Case Studies

Going with the Flow for Better Water Management

September 2005 | San Diego, CA Contributed by Zhen Li, PhD U.S. Geological Survey USGS

The image shows isosurfaces of pressure around the swimmer's body. Red indicates higher pressure, blue indicates lower pressure. Also visible is the triangular unstructured surface mesh used to represent the body.

The Researcher
Dr. Zhen Li is a California State University Sacramento Foundation Hydrologist/Groundwater Modeler working with the California Water Science Center of the U.S. Geological Survey (USGS). One of the primary responsibilities of the USGS within the U.S. Federal Government is to provide hydrologic information and analysis needed for the best use and management of the nation's natural water resources.

To accomplish this, the Water Science Center, in cooperation with state, local, and other federal agencies, systematically collects and analyzes data to evaluate the quantity, quality, and use of the nation's water resources; conducts water-resources appraisals describing the occurrence, availability, and physical, chemical, and biological characteristics of surface and ground water; and conducts hydrologic research to understand hydrologic systems and address specific water-resource problems.

This synchronized animation represents the simulated streamflow gains and losses (right picture) corresponding to ground-water recharge from precipitation (left picture). Green, yellow, to reddish colors on the right picture represent stream reaches losing water to the ground-water-flow system. Similarly, light blue to dark blue represents stream reaches gaining water from the ground-water flow system.
See the full animation >>(5.36MB avi)

Modeling a Regional Ground-Water Flow System
To develop a regional ground-water flow model, Zhen Li explains, diverse types of ground-water-related data, ranging from site-specific to basin-scale, must be analyzed and integrated. Ground-water flow models are widely used to examine hypotheses of subsurface hydrologic systems, evaluate long-term water availability, and predict the response of subsurface hydrologic systems to natural or human-caused stress.

A regional-scale ground-water model typically simulates ground-water flow for one or more basins over multiple time periods. For regions with complex geological settings and hydrological boundaries, large quantities of diverse types of data need to be compiled, analyzed, and visualized before the construction of the model.

During model development, Quality Assurance/Quality Control (QA/QC) is needed to identify errors or flaws associated with data and model conceptualization. This requires the constant display and reassembly of data in order to assure accurate locations and values of significant parameters, to reveal cause and effect relations of critical model components, and ultimately, to match simulation results with other independent measurements.

The process is iterative, time-consuming, and technically challenging for complex ground-water simulation models with decades of simulation length and a variety of comparison data. The use of powerful data-processing and visualization technology is essential to the efficiency and success of developing ground-water models on a regional scale.

This synchronized animation represents the simulated ground-water levels (left picture) in relation to the stream inflow and artificial recharge (right picture) to the ground-water flow system. On the right picture, the blue and purple dots represent stream inflow and artificial recharge, respectively. The size of each dot is proportional to the magnitude of stream inflow and artificial recharge.
See the full animation >> (11.5 MB avi)

This synchronized animation represents the simulated vertical well-bore flows across different aquifers. Left picture shows the top aquifer with ground-water inflows in yellow to red, and outflows in green to blue. The right picture shows the lower aquifer, using the same color-scheme definitions as the left picture.
See the full animation >> (17 MB avi)

Plotting a Course for Better Water-Resource Management
To help visualize the results of the complex ground-water flow model of the Santa Clara Valley (http://water.usgs.gov/pubs/sir/2004/5231/), animations of multi-frame, time-series data were created using Tecplot. The three-dimensional numerical flow model was built using the USGS water-resource application software, MODFLOW, as part of a cooperative investigation between the USGS California Water Science Center (http://ca.water.usgs.gov/)and the Santa Clara Valley Water District (http://www.valleywater.org/).

To create the animations, Zhen Li built a processor to convert the MODFLOW model outputs into a format usable by Tecplot. Then she used Tecplot's multi-frame animation macro to create the animation. The Tecplot animations help visualize the spatial and temporal variations of a complex ground-water flow system over the modeled period of 30 years. The influences of natural and man-caused stresses on the ground-water flow system of the Santa Clara Valley are illustrated in detail through the animation.

Zhen Li believes that animations greatly facilitate the analysis and understanding of the model results. "Synchronized animations help identify the cause and effect relations between significant model components," says Li. "The animations not only help validate the conceptual formulation and the numerical calibration of the Santa Clara Valley ground-water/surface-water flow model, but also help translate large volumes of numeric data into easily-understood motion pictures, which effectively communicates our work to cooperators and the public."

This synchronized animation represents the simulated land subsidence (right picture) in response to water-level changes (left picture). On the right picture, areas with simulated land subsidence are shown in yellow to red, while areas with simulated land uplift are shown in blue. Similarly, on the left picture, simulated ground-water level rises are in yellow to red, while simulated ground-water level declines are in green to blue.
See the full animation >> (2.7 MB swf)

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