A groundwater monitoring well, surrounded by four yellow protective columns, located in an almond orchard that is in full spring blossom. The site depicted is used for research on nutrient management in farms and how fertilizer use affects groundwater quality, especially groundwater nitrate.

Nonpoint Source Pollution and Age Tracer Assesment across Landscapes

The Nonpoint Source Assessment Toolbox (NPSAT) is a groundwater modeling framework designed to evaluate the fate and transport of nonpoint source (NPS) contaminants such as nitrate and salts, but also the fate of age tracers that leach into groundwater from agricultural, urban, and natural land uses. The primary application of NPSAT is to assess groundwater quality in irrigation, public, and domestic supply wells.  We provide detailed information on our NPSAT research applications and available NPSAT software and online tools, including online mapping tools.

The NPSAT framework – in contrast to other groundwater flow and transport models -  is designed specifically (a) for high-resolution nonpoint source contaminant transport across entire groundwater (sub)basins and (b) to facilitate “on-the-fly” evaluation of dozens, hundreds, or thousands of different user-designed nonpoint source contaminant leaching future scenarios. These scenarios represent user-selected application of alternative source management practices associated with user-selected specific land uses and/or crops.

Autumn landscape with a winding river, colorful trees, and mountains under a partly cloudy sky. The photo was taken by Thomas Harter in Scott Valley, Siskiyou County, California, USA.

Groundwater-Surface Water Interaction: Integrated Modeling & Monitoring to Inform Groundwater Sustainability Plans

The reduction and depletion of stream flow and lake levels due to groundwater pumping is an underappreciated impact of groundwater pumping with often devastating effects on ecosystems. California’s new groundwater law (the 2014 Sustainable Groundwater Management Act, SGMA) is one of few state and international water laws that explicitly attempt to protect “interconnected surface waters”. We have been developing novel integrated hydrologic modeling approaches to provide decision-support to local, regional, and state regulatory agencies.  Developing these decision-support tools has been a two-step process: development of a trusted baseline model capable of reproducing and explaining the observed hydrologic history; and development of future model scenarios to inform decision-making.  This provides the basis for the design of appropriate and effective monitoring networks, for prioritizing potential future projects and management actions, and for setting regulatory limits on groundwater-surface water interaction. The modeling development is part of a transdisciplinary collaboratory with a wide diversity of outreach and extension efforts with the affected community’s various actors.  Through their interactions with these models, they participate in the design of the model.

just a test image

Learning About Groundwater in Agricultural Regions

Scientists and engineers in academia, consulting, and in agencies use a wide range of groundwater modeling software to simulate, understand, and predict the behavior of groundwater and of contaminants traveling in groundwater.  Much of our research, outreach, and Cooperative Extension work at UC Davis is focused on the nexus between groundwater and agriculture - both, with respect to water quality, to water supply, and to groundwater-dependent ecosystems.  We develop and use a multitude of computational tools and often detailed, real world monitoring and reconnaissance data. Our tools build on sophisticated open-source software and we take pride in being transparent and "open" with respect to our own software and the data we use.

Our goal is to research, learn, and inform about the groundwater-agriculture nexus. As part of or mission, we here provide our data, software, as well as our intuitive online learning tools to be empoyed by other scientists and engineers, by  water managers, by stakeholders at the agriculture-groundwater nexus, and by the interested public.