The impact of different rainfall products on landscape modelling simulations

Christopher J Skinner,Nadav Peleg,Jim Freer,Niall Quinn,Peter Molnar,Tom J Coulthard

doi:10.1002/esp.4894

Christopher J Skinner, Nadav Peleg + Show 4 more

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https://doi.org/10.1002/esp.4894

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Abstract

AbstractRainfall products can contain significantly different spatiotemporal estimates, depending on their underlying data and final constructed resolution. Commonly used products, such as rain gauges, rain gauge networks, and weather radar, differ in their information content regarding intensities, spatial variability, and natural climatic variability, therefore producing different estimates. Landscape evolution models (LEMs) simulate the geomorphic changes in landscapes, and current models can simulate timeframes from event level to millions of years and some use rainfall inputs to drive them. However, the impact of different rainfall products on LEM outputs has never been considered. This study uses the STREAP rainfall generator, calibrated using commonly used rainfall observation products, to produce longer rainfall records than the observations to drive the CAESAR‐Lisflood LEM to examine how differences in rainfall products affect simulated landscapes. The results show that the simulation of changes to basin geomorphology is sensitive to the differences between rainfall products, with these differences expressed linearly in discharges but non‐linearly in sediment yields. Furthermore, when applied over a 1500‐year period, large differences in the simulated long profiles were observed, with the simulations producing greater sediment yields showing erosion extending further downstream. This suggests that the choice of rainfall product to drive LEMs has a large impact on the final simulated landscapes. The combination of rainfall generator model and LEMs represents a potentially powerful method for assessing the impacts of rainfall product differences on landscapes and their short‐ and long‐term evolution. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

Highlights

Landscape evolution models (LEMs; see review by Tucker and Hancock, 2010) are tools for understanding the role large-scale processes have in the long-term development of the Earth’s surface (103–106 years)
This study aims to test how the different spatiotemporal estimates associated with different rainfall observation techniques impact on simulations of changes to basin geomorphology as they cascade through to LEM outputs
Each product showed a small increase in volume in the conversion from rainfall to discharge that was caused by the setting of a low flow threshold in the CAESAR-Lisflood model

Summary

Introduction

Landscape evolution models (LEMs; see review by Tucker and Hancock, 2010) are tools for understanding the role large-scale processes have in the long-term development of the Earth’s surface (103–106 years). The increase in computational power available has allowed for increasing complexity and detail to be simulated (Coulthard et al, 2013), yet understanding output uncertainties and sensitivities of these models to differences between input data has received far less treatment (Coulthard and Skinner, 2016; Hancock et al, 2016; Skinner et al, 2017; Chandra et al, 2019) Rainfall, both spatially and temporally, is considered a major source of input uncertainty in hydrological modelling (Keijsers et al, 2011; McMillan et al, 2011, 2012; Peleg et al, 2017a). For each of the products, differences in the estimates, spatially and temporally, are expected (e.g. Ciach, 2003; Villarini et al, 2008; Villarini and Krajewski, 2010; Peleg et al, 2013)

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