Annually Resolved Monsoon Onset and Withdrawal Dates Across the Himalayas Derived From Local Precipitation Statistics

Brunello, Camilla Francesca; Andermann, Christoff; Marc, Odin; Schneider, Kirsten; Comiti, Francesco; Achleitner, Stefan; Hovius, Niels

doi:10.1029/2020gl088420

Cited by 13 publications

(15 citation statements)

References 41 publications

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“…Recent work by Brunello et al. (2020) highlighted increasing pre‐monsoon precipitation totals over the last ∼70 years. In conjunction with our findings, a longer and wetter pre‐monsoon season would impact directly on the saturation of the vadose zone, the recharge of groundwater and river discharge, increasing the availability of water for hydropower and irrigation purposes.…”

Section: Discussionmentioning

confidence: 99%

Subsurface Moisture Regulates Himalayan Groundwater Storage and Discharge

et al. 2021

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The fate of water in mountains involves flow pathways through reservoirs with different physical properties and capacities (Alley et al., 2002;Oki & Kanae, 2006). Accurate water budget estimation requires knowledge of these reservoirs and their connections, specifically of groundwater storage dynamics in response to precipitation inputs and its export to discharge. Most water in rivers has an age of years to decades (Gleeson et al., 2016;McGuire & McDonnell, 2006), which suggests that it has spent a significant amount of time in storage. This "old" water concept is especially relevant in steep mountain catchments, where deeper vertical infiltration seems more prevalent than direct runoff (Jasechko et al., 2016). It is widely accepted that these mountain areas act as water towers that supply essential fresh water resources downstream. The prime example is the Himalayan Range, which provides water for ∼800 million people in the Indus, Ganges,

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Section: Discussionmentioning

confidence: 99%

Subsurface Moisture Regulates Himalayan Groundwater Storage and Discharge

et al. 2021

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“…The region experienced strong ground shaking (Wei et al, 2018), widespread landsliding (Roback et al, 2018) and numerous aftershocks (Adhikari et al, 2015). Due to a distinct wet and dry season in which ∼ 80% of the annual precipitation occurs during the Indian Summer Monsoon between ∼ May and ∼ October (Bookhagen & Burbank, 2010;Brunello et al, 2020), the hydrological conditions at this site are highly variable. This combination of pronounced and well-constrained hydrological and seismic forcing makes our field site a suitable location to study the interplay of seismic damage and hydrology.…”

Section: Introductionmentioning

confidence: 99%

Seismic velocity recovery in the subsurface: transient damage and groundwater drainage following the 2015 Gorkha earthquake, Nepal

Illien¹,

Sens‐Schönfelder²,

Andermann³

et al. 2022

Preprint

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Shallow earthquakes frequently disturb the hydrological and mechanical state of the subsurface, with consequences for hazard and water management. Transient post-seismic hydrological behaviour has been widely reported, suggesting that the recovery of material properties (relaxation) following ground shaking may impact groundwater fluctuations. However, the monitoring of seismic velocity variations associated with earthquake damage and hydrological variations are often done assuming that both effects are independent. In a field site prone to highly variable hydrological conditions, we disentangle the different forcing of the relative seismic velocity variations $\delta v$ retrieved from a small dense seismic array in Nepal in the aftermath of the 2015 Mw 7.8 Gorkha earthquake. We successfully model transient damage effects by introducing a universal relaxation function that contains a unique maximum relaxation timescale for the main shock and the aftershocks, independent of the ground shaking levels. Next, we remove the modeled velocity from the raw data and test whether the corresponding residuals agree with a background hydrological behaviour we inferred from a previously calibrated groundwater model. The fitting of the $\delta v$ data with this model is improved when we introduce transient hydrological properties in the phase immediately following the main shock. This transient behaviour, interpreted as an enhanced permeability in the shallow subsurface, lasts for $\sim$ 6 months and is shorter than the damage relaxation ($\sim$ 1 year). Thus, we demonstrate the capability of seismic interferometry to deconvolve transient hydrological properties after earthquakes from non-linear mechanical recovery.

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“…Our results also highlight the significant contribution of nonmonsoonal precipitation across higher elevations. We further provide insights into the mechanisms of nonmonsoonal precipitation, the understanding of which is crucial for accurate glacier mass assessment and complete water management in the WH (Kripalani et al ., 2003; Kapnick et al ., 2014; Brunello et al ., 2020).…”

Section: Discussionmentioning

confidence: 99%

Dynamical and thermodynamical interactions in daily precipitation regimes in the Western Himalayas

Battula

Siems

Mondal

2022

Intl Journal of Climatology

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The mechanisms by which moisture interacts with the Himalayas largely determine the amount of precipitation in Himalayan basins. While many recent studies have focused on mechanisms of independent precipitation events, climatological studies that are essential for a complete understanding of precipitation-generating mechanisms are limited. This work presents synoptic regimes, which produced precipitation across all seasons in the Western Himalayas (WH) from 2000 to 2018. Using the k-means clustering algorithm, seven clusters are employed to define relatively mild, moderate and wet regimes, showing distinct seasonality and a synoptic meteorology. We found positive precipitation anomalies at lower elevations in monsoonal regimes (M1, M2 and M3) but at higher elevations in winter (W1 and W2) and transitional regimes (T1 and T2). Moist monsoonal regimes are associated with dynamical interactions between low-level tropical cyclonic circulations and mid-level subtropical troughs. Synchronous primary and secondary cyclonic circulations facilitate tropical moisture influx and obstruct the further northward movement of cyclonic circulations, which results in large magnitudes of precipitation at lower elevations in monsoonal regimes. On the other hand, winter regimes exhibit intense western disturbances, which enable orographic ascent of tropical moisture towards higher elevations. Despite weaker dynamical interactions, a stronger thermodynamical instability and a steeper terrain gradient trigger deep convection at higher elevations in transitional regimes.Overall, monsoonal regimes account for 52% of rainy days, whereas winter and transitional regimes account for 20 and 28%, respectively. We present a methodology that identifies hotspots of anomalous precipitation over vulnerable higher elevations by tracking atmospheric variables in Delhi. Our results illustrate the dynamical and thermodynamical interactions responsible for precipitation and highlight the significant contribution from nonmonsoonal regimes to the precipitation across higher elevations in the WH.

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Annually Resolved Monsoon Onset and Withdrawal Dates Across the Himalayas Derived From Local Precipitation Statistics

Cited by 13 publications

References 41 publications

Subsurface Moisture Regulates Himalayan Groundwater Storage and Discharge

Subsurface Moisture Regulates Himalayan Groundwater Storage and Discharge

Seismic velocity recovery in the subsurface: transient damage and groundwater drainage following the 2015 Gorkha earthquake, Nepal

Dynamical and thermodynamical interactions in daily precipitation regimes in the Western Himalayas

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