How is overland flow produced under intermittent rain? An analysis using plot-scale rainfall simulation on dryland soils

Dunkerley, David

doi:10.1016/j.jhydrol.2017.11.003

Cited by 33 publications

(16 citation statements)

References 70 publications

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“…Other examples of the importance of short‐term intensity variation were presented by Dunkerley (; ; ). The intermittency of rain at sub‐hourly timescales is important for water partitioning at the ground surface (Dunkerley, ), partly because it influences the formation and dissipation of the surface ponding from which much infiltration takes place. However, despite its importance, intermittency at sub‐hourly timescales has rarely been included in rainfall climatologies.…”

Section: Introductionmentioning

confidence: 99%

How does sub‐hourly rainfall intermittency bias the climatology of hourly and daily rainfalls? Examples from arid and wet tropical Australia

Dunkerley

2018

Intl Journal of Climatology

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Statistical rainfall climatologies for application to problems in ecohydrology or urban flood hydrology employ indices such the average rainfall depth per rain day or rain hour, and the average daily or hourly rainfall intensity. These subsume finetemporal-scale aspects of rainfall arrival such as sub-hourly intermittency that vary among locations with different climatic conditions. Rainfall duration and intensity derived from data aggregated to hourly or daily level thus involve some bias, generally overestimating the duration of rainfall and underestimating rainfall rates, and this bias will vary with location. The magnitude of bias is documented for two Australian locations having rainfall records of high temporal resolution: one arid and one wet tropical. Rainfall data aggregated to hourly or daily level yield substantial overestimates of time raining, and underestimates of rainfall rates. The magnitude of bias is shown to differ between the two field locations where on average rain is only recorded during 3.6 hr (14.9%) of a rain day at the arid location, but 8.2 hr (34%) at the wet tropical site. Resulting bias in estimates of time raining and of rainfall intensities is worse at the arid location. The significance of intermittency in particular for the detection of the effects of climate change on temporal rainfall climatology is explored. If intermittency varies with climate change, but is concealed through the use temporally aggregated rainfall data, erroneous assessments of changes in rainfall intensities may result. The use of rainfall events rather than clock-period data appears to reduce some of these effects, but there is still a failure to reflect shortperiod, high-intensity rainfall that may be important to soil erosion and the loss of carbon, nutrients, and agrochemicals from agricultural land.

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Section: Introductionmentioning

confidence: 99%

How does sub‐hourly rainfall intermittency bias the climatology of hourly and daily rainfalls? Examples from arid and wet tropical Australia

Dunkerley

2018

Intl Journal of Climatology

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“…Therefore, the magnitude of rainfall events, which may trigger colonization processes in natural systems, may determine the resulting pattern to the same extent—or even more—than annual rainfall. Semiarid regions do not exhibit constant, steady precipitation but rather a highly pulsed and intermittent rainfall regime (Modarres & de Paulo Rodrigues da Silva, ; Dunkerley, ; Pilgrim, Chapman, & Doran, ). This work points out that each of those pulsed events may act as a new initial condition, which triggers a new transient process whose final steady state may be determined by the magnitude of the event together with yearly rainfall, as suggested by Ratajczak et al () and Schwinning and Sala ().…”

Section: Discussionmentioning

confidence: 99%

From nonequilibrium initial conditions to steady dryland vegetation patterns: How trajectories matter

Caviedes‐Voullième

Hinz

2020

Ecohydrology

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The multiscale nature of ecohydrological processes and feedbacks implies that vegetation patterns arising in water‐limited systems are directly linked to water redistribution processes occurring at much shorter timescales than vegetation growth. This in turn suggests that the initially available water in the system can play a role in determining the trajectory of the system, together with the well‐known role of the rainfall gradient. This work explores the role of initial hydrological conditions on vegetation dynamics and vegetation patterns. To do so, the HilleRisLambers–Rietkerk model was solved with different rainfall amounts and a large range of initial hydrological conditions spanning from near‐equilibrium to far‐from‐equilibrium conditions. The resulting vegetation patterns and ecohydrological signatures were quantitatively studied. The results show that not only do initial hydrological conditions play a role in the ecohydrological dynamics but also they can play a dominating one even resulting in divergent vegetation patterns that exhibit convergent mean‐field properties, including a new set of hybrid patterns. Our results highlight the relevance of assessing both global ecological and hydrological signatures and quantitatively assessing patterns to describe and understand system dynamics and in particular to determine if the systems are transient or steady. Furthermore, our analysis shows that the trajectories the system follows during its transient stages cannot be neglected to understand complex dependencies of the long‐term steady state to environmental factors and drivers.

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“…However, the necessary simplicity of the accounting tool excludes most catchment variables; the HND relationship must be based on drivers that can be applied in statewide factors. Simple rainfall-runoff modeling in small catchments typically employs lumped precipitation; recent research has established the importance of storm intensity [23]. This type of runoff method, such as the NRCS curve number, was not sufficient for the infiltration factors due to the importance of modeling the effects of event intensity [24,25].…”

Section: Model Selectionmentioning

confidence: 99%

A Rainwater Harvesting Accounting Tool for Water Supply Availability in Colorado

Gilliom

Bell

Hogue

et al. 2019

Water

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Rainwater harvesting (RWH) is a renewable water supply option for nonpotable use, most commonly used for landscaping irrigation. Water rights in Colorado prohibit all RWH except residential rain barrels and a pilot project program that allows centralized rainwater harvesting for new development. Development of a natural catchment creates impervious surfaces, thereby increasing runoff, with a subsequent decrease in infiltration and losses to evapotranspiration; pilot projects are allowed to harvest a volume equal to the predevelopment runoff losses that would have occurred on new impervious areas at the site. To support this administrative policy, a tool was developed for the efficient calculation of daily allowable harvest at nearly any project site in Colorado. A reliable and useful policy tool requires the incorporation of hydrologic science with widely applicable, user-friendly design, a challenging balance of rigor and accessibility that is welcomed by engineers and policymakers alike. The daily allowable harvest is determined for each soil group as a percentage of infiltrated rainfall less the groundwater return. Horton's infiltration method is used to model rainfall-runoff for a range of soil parameters (NRCS hydrologic soil groups) and precipitation events (0.25-to 25-year return periods and 15-min to 24-h durations). For most events, the percent infiltration is 90% of the precipitation depth; this ratio decreases when precipitation exceeds the infiltration rate. Results are simplified in a spreadsheet tool for policy application, with allowable harvest rules binned by event duration and frequency. Simulations using the tool for a 2010-2017 precipitation record from Colorado's Front Range showed that RWH can supply up to 50% of the annual demand for traditional landscaping and over 100% of the water-smart landscaping demand.

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How is overland flow produced under intermittent rain? An analysis using plot-scale rainfall simulation on dryland soils

Cited by 33 publications

References 70 publications

How does sub‐hourly rainfall intermittency bias the climatology of hourly and daily rainfalls? Examples from arid and wet tropical Australia

How does sub‐hourly rainfall intermittency bias the climatology of hourly and daily rainfalls? Examples from arid and wet tropical Australia

From nonequilibrium initial conditions to steady dryland vegetation patterns: How trajectories matter

A Rainwater Harvesting Accounting Tool for Water Supply Availability in Colorado

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