西南丘陵地区土壤有机质含量的空间插值法研究

Research of the Interpolation Methods for Determining Soil Organic Matter Content in the Hilly Regions of Southwestern China

通过对重庆市梁平县仁贤镇105个土壤采样点的有机质含量与海拔高度的关系进行分析,提出了结合海拔高度对逆距离权重法和克里格插值法改进的插值方法,并用改进前后的方法对研究区土壤有机质含量进行插值获取土壤有机质含量的空间分布图,进行交叉检验.结果表明,结合海拔高度改进的插值方法插值结果精度有比较明显的提高.对逆距离权重法,考虑海拔高度的平均绝对误差(MAE)从0.081 9%降到了0.000 8%,均方根误差(RMSE)从0.103 4%降到了0.001 4%;对克里格插值法,考虑海拔高度的平均绝对误差(MAE)从0.076 4%降到了0.003 1%,均方根误差(RMSE)从0.098 6%降到了0.003 9%.在4种插值法中结合海拔高度的逆距离权重法最优.

Renxjan town of Liangping county in Chongqing was taken as the research target area and the relationship between organic matter and altitude was analyzed. Combined with altitude, inverse distance weighting and Kriging interpolation were modified. Organic matter data from 105 soil samples were inter- polated with inverse distance weighting （IDW） and ordinary Kriging（OK）, and then the modified methods were used for a repeated calculation. Cross-validation was applied to evaluate the four methods, using mean absolute error （MAE） and root mean squared error （RMSE）. The results showed that better simulation would be achieved when altitude was taken into consideration. MAE by IDW decreased from 0.0819% to 0.0008% and RMSE decreased from 0.1034% to 0.0014% for OK, MAE decreased from 0. 0764% to 0.0031%, consideration gave RMSE decreased from 0.0986% to 0.0039%. The IDW with altitude being taken into the most precise evaluation.