Interactions Between Multiple Drought Types Across Temporal Scales

Drought is a climatic phenomenon that has increased in severity over time. This study analyzed drought spread in the Alto Patía basin (13,047 km2) in South America, applying the Standardized Precipitation Index (SPI), Vegetation Health Index (VHI), and Streamflow Drought Index (SDI) to assess meteorological, agricultural, and hydrological drought, respectively. Synchronous and asynchronous correlations were estimated, and Wavelet analysis was conducted to verify relationships among drought types. Results show that the lag between drought types varies based on the intensity, temporal continuity, and spatial extent of meteorological drought. A lag of zero months (1–2 months) was observed between meteorological and hydrological drought when moderate (severe) meteorological drought partially (fully) covers the basin. Agricultural drought, however, does not always correspond to meteorological drought during isolated rainfall events. As the first study in Colombia to systematically connect these drought types, this research addresses a gap in understanding how drought impacts progress across systems in regions with complex rainfall patterns. These findings offer critical insights into the interdependencies among drought types, supporting enhanced drought monitoring and early warning systems in similar climatic regions. By identifying specific lags between meteorological and hydrological droughts, this study provides practical guidance for land management, water conservation, and crop planning, offering a foundation for future research on drought resilience strategies.

Drought events occur more frequently under recent climate change. Generally, meteorological drought is the fuse of hydrological drought; thus, it is important to understand the characteristics of meteorological drought and its propagation to hydrological drought for early warning. Taking the Pearl River Basin (PRB) in China as study area, this study adopted K‐means cluster analysis method to divide the PRB into subregions with similar precipitation characteristics. Then, standardized precipitation index and standardized runoff index were used to analyze the characteristics of meteorological drought and hydrological drought, respectively, and the maximum Pearson correlation coefficient was used to determine the drought propagation time (DPT) between these two types of drought. Moreover, the link between meteorological drought and hydrological drought was explored based on continuous wavelet transform and cross wavelet transform. The results revealed that: the PRB has experienced severe meteorological and hydrological droughts since early 2000s, and hydrological drought was more serious than meteorological drought in each of the five subregions in the PRB. The DPTs from meteorological drought to hydrological drought were mainly 2–6 months, and the periodic characteristics of meteorological drought were mainly responsible for those of hydrological drought. Precipitation and runoff could greatly affect the DPT, while the impacts of evapotranspiration and shallow soil moisture on the DPT were not significant. Furthermore, El‐Niño Southern Oscillation and Pacific Decadal Oscillation are important factors that affect the DPT from meteorological to hydrological drought in the PRB.

Groundwater is a vital resource for socio-economic sustainability ye is increasingly threatened by climate change and rising anthropogenic pressures. Lebanon, and particularly the Al Assi River Basin (ARB), experiences recurrent droughts, but limited meteorological and groundwater observations hinder effective water resources monitoring and management. This study employs satellite-derived datasets to investigate the relationship between hydrological and hydrogeological drought indicators across Lebanon, with emphasis on the ARB. The Standardized Precipitation Index (SPI) and the Standardized Precipitation and Evapotranspiration Index (SPEI) were computed from CHIRPS precipitation and CHIRTS-ERA5 temperature data at multiple accumulation periods. Groundwater drought was quantified using the Groundwater Drought Index (GGDI), derived from GRACE terrestrial water storage anomalies. SPI, SPEI, and GGDI were harmonized at a 10 km resolution, and correlation analyses, including lagged correlations, were conducted to examine their temporal relationship. Results show that SPEI at 18-month accumulation exhibits the highest correlation with GGDI (R ≈ 0.70) at zero lag, reflecting the response of the multi-layered ARB aquifer system. Future SPEI projections were derived using bias-corrected outputs from the CNRM-ALADIN53 regional climate model under RCP 4.5 and RCP 8.5 scenarios. Using the regression model resulting from the strongest correlation, future GGDI projections were generated, highlighting a progressive increase in drought-affected areas, with the most severe groundwater deficits expected under RCP 8.5 by the late 21st century. These findings underscore the need for integrated water-resource management that combines climate-informed planning, satellite-based monitoring, and strengthened in-situ hydrogeological networks to improve resilience to future climatic extremes in data-scarce regions. This study assesses how meteorological drought propagates into groundwater systems under climate change in data-scarce Mediterranean regions, with a specific focus on Lebanon and the Al Assi River Basin. The analysis integrates satellite-derived precipitation (CHIRPS), temperature (CHIRTS-ERA5), and GRACE-based terrestrial water storage anomalies to overcome the absence of in-situ hydrometeorological and groundwater records. Meteorological drought indices (SPI and SPEI) were computed at multiple accumulation periods, while the GRACE-derived Groundwater Drought Index (GGDI) was used to characterize hydrogeological drought conditions. Correlation analyses were conducted to identify the most robust proxy for groundwater drought, revealing that SPEI-18 displays the strongest spatial and temporal correspondence with GGDI, reaching up to 97% high-correlation coverage in the ARB at zero lag. Bias-corrected climate projections from the CNRM-ALADIN53 regional model (RCP 4.5 and RCP 8.5) were used to generate future SPEI-18 and GGDI scenarios for three-time horizons (2030–2050, 2060–2080, 2080–2100). Results show a progressive intensification of both meteorological and groundwater drought throughout the 21st century, with the most severe declines projected under RCP 8.5. Drought-affected areas expand substantially, while groundwater drought classes shift toward higher frequency and severity. The findings underscore that satellite-based indicators offer a reliable framework for monitoring groundwater stress where observational networks are limited. Moreover, the study highlights the urgent need for integrated, climate-responsive water-resource management strategies to safeguard long-term water security in Lebanon and similar data-limited Mediterranean basins. Satellite data and drought indices enable robust climate–water assessment in data-scarce regions. GRACE-based groundwater drought index captures cumulative water-mass changes in Lebanon’s multi-layered aquifers. In ARB, SPEI-18 shows the strongest correlation with groundwater drought, reflecting long-term aquifer responses. Future climate projections indicate up to 2.1 °C warming and 14% precipitation decline by 2100.

Spatio-temporal variation of meteorological, hydrological and agricultural drought vulnerability: Insights from statistical, machine learning and wavelet analysis

The propagation of meteorological drought (MD) to agricultural drought (AD) is influenced by various factors, particularly the climate type. This research examined the characteristics of drought propagation, encompassing propagation rates, lag time, and response time, from MD to AD within the context of Iran's diverse climate conditions. This was accomplished using three crucial meteorological and agricultural drought indices, namely the Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), and Standardized Soil Moisture Index. The research data included in-situ and ERA5 datasets from 30 basins (catchments) across Iran in the 1979-2021 period. Based on reports from the Global Drought Observatory, the three most prominent MD events were identified in 1999-2002, 2008-2009, and 2017-2019. The correlation coefficients between MD and AD indices across various timescales, in climates ranging from hyper-arid to humid, exhibited a decline from 0.75 to 0.44. The response time, varying between 2.42 to 6.63months, was determined by the strong correlation between SPI (or SPEI) and SSI1 (or SSI2) within the studied basins. Furthermore, the lag time, which was affected by the onset of MD and AD events, fluctuated between 2 to 6months in hyper-arid and arid basins, revealing a 1-3month variation compared to humid basins. The findings on propagation rates highlighted heightened sensitivity or response from meteorological to agricultural drought in humid climates, as opposed to hyper-arid climates. In light of these outcomes, comprehending the transition from MD to AD holds substantial significance for predicting, issuing early warnings, and fortifying preparedness in managing drought risks.

GRACE based groundwater drought evaluation of Ganga Basin and analysis of drought propagation using wavelet based quantitative approach

Abstract. Drought can be described as a temporary decrease in water availability over a significant period that affects both surface and groundwater resources. Droughts propagate through the hydrological cycle and may impact vulnerable ecosystems. This paper investigates drought propagation in the hydrological cycle, focusing on assessing its impact on a groundwater-fed wetland ecosystem. Meteorological drought indices were used to analyze meteorological drought severity. Moreover, a method for assessing groundwater drought and its propagation in the aquifer was developed and applied. Groundwater drought was analyzed using the variable threshold method. Furthermore, meteorological drought and groundwater drought on recharge were compared to investigate drought propagation in the hydrological cycle. This research is carried out in the Doode Bemde wetland in central Belgium. The results of this research show that droughts are attenuated in the groundwater system. The number and severity of drought events on groundwater discharge were smaller than for groundwater recharge. However, the onset of both drought events occurred at the same time, indicating a quick response of the groundwater system to hydrological stresses. In addition, drought propagation in the hydrological cycle indicated that not all meteorological droughts result in groundwater drought. Furthermore, this drought propagation effect was observed in the wetland.

Each type of drought has different characteristics in different regions. It is important to distinguish different types of droughts and their correlations. Based on gauged precipitation, temperature, simulated soil moisture, and runoff data during the period 1951–2012, the relationships among meteorological, agricultural, and hydrological droughts were analyzed at different time scales in Southwest China. The standardized precipitation evapotranspiration index (SPEI), soil moisture anomaly percentage index (SMAPI), and standardized runoff index (SRI) were used to describe meteorological, agricultural, and hydrological droughts, respectively. The results show that there was a good correlation among the three indices. SMAPI had the best correlation with the 3 month SPEI and SRI values. It indicates that agricultural drought was characterized by a 3-month scale. The three drought indices displayed the similar special features such as drought scope, drought level, and drought center during the extreme drought of 2009–2010. However, the scope and level of SPEI were bigger than those of SMAPI and SRI. The propagation characteristics of the three types of droughts were significantly different. The temporal drought process in typical grids reflect that the meteorological drought occurred ahead of agricultural and hydrological droughts by about 1 and 3 months, respectively. Agricultural drought showed a stable drought process and reasonable time periods for the drought beginning and end. These results showed the quantitative relationships among three types of drought and thus provided an important supporting evidence for regional drought monitoring and strategic decisions.

Storage reservoir systems influence meteorological, hydrological, and socioeconomic droughts. However, teasing out the effects of reservoirs on drought propagation is challenging due to the integrated operation of hydropower systems. We examine how meteorological droughts propagate into hydrological and socioeconomic droughts within the Paraná River Basin (890 000 km2) in Brazil, using 25 years of daily data from 61 hydropower plants. We define socioeconomic drought using the ratio of hydropower generation to installed capacity, and use SPI and SSI for meteorological and hydrological droughts. Our results indicate that all drought types have become more frequent over the years. On average, meteorological droughts take 9 months to propagate through the reservoir system and generate a socioeconomic drought. The slow propagation is contrasted by a faster recovery of socioeconomic droughts, which can be attributed to the operation of the entire system. These findings highlight the importance of considering reservoir cascades in predicting drought developments.

Drought is a complex phenomenon caused by various factors which can be classified into natural and anthropogenic causes. In Korea, the natural drought typically occurs when the high pressure of the Pacific Ocean develops rapidly or becomes stronger than usual in summer, resulting in a short-lived monsoon season. Drought also can be classified into meteorological, agricultural, hydrological, and socioeconomic drought depending on the development process and consequences. Each type of droughts can influence the other drought types directly or indirectly. Drought propagation refers a phenomenon that changes from meteorological drought to agricultural or hydrological drought. In this study, the occurrence and patterns of drought propagation are evaluated. The relationship between meteorological and agricultural droughts was assessed using hydrometeorological data. We classified the types of drought into five categories to evaluate the occurrence and characteristics of drought propagation. As results, we found drought propagation did not occur or delayed until three months, depending on the type of drought. The further generalized relationship of drought propagation is expected to be used for predicting agricultural drought from the preceding meteorological drought.

In the context of global climate change, the cascading risk of compound natural hazards is becoming increasingly prominent. Taking Xilin Gol grassland as study area, we used the Mann–Kendall trend method, the maximum Pearson correlation coefficient method, and Partial least squares structural equations modeling to detect the characteristics of spatiotemporal pattern changes of the three types of droughts. The propagation characteristics and the cascade effects among the three types of droughts was also identified. The standardized precipitation evapotranspiration index, standardized evapotranspiration drought index, and soil moisture index were selected as indicators of meteorological drought, ecohydrological drought, and soil drought, respectively. The results show that the warm and dry trend in Xilin Gol grassland was obvious in the past 30 years. The seasonal propagation of different drought was prominent, with stronger spread relationships in summer. Persistent meteorological drought was more likely to trigger the other two types of droughts. The intensity and range both increased during the propagation from meteorological drought to ecohydrological drought. The cascade effect was differed in different time scales. The multi-year persistent climatic drought has an overwhelming cascade effect on soil drought and ecohydrological drought. For seasonal or annual drought, vegetation cover change has an amplifying or mitigating impact on the cascade effect, where soil moisture, evapotranspiration (ET), and their relationship all play important roles. In eastern areas with better vegetation cover, the reduction of vegetation in the early stage aggravated the cascading effect of meteorological drought to ecohydrological drought through reducing ET. In the northwestern sparsely vegetated areas, ET was mainly influenced by meteorological factors, and the cascade effect of meteorological factors to ecohydrological drought was more obvious than that of soil drought.

Under global climate change, drought has become one of the most serious natural hazards, affecting the ecological environment and human life. Drought can be categorized as meteorological, agricultural, hydrological or socio-economic drought. Among the different categories of drought, hydrological drought, especially streamflow drought, has been given more attention by local governments, researchers and the public in recent years. Identifying the occurrence of streamflow drought and issuing early warning can provide timely information for effective water resources management. In this study, streamflow drought is detected by using the Standardized Runoff Index, whereas meteorological drought is detected by the Standardized Precipitation Index. Comparative analyses of frequency, magnitude, onset and duration are conducted to identify the impact of meteorological drought on streamflow drought. This study focuses on the Jinghe River Basin in Northwest China, mainly providing the following findings. 1) Eleven meteorological droughts and six streamflow droughts were indicated during 1970 and 1990 after pooling using Inter-event time and volume Criterion method. 2) Streamflow drought in the Jinghe River Basin lagged meteorological drought for about 127 days. 3) The frequency of streamflow drought in Jinghe River Basin was less than meteorological drought. However, the average duration of streamflow drought is longer. 4) The magnitude of streamflow drought is greater than meteorological drought. These results not only play an important theoretical role in understanding relationships between different drought categories, but also have practical implications for streamflow drought mitigation and regional water resources management.

In recent years, the global and regional water cycle continues to intensify under the influence of climate change and human activities, which leads to the redistribution of water resources in time and space, resulting in the increasing frequency of drought, which seriously threatens food security, social stability and even human life and property security. Taking the Huaihe River basin as the study region, this study carried out simulations of the fully-coupled WRF/WRF-Hydro model coupled with ET water vapor tracking algorithm under four land use scenarios, i.e., actual, forest, grassland, and cropland scenario respectively. Further the impact of land use on land-atmosphere interactions and the uncertainty of drought propagation between meteorological, agricultural, surface hydrological, and subsurface hydrological drought were explored. The results show that the forest scenario strengthens the east wind with an 0.11% to 0.62% increasement on precipitation recycling ratio in the basin, especially for periods of drought when the precipitation is scarce, while the increase of precipitation recycling ratio under cropland scenario is only 0.03 to 0.14%. The grassland scenario demonstrates a reduction in precipitation recycling ratio within the basin by 0.03% to 0.17%. The characteristics of drought propagation under changing environment will be affected by the characteristics of the year and the climatic conditions in the early period. For the year of 2010-2011, the propagation rate of drought duration from meteorological drought to agricultural drought decreases by 18%, propagation rate of drought severity decreases by 14%, while propagation rate of drought intensity increases by 4% under forest scenario. The drought propagation rate under grassland scenario and cropland scenario exhibit significantly increases. As for drought propagation from meteorological drought to surface and subsurface hydrological drought, the propagation is less affected by the land use with a slightly increase on the propagation rate of drought duration.

Groundwater drought poses a growing threat to water security in India, as groundwater supplies support agriculture, ecosystems, and domestic use. Although meteorological and hydrological droughts and their propagation have been studied, the propagation of drought into groundwater systems in India has not been examined. In this study, we employed Standardized Precipitation Index (SPI), the CGWB-based Standardized Groundwater Index (SGI), and the GRACE-based Groundwater Storage Anomaly (GWSA) to investigate meteorological drought and groundwater drought across the Indian region. We estimated drought propagation duration, recovery duration, mean drought duration, and maximum drought duration. The results show that regions in the north, northwest, northeast, and a few regions in southern India have the longest propagation time from meteorological to groundwater drought, while other zones, such as central India, have relatively shorter propagation times. We also find that regions in northeast and northwest India recover faster from groundwater droughts than other regions. Our results also show that the Dryness Index (DI), Seasonality Index (SI), and Land Surface Controls (NDVI, soil moisture (SM), and Evapotranspiration (ET)) play a significant role in the propagation time of meteorological to groundwater droughts across different zones. Overall, understanding the propagation and recovery plays a vital role in aiding effective management and planning of groundwater resources in India.

Propagation from meteorological to hydrological drought and its application to drought prediction in the Xijiang River basin, South China