Analyzing the Reappearance of Tulare Lake by using Remote Sensing Techniques
Abstract
In 2023, Tulare Lake reappeared due to record rainfall. The lake has been dry for approximately 130 years. Back in the 1920’s waterways were diverted for agriculture. Today the lakebed is mostly covered with farmlands. The winter of 2023 brought so much water that it flooded nearly 100,000 acres in California’s central valley.
This study was conducted by using Google Earth Engine (GEE) to compute a harmonic trend of NDVI over the ancient lake bed. The reason this was chosen is because now that land is used for agriculture. The goal is to analyze how the crops were affected by the flooding. Along with the usage of GEE, R studio also assisted with analyzing the effects through Landsat 8 and Landsat 9 satellite images. These images are from March 2023 and April 2023, which is when the record rainfall and snowfall took place.
Results from the time-series show that there was a significant drop in vegetation health at the lakebed. The record rainfall and snowfall caused overflowing of the many waterways which flooded various agricultural lands. The Sierra Nevada mountain range east from Tulare Lake gained record snowfall and the runoff from those waterways directly fell into California’s Central Valley. A comparison of two images gives a clear visual representation of the flood zone.
Human interference of the Central Valley waterways show how catastrophic natural disasters can be if the wrong methods were taken, such as diverting ancient waterways.
Methods
A few steps were taken to get the results for this study. First Google Earth Engine was used to compute a Harmonic trend of NDVI to analyze vegetation health by using Landsat 8 and Landsat 9 satellite images.
After using GEE, the information was brought over to R Studio to further analyze the specific crops affected by the environmental changes caused from the flooding. In R studio, a randomForest function was conducted and created a new accuracy plot to bring in more visual representation of the study.
Results
The Landsat 8 and 9 NDVI time-series graphs show how in March and April there was a significant drop with crops in the study area around Corcoran, California. The graph also shows how nearly the entire year of 2023 there was a struggle to recover but the following year, especially in the summer months there was a large increase in agriculture production and vegetation health overall.
Another representation of the results is this map that analyzes the crop and non-crop areas. The white in some areas near the crops are the heavily flooded zones around Corcoran, CA.
Discussion
The data exposed how the flood zone impacted the crops and surrounding environment. Corcoran is the largest city near the floods with a population of 22,000. Real world applications of the reemergence of Tulare Lake implies the loss of crops. By looking at the NDVI graph on the left, it clearly demonstrates how the recovery of crops in the area took approximately 8 months to recover.
Conclusion
This study shows how ancient waterways can potentially cause hazardous conditions when rainfall occurs. Over 100 years ago, the lake was originally drained by the divergence of streams and rivers that led to Tulare Lake. The reason the waterways were diverted is because farmers needed more water and soil for agriculture. Then in 2023 farmers were negatively affected the most by the floods which demonstrated how waterways eventually followed ancient drainages.
These two Landsat images were classified and cropped through R studio then brought over to ArcGIS to further edit the layout. These images better display the peak rainfall effects by using RGB 6,5,4 which is for the vegetation analysis but also shows clearly how the flood took over the croplands.
References
Esri. (2025). ArcGIS Pro Documentation. Retrieved from https://pro.arcgis.com/en/pro-app/latest/help/main/welcome-to-the-arcgis-pro-app-help.htm
Google Earth Engine Developers. (2025). Google Earth Engine Platform Documentation. Retrieved from https://developers.google.com/earth-engine
Smithsonian. (2023). Smithsonian Magazine Smart News. Retrieved from https://www.smithsonianmag.com/smart-news/californias-long-dry-tulare-lake-has-returned-180982507
The Guardian. (2023). The Guardian News. Retrieved from https://www.theguardian.com/us-news/2024/mar/24/california-tulare-lake-shrinking
USGS. (2025). USGS Earth Explorer. Retrieved from https://earthexplorer.usgs.gov
USGS. (2025). United States Geological Survey. Retrieved from https://www.usgs.gov/faqs/what-are-band-designations-landsat-satellites