National hydrography dataset--linear referencing

Geospatial data normally have a certain set of standard attributes, such as an identification number, the type of feature, and name of the feature. These standard attributes are typically embedded into the default attribute table, which is directly linked to the geospatial features. However, it is impractical to embed too much information because it can create a complex, inflexible, and hard to maintain geospatial dataset. Many scientists prefer to create a modular, or relational, data design where the information about the features is stored and maintained separately, then linked to the geospatial data. For example, information about the water chemistry of a lake can be maintained in a separate file and linked to the lake. A Geographic Information System (GIS) can then relate the water chemistry to the lake and analyze it as one piece of information. For example, the GIS can select all lakes more than 50 acres, with turbidity greater than 1.5 milligrams per liter.