Development of a Multiaquifer Hydrologic Modeling Package to Support Bureau of Reclamation (Reclamation) Water Use Planning in Rural/Urban Landscapes
Project ID: 60
Principal Investigator: Jennifer Johnson
Research Topic: Water Marketing
Priority Area Assignments: 2012 (Climate Adaptation), 2013 (Climate Adaptation)
Funded Fiscal Years: 2008, 2009, 2010 and 2012
This Science and Technology (S&T) project will focus on Reclamation's need for hydrologic modeling tools that can address conjunctive ground water and surface water management issues of Reclamation's projects that are situated at the interface between rural and urban landscapes.
Is there a way to develop a nonproprietary hydrologic modeling package that combines a multilayer analytic element model (TimML), a finite-difference model (MODFLOW), and a data management tool (ArcGIS) to address these management issues?
Need and Benefit
Ground water hydrologists use analytic element method (AEM) models and finite-difference (FD) models to answer hydrologic questions about changes in land use practices. AEM models are better suited to answer local scale questions, while FD models are often used to answer regional scale questions. Both model types require large amounts of data and can demand significant amounts of time to pre- and post-process the model data. Presently, a public-domain hydrologic modeling package that combines a multilayer analytic element method (AEM) model, a finite-difference model, and a data processing tool does not exist. The purpose of this proposal is to create just such a software package.
AEM models are computer programs that can be used to simulate the interactions between features, such as streams and wells, and the underlying aquifer (i.e., ground water/surface water interactions). Single layer AEM models have been used by ground water hydrologists to investigate many situations, including the effects of pumping on surrounding canals and reservoirs, the interactions between the rivers and nearby canals, and the implications of removing a portion of a canal. While these single layer models provide a useful preliminary solution to the problem, they are not entirely accurate in all cases because many aquifers contain more than one aquifer layer. To be more accurate in these studies, it is necessary to use a multilayer AEM model. TimML is a public-domain multi-layer AEM model. Recent TimML investigations by Reclamation ground water hydrologists include estimating leakage from dams and investigating well interactions in multilayered systems.
FD models are computer programs that provide a numerical solution to general equation for ground water flow. FD models are fundamentally different from AEM models because FD model resolution is limited by a defined grid resolution. On the other hand, AEM model resolution is limited by the distance of one element to another and the resolution of the input data. The most commonly used and most trusted FD model is MODFLOW (developed by the U.S. Geological Survey [USGS]). MODFLOW has been in use for many years and has been used in numerous Reclamation applications.
ArcGIS is a geographical information system that can be used to organize and view spatially referenced data. Many ground water hydrologists use ArcGIS to organize and process ground water data, including high resolution elevation data such as green Light Detection and Ranging (LiDAR) data.
Separately, AEM and FD models provide answers to some conjunctive water management questions. However, combining the capability of these models would provide a powerful decisionmaking tool for ground water hydrologists and water managers.
The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.
Working Document - User's Manual for ArcTim: a GIS based interface for TimML (final, PDF,
By Jennifer Johnson
Manual completed on September 30, 2010