苗栗縣土壤沖蝕指數之推估

Estimation of Soil Erodibility Index for Maioli County

林俐玲(Li-Ling Lin) ； 洪怡美(I-Mei Hung)

《中華水土保持學報》 31卷2期 (2000/06) Pp. 123-132

https://doi.org/10.29417/JCSWC.200006_31(2).0004

摘要

本研究選擇苗栗縣境內，苗栗區塊與紙湖區塊推估該區域之土壤沖蝕指數（K）：採用苗栗區塊221點和紙湖區塊172點之土壤實測質地資料，以幾何平均粒徑方法計算這些地點之土壤沖蝕指數，並分析此兩區塊土壤沖蝕指數之空間變異結構，結果顯示苗栗與紙湖兩區塊之最佳半變異曲線模式均爲球面模式，苗栗區塊半變異圖之截距（nugget）爲0.000048，趨近一定值之半變異數（sill）爲0.0000752，範圍（range）爲793m;紙湖區塊半變異圖之截距爲0.0000118，趨近一定值之半變異數爲0.0000198，範圍爲2176m。由兩區塊之最佳變異曲線模式，以區塊克利金法推估兩區塊未採樣點之土壤沖蝕指數，苗栗區塊增加346點之推估值，紙湖區塊增加500點之推估值。由已知點與推估點所得之區域土壤沖蝕指數，更能顯現K值在空間分佈上之變化趨勢。

關鍵字

土壤沖蝕指數 ； 半變異圖 ； 區塊克利金法

並列摘要

Maioli and Jyhu blocks in Maioli county were selected as sampling locations for this study. 221 points in Maioli block and 172 points in Jyhu block of soil texture were collected to calculate the soil crodibility index by using geometric mean diameter method. Spatial structure of soil erodibility in these two areas were analyzed. The semivariograms for soil erodibility index were found to be represented by the spherical model. The parameters estimated were as follows: For Maioli block, Nugget effect, Co=0.000048 Sill, C=0.0000752 Range, a=793m For Jyhu block, Nugget effect, Co=0.0000118 Sill, C =0.0000198 Range, a=2176m. Block Kriging technique was applied to interpolate the soil erodibility index for unsampling points. 346 more points ware estimated for Maioli block and 500 more points were estimated for Jyhu block. The distribution of the K values shows great details in spatial variability.

並列關鍵字

soil erodiblity index ； geostatistics ； semi-variograms ； block kriging