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Layer: i15_LandUse_Tulare2007 (ID: 0)

Name: i15_LandUse_Tulare2007

Display Field: WATERSOURC

Type: Feature Layer

Geometry Type: esriGeometryPolygon

Description: This data represents a land use survey of western Madera County conducted by DWR, South Central Regional Office staff, under the leadership of Steve Ewert, Senior Land and Water Use Supervisor. The field work for this survey was conducted during the summer of 2011. SCRO staff physically visited each delineated field, noting the crops grown at each location. Land use field boundaries were digitized using 2006 National Agriculture Imagery Program (NAIP) imagery as the base reference. Roads and waterways were delineated from a countywide shapefile using the U.S. Census Bureau's TIGER® (Topologically Integrated Geographic Encoding and Referencing) database and then clipped to match the USGS quadrangle boundaries. Digitized field boundaries were created on a quadrangle by quadrangle basis. Digitizing was completed at 1:4000 scale for the entire survey area. Field boundaries were delineated to depict observable areas of the same (homogeneous) land use type. Field boundaries do not represent legal parcel (ownership) boundaries, and are not meant to be used as formal parcel boundaries. Field work for DWR land use surveys typically occur during the summer and early fall agricultural seasons, so it can be difficult to identify fields where winter crops have been produced earlier during the survey year. To improve the mapping of winter crops, Landsat 5 imagery was analyzed to identify fields with high vegetative cover in late winter/early spring. Visual inspection of the Landsat scene displayed in false color infrared was used to select fields with both high and low vegetative cover as training data sets. These fields were used to develop spectral signatures using ERDAS Imagine and eCognition Developer software. The Landsat image was classified using a maximum likelihood supervised classification to label each pixel as vegetated or not vegetated. Then, the zonal attributes of polygons representing agricultural fields were summarized to identify fields vegetated during the winter. Polygons representing potential winter crops were used as an additional reference during field visits, and closely checked for winter crop residue. Site visits occurred from July through October 2007. Images and land use boundaries were loaded onto laptop computers that, in most cases, were used as the field data collection tools. GPS units connected to the laptops were used to confirm the surveyor's location with respect to each field. Some staff took printed copies of aerial photos into the field and wrote directly onto these photo field sheets. The data from the photo field sheets were digitized and entered back in the office. Land use codes associated with each polygon were entered in the field on laptop computers using ESRI ArcGIS software, version 9.3. Virtually all delineated fields were visited to positively observe and identify the land use type.The primary focus of this land use survey is mapping agricultural fields. Urban residences and other urban areas were delineated using aerial photo interpretation. Some urban areas may have been missed, especially in forested areas. Rural residential land use was delineated by drawing polygons to surround houses and other buildings along with some of the surrounding land. These footprint areas do not represent the entire footprint of urban land.Sources of irrigation water were identified for general areas and occasionally supplemented by information obtained from landowners. Water source information was not collected for each field in the survey, so the water source listed for a specific agricultural field may not be accurate.Before final processing, standard quality control procedures were performed jointly by staff at DWR's South Central Region, and at DSIWM headquarters under the leadership of Jean Woods, Senior Land and Water Use Supervisor. After quality control procedures were completed, the data was finalized. The positional accuracy of the digital line work, which is based upon the orthorectified NAIP imagery, is approximately 6 meters. The land use attribute accuracy for agricultural fields is high, because almost every delineated field was visited by a surveyor. The accuracy is 95 percent because some errors may have occurred. Possible sources of attribute errors are: a) Human error in the identification of crop types, b) Data entry errors.

Copyright Text: DWR, DIRWM, South Central Region Office, Water Conservation and Land and Water Use Section.

Default Visibility: true

MaxRecordCount: 1000

Supported Query Formats: JSON, geoJSON, PBF

Min Scale: 0

Max Scale: 0

Supports Advanced Queries: true

Supports Statistics: true

Has Labels: false

Can Modify Layer: true

Can Scale Symbols: false

Use Standardized Queries: true

Supports Datum Transformation: true

Extent:
Drawing Info: Advanced Query Capabilities:
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HTML Popup Type: esriServerHTMLPopupTypeAsHTMLText

Type ID Field: null

Fields:
Supported Operations:   Query   Query Attachments   Query Analytic   Generate Renderer   Return Updates

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