坡長(zhǎng)坡度因子的生成過程

坡長(zhǎng)坡度因子的生成過程如下:1、要估算坡長(zhǎng)因子，可以利用ARCGIS中的水文模塊提取流水累積量。流水累積量的計(jì)算，要先建立無洼地的DEM。(見水文分析過程)利用jx_srtm數(shù)據(jù)，先生產(chǎn)任意流向圖：flowdir，再尋找洼地：sink，并計(jì)算洼地流域貢獻(xiàn)范圍：sink_watersh。再計(jì)算每個(gè)洼地的最低高程和出水口高程：zonalmin，zonalmax，并可以求出洼地深度：sinkdep=zonalmax-zonalmin。填充洼地：fill_jx_srtm。并計(jì)算無洼地的dem的水流流向：flowdir_fill1。然后計(jì)算流水累積量：flowacc。2、根據(jù)坡長(zhǎng)因子公式(參考文獻(xiàn)：土壤侵蝕研究中的坡長(zhǎng)因子評(píng)價(jià)問題)：L=(入/22.13)m入二flowacc*cellsize其中：m=n/(1+n)，n=(sin9/O.O896)/(3.O*sin0.禺+0.56)這里的。用“jx_slope.img*3.1415926/180”替代依次得到圖：n、m、l_yinzi(1)根據(jù)rastercalculator中的公式，計(jì)算出n(Sin([jx_slope.img]*3.1415926/180)/0.0896)/(3.0*Pow(Sin([jx_slope.img]*3.145926/180),0.8)+0.56)(2)根據(jù)rastercalculator中的公式，計(jì)算出m瞬RasterCafcufatorLa)rens:flowaccflowdirjx_slope.imgsjinzi.irng*|7|B|3|=|=：>|And|_d勺-I1I2I3I<I<=IJirid°IIAboutBuildingExpressionsEvaluateArithmeticAbsIntCeilFloatRoorIsNullLDgarithmsExpLogExp2LngZExpWLogWTrigonometricPowersSqrtISqrRow(3)根據(jù)rastercalculator中的公式，計(jì)算出l_yinziPow([flowacc]*87.72085638/22.13,[m])對(duì)得到的l_yinzi(l_yinzi1.img)進(jìn)行去除異常值：利用ERDAS中的圖像增強(qiáng)工具，對(duì)異常值進(jìn)行平滑處理。

這里，我們選擇以下的運(yùn)算模板:因此，得至U圖：l_yinzi_convolution.img。GIS再利用建模工具，對(duì)l_yinzil.img和l_yinzi_convolution.img求值。（參考文獻(xiàn):支持下的土壤侵蝕量估算—以江西省泰和縣灌溪鄉(xiāng)為例）GIS(3回ISAvailableInputs:$n1_Uinzi1$n2_l_j(3回ISAvailableInputs:$n1_Uinzi1$n2_l_jIJinzi_convolution列匕丄I_l_JJJJ_dJJJ丄IzJ丄I丄IUl丄IFunctions:AnalysisCLUMP[<layer>,4)CLUMP[<layer>,B)CONVOLVE〔<raster>,<kernel>]CORRELATION(<covariaric&_m3tnw：CORRELATION(<raster>)匚CIRFIELATICIN(<raster>.IGNORE-COVARIANCE〔<raster>]TOVARIANILE〔<raster>.IGNORE<.\DELROWG[<dsctable>”<sievetableDIRECTLOOKUP〔<arg1>,<table>]FIPiFMMATRI,x,f1L>也FunctionDefinitrora:CONDIT(ONALCONDITIONAL{($n2_l_yinzi_convolution<OJ0,($n1_l_jinzi1>250AND$n2_l_yinzi_convolution>0]$n2_l_yinzi_convolution>0J$n1_l_yinzi1<250)$n1_l_yinzi1}DK：|Cle曰rCancelHelp得到圖：l_yinzi_model.img，為最后的L因子圖。3、根據(jù)坡度因子公式:S=10.8*sin°+0.033v5).(5<=0<10),(0>=10)16.8*sin0(5<=0<10),(0>=10)21.9*sin0-0.96利用建模工具，得到s_yinzi.img口回岡鬼|_2_|丄3_JJ丄口回岡鬼|_2_|丄3_JJ丄IzJ丄I丄IFunctions:ConditionalCONDITIONAL!(<test1>)<arg1>.(<test；EITHER<arg1>IF(<test>]OR<arg2>0INDEX[<test>]{<arg1>.<arg2>“<argjPICK(<number>){<arg1>,<arg2>”<an<五]i>_ESFuncfionDefinition:CONDITIONALCONDITIONAL{($n1_|K_slope<5J1O.EHSIN($r1_|H_SlopeH2H3.1415926】360)+0.03J$n1jK_slope>=5and$n1|xslope<10)16.0xSIN($n1jxslopeK2x3^1415926/360]-0.50,($n1jxslope>=10)21.9KSIN汪I云e]x2x3.1415926/360)-"b.96]~-OKClearICancelIHelp4、坡長(zhǎng)坡度因子LS=L*