California Drought

Wet Year (2011) vs. Dry Year (2014)

ES 771 Remote Sensing Fall 2014
Kyle Jackson & Calif Tervo

Conclusion

The 2011 and 2014 NDVI images from the Silver City area of Sequoia National Park show a much stronger contrast than any of the composite images. The 2011 NDVI image shows a strong amount of photosynthetic activity, especially in the western portion of the image, where most of the montane forest occurs. The 2014 image also shows most of the photosynthetic activity in the montane forest. However, photosynthetic activity in this image appears to be significantly less in the 2014 image than the 2011 image. It is likely that the reduction in photosynthetic activity in 2014 is due to the demise of plants that are less adapted to tolerate drought. Most of the active vegetation in 2014 is probably comprised of pine, sequoia, and fir trees. The montane forested areas appear to have tolerated the drought more than lower regions with plants that rely more heavily on precipitation. However, regions immediately surrounding the rivers also show higher amounts of photosynthetic activity. This could indicate that at least the main rivers and creeks have maintained water throughout the drought.

For both Spanish Flat and the Santa Cruz Mountains, the NDVI images seem to be the best indicators of the drought. The Santa Cruz Mountains showed the least effect of the drought. This may be because it adjoins the ocean and receives some amount of moist air, fog, or dew that is beneficial but goes unrecorded.

The effects of the drought are not as pronounced in these montane environments as in some other areas. There appears to be no noticeable tree die off. If that happened, then the differences between 2011 and a future year may be more pronounced.

It was much more difficult to get good quality images for desired times than we thought it would be. We were often thwarted by cloud cover near the coast, haze in the inland locations, and Landsat 7’s non-functioning Scan Line Corrector (SLC).