Land Atmosphere Water Simulator (LAWS)
Efficient tools for comparing alternative field-scale land and crop management practices, infrastructure characteristics, and multi-organizational daily delivery decisions are needed by water managers to analyze their integrated effects on reservoir supplies and river water quality.
The Land Atmosphere Water Simulator (LAWS) addresses these needs with a fully integrated, flexible and scalable tool with Geographical Information System (GIS) functionality built into its graphical user interface (GUI). The GUI allows users to rapidly perform and analyze simulations of alternative land, vegetation, infrastructure, and water management strategies using either historic or forecasted meteorology.
Proposed enhancements to LAWS will provide new wetland and municipal land use types, additional tools for reservoir and water account management, improved integration with existing planning, operations, and water quality models, root zone salinity modeling, and remote access to LAWS simulations via the internet.
Need and Benefit
LAWS differs in several significant ways from existing water resource planning and operations models currently available to Reclamation managers, planners, and operators.
First, LAWS simulates daily, field-scale land, crop, and water management practices. It provides users with tools to simulate alternative methods for managing soil moisture on a daily basis during the irrigation season based on soil properties, crop type and growth stage. This approach permits LAWS to compute evapo-transpiration (ET), soil water content, surface water ponding, runoff, canal and drain losses, return flows to rivers, and deep percolation to ground water at level of spatial and temporal resolution not present in existing planning and operations models. Although LAWS performs these calculations at the field scale, LAWS also provides users with ability to aggregate these results within larger user definable areas so that water budgets can be readily computed for arbitrary organizational regions.
Second, LAWS is not an optimization model. Although LAWS provides users with multiple methods for allocating water supplies and making priority based delivery decisions, LAWS does not employ any mathematical methods to determine the "best" allocation of water. In contrast, LAWS provides users with a powerful GUI that allows users to readily change water allocation and delivery priorities, land and crop management practices, and infrastructure characteristics to compare the effects of alternative system configurations on reservoir water supplies.
Third, LAWS has a native GIS capability built directly into the GUI. This GIS capability allows users to setup and analyze spatially accurate LAWS simulations across a span of scales ranging from large regional watersheds to sub-regions contained with individual fields. LAWS also provides users with the capability to import imagery, maps, and GIS information developed with commercially available software packages. Furthermore, LAWS has been developed from the U.S. Army Corps of Engineers (Corps) Water Management System (CWMS) software from which it has inherited a powerful suite of tools to examine model outputs including side-by-side comparisons of outputs from multiple alternative simulations and animations of spatial and temporal time series results.
The LAWS enhancements proposed in this project will continue to build on LAWS unique capabilities. The addition of explicit land types for wetlands and municipal areas will provide LAWS users with the ability to simulate consumptive use by these important water users more readily than is currently available in LAWS. Additional tools for reservoir and water account management will provide LAWS users with capabilities to simulate more complex water allocation and transfer strategies:
* Improved integration of LAWS with RiverWare, HEC-ResSim, CALSIM and ModSim models would allow users of these models to generate spatially accurate water demand and water budget time series using LAWS. These results can then be imported into their models and used for simulations. Similarly, reservoir releases from these models can be used as constraints in a LAWS simulation to determine their effects on water deliveries and water budgets down to the field scale.
* The development of a root zone model to simulate salinization and leaching processes associated with various land management practices will provide time series water quality outputs that can be used by other water quality models such as HEC-5Q or RMA2/11 for the evaluation of river water quality impacts.
* The development of a capability for remote access to LAWS models via the internet will provide users with a mechanism to view key simulation characteristics from multiple alternative simulations at a remote location. This capability will provide a new way for LAWS users to better serve the information needs of water managers and stakeholders during meetings and discussion sessions.
The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.
Land Atmosphere Water Simulator (LAWS) Version 1.5 (final, PDF,
By Dr. Michael Tansey, Dr. Charles Young, John DeGeorge and Shannon Larson
Report completed on August 03, 2011