People | Holly Michael

• B.S., Civil Engineering, University of Notre Dame, 1998.
• Ph.D., Hydrology, Massachusetts Institute of Technology, 2005.

My primary research interest is groundwater-surface water interaction in dynamic coastal systems. This includes quantification of the flux of fresh and saline groundwater and associated chemicals into nearshore marine systems, characterization of time-dependent physical forcing mechanisms that drive flow and transport, and prediction of the potential effects of changes in climate on coastal aquifer systems. I am also interested in sustainability of water supply, particularly in developing countries,  geostatistical methods for modeling subsurface heterogeneity, and hydro-economics.

For more information, see the Hydrogeology Group Website:

http://www.geosci.udel.edu/geosci/hydrogeology

CLIMATE CHANGE 

In the next decades, climate change is expected to include changes in sea level, precipitation, and evapotranspiration, disrupting the balance between terrestrial hydrology and the ocean that defines coastal groundwater systems. Adjustment to a new equilibrium will result in changes in groundwater flow and water quality that have implications for coastal systems and water supply.

Implications of Climate Change on Coastal Groundwater Resources of Bangladesh
This project is part of a larger World Bank effort to understand the potential effects of climate change on food security in Bangladesh. Our role is to characterize the impacts of changes in climate on groundwater resources of Bangladesh, particularly the impacts of intrusion of saltwater by various mechanisms. We are using variable-density numerical modeling to study salinization of groundwater used for drinking water and irrigation due to rising sea level and increases in the intensity and frequency of storm surges. The analysis will focus on both the pattern and response time of the subsurface distribution of salinity, with a view toward sustainability of current and future water use under climate change stress. (Funded jointly with Clifford Voss at the USGS by the World Bank and the Bank-Netherlands World Partnership Program)

Figure: False-color image of coastal Bangladesh. Dark green area is the Sundarbans mangrove forest. Tidal channels and the enormous sediment load into the Bay of Bengal can be seen in purple.

Modeling Dynamic Effects of Climate Change on Coastal Groundwater Systems
We are developing a structure for classification of coastal groundwater systems according to their vulnerability to the effects of climate change. Variable-density numerical modeling is being used to quantify the effects of various climatic factors on aquifer systems with differing controlling physical characteristics. This work will form a theoretical basis for study and classification of actual coastal groundwater systems, and may allow for mapping of aquifer vulnerability based on system characteristics. (Funded by the University of Delaware Research Foundation)

COASTAL GROUNDWATER DYNAMICS

We are using field measurements and variable-density numerical modeling of flow and solute transport to better understand the physical forcing mechanisms that drive exchange of water between aquifers and the coastal ocean. The mechanisms include steady forcing due to upland recharge and density gradients, as well as transient forcing on wave, tidal, seasonal, and climatic timescales.

Figure: Cartoon of coastal groundwater flowpatterns driven by various forcing mechanisms.

WATER SUPPLY SUSTAINABILITY 

I am working with Clifford Voss of the USGS and others to assess the sustainability of water supply in regional and local areas of the Bengal Basin. In Bangladesh, we are working with Professor Kazi Matin Ahmed and Anwar Zahid at Dhaka University, focusing on the sustainability of deep groundwater in Kachua Upazila, where the shallow aquifer is highly contaminated with dissolved arsenic, as a source of safe water for drinking.

Figure: Map of modeled sustainable (green) and unsustainable (red) zones for a future pumping scenario in the Bengal Basin.

In India, we are working with Professor Pradip Sikdar and Paulami Sahu at the Indian Institute of Social Welfare and Business Management. We are studying the effect of pumping in and around Kolkata City on the advection of groundwater from contaminated sites such as the East Kolkata Wetlands.

Figure: A handpump well being used in West Bengal, India.

GEOSTATISTICS

I am working with Steven Gorelick and Jef Caers at Stanford University to develop a methodology for representing discretely heterogeneous, non-stationary geological systems with geostatistical methods. We are using a deepwater turbidite system modeled at ExxonMobil using a process-based technique as a source of statistics. The methodology incorporates multiple geostatistical methods, including two-point, multiple-point, and object-based techniques, to simulate realistic subsurface heterogeneity that is fully conditioned to geologic data.

Figure: Top panel is model topography and conditioning well locations. Bottom panel is simulated coarse-grained turbidite lobes within the model.

 See Hydro Group Homepage: http://www.geosci.udel.edu/geosci/hydrogeology

GEOL 428/628 Hydrogeology

GEOL 466/666 Modeling Groundwater Flow and Solute Transport

GEOL 466/666 Coastal Hydrogeology Seminar

GEOL 466/666 Mathematical Modeling for the Geosciences (with Jim Pizzuto)

CV (March 2012)

Radloff, KA, Y Zheng, HA Michael, M Stute, BC Bostick, I MIhajlov, M Bounds, MR Huq, I Choudhury, MW Rahman, P Schlosser, KM Ahmed, A van Geen (2011) Arsenic migration to deep groundwater in Bangladesh influenced by adsorption and water demand, Nature Geoscience, doi: 10.1038/NGEO1283.

Michael, HA, MA Charette, CF Harvey (2011) Patterns and variability of groundwater flow and radium activity at the coast: a case study from Waquoit Bay, Massachusetts, Marine Chemistry, doi: 10.1016/j.marchem.2011.08.001.

S Fendorf, HA Michael, and A van Geen (2010) Spatial and temporal variations of groundwater arsenic in South and Southeast Asia, Science, 328: 1123-1127.

Michael, HA, H Li, A Boucher, T Sun, J Caers, and SM Gorelick (2010) Combining geologic-process models and geostatistics for conditional simulation of 3-D subsurface heterogeneity, Water Resources Research, 46, W05527, DOI 10.1029/2009WR008414.

Burgess WG, MA Hoque, HA Michael, CI Voss, GN Breit, KM Ahmed (2010) Vulnerability of deep groundwater in the Bengal Aquifer System to contamination by arsenic, Nature Geoscience, DOI 10.1038/ngeo750. 

Michael, HA and CI Voss (2009) Controls on groundwater flow in the Bengal Basin of India and Bangladesh: regional modeling analysis, Hydrogeology Journal, DOI 10.1007/s10040-008-0429-4. 

Michael, HA and CI Voss (2009) Estimation of regional-scale groundwater flow properties in the Bengal Basin of India and Bangladesh, Hydrogeology Journal, DOI 10.1007/s10040-009-0443-1

Michael, HA, H Li, T Li, A Boucher, SM Gorelick, and J Caers (2008) Combining methods for geologically-realistic reservoir simulation, In: Proceedings of the Eighth International Geostatistics Congress, JM Ortiz and X Emery (eds.), Gecamin Ltd., Santiago, 1167-1172.

Michael, HA and CI Voss (2008) Evaluation of the sustainability of deep groundwater as an arsenic-safe resource in the Bengal Basin, Proceedings of the National Academy of Sciences, 105 (25) 8531-8536. Online Supplement

Harvey, CF, AN Khandaker, W Yu, ABM Badruzzaman, MA Ali, PM Oates, HA Michael, RB Neumann, R Beckie, S Islam, MF Ahmed (2006) Groundwater dynamics and arsenic contamination in Bangladesh, Chemical Geology, 228 112-136.

Michael, HA, AE Mulligan, and CF Harvey (2005) Seasonal oscillations in water exchange between aquifers and the coastal ocean, Nature, 436 1145-1148. Online Supplement

Michael, HA, JS Lubetsky, and CF Harvey (2003) Characterizing submarine groundwater discharge: a seepage meter study in Waquoit Bay, Massachusetts, Geophysical Research Letters, 30 (6) 1297.