Comparison of different interpolation techniques for sub-basins located in Madrid.

Soil hydrophysical properties can be very spatially and temporally heterogeneous even in small areas. Due to this spatial and temporal variability, it is impossible to obtain real data for each point of interest. Therefore, the possibility to obtain the optimal estimated value, at any desired point, is decisive. The aim is to evaluate different methods to minimise the error made in this measurement.

Two basins were selected in the Autonomous Community of Madrid (Spain), where hydraulic conductivity data were taken at different points. All sampling point in both basins were georeferenced. For each basing different interpolation methods were tested. The methods used are Spline, Inverse Distance Weighted Interpolation (IDW), Kriging, and Thiessen Polygons. With the help of the Matlab program, the values for each method were obtained. Finally, the error is used for the analysis.

Differences among the obtained data by each method are expected to be found. In addition to the differences between the number of samples and the error, and the location in the basin of the samples.

In conclusion, it is hoped to find the most appropriate method for obtaining a value as close to reality as possible. Furthermore, it is expected to be able to use this methodology in other situations.

Acknowledgements: This research Project has been funded by the Comunidad de Madrid through the call Research Grants for Young Investigators from Universidad Politécnica de Madrid