Venkatesh et al. (2026) Spatiotemporal water dynamics and micro-administrative (Hobli) scale storage variations in the coastal area of Mangaluru Taluk, India: a geospatial approach for sustainable water management

Identification

• Journal: Journal of Water and Climate Change
• Year: 2026
• Date: 2026-04-07
• Authors: Apoorva Kowdley Venkatesh, Subrahmanya Kundapura
• DOI: 10.2166/wcc.2026.380

Research Groups

• Department of Water Resources and Ocean Engineering, National Institute of Technology Karnataka, Mangaluru, Karnataka, India

Short Summary

This research investigates spatiotemporal variations in terrestrial and groundwater storage in the Mangaluru coastal region, India, at the micro-administrative (hobli) level over two decades using geospatial techniques. It reveals significant seasonal variability, long-term groundwater depletion, and the exacerbating effects of urbanisation and land-use change, underscoring the need for localised adaptive water management.

Objective

• To examine the spatiotemporal water dynamics of the Mangaluru coastal area by analysing seasonal and long-term variations in terrestrial water storage (TWS) and groundwater storage (GWS) at the hobli (micro) administrative level.

Study Configuration

• Spatial Scale: Mangaluru Taluk, India (approximately 569.414 km²), divided into five hobli (micro-administrative units): Mangaluru – A, Mangaluru – B, Gurupura, Surathkal, and Mulki.
• Temporal Scale: Two decades (2003–2022) for satellite data; 2000–2019 for in-situ groundwater monitoring well data.

Methodology and Data

• Models used: Modified Mann–Kendall (MMK) test, Innovative Trend Analysis (ITA), Empirical Orthogonal Function (EOF) with Principal Component Analysis (PCA), Correlation analysis, Lag analysis, Inverse Distance Weighted (IDW) interpolation.
• Data sources:
  • Satellite: Gravity Recovery and Climate Experiment (GRACE) data (GLDAS-2.2 GRACE-DA product, Catchment-F2.5), LANDSAT 7 satellite data (for Normalised Difference Built-up Index - NDBI).
  • Observation: In-situ groundwater monitoring well data (29 wells) from the Central Ground Water Board (CGWB) via the India Water Resources Information System (India WRIS).
  • Reanalysis/Other: Global Land Data Assimilation System Version 2 (GLDAS-2) for Surface Soil Moisture (SSM), Terrestrial Water Storage (TWS), Groundwater Storage (GWS), and Surface Soil Temperature (SST). Climate Hazards Group InfraRed Precipitation (CHIRPS) for rainfall data (0.05° resolution). Demographic data from the Census of India and the District Statistical Department.

Main Results

• Terrestrial Water Storage (TWS) and Groundwater Storage (GWS) exhibited significant seasonal variability, with increases during winter and post-monsoon and declines during pre-monsoon and monsoon periods.
• Long-term in-situ groundwater monitoring showed progressive depletion, with groundwater depth fluctuations increasing from 9.41 meters below ground level (mbgl) in 2000 to 16.8 mbgl in 2019.
• The Modified Mann–Kendall (MMK) test indicated no significant annual trend for TWS and GWS across all hoblis, but revealed increasing trends during winter (e.g., Mangaluru-A TWS slope = 6.09 mm/season, GWS slope = 4.78 mm/season).
• Lag correlation analysis identified delayed groundwater responses, with a +2-year lag for recharge during pre-monsoon and monsoon seasons, and a -3-year lag in winter, suggesting antecedent conditions influence subsequent storage.
• Empirical Orthogonal Function (EOF) analysis captured dominant spatiotemporal patterns of groundwater variability, with EOF1 showing coherent patterns influenced by urban development and hydrogeology.
• Land-use change (non-agricultural land use increased from below 20% in 1991–1992 to nearly 50% by 2020–2021) and urban expansion (increased NDBI values) were found to intensify pre-monsoon water scarcity.
• Hobli-level analysis highlighted greater groundwater fluctuations and weaker post-monsoon recovery in highly urbanised areas (Mangaluru-A and Mangaluru-B).

Contributions

• Provides the first explicit resolution of groundwater storage variability at the micro-administrative (hobli) level in Mangaluru Taluk, aligning hydrological analysis with local decision-making units.
• Integrates GRACE satellite data with Google Earth Engine (GEE) and in-situ well observations to offer a comprehensive and robust assessment of spatiotemporal water dynamics in a rapidly urbanising coastal region.
• Employs a complementary suite of advanced trend detection methods (MMK, ITA, EOF-PCA) to capture diverse characteristics of groundwater storage variability, including non-monotonic trends and structural shifts.
• Quantifies lead-lag dynamics between satellite-derived and ground-measured groundwater levels, providing critical insights into recharge delays and storage persistence within shallow coastal aquifers.
• Offers a reproducible framework for sustainable water management, decentralised planning, and adaptive policy design to mitigate water stress in similar coastal environments.

Funding

• National Institute of Technology, Karnataka (for infrastructure).

Citation

@article{Venkatesh2026Spatiotemporal,
  author = {Venkatesh, Apoorva Kowdley and Kundapura, Subrahmanya},
  title = {Spatiotemporal water dynamics and micro-administrative (Hobli) scale storage variations in the coastal area of Mangaluru Taluk, India: a geospatial approach for sustainable water management},
  journal = {Journal of Water and Climate Change},
  year = {2026},
  doi = {10.2166/wcc.2026.380},
  url = {https://doi.org/10.2166/wcc.2026.380}
}