My general research interests include hydrogeology, water chemistry, age dating groundwaters, groundwater recharge and discharge processes, watershed hydrology and chemistry, evaluating water resources, and water resource potability and sustainability in developing countries. My research is primarily in three geographic areas: 1) northern Nevada watersheds, particularly the Lake Tahoe and Walker Lake watersheds; 2) southern and eastern Nevada; and 3) West Africa.
Lake Tahoe clarity has been declining about 1 foot per year since the first clarity measurements in the late 1960’s. A major effort of my research has been providing decision makers and regulators with information to set policy on how best to restore Lake Tahoe clarity. This research includes nutrient and fine sediment loading to the lake from surface-water runoff and groundwater inflow to the lake. Research projects include evaluating the effectiveness of best management practices (BMPs), including both natural and engineered structures to remove fine sediment and nutrients from surface-water runoff. These studies also include (1) the evaluation of land use on runoff and the associated fine sediment and nutrient concentrations; (2) phosphorus adsorption on sediments beneath settling basins; (3) determining the source of fine sediments in watersheds with surface water flow into the lake.
My research in the Walker Lake basin focuses on the hydrology of the Walker Lake watershed including determining the hydrologic and dissolved salt budgets of Walker Lake. My research projects have also focused on groundwater flow to Walker Lake and groundwater flow and nutrient loading to Bridgeport Reservoir in the Walker Lake watershed. The Walker Lake basin is a unique internally drained watershed in the Great Basin of the western United States. The lake has no outlet, so the lake depends solely on surface water and groundwater inflow to maintain a hydrologic balance. Thus, the total dissolved salt (TDS) concentration of the lake depends on the amount of salt entering the lake from surface water and groundwater inflow and atmospheric deposition on the lake surface and the volume of water in the lake. Diversions of surface water in valleys upstream of Walker Lake for irrigation, beginning with the Bodie, California gold rush in the 1860’s when water was diverted to grow vegetables and beef for the nearby remote mining community, have resulted in the level of Walker Lake to steadily declined. The current volume of Walker Lake is about 80 percent of it’s volume in the 1800s. This dramatic reduction in lake volume has resulted in the lake salinity, TDS, increasing from about 2500 mg/l to 15,000 mg/l.
Southern and Eastern Nevada:
My research in southern and eastern Nevada has focused on regional groundwater flow system sources, travel times, and water budgets. The Death Valley flow system in southern Nevada and the White River flow system in eastern and southeastern Nevada encompass numerous valleys and hundreds of square miles with groundwater flowing beneath topographic divides and discharging at regional springs. Understanding the sources and amounts of groundwater in these regional flow systems and the time it takes groundwater recharged in mountainous recharge areas to flow to regional spring discharge areas is extremely important for water resource management in Nevada. Additionally, understanding the time involved in the potential radionuclide migration.
My research in West Africa has involved developing water supplies for rural villages in Ghana, Mali, and Niger. Rural villagers often lack a potable source of drinking water and non-potable sources of water often disappear during the dry season. Hand pumps are installed for village water supplies when successful wells are drilled. Developing reliable water supplies in rural villages also requires that the water is safe to drink. Water quality is a very important part of this project because high fluoride concentrations are often observed in the groundwater in these West Africa countries. This high fluoride, along with other trace elements such as arsenic, need to be treated to ensure that safe drinking water is being supplied to the villagers. Bacterial testing is also important to identify any wells with groundwater that is being contaminated from land surface sources so that the problem can be fixed.