Improved interpolation of meteorological forcings for hydrologic applications in a Swiss Alpine region

• Published in: Journal of hydrology (Amsterdam) Vol. 401; no. 1; pp. 77 - 89
• Main Authors: Tobin, Cara, Nicotina, Ludovico, Parlange, Marc B., Berne, Alexis, Rinaldo, Andrea
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 20.04.2011; Elsevier
• Subjects: Anisotropy; Earth sciences; Earth, ocean, space; Elevation; Exact sciences and technology; Floods; Hydrological modeling; Hydrology; Hydrology. Hydrogeology; Interpolation; Kriging; Kriging with external drift; Mathematical models; Orographic effect; Partitioning; Rainfall; Rainfall and temperature interpolation; Time-varying lapse rates; Alps; Europe; Swiss Alps; Time-varying lapse rates; Kriging with external drift; Hydrological modeling; Orographic effect; Anisotropy; Rainfall and temperature interpolation; advection; floods; models; rainfall; terrains; kriging; anisotropy; variograms; accuracy; precipitation; interpolation; management; snow; discharge; prediction; temperature; errors; storms
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2011.02.010

► Generating reliable spatially distributed flood modeling inputs is this study’s goal. ► Anisotropic variograms agree with dominant wind and orographic patterns. ► KED with elevation drift (precip. and temp.) show the least error for 3 flood events. ► Variable lapse rates generated by KED enable improved snow/rainfall partitioning. ► Testing interpolated input fields in a hydrological model is essential. This paper presents a comparative study on the mapping of temperature and precipitation fields in complex Alpine terrain. Its relevance hinges on the major impact that inadequate interpolations of meteorological forcings bear on the accuracy of hydrologic predictions regardless of the specifics of the models, particularly during flood events. Three flood events measured in the Swiss Alps are analyzed in detail to determine the interpolation methods which best capture the distribution of intense, orographically-induced precipitation. The interpolation techniques comparatively examined include: Inverse Distance Weighting (IDW), Ordinary Kriging (OK), and Kriging with External Drift (KED). Geostatistical methods rely on a robust anisotropic variogram for the definition of the spatial rainfall structure. Results indicate that IDW tends to significantly underestimate rainfall volumes whereas OK and KED methods capture spatial patterns and rainfall volumes induced by storm advection. Using numerical weather forecasts and elevation data as covariates for precipitation, we provide evidence for KED to outperform the other methods. Most significantly, the use of elevation as auxiliary information in KED of temperatures demonstrates minimal errors in estimated instantaneous rainfall volumes and provides instantaneous lapse rates which better capture snow/rainfall partitioning. Incorporation of the temperature and precipitation input fields into a hydrological model used for operational management was found to provide vastly improved outputs with respect to measured discharge volumes and flood peaks, with notable implications for flood modeling.