into specific individual services for ease of use and to reduce service latency. Please refer to the individual programs for detailed information.
- RAD_evt_303d_image - this service provides impaired waters maps.
- RAD_evt_303d_feature - this service provides impaired waters feature data.
- RAD_evt_305b_image - this service provides assessed waters maps.
- RAD_evt_305b_feature - this service provides assessed waters feature data.
- RAD_evt_beach_image - this service provides beaches maps.
- RAD_evt_beach_feature - this service provides beaches feature data.
- RAD_evt_cso_image - this service provides combined sewer overflow maps.
- RAD_evt_cso_feature - this service provides combined sewer overflow feature data.
- RAD_evt_cwns_image - this service provides clean water needs maps.
- RAD_evt_cwns_feature - this service provides clean water needs feature data.
- RAD_evt_fish_image - this service provides fish maps.
- RAD_evt_fish_feature - this service provides fish feature data.
- RAD_evt_grts_image - this service provides nonpoint source project maps.
- RAD_evt_grts_feature - this service provides nonpoint source project feature data.
- RAD_evt_ndz_image - this service provides sewage no-discharge zones map.
- RAD_evt_ndz_feature - this service provides sewage no-discharge zones feature data.
- RAD_evt_pcs_image - this service provides facilities that discharge to water maps.
- RAD_evt_pcs_feature - this service provides facilities that discharge to water feature data.
- RAD_evt_tmdl_image - this service provides total maximum daily load maps.
- RAD_evt_tmdl_feature - this service provides total maximum daily load feature data.
- RAD_evt_wqs_image - this service provides water quality standards maps.
- RAD_evt_wqs_feature - this service provides water quality standards feature data.
- RADEventLayers_image - this service provides all of the event programs maps.
- RADEventLayers_feature - this service provides all of the event programs feature data.
- NHDLayers_image - this service provides all of the NHDLayers maps.
- NHDLayers_feature - this service provides all of the NHDLayers feature data.
The table below lists
all of the layers available in the RAD IMS services, and the raw SDE
source table that the layer is derived from.
