Drought Assessment of California Using ArcGIS and Remote Sensing

The objective of this study is to assess the severity of drought in California through multiple techniques using ArcGIS. We first collect precipitation data for the period 2011 to 2017 from weather stations in California, and calculate the Standardized Precipitation Index (SPI) to determine the drought level. Second, we select several vegetation rich sites and compare the Normalized Difference Vegetation Index (NDVI) from 2011 – 2017 to establish the interannual variations of green vegetation. Lastly we examine annual changes in lake surface area by manual digitization of remote sensing images. NDVI and SPI analysis showed California transition from slight, to moderate, and to severe drought conditions. NDVI decreased by more than 20% in certain areas, and lakes and reservoirs saw significant surface area reduction due to a lack of precipitation to recharge lake levels. However, 2017 has seen a large increase in precipitation, leading to the reversal of drought condition, but also regional flooding