Leveraging innovations in hydrologic sciences: deploying actionable information using USACE Civil Works tools

The Time Series Toolbox (TST) and Climate Hydrology Assessment Tool (CHAT) are online R Shiny tools that provide users with easy-to-navigate platforms for the analysis of hydrologic data. Without programming expertise, users can deploy streamlined analysis pipelines, enabling the kind of scientifically sound, repeatable analyses essential for evaluating changes to project performance and project risk as streamflows respond to climate change. For example, a user could apply these tools to a wetland restoration project to determine whether a long-term average favorable streamflow condition masks declining trends in precipitation and streamflow. This could mean habitat benefits are being overestimated and the proposed project may not be viable in the long run. This type of analysis is required for Civil Works projects by U.S. Army Corps of Engineers (USACE) Engineering and Construction Bulletin (ECB) 2018-14, which provides guidance for considering observed and projected changes to hydrologic processes. This guidance helps project planning teams understand how such changes might affect USACE Civil Works water resources project planning, design, construction, operation, and maintenance.

The Time Series Toolbox (TST) is designed to enable robust analysis of hydrologic and other time series data using an automated, user-friendly interface. This tool was developed in conjunction with USACE Engineering Technical Letter (ETL) 1100-2-3, “Guidance for Detection of Nonstationarities in Annual Maximum Discharges,” to detect nonstationarities in maximum annual flow time series. Per ETL 1100-2-3, engineers are required to assess the stationarity of all streamflow records analyzed in support of hydrologic analysis carried out for USACE planning and engineering decision-making purposes.

The TST can explore different components of time series analysis for either: (1) preloaded instantaneous streamflow and gage height data from all 29,000 United States Geological Survey (USGS) National Water Information System gages or (2) a time series uploaded by the user. The tool helps detect trends, seasonality, and change points within the data and allows users to fit autoregressive integrated moving average (ARIMA) models to their time series data. The tool features many visualizations, including time series graphs, model forecasts, and heat maps, that provide an effective way to communicate insights found within the data and help users better interpret results.

The CHAT allows users to visualize simulated hydrology over the historical period (1950-2005) and two projected future scenarios for the period 2006-2100. The data are derived from a 32-member Coupled Model Intercomparison Project Phase 5 (CMIP5) climate model ensemble downscaled using the localized constructed analogs (LOCA) method. Overland flows are generated using a variable infiltration capacity (VIC) model and routed using the mizuRoute method to produce uncalibrated, unregulated flows. Using these visualizations, users can efficiently conduct repeatable analyses that apply climate change impact to hydrologic parameters of interest. CHAT users can analyze the range, trend, and epoch-based changes of simulated streamflow variables. Additionally, users can analyze the slope and significance of a linear trend fit to the mean for the simulated historical and projected periods separately. Epoch-based changes (i.e., the difference between simulated historical and projected epoch means) can be analyzed on the monthly or annual scale. The visualization of monthly epoch-based changes allows users to assess seasonal changes in hydrology.

This presentation offers an overview of USACE’s TST and CHAT online tools, underscoring their utility in hydrology analysis and alignment with the guidelines set by ETL 1100-2-3 and ECB 2018-14 for USACE Civil Works projects.