Location: Watershed Physical Processes Research
2023 Annual Report
Objectives
1. Develop physically based multidimensional numerical models and technology for watershed erosion and sediment transport processes, water quality issues due to agro-pollution, and surface-groundwater interactions in agriculture landscapes.
1.1. Expand CCHE1D model capabilities.
1.2. Simulate rain-induced watershed soil erosion over tilled and non-tilled agricultural land and sediment transport.
1.3. Develop a coupled surface-subsurface water model.
1.4. Improve CCHE water quality and pollutant transport models.
2. Enhance the Decision Support System for the web-based Agricultural Integrated Management System (AIMS) by integrating watershed and channel network technology with geospatial and remote sensing data for effective watershed runoff, sediment, and water quality management.
2.1. Improve AIMS and AnnAGNPS integration.
2.2. Integrate CCHE1D channel network delineation model and multiple-scaled channel networks and flow model into AIMS.
2.3. Develop assessments of the AIMS integrated technology with case studies.
2.4. Explore cloud computing capability for AIMS.
Approach
In order to better assess and predict the direct impacts of water availability and soil erosion from agricultural fields, gullies and channels, existing technology must be developed and upgraded to assess and improve predictions for more realistic conditions. This includes technology that is needed for decision making in identifying, targeting and implementing conservation practices that protect the landscape. The first objective of the project plan focuses on the development and improvement of numerical models associated with watershed erosion and sediment transport processes, water quality issues due to agro-pollution, and surface-groundwater interactions in agriculture landscapes. This objective relates to the ARS National Program Action 211, Component 1 (Effective Water Management in Agriculture) and Component 2 (Erosion, Sedimentation, and Water Quality Protection). The second objective focuses on the development and improvement of a watershed management tools to assess runoff, sediment, and water quality conservation practice impacts. This objective is related to NP 211 Component 1 and Component 4 (Watershed Management to Improve Agroecosystem Services).
Progress Report
Subobjectives (1.1.1--1.1.4): The development of CCHE1D looped channel network model consisted of two parts: the development of CCHE1D numerical model and the development of CCHE1D-GUI (Graphic User Interface). As for the CCHE1D numerical model, the junction-point water stage prediction and correction (JPWSPC) method was implemented to solve the looped channel network with both flow confluences and divergences. The new CCHE1D looped channel network model and its new solver have been validated by benchmark convergent flow, divergent flow, unsteady flow, and urban flooding cases. And as for the CCHE1D-GUI, the watershed-merging delineation has been integrated and a digitization tool for looped channel network generation were developed. A new automatic channel network generation algorithm for dendritic channel network for overland flow simulations based on the watershed-merging algorithm has also been developed, which can be considered the basic framework for the automatic looped channel network generation.
Subobjectives (1.2.1--1.2.3): The CCHE2D soil erosion model, a physically-based hydrodynamic numerical model, with updated raindrop erosion effects, has been developed and applied to simulate landscape evolution processes as a result of raindrop impact and overland flow. This model simulates a thin layer of runoff and concentrated flow over complex terrains, and predicts sediment transport due to raindrop splash detachment, transport and soil surface erosions.
The CCHE2D-CUDA model for GPU (Graphic Process Unit) is being developed, based on which the computing efficiency of the CCHE2D soil erosion model will be enhanced. In CCHE2D-CUDA, the parallelized ADI (Alternate Direction Implicit) solver has been refined and the parallelized SIP (Strong Implicit Procedure) solver is under development. A technical manual describing this CCHE2D-CUDA model has been drafted.
The CCHE2D-Hybrid for sediment transport model has been developed. This model is based on a hybrid unstructured mesh system consisting of triangle and quadrilateral cells. It adopts a conservative accurate edge interpolation method and a multi-point momentum interpolation correction method. This single-phase non-equilibrium sediment transport model aims for non-uniform non-cohesive sediments in unsteady turbulent flows.
Subobjectives (1.3.1--1.3.3): The technical manual of the three-dimensional finite element groundwater model, CCHE3D-GW, has been completed. CCHE3D-GW, which includes the compiled executable file, technical manual and quick start guide, has been uploaded online (https://www.ncche.olemiss.edu/cche3d-gw/). In addition, a new three-dimensional meshless model, CCHE3D-GW-Meshless, using meshless weak-strong form method has been developed. CCHE3D-GW-Meshless has been verified with three representative cases which are (a) one-dimensional infiltration in an initially unsaturated soil (unsaturated groundwater flow), (b) pumping in a confined alluvial aquifer near a river (fully saturated groundwater flow) and (c) pumping in an unconfined aquifer which includes the vadose zone (pumping in the variably saturated groundwater flow). CCHE3D-GW-Meshless has then been applied to a field case which is a pumping near a meandering river located in Shellmound, Mississippi, USA.
A numerical groundwater model has been developed for the Groundwater Transfer and Injection Pilot (GTIP) project at Shellmound, Mississippi, USA, using CCHE3D-GW. In addition to the saturated zone, the hydraulic properties of the vadose zone (unsaturated zone) were found significant to affect the hydrological processes controlling groundwater pumping and injection in the aquifer by our numerical experiments. As a result, precipitation, evapotranspiration and soil moisture data from the NASA North American Land Data Assimilation System (NLDAS) were used to estimate the soil properties in the vadoes zone through data assimilation. Good agreement between the simulation results and the measured data indicates the potential of using this model to facilitate the decision-making on the aquifer recharge project.
A nonlinear floodwave response model (NFRM) that can consider the nonlinearity resulting from the time-varying streambed conductivity has been developed using a space-time collocation Trefftz method. Compared to the traditional floodwave response model concerning the groundwater-surface water interaction, this NFRM is not limited by the conditions of stationary linear aquifer-stream system and a hydrostatic equilibrium initial condition, making it more broadly applicable. This NFRM has been verified with multiple synthetic cases. It has then been applied to the Tallahatchie River at the site in the Leflore County, Mississippi, USA to estimate the time-varying streambed conductivity.
Subobjectives (1.4.1-1.4.5): A new water quality module has been developed to simulate the particulate and dissolved nutrients for the CCHE_2D/3D_WQ model. The phosphate (PO4), organic phosphorus (OP), and organic nitrogen (ON) were each partitioned into particulate and dissolved forms that are simulated separately. The processes of adsorption/desorption, bed release, and exchange due to sediment deposition/resuspension were considered. The concentrations of particulate/dissolved nutrients as well as total nutrients can be simulated by this module.
The CCHE_MIX_WQ model and AnnAGNPS watershed model have been linked to study the response of lake water quality to the upland agricultural practices. The AnnAGNPS model was applied to simulate runoff, loads of sediment and nutrients from upland watersheds under alternative agricultural practices. The outputs of AnnAGNPS were set as inlet boundary conditions for CCHE_MIX_WQ to simulate water quality in the receiving waterbody. The CCHE water quality and pollutant transport models have been tested and validated using field measurements provided by NSL researchers to NCCHE researchers. This model has been tested for Beasley Lake watershed to study the lake water quality response to alternative tillage practices in the watershed.
In general, wind-generated waves are not an important concern in rivers due to the limited fetch length and flow depth. However, wind-generated waves can become large enough to have a significant impact on the banks of large, wide, impounded rivers, large canals, embayments and reservoirs. To estimate the relative contribution of wind-generated waves on embankment erosion and provide reliable tools for the analysis of bank-retreat processes and effective mitigation strategies, a wind-generated wave erosion module was developed. A new wave erosion module was developed and added to the Bank Sediment Transport Erosion Model (BSTEM). The module calculates the additional bed shear stress resulting from wind-generated waves by considering wave transformation and breaking along the bank profile. The updated BSTEM-Dynamic model was applied to a synthetic bank retreat test case.
Subobjectives (2.1.1-2.4.1): Agricultural Integrated Management System (AIMS) is a web-based decision support tool for running watershed and channel models with automated input data preparation. AIMS serves as an environment for evaluating the impacts of agricultural and channel conservation management practices for any watershed in the United States.
AIMS system has been migrated to a new environment under the Django framework. The state-of-the art Django framework allows using Python-based modules/apps for geospatial data layers and databases. Currently the new version of AIMS portal allows users to create accounts, create projects and scenarios under projects, as well as visualize various geospatial data layers.
Integration of TOPAGNPS into AIMS has been completed. This integration included running TOPAGNPS for the entire United States at approximately 30 m resolution. The new procedure allows users to view the AnnAGNPS cells and stream network for any watershed of HUC12 size or larger. Since the data is already generated, TOPAGNPS results are provided to the users instantly through the web interface. With a single user-identified outlet point on the web interface, AIMS automatically assembles the watershed draining to the user-provided outlet.
Integration of CCHE1D Model and other geospatial data layers including the High-Resolution National Hydrography Dataset (NHDplus) and NASA remotely sensed data into AIMS is also ongoing. Data input/output connections between TOPAGNPS and CCHE1D has been completed. NHDplus stream network and HUC boundaries have been integrated and currently available on the AIMS interface.
With the current development work underway for AIMS, the system backend operation is based on the Django framework. This is a high-level Python framework and, as such, allows for programmatic access to Google Cloud Services (GCS) using the Google Cloud Python API. Feasibility testing has already been performed with the creation of the Python code necessary to “spin up” single-purpose GCS instances in order to process compute jobs and transfer the results back to on-premise systems (the AIMS storage server).
Accomplishments
1. An automatic tool for dendritic channel network generation for overland flow simulation. This tool is based on geometric and hydrologic principles. The geometric principle requires that the generated channel network covers the whole study domain without overlapping, while the hydrologic principle requires that the generated channel network follows the steepest slope. Correspondingly, the proposed generation algorithm includes two main processes: (1) the extraction of channel network using a slope-calculation-based delineation algorithm; and, (2) the generation of cross sections with automatic channel width determination by comprehensively considering the aspects of the geometric complexity, the hydrologic validity, and the hydrodynamic computations. This tool will significantly alleviate the difficulties and boost the efficiency in generating 1D channel networks for CCHE1D model.
2. A 1D hydrodynamic model for overland flow simulations on complex 2D domains. Conventionally, two-dimensional (2D) models are used to simulate 2D overland flow with a non-overlapping 2D computational mesh. However, 2D models may have computing efficiency concerns for large-scale domains. ARS researchers in Oxford, Mississippi, developed a modified CCHE1D model for 2D overland flow simulations in order to make use of its high computing efficiency. Based on the channel network generated by following geometric principles and hydrologic principles, CCHE1D model is capable of efficiently simulating overland flow on 2D complex domains with comparable accuracy. Two corresponding journal papers have been drafted to be submitted to the Journal of Applied Sciences. This developed model can be used by USDA and other governmental agencies to evaluate soil erosion control practices for agricultural land management.
3. A physically based numerical model for the landscape evolution of soil-mantled watersheds driven by rainfall and overland flow. The CCHE2D soil erosion model solves hydrodynamic flow equations for rainfall-induced overland flows and concentrated flows, and bed-load transport equation combined with the rain splash induced erosion and transport mechanisms. This model is capable of simulating detailed sheet flow and concentrated flow in flat surfaces, rills and gullies, and raindrop detachment, transport and soil erosion due to these flows. Distinguished from larger-scaled hydrology models, such as RUSLE, this developed model can be used for small-scaled soil erosion control practices with more details in agricultural land management.
4. A 2D hybrid sediment transport model. The CCHE2D-Hybrid is a two-dimensional hydrodynamic sediment transport model that uses the Finite Volume Method based on a computational mesh that decomposes rivers, reservoirs, lakes or agricultural fields using triangular and quadrilateral cells. This model is a single-phase non-equilibrium sediment-transport model for non-uniform and non-cohesive sediments in unsteady turbulent flows that considers multiple sediment transport processes such as deposition, erosion, transport, and bed sorting. This model is featured with a hybrid unstructured mesh system for easy mesh generation in complex domains. To avoid interpolation from vertices in conventional unstructured models, this model adopted a second-order accurate edge gradient evaluation method to consider the mesh irregularities based on Taylor’s series expansion. In addition, the multi-point momentum interpolation corrections were integrated to avoid possible non-physical oscillations during the wetting-and-drying process, common in unsteady sediment transport problems, to ensure both the numerical stability and the numerical accuracy. This sediment transport model can provide guidance for reservoir operations and prevention measures for erosion in rivers and gullies.
5. Development and documentation of the CCHE3D-GW model. A process-based numerical model is a useful decision-support tool for sustainable agriculture, because it can enhance our understanding of the hydrological processes of groundwater flow as well as objectively evaluate practices for effective groundwater resources management. Unsaturated groundwater flow is important for agricultural practices, with the most used groundwater model, MODFLOW, focusing only on the saturated zone. To fill this gap, a three-dimensional finite element model, CCHE3D-GW, has been developed by ARS researchers in Oxford, Mississippi. This model can simulate the saturated and unsaturated groundwater at the same time, and has been successfully applied to a managed aquifer recharge experimental site installed by USDA-ARS at Shellmound, Mississippi. With this new groundwater model, our USDA-ARS partners can consider the impacts of agricultural practices, such as irrigation and percolation, which will make the results more realistic.
6. Development of the CCHE3D-GW-meshless. Physics-based numerical groundwater model can accurately simulate complex hydrodynamic processes, making it a good candidate as a decision-support tool for groundwater resources management. Meshless numerical models have recently been developed of the difficulty in mesh generation to describe groundwater systems. Current meshless numerical groundwater models either only focus on pumping in the fully saturated zone or merely simulate the variably saturated groundwater flow without pumping. However, both pumping and variably saturated groundwater flows are essential components for a groundwater model. As a result, a new three-dimensional model, CCHE3D-GW-Meshless, using a state-of-the-art meshless method has been developed by ARS researchers in Oxford, Mississippi, for the variably saturated groundwater flow with the consideration of pumping/injection. This new model has been applied to study an experimental groundwater pumping and injection operation at Shellmound, Mississippi, USA, from April 14 to April 19 in 2021. Meandering rivers are commonly encountered in the study of the groundwater-surface water interactions in the Mississippi River valley alluvial aquifer, whereas it is often hard to generate a high-quality mesh for such a complex geometry. This cumbersome and time-consuming mesh generation can be avoided by using this meshless model.
7. Incorporation of NASA NLDAS climate and soil moisture data into a groundwater model. The hydraulic properties of the vadose zone (unsaturated zone) has been found important to not only the agricultural practices but also the pumping and injection in the saturated zone. However, most of current studies of managed aquifer recharge ignore this area. To fill this gap, the NASA North American Land Data Assimilation System (NLDAS) has been used by ARS researchers in Oxford, Mississippi, to estimate the soil properties in the vadose zone. The estimated unsaturated soil properties were then implemented into a groundwater model for Shellmound, Mississippi, USA. With this dataset, the impact from the unsaturated zone has been considered in the groundwater model, which improves the quality of the simulation results. With the incorporation of the NASA NLDAS data, the hydrology of the vadose zone can be better simulated, which can facilitate future studies of the agricultural irrigation, percolation, evapotranspiration and rainfall-induced precipitation.
8. Development of nonstationary floodwave response model. Streambed conductivity can vary significantly over short time intervals during flood events, altering groundwater-surface water interactions. Traditional floodwave response model (FRM), including our FRM developed last year, developed by linking a unit step response function with the convolution integral are limited by the conditions of a stationary aquifer-stream system and a hydrostatic equilibrium initial condition. However, these two conditions can hardly be satisfied when streambed conductivity changes with time. As a result, a new computer model is being used by ARS researchers in Oxford, Mississippi, that can consider time-varying streambed conductivity is developed this year. This model can be used to either compute groundwater responses to the fluctuations of river stage with known streambed conductivity or estimate time-varying streambed conductivity with measured river stage and groundwater head. With this tool, ARS partners can rapidly obtain the streambed conductivity based on the groundwater responses to the river stage variations. Because streambed conductivity is an imperative parameter for the groundwater-surface water interaction, this novel model is the foundation for the future studies concerning the stream-aquifer exchange in the Mississippi River valley alluvial aquifer.
9. The CCHE1D_WQ model has been updated for simulating water quality constituents in surface waterbodies. This model can be used to simulate the nitrogen cycle, phosphorus cycle, phytoplankton kinetics and dissolved oxygen balance. It has been linked with the AnnAGNPS watershed model to simulate water quality in channel network by considering sediment and nutrient loads from upland watersheds. This linked modeling system provides useful information to ARS researchers in Oxford, Mississippi, for water quality management in the watersheds and surface waterbodies. It has been applied to Goodwin Creek Watershed for modeling flow, sediment, and nutrients.
10. A new module has been developed for simulating particulate and dissolved nutrients as part of the CCHE_2D/3D_WQ model. The processes of adsorption/desorption of nutrients by sediment, and nutrient release from bed sediment were considered. In addition, the nutrient exchanges due to sediment erosion/deposition were also considered. The concentrations of particulate and dissolved nutrients, as well as total nutrients can be simulated by this module. This assisted ARS researchers in Oxford, Mississippi, to improve their understandings on the interactions between sediments and nutrients in waterbodies.
11. The CCHE_MIX_WQ model and AnnAGNPS watershed model have been linked to study the response of lake water quality to upland agricultural practices. The AnnAGNPS model was applied to simulate runoff and loads of sediment and nutrients from upland watershed. The simulated results were used as boundary conditions by ARS researchers in Oxford, Mississippi, for CCHE_MIX_WQ to simulate water quality constituents in surface waterbodies. Two models were calibrated and validated using measured data in Beasley Lake Watershed. This integrated modeling system was applied to analyze the effects of cropping and tillage systems on the water quality in Beasley Lake. This integrated modeling system has been tested for the Beasley Lake watershed.
12. A new computational module has been developed to estimate wave-induced erosion of embankments. The model is designed to accept either wind parameters or wave parameters. Wind data include the mean wind speed at a 10 m elevation and the effective fetch length, which is the offshore distance over the water surface in the direction of the wind. Wave data include the spectral description of the significant wave height (four times the standard deviation of the wave signal) and peak wave period (the wave period corresponding to the spectral peak). When wind information is provided as input, the model calculates the significant wave height and peak wave period based on JONSWAP spectrum. The wind-wave prediction algorithm using JONSWAP spectrum is tested using an existing field dataset. The model also considers wave height variation along the shoreline due to processes such as refraction, shoaling, breaking and runup, and calculates the wave related shear stress along the embankment face. This module has been successfully tested by ARS researchers in Oxford, Mississippi, for a set of hypothetical bank erosion situations.
13. The Agricultural Integrated Management System (AIMS) web-based system and its components have been upgraded to facilitate the implementation of the new technology described in subobjectives 2.1-2.3. The migration of AIMS to the new Python-based Django framework has been successfully completed by ARS researchers in Oxford, Mississippi. To store these results, a database was designed and implemented on the AIMS testbed, including cell and reach data sections. Furthermore, geospatial data tables were created to store cell and reach geometries, which are used to display various simulation boundaries and features. Database functions were developed to assemble AnnAGNPS network and cells based on user-provided outlet points, dynamically creating watershed boundaries and relevant data. The soil data for the entire United States was downloaded from the NRCS Soil Data Access service and then processed with software NITA (NASIS Import To AnnAGNPS). NASA NLDAS climate data were tested through a pilot study, and corresponding papers have been presented at conferences and prepared for journal submission. A "Technical Procedures" document for AIMS has been drafted, providing guidance on system operations. AIMS' capabilities were demonstrated at the SEDHYD-2023 Computer Demonstration Session, showcasing its advancements.
Review Publications
Zhang, Y., Al-Hamdan, M., Wren, D.G. 2023. Development of a two-dimensional hybrid sediment transport model. Applied Sciences. 2023. 13. 1940. https://doi.org/10.3390/.
Chao, X., Witthaus, L.M., Bingner, R.L., Jia, Y., Locke, M.A., Lizotte Jr, R.E. 2023. An integrated watershed and water quality modeling system to study lake water quality responses to agricultural management practices. Environmental Modelling & Software. 164. https://doi.org/10.1016/j.envsoft.2023.10569.
Camacho, R., Zhang, Z., Chao, X. 2022. Receiving water quality models. In: Total Maximum Daily Load Development and Implementation Models, Methods, and Resources. Zhang, H.X; Quinn, N.W.T; Borah, D.K,; Pandmanabhan, G. Eds. American Society of Civil Engineers. Vol. 150, p 85-106.
Jia, Y., Wells, R.R., Momm, H.G., Zhang, Y., Bennett, S. 2023. Physically based numerical model for the landscape evolution of soil-mantled watersheds driven by rainfall and overland flow. Journal of Hydrology. 620 (2023) 129419. https://doi.org/10.1016/j.jhydrol.2023.129419.
