Drought Sensitivity and Trends of Riparian Vegetation in Nevada

Project Description

Maintaining the ecological integrity of riparian areas and other groundwater-dependent ecosystems (GDEs) is an important objective for natural resource and water managers, given the role of these systems in sustaining biodiversity and the other ecosystem services they provide. Long-term monitoring data are required to understand status and trends in these systems, which are often confounded by the influences of interannual climate variability. Yet, these data are expensive to collect and maintain and have historically not been widely available. Recent advances in cloud computing can now help to address these challenges, by allowing efficient and cost-effective processing and analysis of multiple decades’ worth of satellite remote sensing and climate datasets over large geographic extents.

In this study we analyzed climate-adjusted trends in riparian vegetation across the state of Nevada from 1985 to 2018 based on the 30 meter resolutionMap of Riparian Vegetation in Nevada. To accomplish this, we established relations between the Standardized Precipitation-Evapotranspiration Index (SPEI; a drought index representing the difference between precipitation and potential evapotranspiration for a select time period) and Landsat-derived normalized difference vegetation index (NDVI, an indicator of vegetation vigor) using linear regression. We then used this relationship to adjust for the influence of drought on NDVI and assessed the NDVI trend over time using a non-parametric Mann-Kendall trend test.

Our results highlight areas where changes in riparian vegetation have occurred that are likely due to natural disturbances or human impacts, as opposed to drought or interannual climate variability. This information helps to clarify and quantify the effects of management actions and can be used to target locations for field investigation or alternative management. We have coupled this work with targeted analyses of groundwater well trends and drone-based field assessments in high priority GDEs to interpret our results and identify potential causal factors of change.

The dataset is available for viewing here: https://dri-apps.earthengine.app/view/nv-riparian-trends

A publication describing the study is available here: https://www.mdpi.com/2072-4292/12/9/1362 – Albano, C.M.; McGwire, K.C.; Hausner, M.B.; McEvoy, D.J.; Morton, C.G.; Huntington, J.L. Drought Sensitivity and Trends of Riparian Vegetation Vigor in Nevada, USA (1985–2018). Remote Sens. 2020, 12, 1362.

The 30-meter resolution (1 GB) dataset is available upon request.

Please contact fill out the form below for access.

Christine M. Albano
Postdoctoral Fellow, Ecohydrology
Division of Hydrologic Sciences
Desert Research Institute
2215 Raggio Parkway
Reno, NV 89512
Christine.Albano@www-dev.dri.edu