Understanding GIS. David Smith

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СКАЧАТЬ at esri.com/UnderstandingGIS4. Go here to access the data and get lesson results.

      Lesson results. The book’s exercises are cumulative, with the results of one exercise defining the starting point of the next. For this reason, your results at the end of every lesson must be correct. The lessons include many screen captures as visual confirmations of progress, so by the end of an exercise, you should know whether you got the correct results. If you did, you can carry them forward. If you have problems, or if you skip an exercise, you can get the resulting project files (containing data, maps, and layouts) for any lesson. Results are available on the book’s resource web page.

      Other resources. The ArcGIS Desktop Help system, accessible online, provides comprehensive descriptions of software concepts and tools. Additional online resources, such as blogs, forums, map galleries, videos, user communities, and access to technical support and training, can be found at this website: http://resources.arcgis.com.

       Disclaimer

      The data used in this book is real. So are the efforts of the City of Los Angeles and several interest groups to improve the environmental quality of the Los Angeles River and its surroundings. The GIS project in this book, however, was developed entirely at Esri. For the sake of a story, we pretend that the project was sponsored by the Los Angeles City Council. In fact, neither the book nor the project has any affiliation with the city beyond permission to use its GIS data. Likewise, there is no affiliation with the Los Angeles River Revitalization Corporation or with any Los Angeles River advocacy organization.

       Acknowledgments

      This book would not have been possible without the cooperation of the City of Los Angeles Department of Public Works and the Bureau of Engineering. Special thanks to Randy Price and Ann-Kristin Karling of the bureau’s Mapping Division, and to City Engineer Gary Lee Moore, for giving us access to the city’s data. We thank the City of Los Angeles Department of Recreation and Parks for providing its parks data. We note that land parcels and attributes are maintained by the Los Angeles County Assessor’s Office.

      The idea for the GIS project in this book was inspired by the Los Angeles River Revitalization Master Plan (available at http://www.lariver.org). Images from the master plan are used in lesson 1 by permission.

      Many Esri employees reviewed the book in whole or in part, tested exercises, and gave advice or help. Thanks to all of them for their skill and dedication.

      Thanks to the University of Redlands students who tested and provided valuable feedback on the exercises for this fourth edition. We want to acknowledge the support of the University of Redlands and the Center for Spatial Studies as well as Center for Spatial Studies GIS interns Anyssa Haberkorn, Adrian Laufer, and Jack Hewitt. Special thanks to the students of SPA 110—Introduction to Spatial Analysis and GIS, from the fall 2015 through spring 2017 semesters, who provided valuable constructive feedback on the workbook lessons.

      And, most of all, a huge thanks to Clint Brown of Esri for supporting this project through thick and thin.

      Required software version

      This book requires ArcGIS Pro 2.2 software with an Advanced license. Earlier software versions may not be fully compatible with exercise data and do not operate as described in the exercises.

       Data license agreement

      Downloadable data that accompanies this book is covered by a license agreement that stipulates the terms of use.

       Installing the project data

      To install the exercise data, go to the link on the book resource web page.

      You will need to read and accept the data license agreement terms.

      Accept the default installation folder or navigate to the drive or folder location where you want to install the data. The exercise data will be installed on your computer in a folder called C:\EsriPress\UGIS4 (or \UGIS4 in the folder where you installed the exercise data).

Lesson 1

Frame the problem and explore the study area

      THE VOLATILE LOS ANGELES RIVER is the reason that America’s second-largest city was founded in its present Southern California location by Spaniards in 1781. (The area was originally settled thousands of years earlier by the Gabrielino/Tongva Nation, a California Indian tribe also known as the San Gabriel Band of Mission Indians.) Its water was tapped for drinking and irrigation, and a new city spread out from the river across the coastal plain. By the turn of the 20th century, the river was surrounded by a thriving urban center. Every few decades, raging floods would crest the banks at various points, submerging entire neighborhoods. After the historic floods of 1938, which claimed more than 100 lives and washed out bridges from Tujunga Wash to San Pedro (figure 1-1), city leaders had seen enough. By 1941, the US Army Corps of Engineers had begun to straighten, deepen, and reinforce the once wild waterway. Much of its length was eventually lined in concrete, and the river was more or less tamed.

      Figure 1-1. The historic floods of 1938 washed out bridges up and down the Los Angeles River, including this one at Colfax Street and Vernon Boulevard.

      Today, the City of Angels—home to nearly four million people—is a vibrant world center of business and culture. Running straight through the heart of the city, the Los Angeles River now serves as a flood control channel (figure 1-2). Sadly, this once bucolic waterway that was so instrumental to the formation of the city later became known as something ugly and marginal. Mile after mile of angled concrete appealed only to graffiti artists and filmmakers, and save for the occasional televised rescue of some hapless Angeleno swept away by a winter storm-fed torrent, the river remained a part of the city ignored by most. The negative perception has stuck with the neglected river for decades.

      Figure 1-2. The Los Angeles River now serves as a flood control channel though the river corridor is the focus of city regreening efforts.

      But in recent years, as the city has densified and much of Southern California’s wild lands have been appropriated for development, new attention has focused on the river corridor and the scattered pockets of open space that line its length. Although it must always serve its important flood control function, the river and adjacent lands are increasingly recognized as underutilized, providing opportunities for regreening and psychic restoration for people living in an overbuilt city. Adventuresome and resourceful citizens have discovered peaceful pockets of sanctuary along the river and made these places their own. A vital and concerned activist community has raised awareness of the river and pushed for its beautification and redevelopment.

      In 2005, the city launched a major public works project focused on the human dimensions of the river. A landmark study, the Los Angeles River Revitalization Master Plan, demonstrated the significant potential of redevelopment to improve the quality of life for citizens living near the river corridor. Then mayor Antonio Villaraigosa said at the time, “We have an opportunity to create pocket parks and landscaped walkways СКАЧАТЬ