About

Peter Knappett is an Associate Professor in the Department of Geology & Geophysics at Texas A&M University, with a focus on hydrogeology and environmental health. His research interests include predicting the impacts of intensive groundwater pumping on regional groundwater quality, particularly concerning naturally occurring toxic concentrations of arsenic and fluoride, as well as anthropogenic contamination. He investigates how dynamic interactions between rivers and aquifers influence the biochemical composition and supply of groundwater, often working in regions lacking reliable geological, geospatial, water level, pumping, and chemical data by collecting primary field data and utilizing custom software for visualization, modeling, and interpretation. His educational background includes a PhD in Earth & Planetary Sciences from the University of Tennessee at Knoxville, a Masters of Applied Science in Civil Engineering from the University of Waterloo, and an Honours Bachelor of Science in Earth Science from the University of Waterloo. His professional experience encompasses roles as an Assistant and Associate Professor at Texas A&M University, a visiting professor at ETH Zurich, and research positions at Columbia University’s Lamont-Doherty Earth Observatory, among others. Knappett's work has contributed to understanding groundwater contamination issues in regions such as Bangladesh and Mexico, with a particular emphasis on geogenic contaminants like arsenic and fluoride, and their implications for environmental health. He has received awards including the Kohout Early Career Award from the Geological Society of America and the Arts & Sciences Divisional Achievement Award in Natural Sciences at the University of Tennessee.

Research topics

• Environmental chemistry
• Geology
• Environmental science
• Chemistry
• Ecology
• Geotechnical engineering
• Paleontology
• Environmental engineering
• Oceanography

Selected publications

• Silt layers in sandy riverbanks counteracts the removal of arsenic within hyporheic zones

  2025-01-01

  article1st authorCorresponding
  PublisherDOI

• Deformation in Dhaka Induced by Changing Water Levels Above and Below the Ground Surface

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Quantifying the Influence of Baseflow and Water Sources on Nitrogen Export in a Large Multi-Order Watershed on the Brazos River, Texas

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Tidal and Seasonal Groundwater-Surface Water Mixing Zones: Hot or Cold Spots for Arsenic Contamination?

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• BEHAVIOR OF GEOGENIC ARSENIC IN SHALLOW AQUIFERS UNDER THE INFLUENCE OF DYNAMICALLY FLUCTUATING RIVERS

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• The Effects of Tidal and Seasonal Scale Flooding and Soil Texture on Surface Water‐Groundwater Interactions Along a Fluvio‐Deltaic Floodplain: The Meghna River, Bangladesh

  Water Resources Research · 2025-10-01

  articleOpen access

  Abstract River corridors in coastal and fluvio‐deltaic plains (FDPs) experience tidal fluctuations and seasonal flooding which result in variable sediment transport regimes and a mix of sand, silt, and clay deposits in the channel and floodplain. In FDPs, river fluctuations influence the extent and dynamics of hyporheic zone mixing and groundwater flow relative to the river. We analyzed the combined effects of external forcing by tidal and seasonal flooding and internal controls by sediment texture on groundwater‐surface water (GW‐SW) interactions in the Meghna River in Bangladesh. We conducted numerical simulations to assess the relative importance and interaction of these factors on GW‐SW mixing. We assessed the influence of complex river stage fluctuations, capturing both semi‐diurnal and seasonal‐scale variations in the mid dry period, early wet period, and the early dry period following the wet season. Sensitivity analyses were conducted to assess the influence of sand, silt, and clay percentage and their predicted van Genuchten soil‐water retention parameters on mixing dynamics. The simulations reveal that mixing zone dynamics are highly sensitive to seasonal periods and soil texture. We found that vertical infiltration of river water was limited to <1 m depth in most scenarios and most promoted in the early wet period. In contrast, lateral infiltration was favored during the early dry period. Higher sand content promoted greater lateral and vertical infiltration, while relatively higher silt and clay contents contributed to thicker capillary fringes and greater water retention closer to the surface. Generally, GW‐SW mixing appears to be limited in low‐energy and tidally influenced fluvio‐deltaic settings.

  PublisherOA PDFDOI

• Tracking the Transformation of Dissolved Organic Carbon Species in the Brazos River and its Riverbanks during and after Storm Events

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• Reply for comment on “Tracking nitrate and sulfate sources in groundwater of an urbanized valley using a multi-tracer approach combined with a Bayesian isotope mixing model by Torres-Martínez et al. [Water Research 182 (2020) 115962]”

  Water Research · 2025-05-13

  article
  PublisherDOI

• Data for "Diverse sedimentary organic matter within the river-aquifer interface drives arsenic mobility along the Meghna River Corridor in Bangladesh"

  HydroShare Resources · 2024-05-02

  datasetOpen access
  PublisherDOI

• Hotspots of Dissolved Arsenic Generated from Buried Silt Layers along Fluctuating Rivers

  Environmental Science & Technology · 2024-08-13 · 9 citations

  articleOpen accessSenior author

  Previous studies along the banks of the tidal Meghna River of the Ganges-Brahmaputra-Meghna Delta demonstrated the active sequestration of dissolved arsenic (As) on newly formed iron oxide minerals (Fe(III)-oxides) within riverbank sands. The sand with high solid-phase As (>500 mg/kg) was located within the intertidal zone where robust mixing occurs with oxygen-rich river water. Here we present new evidence that upwelling groundwater through a buried silt layer generates the dissolved products of reductive dissolution of Fe(III)-oxides, including As, while mobilization of DOC by upwelling groundwater prevents their reconstitution in the intertidal zone by lowering the redox state. A three end-member conservative mixing model demonstrated mixing between riverbank groundwater above the silt layer, upwelling groundwater through the silt layer, and river water. An electrochemical mass balance model confirmed that Fe(III)-oxides were the primary electron acceptor driving the oxidation of DOC sourced from sediment organic carbon in the silt. Thus, the presence of an intercalating silt layer in the riverbanks of tidal rivers can represent a biogeochemical hotspot of As release while preventing its retention in the hyporheic zone.

  PublisherDOI

Recent grants

• Collaborative Research: The dynamic iron curtain surrounding fluctuating rivers and its impacts on arsenic fate and transport

  NSF · $309k · 2019–2023

Frequent coauthors

• Saugata Datta

  The University of Texas at San Antonio

  59 shared

• Kazi Matin Ahmed

  University of Dhaka

  54 shared

• Alexander van Geen

  Lamont-Doherty Earth Observatory

  54 shared

• M. Bayani Cardenas

  The University of Texas at Austin

  39 shared

• Harshad Kulkarni

  Indian Institute of Technology Mandi

  39 shared

• Brian J. Mailloux

  32 shared

• G. R. Miller

  24 shared

• Kyungwon Kwak

  22 shared

Labs

• Geology & Geophysics Department, Texas A&M UniversityPI

Education

• Ph.D., Geology

  University of Texas at Austin

  1992

• M.S., Geology

  University of Texas at Austin

  1988

• B.S., Geology

  University of Texas at Austin

  1985

Awards & honors

• Arts & Sciences Divisional Achievement Award in Natural Scie…
• Kohout Early Career Award, Hydrogeology Division, Geological…
• H. Gordon Award for Exceptional Professional Promise, Earth…
• Interdisciplinary Research Award, Earth & Planetary Sciences…