Recent Advances in Modeling Groundwater Dynamics
Prof. Chunmiao Zheng @ EIT / SUSTech
Eastern Institute of Technology (EIT), Ningbo, China
Southern University of Science and Technology (SUSTech), Shenzhen, China
Abstract
Groundwater refers to the water beneath the Earth's surface, occurring in the pores, fractures, and karstified channels within soil and rock formations. It is essential for sustaining life on Earth, storing 99% of the planet's liquid freshwater, providing primary drinking water for about half of the global population, supplying over 40% of irrigation water for agricultural food production worldwide, and sustaining the majority (>50%) of global river flows. Groundwater is becoming an increasingly dynamic and complex component of the global water cycle, driven by climate change and human activities. Numerical modeling is a powerful tool for understanding the complexities of groundwater flow systems and supporting sustainable water management practices.
This presentation will highlight recent advances in groundwater modeling through two case studies. The first explores the groundwater dynamics of the Tibetan Plateau, often called "Asia’s Water Tower". This region presents unique challenges due to its high-altitude mountain hydrology, cold-region permafrost, and limited data availability. The second case study integrates surface water, groundwater, soil erosion, and nutrientdynamics to enhance our understanding of nutrient sources and behaviors in the Pearl River Basin in southern China. Tackling these complex issues necessitates the use of big data, AI, and an interdisciplinary approach. The presentation will conclude by discussing future trends in groundwater modeling, focusing on large-scale applications ranging from continental to global scales.
Bio:
Chunmiao Zheng is a distinguished professor of hydrologic and environmental science at the Eastern Institute of Technology in Ningbo, China, and the Southern University of Science and Technology in Shenzhen, China. His research interests include groundwater hydrology, ecohydrology, and environmental health. He has previously served as the George Lindahl Endowed Professor of Hydrogeology at the University of Alabama and held a chair professorship at Peking University in Beijing. Prof. Zheng is the developer of the MT3D/MT3DMS contaminant transport model, a standard tool used in over 100 countries. He has authored over 400 peer-reviewed journal papers and 6 books, with his work cited over 28,000 times (Google Scholar). Prof. Zheng has received several prestigious awards, including the O.E. Meinzer Award from the Geological Society of America, the M. King Hubbert Award from the National Ground Water Association, and the Prince Sultan Bin Abdulaziz International Prize for Water (PSIPW). In 2019, he was elected as a fellow of the American Geophysical Union.
Summary:
Focus on groundwater:
Shallower ground: Unsaturated (some water and some gaps)
Deeper: Fully saturated with water
Boundary: water table
Types: Water through …
Voids in rocks
Fractures in bedrocks
Channels/caves dissolved from carbonate rocks
Ground and surface water are a single, connected resource
Naturally groundwater is near the surface
In stressed conditions groundwater is deep and hard to access for plant roots and wells
99% of all liquid freshwater is groundwater
½ humanity drinks groundwater
70% of food irrigation has groundwater origins (much from irreversible depletion)
Nearly all aquifers are contaminated to some degree
Groundwater vulnerability
Conflict,
Ecosystems
Hazards
Energy & resources
Food security
Human Health
Numerical modeling of groundwater flow/transport
Hydraulic head
Mass transport
3D
The changing nature of groundwater in the global water cycle, 2024: https://www.science.org/doi/10.1126/science.adf0630
Climate change has significantly impacted groundwater
Major gaps in research (modeling, data, etc.)
Key to model cycle of water through the economy and agriculture
Modeling groundwater dynamics in Asia’s Water Tower
Tibetan Plateau: 2.5 million km2
Water for ~2billion people
>500GW Hydropower
Focus: Yarlung Zangbo River Basin
Mountain hydrology
Limited data
Challenging ground (e.g. permafrost)
Key questions:
Where does Himalayan river water come from and
What is the role of groundwater
Comprehensive hydrological models
Groundwater, surface water, glacial melt, evaporation
Rainfall: 40%, snowmelt: 24%, groundwater 36%
Excess water; suspected that it is discharging to deep fractured bedrock aquifers
Many deep faults in the basin
Simulated structure of water tower: good agreement with GRACE satellite data, all the way to discharge to Indian ocean
As glaciers melt the total availability of water will not change (still precipitation) but lack of storage means more variability year to year
Permafrost
Permafrost is degrading due to climate change
This modifies hydrology and landscape
Direct impacts:
More water goes into ground (more space in melted ground)
Less overall surface water
More streamflow as water is discharged from permafrost
Integrated modeling of flow, soil, nutrients
HEIFLOW: hydro-ecological integrated watershed-scale model based on USGS GSFLOW
Ecological modules
Soil erosion/nutrient
Surface vs groundwater
2km x 2km
Marine model: FVCOM
Land-sea Boundary conditions for Hydrological model
60-7000m grid
Subsurface parameterization from boreholes and geological maps
Application: Wastewater Treatment Plant (WWTP) discharge prediction
Predict flow of waste to water system
Used population migration map and data on locations of WWTP plants but not how much they discharge
Establish daily point source discharge database with some confidence based on hydrology and chemical sensor data
Coastal Algal Blooms from Remote sensing
Remote sensing identifies algal blooms (challenge: ⅔ of days are cloudy, so no data then)
Hydrological models infer their likely sources
Applied to the Pearl River
Highlight: “MODFLOW and MORE” conference (Theme: AI, global change and the future)
Groundwater modeling in the Global Energy and Water Exchanges (GEWEX) Project: https://www.gewex.org/
Groundwater is the missing link in Earth System Models
Challenges:
Data availability and quality
Model complexity and scale
Climate and human impacts
Need global scale groundwater models
Examples:
Canada1Water model: https://www.canada1water.ca/
Physics-based model of the complete water cycle for Canada and connected watersheds
Bedrock, soil, etc.
ParFlow CONUS 2.0: https://hydroframe.org/parflow-conus2
China groundwater model
Identifies dropping groundwater levels and ove-rpumping in North/Northwest
Groundwater storage trends (1945-2020)
Modeling trends:
Larger scale
Higher resolution
More comprehensive (physical-chemical-biological interactions)
Innovative approaches (AI, big data, big compute)