A Quantitative Hydrological Climate Classification Evaluated With Independent Streamflow Data

Knoben, Wouter; Woods, Ross; Freer, J. E.

doi:10.1029/2018wr022913

Cited by 115 publications

(176 citation statements)

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“…For example, the distinct boundary between long/short rain and soil moisture floods in the Central–Southern United States (Figures and S5b) is well mirrored in the aridity distribution in that area (e.g. Knoben et al, ). Arid and semi‐arid regions rarely experience excess rainfall floods, and short rainfall and long rainfall are the prevalent generating processes there (Figure S5b).…”

Section: Discussionmentioning

confidence: 99%

“… Figure S5 Density distribution of available water capacity (AWC) against distribution of dominant flood generating process (a), point plot of moisture index against moisture seasonality for all catchments, colour indicating dominant flood generating process. The moisture index represents aridity (−1 indicating arid, 1 indicating wet conditions); the moisture seasonality represents seasonality of aridity (0 indicating constant, 2 indicating seasonal aridity) (Knoben, Woods, & Freer, ). Moisture index and moisture seasonality were calculated using monthly potential evaporation data from CRU TS v.4.03 (Harris et al, 2014).…”

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Event‐based classification for global study of river flood generating processes

Stein

Pianosi

Woods

2019

Hydrological Processes

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Better understanding of which processes generate floods in a catchment can improve flood frequency analysis and potentially climate change impacts assessment. However, current flood classification methods are either not transferable across locations or do not provide event‐based information. We therefore developed a location‐independent, event‐based flood classification methodology that is applicable in different climates and returns a classification of all flood events, including extreme ones. We use precipitation time series and very simply modelled soil moisture and snowmelt as inputs for a decision tree. A total of 113,635 events in 4155 catchments worldwide were classified into one of five hydro‐climatological flood generating processes: short rain, long rain, excess rainfall, snowmelt and a combination of rain and snow. The new classification was tested for its robustness and evaluated with available information; these two tests are often lacking in current flood classification approaches. According to the evaluation, the classification is mostly successful and indicates excess rainfall as the most common dominant process. However, the dominant process is not very informative in most catchments, as there is a high at‐site variability in flood generating processes. This is particularly relevant for the estimation of extreme floods which diverge from their usual flood generation pattern, especially in the United Kingdom, Northern France, Southeastern United States, and India.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Event‐based classification for global study of river flood generating processes

Stein

Pianosi

Woods

2019

Hydrological Processes

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112

116

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“…We calculated the AUC‐ROC for seven exiting metrics of climate seasonality to compare their ability to distinguish Mediterranean climates within the Köppen‐Geiger classification from other seasonally dry climates: (1) The current proposed asynchronicity index ( ASI ), (2) the centroid difference (in months) between the seasonal precipitation and PET pmfs (i.e., dCentroid ), and a series of seasonality indices proposed by (3) Walsh and Lawler () (i.e., WalshS ), (4) Milly () (i.e., MillyS ), (5) Woods () (i.e., dP* ), (6) Feng et al () (i.e., SI ), and (7) Knoben et al () (i.e., Imr ). Brief explanations of these metrics and their abbreviations are summarized in Table S1.…”

Section: Methodsmentioning

confidence: 99%

Quantifying Asynchronicity of Precipitation and Potential Evapotranspiration in Mediterranean Climates

Feng

Thompson

Woods

et al. 2019

Geophysical Research Letters

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Recent climate change has contributed to shifts in the seasonal interplay between precipitation and potential evapotranspiration, which have in turn increased droughts and reduced freshwater availability in Mediterranean climate regions. To overcome limitations in existing indices for comparing these seasonal hydroclimatic drivers at the global scale, we introduce an information theory-based, nonparametric asynchronicity index that captures both the temporal alignment and relative magnitudes of precipitation and potential evapotranspiration. We use this asynchronicity index to first identify Mediterranean climates around the world. We then apply the asynchronicity index over two Mediterranean climate regions and show that their boundaries have shifted between 1960 and 2018, resulting in a regional expansion in the U.S. Pacific Northwest and a contraction in southwestern Australia. These results highlight the need for globally consistent measures of seasonal climatic water supply and demand for diagnosing potential changes in water resources and ecosystem responses within Mediterranean climate regions. Plain Language Summary Climate change is likely to change the boundaries of what aretypically considered Mediterranean climate regions, which have dry summers and mild, wet winters. To analyze how these regions' water availability may be influenced by climate change, we introduce a metric for quantifying the mismatch in the timing and amount of precipitation relative to atmospheric water demand. This new metric is able to identify the boundaries of Mediterranean climate regions more effectively than other existing indices and can be used to analyze how these boundaries shift over time.

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“…Given this, a number of attempts have been made to apply standard climate classifications to the development of flow regime categorisations. However, as pointed out by Knoben, Woods, and Freer (), many climate classifications are bio‐climatic in origin and lack hydrologically relevant details essential for a meaningful categorisation of flow regimes. For example, Haines et al, (1988), in an attempt to construct a global classification of flow regimes noted although the Koppen‐Geiger climate classification was partially successful in predicting flow regimes with a matching of regime types with climate zone, there was a lack of specificity as any one flow regime could be found across a number of climate zones; 15 different global streamflow patterns were identified by Haines, Finlayson, and McMahon ().…”

Section: River Flow Regimesmentioning

confidence: 99%

“…To address the problem associated with applying standard climate classifications to flow regime categorisation, Knoben et al () developed a hydrologically informed climate classification using three dimensionless climate indices, namely, annual aridity, aridity seasonality, and precipitation as snow. Acknowledging that there may be varying degrees of membership of a catchment to a particular climate class and therefore flow regime, as noted by Sawicz, Wagener, Sivapalan, Troch, and Carrillo (), they identified 16 flow regimes from the analysis of the covariant behaviour of the three aforementioned climate indices for 1,103 catchments (Figure ).…”

Section: River Flow Regimesmentioning

confidence: 99%

Climate and rivers

McGregor

2019

River Research & Apps

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Over the last few decades as hydrologists have slowly raised their line of sight above the watershed boundary, it has become increasingly recognised that what happens in the atmosphere, as a major source of moisture for the terrestrial branch of the hydrological cycle, can strongly influence river dynamics at a range of spatial and temporal scales. Notwithstanding this, there is still a tendency for some in the river research community to restrict their gaze to the river channel or floodplain. However, Geoff Petts, the person to which this special issue is dedicated, understood well and widely encouraged a holistic view of river catchment processes. This included an acknowledgment of the role of climate, in its broadest sense, in shaping what happens within and without the river channel. The purpose of this paper therefore is to offer a broad overview of the role of some aspects of climate science in advancing knowledge in river research. Topics to be addressed include the role of climate in influencing river flow regimes, a consideration of the large‐scale climate mechanisms that drive hydrological variability within river basins at interannual to decadal timescales and atmospheric rivers and their link to surface hydrology. In reviewing these topics, a number of key knowledge gaps have emerged including attributing the causes of river flow regime changes to any one particular cause, the nonstationary and asymmetric forcing of river regimes by modes of climate variability and establishing links between atmospheric rivers, and terrestrial river channel processes, fluvial habitats, and ecological change.

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A Quantitative Hydrological Climate Classification Evaluated With Independent Streamflow Data

Abstract: Key points

Cited by 115 publications

References 54 publications

Event‐based classification for global study of river flood generating processes

Event‐based classification for global study of river flood generating processes

Quantifying Asynchronicity of Precipitation and Potential Evapotranspiration in Mediterranean Climates

Climate and rivers

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