Spatio-temporal Dynamics of a Soil Moisture Field: Sampling Error Analysis with Simulation Study

Year 2009, Volume: 1 Issue: 2, 8 - 13, 15.06.2009

Gwangseob Kim

Abstract

In this study, effects of intermittent visit of observation satellite, partial coverage of remote sensing, heterogeneity of soil properties and precipitation on soil moisture estimations were investigated to develop a sampling strategy. In the soil moisture sampling error analysis, a modified form of theoretical soil moisture model proposed by [1], the WGR model proposed by [2] for use of generating rainfall and the Turning Bands Method for use of generating two dimensional random fields were employed. The evaluation of study results indicates that the sampling error is mainly dominated by sampling interval. The effect of heterogeneity of soil properties and rainfall on sampling error is considerably smaller than that of intermittent visit of observation satellite. The study results suggest that the sampling error generated by other factors such as heterogeneity of rainfall and soil properties, topography and climate conditions can be significantly reduced by increasing the sampling interval, for example, at least twice per day. The effect of partial coverage on sampling error can be ignored provided that the annual mean of coverage portion is higher than 90 %. The impact of water retention capacity of fields on the sampling error seems to be significant. More specifically, the smaller the water retention capacity of fields (i.e., a smaller soil porosity and a thinner active soil depth) the larger the sampling error.

Keywords

Soil moisture estimation, sampling error, remote sensing, the WGR model, the Turning Bands Method

References

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