TY - JOUR

T1 - Comparison of rainfall generators with regionalisation for the estimation of rainfall erosivity at ungauged sites

AU - Pidoto, Ross

AU - Bezak, Nejc

AU - Müller-Thomy, Hannes

AU - Shehu, Bora

AU - Callau-Beyer, Ana Claudia

AU - Zabret, Katarina

AU - Haberlandt, Uwe

N1 - Funding Information: Financial support. The results of the study are part of the bilateral research project between Slovenia and Germany “Stochastic rainfall models for rainfall erosivity evaluation” and research programme P2-0180 “Water Science and Technology, and Geotechnical Engineering: Tools and Methods for Process Analyses and Simulations, and Development of Technologies” (P2-0180) that is financed by the Slovenian Research Agency (ARRS). Hannes Müller-Thomy has been financially supported by the DFG e.V., Bonn, Germany, as a Research Fellowship (MU 4257/1-1). Additionally, part of the results were also obtained in the scope of the bilateral project between Slovenia and Germany “Validation of precipitation reanalysis products for rainfall-runoff modelling in Slovenia (PRE-PROMISE)”, funded by the German Federal Ministry of Education and Research (BMBF). Funding Information: This open-access publication was funded by Technische Universität Braunschweig. Funding Information: The results of the study are part of the bilateral research project between Slovenia and Germany "Stochastic rainfall models for rainfall erosivity evaluation" and research programme P2-0180 "Water Science and Technology, and Geotechnical Engineering: Tools and Methods for Process Analyses and Simulations, and Development of Technologies" (P2-0180) that is financed by the Slovenian Research Agency (ARRS). Hannes Müller-Thomy has been financially supported by the DFG e.V., Bonn, Germany, as a Research Fellowship (MU 4257/1- 1). Additionally, part of the results were also obtained in the scope of the bilateral project between Slovenia and Germany "Validation of precipitation reanalysis products for rainfall-runoff modelling in Slovenia (PRE-PROMISE)", funded by the German Federal Ministry of Education and Research (BMBF).Publisher Copyright: Copyright © 2022 Ross Pidoto et al.

PY - 2022/8/15

Y1 - 2022/8/15

N2 - Rainfall erosivity values are required for soil erosion prediction. To calculate the mean annual rainfall erosivity (R), long-term high-resolution observed rainfall data are required, which are often not available. To overcome the issue of limited data availability in space and time, four methods were employed and evaluated: direct regionalisation of R, regionalisation of 5 min rainfall, disaggregation of daily rainfall into 5 min time steps, and a regionalised stochastic rainfall model. The impact of station density is considered for each of the methods. The study is carried out using 159 recording and 150 non-recording (daily) rainfall stations in and around the federal state of Lower Saxony, Germany. In addition, the minimum record length necessary to adequately estimate R was investigated. Results show that the direct regionalisation of mean annual erosivity is best in terms of both relative bias and relative root mean square error (RMSE), followed by the regionalisation of the 5 min rainfall data, which yields better results than the rainfall generation models, namely an alternating renewal model (ARM) and a multiplicative cascade model. However, a key advantage of using regionalised rainfall models is the ability to generate time series that can be used for the estimation of the erosive event characteristics. This is not possible if regionalising only R. Using the stochastic ARM, it was assessed that more than 60 years of data are needed in most cases to reach a stable estimate of annual rainfall erosivity. Moreover, the temporal resolution of measuring devices was found to have a significant effect on R, with coarser temporal resolution leading to a higher relative bias.

AB - Rainfall erosivity values are required for soil erosion prediction. To calculate the mean annual rainfall erosivity (R), long-term high-resolution observed rainfall data are required, which are often not available. To overcome the issue of limited data availability in space and time, four methods were employed and evaluated: direct regionalisation of R, regionalisation of 5 min rainfall, disaggregation of daily rainfall into 5 min time steps, and a regionalised stochastic rainfall model. The impact of station density is considered for each of the methods. The study is carried out using 159 recording and 150 non-recording (daily) rainfall stations in and around the federal state of Lower Saxony, Germany. In addition, the minimum record length necessary to adequately estimate R was investigated. Results show that the direct regionalisation of mean annual erosivity is best in terms of both relative bias and relative root mean square error (RMSE), followed by the regionalisation of the 5 min rainfall data, which yields better results than the rainfall generation models, namely an alternating renewal model (ARM) and a multiplicative cascade model. However, a key advantage of using regionalised rainfall models is the ability to generate time series that can be used for the estimation of the erosive event characteristics. This is not possible if regionalising only R. Using the stochastic ARM, it was assessed that more than 60 years of data are needed in most cases to reach a stable estimate of annual rainfall erosivity. Moreover, the temporal resolution of measuring devices was found to have a significant effect on R, with coarser temporal resolution leading to a higher relative bias.

UR - http://www.scopus.com/inward/record.url?scp=85136829440&partnerID=8YFLogxK

U2 - 10.5194/esurf-10-851-2022

DO - 10.5194/esurf-10-851-2022

M3 - Article

AN - SCOPUS:85136829440

VL - 10

SP - 851

EP - 863

JO - Earth surface dynamics

JF - Earth surface dynamics

SN - 2196-6311

IS - 4

ER -