This map service is an information surface representing the amount of available water storage (AWS) that is available to plants in the top 150cm (4.92 Feet) of soil. Available Water Storage (AWS) is expressed as centimeters of water, reported as the average of all components in the map unit. AWS is calculated from AWC (Available Water Capacity) which is commonly estimated as the difference between the water contents at 1/10 or 1/3 bar (field capacity) and 15 bars (permanent wilting point) tension, and adjusted for salinity and fragments.
Available Water Storage (AWS) surfaces are available through arcgis.com for four soil depths, 25, 50, 100, and 150 centimeters from the surface of the soil. They are available for the entire United States and are published by the US Natural Resources Conservation Service. Esri is providing NRCS SSURGO content here without modification except for some cartography and publishing necessary to facilitate esri user access to these data.
This map service is a representation of the NRCS SSURGO data table MUAGGATT, field AWS0150WTA. The map service will display at scales between 15,000 and 600,000, but the intended scale of the data is 1:24,000. It is based entirely on the US Natural Resources Conservation Service SSURGO polygon dataset, mapped for every part of the United States that has come under survey. Some parts of the United States have not yet been mapped, and in a sense the SSURGO dataset is a seamless collection of individual soil survey maps rather than a single map for the whole United States. As a result, there may be inconsistencies between adjacent surveys because surveys may have been compiled in different decades and with slightly different methods and staff.
The map service is being served to you from a service in the amazon cloud. The map service is published in unprojected geographic space, in coordinate system WGS84. Because the map is published unprojected, it can be projected dynamically to order into the projection of your choosing. This means you can use the map service in any map, not just a "web mercator" projection. This also may mean it will take a second or two to draw your map to order. We welcome your comments on the speed and convenience of this map service.
For best results, this map service is designed to be shown over relief with about 50% transparency. We also recommend for context using the US Hydro Reference Overlay available from arcgis.com here.
