EDNA Stage 2 Vector Editing
The delineations produced in Stage 1 are passed on to appropriate cooperators, who will provide an intensive QA/QC. The derived watersheds will be overlain on 1:24,000 map sheets (as DRGs) and the watershed boundaries will be revised using standard vector editing techniques. These revised boundaries will provide the Stage 2 delineation. Watershed areas found to be in conflict with the DRGs will be flagged as problem areas. An additional QA/QC will be performed through comparison of the synthetic streamlines derived from EDNA with the 1:100,000 scale National Hydrography Dataset (NHD). Derived streamlines in conflict with the NHD will be flagged, as well.
Arcview tools have been developed at EDC to facilitate the Stage 2 processing of the data. Locations of current cooperators are displayed in this graphic
Two distinct tasks are accomplished in the Stage II EDNA Process. First, the preliminary Watershed and Subwatershed boundaries are defined. Second, the data and products previously created in Stages I and II are subjected to a thorough quality control review to identify, resolve, and document all significant discrepancies between the various data sets. In Stage II the automated functions are designed to direct the process through a logical and consistent sequence of events, to present the appropriate information at the appropriate time to facilitate the analysis and decision making tasks, to search the Cataloguing Unit in a systematic manner to ensure that no area or potential problem is overlooked, and to provide an efficient means of implementing, annotating, and recording decisions made by the analyst. Stage II is an Arc/View process. It consists of a series of Avenue scripts that step the Stage II analyst through the process, provide data (via display), information, and suggestions to expedite the decision process. It also provides the analyst with the tools to implement decisions (when creating preliminary watershed and subwatershed boundaries), and with the tools to record and annotate decisions that are to be executed in Stage III.
Step one of the Stage II process is a general overview of the Cataloguing Unit to identify issues (for example streamline density differences between the synthetic drainage and the NHD) that won't interfere with Stage II processing but should be addressed before final EDNA products are created. Also in Step one, the "general metadata," "edit graphic," and "edit metadata" files are created. The "general metadata" file contains information common to the entire Cataloguing Unit (CU name and number, date, analysts name and organization, contact information, general remarks, etc.). The "edit graphic" and "edit metadata" files will be used in Step 4 to provide graphic and textual information to guide the Stage III process.
Step two is the definition of the preliminary boundaries for the watersheds (level 5 subdivisions). Based on the delineation guidelines, the size, shape, and drainage pattern of the Cataloguing Unit, and local information, the analyst determines the number and approximate boundaries of the watersheds. He/she then aggregates the "catchments" to form, as nearly as possible, the desired result. (NOTE: If the desired "seed point" is not located at a point immediately above a confluence, aggregation of the catchments will not produce the desired result. If the desired "seed point" is immediately below a confluence, aggregation of the catchments will closely approximate, but not precisely produce the desired result. In these cases the analyst must direct the Stage III process to "move" the "seed point" to the desired location.)
Step three is the definition of the preliminary boundaries for the subwatersheds (level 6 subdivisions). Repeat step two.
Step four is the QA/QC process. It consists of a systematic review of each subwatershed. The objective of Step four is to identify all of the adjustments that must be made to the process (i.e. adjust threshold values) and to the data (i.e. revise "seed points," edit the digital elevation data) in order to produce a logical and accurate model of the current hydrology and products that are consistent with the guidelines for the Watershed Boundary Dataset and for synthetic streamline delineation. Also, to record the information and to convey it to the Stage III process in a manner that will ensure that the required modifications are made correctly and accurately.
The delineations produced in Stage 1 are passed on to appropriate cooperators, who will provide an intensive QA/QC. The derived watersheds will be overlain on 1:24,000 map sheets (as DRGs) and the watershed boundaries will be revised using standard vector editing techniques. These revised boundaries will provide the Stage 2 delineation. Watershed areas found to be in conflict with the DRGs will be flagged as problem areas. An additional QA/QC will be performed through comparison of the synthetic streamlines derived from EDNA with the 1:100,000 scale National Hydrography Dataset (NHD). Derived streamlines in conflict with the NHD will be flagged, as well.
Arcview tools have been developed at EDC to facilitate the Stage 2 processing of the data. Locations of current cooperators are displayed in this graphic
Two distinct tasks are accomplished in the Stage II EDNA Process. First, the preliminary Watershed and Subwatershed boundaries are defined. Second, the data and products previously created in Stages I and II are subjected to a thorough quality control review to identify, resolve, and document all significant discrepancies between the various data sets. In Stage II the automated functions are designed to direct the process through a logical and consistent sequence of events, to present the appropriate information at the appropriate time to facilitate the analysis and decision making tasks, to search the Cataloguing Unit in a systematic manner to ensure that no area or potential problem is overlooked, and to provide an efficient means of implementing, annotating, and recording decisions made by the analyst. Stage II is an Arc/View process. It consists of a series of Avenue scripts that step the Stage II analyst through the process, provide data (via display), information, and suggestions to expedite the decision process. It also provides the analyst with the tools to implement decisions (when creating preliminary watershed and subwatershed boundaries), and with the tools to record and annotate decisions that are to be executed in Stage III.
Step one of the Stage II process is a general overview of the Cataloguing Unit to identify issues (for example streamline density differences between the synthetic drainage and the NHD) that won't interfere with Stage II processing but should be addressed before final EDNA products are created. Also in Step one, the "general metadata," "edit graphic," and "edit metadata" files are created. The "general metadata" file contains information common to the entire Cataloguing Unit (CU name and number, date, analysts name and organization, contact information, general remarks, etc.). The "edit graphic" and "edit metadata" files will be used in Step 4 to provide graphic and textual information to guide the Stage III process.
Step two is the definition of the preliminary boundaries for the watersheds (level 5 subdivisions). Based on the delineation guidelines, the size, shape, and drainage pattern of the Cataloguing Unit, and local information, the analyst determines the number and approximate boundaries of the watersheds. He/she then aggregates the "catchments" to form, as nearly as possible, the desired result. (NOTE: If the desired "seed point" is not located at a point immediately above a confluence, aggregation of the catchments will not produce the desired result. If the desired "seed point" is immediately below a confluence, aggregation of the catchments will closely approximate, but not precisely produce the desired result. In these cases the analyst must direct the Stage III process to "move" the "seed point" to the desired location.)
Step three is the definition of the preliminary boundaries for the subwatersheds (level 6 subdivisions). Repeat step two.
Step four is the QA/QC process. It consists of a systematic review of each subwatershed. The objective of Step four is to identify all of the adjustments that must be made to the process (i.e. adjust threshold values) and to the data (i.e. revise "seed points," edit the digital elevation data) in order to produce a logical and accurate model of the current hydrology and products that are consistent with the guidelines for the Watershed Boundary Dataset and for synthetic streamline delineation. Also, to record the information and to convey it to the Stage III process in a manner that will ensure that the required modifications are made correctly and accurately.