Trends in Irrigation and Streamflow in the National Climate Assessment-LDAS using the NASA Land Verification Toolkit software

The heavily interconnected nature of the U.S. hydrologic system means that studies of the impact of climate change cannot be reliant on individual metrics. Instead, observing the connections between a wide variety of metrics are necessary to fully understand how the hydrologic system is changing. The aim of this project is to investigate recent trends in streamflow and irrigation in particular, using the National Climate Assessment – Land Data Assimilation System (NCA-LDAS) dataset. The NASA Land Verification Toolkit (LVT) software was used to calculate a variety of useful indicators and metrics from Land Information System (LIS) model output. The three types of metrics used in this project were mean, correlation, and trend. All were calculated over a variety of time scales over varying parts of the NCA-LDAS dataset. Also tested were the effects of varying metric computation frequencies and the confidence intervals used in Mann-Kendall tests to determine the statistical significance of detected trends. The results showed generally increasing streamflow in the Great Plains and the Northeast, while streamflow decreased in the Southeast and the West. Furthermore, irrigation in the West showed a strong inverse correlation with precipitation while irrigation in the Great Plains showed less correlation with precipitation. Finally, the trends in streamflow in NCA-LDAS showed good correspondence with trends in USGS streamflow gauge observations.