Abstract

This study focuses on the impacts of climate change on rainfall erosivity in the Huai Luang watershed, Thailand. The multivariate climate models (IPCC AR5) consisting of CCSM4, CSIRO-MK3.6.0 and MRI-CGCM3 under RCP4.5 and RCP8.5 emission scenarios are analyzed. The Quantile mapping method is used as a downscaling technique to generate future precipitation scenarios which enable the estimation of future rainfall erosivity under possible changes in climatic conditions. The relationship between monthly precipitation and rainfall erosivity is used to estimate monthly rainfall erosivity under future climate scenarios. The assessment compared values of rainfall erosivity during 1982–2005 with future timescales (i.e., the 2030s, 2050s, 2070s and 2090s). The results indicate that the average of each General Circulation Model (GCM) combination shows a rise in the average annual rainfall erosivity for all four future time scales, as compared to the baseline of 8302 MJ mm ha−1 h−1 year−1, by 12% in 2030s, 24% in 2050s, 43% in 2070s and 41% in 2090s. The magnitude of change varies, depending on the GCMs (CCSM4, CSIRO-MK3.6.0, and MRI-CGCM3) and RCPs with the largest change being 82.6% (15,159 MJ mm ha−1 h−1 year−1) occurring under the MRI-CGCM3 RCP8.5 scenario in 2090s. A decrease in rainfall erosivity has been found, in comparison to the baseline by 2.3% (8114 MJ mm ha−1 h−1 year−1) for the CCSM4 RCP4.5 scenario in 2030s and 2.6% (8088 MJ mm ha−1 h−1 year−1) for the 2050s period. However, this could be considered uncertain for future rainfall erosivity estimation due to different GCMs. The results of this study are expected to help development planners and decision makers while planning and implementing suitable soil erosion and deposition control plans to adapt climate change in the Huai Luang watershed.

Highlights

  • Rainfall erosivity (R factor) represents a measure of the erosive force of rain or its potential to cause soil erosion

  • The use of multiple General Circulation Model (GCM) to estimate future rainfall erosivity helps to address the uncertainties inherent in global climate modeling as they provide a range of reasonable future climatic conditions

  • Under RCP4.5 and RCP8.5 scenarios to predict average monthly and average annual rainfall erosivity in the Huai Luang watershed located in the Northeastern Thailand

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Summary

Introduction

Rainfall erosivity (R factor) represents a measure of the erosive force of rain or its potential to cause soil erosion. The R factor quantifies the impact of rainfall and reflects the amount and rate of runoff that can be associated with soil erosion. The rainfall erosivity for a given storm as per USLE [2] or its revised version, RUSLE [1] is equal to the product of the total storm energy (E) and the maximum 30-min rainfall intensity (I30 ). The use of EI30 alone is not sufficient to describe the relative rainfall erosivity [3]. It requires continuously recorded rainfall data which is not commonly available in remote areas. An index based on kinetic and momentum of run-off can be used to estimate the monthly or annual values of rainfall erosivity with accurate record

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