<html style="direction: ltr;">
<head>
<meta content="text/html; charset=windows-1255"
http-equiv="Content-Type">
<style type="text/css">body p { margin-bottom: 0cm; margin-top: 0pt; } </style>
</head>
<body style="direction: ltr;"
bidimailui-detected-decoding-type="preferred-charset"
bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">On 08/09/2013 07:31 PM, Admin wrote:<br>
</div>
<blockquote
cite="mid:!&!AAAAAAAAAAAYAAAAAAAAAG+QzjzdGUNEtmYcS16YDAHCgAAAEAAAAL2w06vhcppCnMtRo%2FMoNC0BAAAAAA==@shaw.ca"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1255">
<meta name="Generator" content="Microsoft Word 12 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman","serif";
color:black;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0cm;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
span.EmailStyle18
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:Consolas;
color:black;}
span.EmailStyle21
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D">Thanks a lot
Micha,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I am not that
efficient in gis. I tried to follow your instruction but I
could not import DEM file to GRASS<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I am using QGIS
1.8.0-Lisboa , installed GRASS plugins but could not import
DEM data. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">To make it
clear, I have a basin of about 600 sq km. my model is run
on 15 km x 15 km grid. Some part of the grid falls outside
of the basin boundary apparently. I have 25 grids in total
and I am looking for average slope for 25 grids, those out
of basin are set to 0 anyways. I created slope map from
DEM using raster terrain analysis but to grid them into
15x15km and find average slope for each grid is my problem<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
</div>
</blockquote>
<p><br>
</p>
<p><font face="sans-serif">Sorry, but I guess I misunderstood. When
you say "25 grids" are these 25 tiles that cover the whole
basin? or large grid cells of 15 km resolution? <br>
</font></p>
<p><br>
</p>
<p><font face="sans-serif">Your question "grid them into 15x15km ...
" makes me think you mean square polygons of 15km on each side.
Is this your situation? So you want to find the average slope in
each of the 15x15 polygon squares? GOing back to GRASS, there is
a module "v.rast.stats" that calculates various statistics from
a raster for each polygon in a polygon vector layer. That might
be what you need.<br>
</font></p>
<p><font face="sans-serif"> </font></p>
<p><font face="sans-serif">Perhaps if you could mention what
original data you have, then someone on the list could offer a
specific work flow. Do you have an elevation raster? a slope
raster? Have you delineated the actual basin boundary?</font><br>
</p>
<p><br>
</p>
<blockquote
cite="mid:!&!AAAAAAAAAAAYAAAAAAAAAG+QzjzdGUNEtmYcS16YDAHCgAAAEAAAAL2w06vhcppCnMtRo%2FMoNC0BAAAAAA==@shaw.ca"
type="cite">
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I highly
appreciate your help<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Moges<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
Micha Silver [<a class="moz-txt-link-freetext" href="mailto:micha@arava.co.il">mailto:micha@arava.co.il</a>] <br>
<b>Sent:</b> August 9, 2013 5:31 AM<br>
<b>To:</b> Admin<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:qgis-user@lists.osgeo.org">qgis-user@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [Qgis-user] grid avevarage slope<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On 08/08/2013 04:57 AM, Admin wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Hi all,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I need your help. I am working on a
basin. The model I am working with entails average surface
slope on grid basis. My basin has a number of grids. I
clipped and tried to get average slope but I am not happy
with the results.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Is there anyway I can do it? <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"">Using GRASS is one approach.
If you don't yet have a slope grid, then import it into
GRASS, and run the GRASS module r.slope aspect on your
elevation grid. Then clip it to the basin area. Now run the
r.univar module on the clipped slope grid to get a set of
univariate statistics from the grid.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"">If you already have a clipped
slope grid then import that into GRASS, and try the same
r.univar to get the stats.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"">Note that there is also a
group of GRASS addons for basin analysis: r.stream.* One of
the addons is r.stream.stats which gives you lots of basin
statistics, including two different approaches to "average"
slope in a watershed.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif""><o:p> </o:p></span></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Moges<o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif""><br>
<br>
This mail was received via Mail-SeCure System.<br>
<br>
<br>
<br>
<o:p></o:p></span></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>Qgis-user mailing list<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:Qgis-user@lists.osgeo.org">Qgis-user@lists.osgeo.org</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://lists.osgeo.org/mailman/listinfo/qgis-user">http://lists.osgeo.org/mailman/listinfo/qgis-user</a><o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>This mail was received via Mail-SeCure System.<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre><o:p> </o:p></pre>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif""><br>
<br>
<br>
<o:p></o:p></span></p>
<pre>-- <o:p></o:p></pre>
<pre>Micha Silver<o:p></o:p></pre>
<pre>GIS Consultant, Arava Development Co.<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.surfaces.co.il">http://www.surfaces.co.il</a><o:p></o:p></pre>
</div>
<br>
<br>
This mail was received via Mail-SeCure System.<br>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Micha Silver
GIS Consultant, Arava Development Co.
<a class="moz-txt-link-freetext" href="http://www.surfaces.co.il">http://www.surfaces.co.il</a></pre>
</body>
</html>