Simulation of flood associated with extreme rainfall events over the urban city, Bengaluru, India
Smrati Purwar, G. N. Mohapatra, and V. Rakesh
Urban flooding affects millions of people in Indian major cities during past decades and is expected to be severe in near future under the warming climate scenario. Rapid urbanization and demography changes in the Bengaluru city in the past has led to significant hydrological and environmental stress contributing to the severity of urban flooding. The whole Bengaluru city (Urban as well as Rural) consists of four watershed valley and here, we have chosen Koramangala-Challaghatta (KC) valley as our study area which is known for its low-lying topography and frequent flooding events. In this study, we selected four Extreme Rainfall Events (EREs), occurred on 07 September 2015, 1 June 2016, 15 August 2017, and 24 September 2018, for simulation using the Storm Water Management Model (SWMM). The digital elevation model (DEM) is examined to understand the topography of high and low-lying areas to assess the flood impacts of EREs in various regions. Based on the frequency distribution, the 99th percentile of daily rainfall intensity (39.5 mm/day) is considered as the threshold for defining EREs in the study region, and long-term rainfall data (1998–2024) revealed a clear increasing trend in frequency of EREs. Results indicate that rainfall exceeding 30 mm/day leads to flooding in more than half of the area in KC Valley, with flash floods occurring when rainfall surpasses 55 mm/day. The most flood-prone locations are those near historical natural lakes, where urban encroachment has diminished natural flood detention capacity. Evaluation using multiple statistical metrics demonstrates reliable performance of SWMM in flood simulation, particularly for high-intensity rainfall events. The bias in simulated stormwater discharge ranges from + 4 to −4 m3/s, indicating useful skill of the model. The reliable methodological framework to tackle hydrometeorological challenges presented in this study can be handy tools for designing integrated flood management strategies for urban cities.
Assessing the Impact of Parameter Sensitivity and Multi-Configurational Ensembles of WRF- Hydro Model on Simulated Hydro-Meteorological Variables—A Multifaceted Evaluation over Krishna River Basin of India
by Sumana Sarkar & P. Lakshmikanthan
Quantifying the variability of hydro-meteorological variables and various land-surface processes in response to the diverse sources of uncertainties arising from the structure of hydrological models, model parameters, calibration procedures, and schemes related to the various physical process representations is a significant scientific endeavour with important implications in hydrology. Sensitivity analysis is the only plausible way to provide valuable insights into how different parameters influence model outputs and helps evaluate the rationality of each model parameter. Hence, the present study employs sensitivity analysis for comprehensive evaluation of the impact of an enhanced hydrological parameterized and newly developed WRF-Hydro model towards the simulation of hydro-meteorological variables, in terms of model parameter uncertainty and structural variability. The study is carried out in the vicinity of the Krishna River basin in India with a sub grid-scale of 200 m. We evaluate the model's fidelity to accurately simulate streamflow and key hydrometeorological variables, including Evapotranspiration, soil moisture, and land heat and moisture fluxes, through a series of sensitivity experiments. These experiments quantify the impact of uncertainties related to land surface model parameterization, thresholds of model parameters, and structural configurations of the WRF-Hydro framework. The characteristics of the simulations thus generated have been validated against in-situ gauge data and remote sensing-based multi-platform observations, revealing a significant improvement in the simulation accuracy, with correlation coefficients exceeding 0.9 and 0.7 for soil moisture and soil temperature, respectively. Our findings show marked enhancement in the model’s predictive accuracy. By identifying the configurations with superior performance, this study provides practical insight for selecting optimal model parameterizations, thereby contributing to improving the hydro-meteorological forecasting frameworks and supporting better water management practices in regions with limited data availability.
Evaluation of CMIP6 multi-model ensemble for assessing the intensity and duration of Indian monsoon under future warming scenarios
by Smrutishree Lenka, Krushna Chandra Gouda, Rani Devi & T. S. Mohan
This study evaluates future changes in Indian summer monsoon (ISM) rainfall, seasonal duration, and impact of pre-monsoon temperature rise using the simulations from twelve CMIP6 climate models under multiple Shared Socioeconomic Pathways (SSPs). Analysis indicates that historical simulations (1951–2014) from the models, assessed against India Meteorological Department (IMD) gridded observational data led to the selection of five models that closely capture observed monsoon rainfall patterns within one standard deviation. Analysis indicates that, over central Indian region extreme rise in temperature > 5.4 °C accompanied by a 3.2% increase in monsoon rainfall in the far-future (2075–2100) scenario. Further, the ISM length at each grid point computed using a novel algorithm from the historical analysis reveals that Northwestern India experiences a comparatively shorter monsoon season. Projections under more intense emission scenarios like SSP-370 and SSP-585, exhibits the ISM-length .decrease by nearly 7–8 days over the next 76 years. At the same time, future projections in indicate a substantial rise in ISM rainfall under high-emission scenarios, suggesting an intensification of the monsoon despite a shortened duration. This paradox is closely linked to increasing pre-monsoon temperatures, which enhance atmospheric moisture-holding capacity and lead to more compound extreme events. The study quantifies the sensitivity of monsoon rainfall to pre-monsoon warming, highlighting spatial variability in rainfall response per 1 °C temperature increase and found that that pre-monsoon temperatures continue to be on the higher side in both SSP5-8.5 and the far-feature scenarios. These findings indicate a growing risk of hydro-meteorological extremes such as heatwaves and urban flooding, especially under high-emission futures like SSP3-7.0 and SSP5-8.5. The projected combination of shorter rainy seasons and more intense rainfall events underscores the urgent need for targeted adaptation and resilience planning across sectors and regions in India.
Source: https://doi.org/10.1007/s00382-025-07923-1
Retrieval of precipitable water vapor from sun-sky radiometer (POM-01) at 940 nm absorption band: Calibration, measurement and validation
by Swagata Mukhopadhyay, Shantikumar S. Ningombam, Akihiro Uchiyama, Sonam Jorphel, Chiranjeevi G. Vivek, T.S. Shrungeshwara, Sreedevi P., Tsuneo Matsunaga, Som K. Sharma, Pawan Gupta, Dorje Angchuk, Sridevi Jade
Mapping seismic hazards in the Himalayas
by Imtiyaz A. Parvez and Sanjeev Ekka
The Himalayas rank among the world’s most seismically active regions, as evidenced by major historical earthquakes, including the 1905 Kangra (Mw 7.8), 1934 Bihar–Nepal (Mw 8.2), 1950 Assam (Mw 8.4), 2005 Kashmir (Mw 7.6), and 2015 Gorkha (Mw 7.8) events. These earthquakes underscore the ongoing tectonic activity along the Himalayan arc and have caused substantial human and economic losses. Seismic hazard assessment is a critical tool for mitigating such impacts, informing preparedness efforts, risk reduction strategies, and policy formulation. Significant advancements have been made in recent decades in assessing seismic hazard and risk across the Himalayas. This article reviews key developments in probabilistic and deterministic seismic hazard studies, integrating both historical and instrumental earthquake data. Notably, peak ground accelerations (PGA) in certain Himalayan regions surpass 0.6 g, with areas near the 1897 and 1950 Assam earthquake epicenters recording extreme PGA values of 1.2–1.3 g. These zones also exhibit high ground velocities and permanent displacements, reflecting the severe ground-shaking potential of large Himalayan earthquakes. The article further explores how local geological conditions and source characteristics influence ground motion, emphasizing their role in microzonation studies. Despite progress, critical research gaps remain, particularly the need for high-resolution seismic hazard mapping across the Himalayan arc to enhance risk reduction and resilience-building efforts.
Source: https://doi.org/10.1007/s43538-025-00626-5
- Studying the dynamics of cloudburst events over Indian Himalayan region using model simulation
- Seismo-ionospheric anomalies associated with the 2025 Mw 7.7 Myanmar earthquake: a case study
- Quantifying weather-rice crop production relationships across different physiographical zones in Odisha, India
- Impact of the Gannon Superstorm on the Equatorial Ionization Anomaly Dynamics During Its Recovery Phase on 11 May 2024
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