Re: land use percentage data
Gus Yates <[email protected]> Wed, 02 Jun 2004 08:47:15 -0700
| Newsgroups | gmane.politics.activism.buildacarfreecity |
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--=====================_2922234==.REL Content-Type: text/html; charset=US-ASCII Content-Transfer-Encoding: 7bit <html> <body> David,<br><br> The percentage of land area that is impervious is an important parameter in stormwater modeling. Unfortunately, hydrologists lump paving and rooftops together when calculating impervious area. If it's of any use, here are the "typical" impervious percentages for various land uses in the U. S. from the standard hydrology reference manual (Maidment, D. R., ed. 1993. Handbook of hydrology. McGraw-Hill. New York, NY. p. 9.24):<br><br> Commercial and business: 85% impervious<br> Residential (lot size)<br> <= 1/8 acre 65%<br> 1/4 acre 38<br> 1/3 acre 30<br> 1/2 acre 25<br> 1 acre 20<br><br> Although this is from the "bible" of hydrology, I find the numbers suspicious, especially at the low-density end. For example, when lot sizes go from 1/2 acre to 1 acre, my impression is that the additional area is typically garden and yard. The above percentages suggest that impervious area increases from 5,445 sq. ft. for a half-acre lot to 8,712 sq. ft. for a 1-acre lot, or a 60% increase in the amount of roof and paving. I guess rich people need big driveways to park all their hummers....<br><br> I have personally digitized impervious percentages from air photos on a couple of occasions. The scale of the photos was a bit small for precise delineation, but I got 67% impervious for a typical block in the Sunset District in San Francisco and 50% impervious for 1/6-acre lots in Los Osos (near Morro Bay). The latter value is consistent with the table above.<br><br> Gus<br><br> At 07:51 PM 6/1/2004 -0700, you wrote:<br> <blockquote type=cite class=cite cite><font face="arial" size=2>hi all</font><br> <br> <font face="arial" size=2>sorry about the cross posting</font><br> <br> <font face="arial" size=2>I am looking for the following info. If anyone can help me track it down, I would appreciate it.</font><br> <br> <font face="arial" size=2>Joel Crawford, in his book, CARFREE CITIES, page 142-143, describes the land use percentages as they would be in a carfree district. He lists the following:</font><br> <br> <font face="arial" size=2>buildings: 38.3%</font><br> <font face="arial" size=2>streets/ pavement: 28.9%</font><br> <font face="arial" size=2>open space: 31.0%</font><br> <font face="arial" size=2>metro freight line: 1.8%</font><br> <br> <font face="arial" size=2>i would love to have similar figures for any cities or suburbs anywhere in the world, but especially in the U.S. I want to have these figures to use in educational materials to be able to demonstrate what the advantages of carfree developments can be.</font><br> <br> <font face="arial" size=2>i have tried contacting city planning departments via e-mail, and have either gotten no response or the response that they do not have that data. I imagine that it could be calculated using aerial fotos.</font><br> <br> <font face="arial" size=2>Does anyone have any ideas of where I might find this data? Also, if people could find out the data for their particular town or city (and pass it along to me), I could compile it and put it on our website.</font><br> <br> <font face="arial" size=2>I think that it would be very valuable to have.</font><br> <br> <font face="arial" size=2>Thanks in advance for your help.</font><br> <br> <font face="arial" size=2>Best</font><br> <br> <font face="arial" size=2>David Ceaser</font><br> <font face="arial" size=2>CarFree City, USA</font><br> <font face="arial" size=2><a href="mailto:[email protected]">[email protected]</a></font><br> <br><br> <font size=2 color="#003399"><b>Yahoo! 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Terms of Service</a>. </blockquote> <x-sigsep><p></x-sigsep> </ul>~~~~~~~~~~~~~~~~~~~~<br> Gus Yates, RG, CHG<br> 1809 California Street<br> Berkeley, CA 94703<br> Tel/Fax: 510-849-4412<br> [email protected] <br> <!-- |**|begin egp html banner|**| --> <br> <tt><hr width="500"> <b>Yahoo! Groups Links</b><br> <ul> <li>To visit your group on the web, go to:<br><a href="http://groups.yahoo.com/group/BuildaCarFreeCity/">http://groups.yahoo.com/group/BuildaCarFreeCity/</a><br> <li>To unsubscribe from this group, send an email to:<br><a href="mailto:BuildaCarFreeCity-unsubscribe-hHKSG33TihhbjbujkaE4pw@public.gmane.org?subject=Unsubscribe">BuildaCarFreeCity-unsubscribe-hHKSG33TihhbjbujkaE4pw@public.gmane.org</a><br> <li>Your use of Yahoo! Groups is subject to the <a href="http://docs.yahoo.com/info/terms/">Yahoo! Terms of Service</a>. </ul> </tt> </br> <!-- |**|end egp html banner|**| --> </body> </html> --=====================_2922234==.REL Content-Type: image/jpeg; name="2c8cf7.jpg"; x-mac-type="4A504547"; x-mac-creator="4A565752" Content-ID: <.0> Content-Transfer-Encoding: base64 Content-Disposition: inline; filename="2c8cf7.jpg" /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEB AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH/2wBDAQEBAQEBAQEBAQEBAQEBAQEBAQEB AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH/wAARCAD6ASwDASIA AhEBAxEB/8QAHwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQA AAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3 ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWm p6ipqrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEA AwEBAQEBAQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSEx BhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElK U1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3 uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq8vP09fb3+Pn6/9oADAMBAAIRAxEAPwD/AD/6 KKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAoo ooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiii gAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKA CiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAK KKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAoo ooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiii gAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKA CiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAK KKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAoo ooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiii gAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKA CiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAK KKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAoo ooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiii gAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKA CiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAK KKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAoo ooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiii gAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKA CiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAK KKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAooooAKKKKACiiigAoo ooAKKKKACiiigAooooAKKKKAP//Z --=====================_2922234==.REL Content-Type: image/jpeg; name="2c8d65.jpg"; x-mac-type="4A504547"; x-mac-creator="4A565752" Content-ID: <.1> Content-Transfer-Encoding: base64 Content-Disposition: inline; filename="2c8d65.jpg" /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEB AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH/2wBDAQEBAQEBAQEBAQEBAQEBAQEBAQEB AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQH/wAARCAABAAEDASIA AhEBAxEB/8QAHwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQA AAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3 ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWm p6ipqrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEA AwEBAQEBAQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSEx BhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElK U1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3 uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq8vP09fb3+Pn6/9oADAMBAAIRAxEAPwD/AD/6 KKKAP//Z --=====================_2922234==.REL--