Rainfall intensity bursts and the erosion of soils: an analysis highlighting the need for high temporal resolution rainfall data for research under current and future climates

Dunkerley, David

doi:10.5194/esurf-7-345-2019

Cited by 43 publications

(29 citation statements)

References 91 publications

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“…Approximately 15 min, 1 h and 1.5 h were needed to initiate the stemflow of palms (Germer, 2010), pine trees and oak trees (Cayuela et al, 2018), respectively. In addition, an almost instantaneous start of stemflow was also observed as rain began for Quercus rubra (Durocher, 1990), Fagus grandifolia and Liriodendron tulipifera (Levia et al, 2010). Com-pared to the positive TLE dominating xerophytic shrubs, the TLE greatly varied with tree species.…”

Section: Stemflow Temporal Dynamicsmentioning

confidence: 95%

Temporally dependent effects of rainfall characteristics on inter- and intra-event branch-scale stemflow variability in two xerophytic shrubs

Yuan

Gao

et al. 2019

Hydrol. Earth Syst. Sci.

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Abstract. Stemflow is important for recharging root-zone soil moisture in arid regions. Previous studies have generally focused on stemflow volume, efficiency and influential factors but have failed to depict stemflow processes and quantify their relations with rainfall characteristics within events, particularly for xerophytic shrubs. Here, we measured the stemflow volume, intensity, funneling ratio and time lags to rain at two dominant shrub species (Caragana korshinskii and Salix psammophila) and rainfall characteristics during 54 events at the semiarid Liudaogou catchment of the Loess Plateau, China, during the 2014–2015 rainy seasons. The funneling ratio was calculated as the ratio between stemflow and rainfall intensities at the inter- and intra-event scales. Our results indicated that the stemflow of C. korshinskii and S. psammophila, on average, started at 66.2 and 54.8 min, maximized 109.4 and 120.5 min after rain began, and ended 20.0 and 13.5 min after rain ceased. The two shrubs had shorter stemflow duration (3.8 and 3.4 h) and significantly larger stemflow intensities (517.5 and 367.3 mm h−1) than those of rain (4.7 h and 4.5 mm h−1). As branch size increased, both species shared the decreasing funneling ratios (97.7–163.7 and 44.2–212.0) and stemflow intensities (333.8–716.2 and 197.2–738.7 mm h−1). Tested by the multiple correspondence analysis and stepwise regression, rainfall amount and duration controlled stemflow volume and duration, respectively, at the event scale by linear relations (p < 0.01). Rainfall intensity and raindrop momentum controlled stemflow intensity and time lags to rain for both species within the event by linear or power relationships (p < 0.01). Rainfall intensity was the key factor affecting stemflow process of C. korshinskii, whereas raindrop momentum had the greatest influence on stemflow process of S. psammophila. Therefore, rainfall characteristics had temporally dependent influences on corresponding stemflow variables, and the influence also depended on specific species.

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Section: Stemflow Temporal Dynamicsmentioning

confidence: 95%

Temporally dependent effects of rainfall characteristics on inter- and intra-event branch-scale stemflow variability in two xerophytic shrubs

Yuan

Gao

et al. 2019

Hydrol. Earth Syst. Sci.

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“…Subhourly precipitation, however, can play a crucial role in incidents of flashflooding. Hydrological models also benefit greatly from high spatiotemporal resolution input [19] for stress testing of hydraulic infrastructure, processorientated case studies [20] and future climate-change 'storylines' [21]. While there have been tentative studies looking at future changes in extreme subhourly precipitation [22,23], without evaluation of CPM subhourly precipitation for the present climate we cannot have confidence in the future projections.…”

Section: Introductionmentioning

confidence: 99%

“…It could be, for example, that events of subhourly duration are too weak and too long-lasting in models, or too intense and too short-lived, giving accurate hourly totals for the wrong reasons and misrepresenting subhourly totals. The same amount of precipitation spread over different time periods will affect many land surface processes [19], such as the amount of precipitation absorbed by the soil, converted to runoff, and re-evaporated by the atmosphere, all of which are important considerations in hydrological modelling and climate modelling in general. Future changes in the intermittency of rainfall may be masked at hourly timescales, leading to flawed estimates of changes in precipitation intensities and their impacts [24].…”

Section: Introductionmentioning

confidence: 99%

Subhourly rainfall in a convection-permitting model

Meredith

Ulbrich

Rust

2020

Environ. Res. Lett.

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Convection-permitting models (CPMs)-the newest generation of high-resolution climate modelshave been shown to greatly improve the representation of subdaily and hourly precipitation, in particular for extreme rainfall. Intense precipitation events, however, often occur on subhourly timescales. The distribution of subhourly precipitation, extreme or otherwise, during a rain event can furthermore have important knock-on effects on hydrological processes. Little is known about how well CPMs represent precipitation at the subhourly timescale, compared to the hourly. Here we perform multi-decadal CPM simulations centred over Catalonia and, comparing with a high temporal-resolution gauge network, find that the CPM simulates subhourly precipitation at least as well as hourly precipitation is simulated. While the CPM inherits a dry bias found in its parent model, across a range of diagnostics and aggregation times (5, 15, 30 and 60 min) we find no consistent evidence that the CPM precipitation bias worsens with shortening temporal aggregation. We furthermore show that the CPM excels in its representation of subhourly extremes, extending previous findings at the hourly timescale. Our findings support the use of CPMs for modelling subhourly rainfall and add confidence to CPM-based climate projections of future changes in subhourly precipitation, particularly for extremes.

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“…Many studies of landsurface hydrologic and geomorphic processes have highlighted the effects of short-lived but intense periods of rain [1]. These intense periods commonly occur within longer rainfall events in which the intensity is generally lower.…”

Section: Introductionmentioning

confidence: 99%

How Is the Intensity of Rainfall Events Best Characterised? A Brief Critical Review and Proposed New Rainfall Intensity Index for Application in the Study of Landsurface Processes

Dunkerley

2020

Water

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In many studies of landsurface processes, the intensity of rainfall events is expressed with clock-period indexes such as I30, the wettest 30-minute interval within a rainfall event. Problematically, the value of I30 cannot be estimated for rainfall events shorter than 30 min, excluding many intense convective storms. Further, it represents a diminishing proportion of increasingly long rainfall events, declining to <2% of the duration of a 30-hour event but representing 25% of the duration of a two-hour event. Here, a new index termed EDf5 is proposed: It is the rainfall depth in the wettest 5% of the event duration. This can be derived for events of any duration. Exploratory determinations of EDf5 are presented for two Australian locations with contrasting rainfall climatologies—one arid and one wet tropical. The I30 index was similar at both sites (7.7 and 7.9 mm h−1) and was unable to differentiate between them. In contrast, EDf5 at the arid site was 7.4 mm h−1, whilst at the wet tropical site, it was 3.8 mm h−1. Thus, the EDf5 index indicated a greater concentration of rain at the arid site where convective storms occurred (i.e., the intensity sustained for 5% of event duration at that site is higher). The EDf5 index can be applied to short, intense events that can readily be included in the analysis of event-based rainfall intensity. I30 therefore appears to offer less discriminatory power and consequently may be of less value in the investigation of rainfall characteristics that drive many important landsurface processes.

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Rainfall intensity bursts and the erosion of soils: an analysis highlighting the need for high temporal resolution rainfall data for research under current and future climates

Cited by 43 publications

References 91 publications

Temporally dependent effects of rainfall characteristics on inter- and intra-event branch-scale stemflow variability in two xerophytic shrubs

Temporally dependent effects of rainfall characteristics on inter- and intra-event branch-scale stemflow variability in two xerophytic shrubs

Subhourly rainfall in a convection-permitting model

How Is the Intensity of Rainfall Events Best Characterised? A Brief Critical Review and Proposed New Rainfall Intensity Index for Application in the Study of Landsurface Processes

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