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Need very urgent help with LSFactor(USLE)Calculation in ArcGis10(get a strange result

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08-12-2012 10:11 AM
by Anonymous User
Not applicable
Original User: Julia.Hauczinger

I wanted to calculate the LS Factor of the USLE (Universal Soil Loss Equation) with the tool Raster Calculator in ArcGis 10.
First, I filled my DEM with the tool Fill. (DEM was calculated in UTM)
Second, I calculated the Flow Direction with the Toll Flow Direction.
Third, I calculated the Flow Accumulation with my Flow Direction as Inputfile.[ATTACH=CONFIG]16865[/ATTACH]
fourth, I calculated the Slope in Degrees by the Spatial Analyst tool Surface and Slope. [ATTACH=CONFIG]16866[/ATTACH]
fifthly, I used the Equation by Moore and Burch 1986: LS = (Flow Accumulation * Cell Size/22.13)^0.4 * (sin (slope/0.0896))^1.3
sixthly: I typed in the raster calculator the equation:

(Power((("FlowAcc" * 92.46745509) / 22.13),0.4)) * (Power((Sin("Slope_Degree" / 0.0896)),1.3))

But my result look very very strange! There a lot of white areas! The Raster is not like cover areas.... It looks like that every calculated value is seperated... It looks like a dotted map....What did I wrong??

[ATTACH=CONFIG]16867[/ATTACH]
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2 Replies
by Anonymous User
Not applicable
Original User: jbswain

Initially, based on your screenshots and reported entries. It seems as if the calculation is made with decimals as the decimal and your inputs are with comma as the decimal.  What regional settings are you using?  I would recommend changing either the syntax of the tool to match the regional settings or making the regional settings match the syntax.
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Munuvelu_vese
Emerging Contributor

you need to first convert your slope degree map to radian and then calculate sin slope

 

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