Early Warning Indicators of Groundwater Drought in Mountainous Regions

Abstract

Aquifers in mountainous regions are susceptible to drought. However, the diverse hydroclimatology, the small and responsive aquifers, and the varied nature of interactions between groundwater and surface water lead to complex groundwater level responses that are challenging to interpret for understanding groundwater drought. In this study, generalized additive models (GAMs) are used to explore the sensitivity of summer groundwater levels to various climate and hydrological predictor variables (indicators) in each of a snowmelt‐ and rainfall‐dominated hydroclimatic regime in British Columbia, Canada. A sensitivity analysis explores individual seasonal predictor variables, station versus gridded climate data, teleconnection indices, and time series length. GAMs are then generated for different combinations of predictor variables to identify the best combination for each region. In the snowmelt‐dominated regime, maximum spring temperature, maximum snow water equivalent, and the winter Nino 3.4 index is the best combination of variables for predicting summer groundwater levels. In the rainfall‐dominated regime, maximum spring temperature, winter precipitation, and spring streamflow is the best combination. The unique combinations of predictor variables for each region can be used as early warning indicators for groundwater drought preparedness by water managers prior to the beginning of the summer. The Standardized Groundwater Level Index (SGI) is also effective at indicating which wells had pronounced responses to periods of drought in each region. However, the SGI differed among aquifers of similar type, suggesting other factors such as aquifer response mechanism and groundwater pumping may have an important influence on the SGI.

Groundwater Responses to Deluge and Drought in the Fraser Valley, Pacific Northwest

“…Coastal groundwater systems relying on snowpack melt for recharge and baseflow supply during summers face heightened risk (Islam et al, 2017;Mote et al, 2005), which is well documented in the mountainous regions of the PNW (Dierauer et al, 2018). Overall, mountainous aquifers are particularly sensitive to region-specific climate and hydrological variables (Gullacher et al, 2023).…”

Explaining the Mechanism of Multiscale Groundwater Drought Events: A New Perspective From Interpretable Deep Learning Model

“…The initial definition of groundwater drought by Bloomfield and Marchant (2013) was set as SGI <0. However, due to the complexity of groundwater aquifer response mechanisms and the influence of factors such as human activities, this threshold does not have a uniform standard (Gullacher et al, 2023;M. Guo et al, 2021).…”

“…The empirical method is typically suited for investigating large-scale regions, as the uncertainties associated with regional climate in smaller catchments and the complexities of the confluence process make empirical evaluation challenging. Consequently, methods that analyze time series of GWLs, such as water table fluctuation method (Bloomfield et al, 2015;Boumis et al, 2022) and wavelets analysis (Serravalle Reis Rodrigues et al, 2023), can identify underlying temporal patterns and correlations in the data, thereby assisting in the assessing and warning of groundwater drought events in specific (Gullacher et al, 2023). Another strategy for assessing groundwater drought involves analyzing different types of drought indicators to understand how they propagate to groundwater droughts.…”

“…Generally, droughts are classified into four categories, including meteorological drought, hydrological drought, agricultural drought, and socio‐economic drought (Y. Guo et al., 2020; Mishra & Singh, 2010; Shi et al., 2018; Zhou et al., 2021), while groundwater drought is a sub‐category of hydrological drought, which refers to a period of decreased groundwater level (GWL) or groundwater storage (GWS) leading to an inadequacy to meet water demand (Van Lanen & Peters, 2000; Van Loon, 2015). The definition of groundwater drought adopted in this study is when the GWL or GWS falls below a critical or threshold value over a specific time period (Chang & Teoh, 1995; Eltahir & Yeh, 1999; Gullacher et al., 2023). Like other hydrological aspects of drought, groundwater droughts are not a simple function of hydrometeorological drivers (Bloomfield et al., 2015).…”

Three Decades of Groundwater Drought Research: Evolution and Trends

“…In order to strengthen the resilience of groundwater to drought events, it is necessary to adopt responsible and sustainable management strategies that include monitoring and surveillance systems capable of identifying and tracking long-term patterns [15]. As these techniques are mostly expensive and require very advanced human and technological resources [16,17], the contribution of scientific research is crucial in developing cost-effective alternatives that can provide early warnings and proactive measures to prevent the depletion and overexploitation of this vital resource [18,19]. Throughout time, numerous innovative methods have been adopted to tackle this challenge on both local and international levels.…”