Analysis of persistence in the flood timing and the role of catchment wetness on flood generation in a large river basin in India

Flood is a complex phenomenon that results from a combination of factors associated with land and atmospheric conditions. For instance, floods in a river basin are driven by the combined role of the meteorological, catchment, and river system characteristics (Andrés-Doménech et al., 2015;Bertola et al., 2019;Johnson et al., 2016). However, heavy precipitation is mainly associated with flood generation in Indian river basins (Ali et al., 2019). The projected rise in the water holding capacity of the atmosphere, as explained by the Clausius Clapeyron relationship in response to global warming, can result in increased extreme precipitation leading to floods (

Section: Resultsmentioning

confidence: 99%

Multiday Precipitation Is a Prominent Driver of Floods in Indian River Basins

Nanditha

Mishra

2022

“…For example, despite increases in extreme precipitation intensities across many parts of the world (Alexander et al, ; Donat et al, ; Westra et al, ), these increases have not necessarily translated to increases in annual flood maxima (Do et al, ) due to decreases in antecedent soil moisture (Sharma et al, ; Wasko et al, ; Wasko & Nathan, ). The seasonality of flood timing has been linked to soil moisture amount (Berghuijs et al, ; Black & Werritty, ; Collins, ; Ganguli et al, ; Parajka et al, ) and changes in snowmelt and associated changes in antecedent soil moisture (Parajka et al, ).…”

Section: Introductionmentioning

confidence: 99%

Changes in Antecedent Soil Moisture Modulate Flood Seasonality in a Changing Climate

Wasko

Peel

2020

102

Due to difficulties in identifying a climate change signal in flood magnitude, it has been suggested that shifts in flood timing, that is, the day of annual streamflow maxima, may be detectable. Here, we use high‐quality streamflow, largely free of snowmelt, from 221 catchments across Australia to investigate the influence of shifts in soil moisture and rainfall timing on annual streamflow maxima timing. In tropical areas we find that flood timing is strongly linked to the timing of both rainfall and soil moisture annual maxima. However, in southern Australia flood timing is more correlated with soil moisture maxima than rainfall maxima. The link between flood, soil moisture, and rainfall timing is confounded by event severity: For less extreme events flood timing is more likely to correspond to soil moisture timing, whereas rainfall timing becomes increasingly important as flood severity increases. Using circular regression to investigate nonstationarity, we find that flood timing is shifting to earlier in the year in the tropics and later in the year in the southwest of the continent, consistent with changes in mean and extreme rainfall and shifts in soil moisture timing due to tropical expansion. In southeast Australia, there is evidence that the mechanisms controlling flood seasonality are changing with a reversal of trends post Millennium Drought. Overall, changes in soil moisture timing, compared to changes in rainfall timing, are found to have a greater influence on changes in annual maxima streamflow flood timing.

“…Analysis of flood timing informs the understanding of flood generation mechanisms related to peak rainfalls (Black & Werritty, 1997;Koutroulis et al, 2010;Parajka et al, 2010), antecedent soil moisture conditions (Berghuijs et al, 2016(Berghuijs et al, , 2019Ganguli et al, 2019), and snowmelt (Burn, 1994;Matti et al, 2017;Vormoor et al, 2015). Flood timing is also used to identify climatically homogenous regions (Burn, 1997;Formetta et al, 2018;Hall & Blöschl, 2018;Ouarda et al, 2006) and detect shifts due to climate change (Burn, 1994;Matti et al, 2017;Zhang et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Trends in Global Flood and Streamflow Timing Based on Local Water Year

Wasko

Peel

2020

Analysis of flood and streamflow timing has recently gained prominence as a tool for attribution of climatic changes to flooding. Such studies generally apply circular statistics to the day of maximum flow in a calendar year and use nonparametric linear trend tests to investigate changes in flooding on a local or regional scale. Here we investigate both the center timing of streamflow and the day of maximum flow using a local water year. For each station, the start of the water year is defined as the month of lowest average monthly streamflow. This definition of water year prevents ambiguity in the direction of computed trends and enables flood and streamflow timing to be described by a normal distribution. Using the assumption of normality, we calculate the historical trend in both flood and streamflow timing using linear regression. While shifts in flood and streamflow timing are consistent with climate change and are shifting in a similar direction, shifts in the timing of the annual maxima flood are approximately three times that of streamflow timing. The results here have implications for water resources and environmental management where streamflow and flood timing are critical to planning. The applicability of the normal approximation to flood and streamflow timing will enable future analyses to use parametric statistics.