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SPDSS Memorandum <br />To: Ray Alvarado, Ray Bennett <br />From: Riverside Technology, inc., Steve Malers, Tim Martin, and Amnon Nevo <br />Subject: Deliverable 96.1 -Approach for Linking NHD and HydroBase Spatial Data <br />Date: 28 October 2005 <br />1. Introduction <br />This memorandum recommends procedures for the use of the National Hydrography Dataset (NHD) with <br />key structures in HydroBase and is a deliverable for the SPDSS Spatial System Integration Task 96. <br />96.1 A memorandum describing the approach for creating a linked river network layer from <br />a hydrographic data source and HydroBase for use in the CDSS. <br />The networked stream data can be used to select and display data based on upstream/downstream <br />relationships. This memo provides recommendations to enhance HydroBase by linking it to the NHD <br />developed by the US Geological Survey (USGS). Included in this memorandum is the following <br />information: <br />• General background information about NHD (e.g., how to download data). <br />• Background information about the NHD data model for understanding the key data and to <br />provide a reference since the NHD documentation is currently not complete. <br />• A summary of tools that can be used with NHD. <br />• Information about merging separate NHD databases into a larger database. <br />• A recommendation for linking NHD with HydroBase stream data. <br />• A recommendation for linking NHD with HydroBase diversion point data. <br />• Outstanding issues from the evaluation. <br />This memo serves as a background for completing the other two deliverables for Task 96: a stream <br />network and key structures linked to the stream network. <br />2. Background <br />Linking HydroBase and NHD requires technical background information, which is provided below. This <br />memorandum includes extensive background about NHD to facilitate use by the CDSS team. Following <br />these background subsections are recommended procedures for creating the link between NHD and <br />HydroBase. <br />2.1 Hydrobase <br />HydroBase stores stream information in the stream and wd_water tables, which are associated with the <br />structure and other tables. The data in these tables are used by the Water Information Sheet (WIS) tool <br />and for basic StateView data displays that indicate the source of water for structures and water rights. <br />Basic StateView displays show only the water source and do not provide tools to query HydroBase using <br />upstream/downstream requests. The WIS mainly uses the water source to provide lists of structures for a <br />stream and to help users understand confluences. The SPDSS Task 106 memorandum (16 June 2004) <br />provides background on the use of these tables in CDSS, and potential changes needed to consolidate the <br />Page 1 Of 17 ~RlversFtfe reclrnology, Inc. <br />Wxeror Researres Errginer.: mg and Cuns~~@rng <br />