John F Walker
I have focused on conducting research investigating groundwater and surface water in natural systems and the application of statistics to a variety of problems in hydrology during my career with the USGS. This research effort has used a variety of approaches such as traditional field investigations using ion and isotope chemistry, hydrologic modeling and novel application of statistical methods.
Research Focus Areas
Ground-water/surface-water interactions, including hydrology and geochemistry; modeling climate and land-use change impacts on hydrologic systems; flood frequency analysis and prediction; assessing the effectiveness of nonpoint best-management practices; hydraulics of flow under ice.
TROUT LAKE WEBB PROJECT
The overall objective of this project is to understand processes underlying the responses of hydrological, biological, and chemical systems in the study area to climate variations and human activities. The overall approach involves: (1) detailed moisture accounting and isotope sampling of precipitation, streamflow, and the unsaturated and saturated zones of hillslope transects intersecting the stream; (2) fine-scale sampling at the sediment/water interface of Trout Lake and tributary streams; (3) intensive sampling of carbon-flux terms in various compartments of the carbon cycle; (4) the use of a groundwater model to identify potential flow paths, selected sampling for flow path verification and model refinement, and detailed sampling along the final flow paths; and (5) the use of a comprehensive hydrologic model to predict the response of the stream’s hydrologic and solute budgets to various stresses (e.g., climate change, development, clear cutting). My specific research has focused on the hillslope processes, the flow-path work, and the hydrologic modeling effort. As site coordinator I oversee the overall management of the project and coordinate with outside groups to foster collaboration.
GLRI CLIMATE CHANGE
The objectives of this project are to 1) build a model capable of predicting streamflow into the Great Lakes, 2) run the model for current conditions and future climate predictions, 3) provide streamflow estimates for GLRI restoration efforts, and 4) build fine-scale models as insets from coarse scale model to look at small scale restoration efforts. My role on the project includes assisting with model development, setting up automated calibrations, evaluating the calibration results, and running and interpreting the results from climate-change scenarios.
FLOOD FREQUENCY CHARACTERISTICS IN WISCONSIN
The objectives of this project are to (1) operate a statewide network of crest-stage gages, (2) develop improved regression equations for the entire state, and (3) develop plans to better estimate flood frequency in urban areas. My role on the project includes coordination of the crest-gage network, periodic evaluation of flood-frequency characteristics, and development and publication of regional regressions. I plan to add several innovations to the program, including addition of new basin characteristics using GIS techniques, evaluation and incorporation of trends into the analyses, incorporation of measurement uncertainty into the regression analysis and investigation of flood-frequency techniques in urbanizing areas with non-stationary flood frequency characteristics. The project is well funded; however a large portion of the budget is devoted to data collection and maintaining the database.