Part 1 - Eco-Hydrology Engineering Design Tool - GSSHA Capabilities - Flow, Sediment, and Water Temperature
Authors: Johnson Billy , Downer Charles Downer , Byrd Aaron , Pradhan Nawa , Steissberg Todd , Zhang Zhonglong 
Published: February 2023

&lt;p&gt;The U.S. Army Corps of Engineers (USACE) has a major responsibility for the regulation of the Nation&amp;#8217;s streams, rivers, and waterways. This often requires developing water quality models to resolve issues and concerns with regard to the environment and ecosystems. USACE Engineer Research and Development Center (ERDC) is currently developing an Eco-Hydrology Engineering Design Tool supported by years of research and development. This tool development integrates Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model and a suite of Water Quality and Ecosystem Models (Clearwater Water Quality Modules - ClearWater).&lt;/p&gt;
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&lt;p&gt;Weather is not the only cause of flooding, stream erosion, and pollution. These problems usually occur from human impacts to watersheds, including urban development, construction activities, hydrologic modifications, forestry, mining, and agricultural practices.&lt;/p&gt;
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&lt;p&gt;To help control the impact of these serious economic and environmental issues, experts in watershed engineering at the U.S. Army Engineer Research and Development Center (ERDC) developed the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) tool to conduct studies in watershed modeling.&lt;/p&gt;
&lt;p&gt;&amp;#160;&lt;/p&gt;
&lt;p&gt;With GSSHA, engineers can perform complex studies of atmospheric, land-based, wetland, riverine, and coastal systems to help predict and mitigate watershed management problems. ERDC studies in watershed modeling and analysis integrate hydrology, hydraulics, and water quality. This helps city or military installation planners, civil engineers, and others involved in planning and resource management make informed decisions about watershed management.&lt;/p&gt;
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&lt;p&gt;GSSHA is a multidimensional modeling technology that uniformly couples overland, surface, and subsurface flow for accurate watershed simulation. GSSHA is a physics-based, distributed, hydrologic, sediment and constituent fate and transport model featuring the following: 1) Two-dimensional (2D) overland flow and groundwater flow, and one-dimensional (1D) stream flow and soil moisture; 2) Fully dynamic pipe networks for urban and agricultural drainage systems; 3) Wetland peat layer hydrodynamics and several in-stream weir and culvert models; 4) Lakes, detention basins, levees, rating and rule curve releases; 5) Boundary conditions for hurricane storm surge or levee breach inundation modeling; 6) Full coupling among groundwater, vadose zone, streams, and overland flow; 7) Full-Gr-coupled groundwater to surface-water interaction to model Hortonian and non-Hortonian basins; 8) GSSHA can be used as an episodic or continuous model where soil surface moisture, groundwater levels, stream interactions, and constituent fate are continuously simulated; and 9) Full Energy Based Water and Soil Temperature for Overland and Channel systems.&lt;/p&gt;
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&lt;p&gt;This presentation will discuss current GSSHA capabilities and introduce Water Quality and Ecosystem developments to be presented in more detail in &amp;#8220;Part 2 - Eco-Hydrology Engineering Design Tool - ClearWater Capabilities - General Constituents, Nutrients, and Contaminants&amp;#8221;.&lt;/p&gt;