Lake Tahoe – Land Use Land Cover Analysis – 1997 & 2024
(Geographic
Information System – Remote Sensing Final)
Lake Tahoe, the largest alpine lake
in North America, bordering California and Nevada has become increasingly
eutrophic (having an excessive richness of nutrients) over the past 3
decades. Nutrients have increased 5%
annually and clarity have decreased at an average rate of 0.25 meters per
year. The Lake Tahoe region has
undergone rapid urbanization over the past 3 decades and fine sediment,
resulting from land disturbance in the basin, accounts for about half of lake
contamination resulting in the lakes loss of clarity. The
largest source of fine sediment particles to Lake Tahoe is suspected to be from
urban upland storm-water runoffs, comprising 73% of the total fine sediment
particle load. It is also projected that
historic clarity, of approximately 30 meters, can be achieved by reducing
approximately 75% of fine sediment from urban sources. The goal of the Lake Tahoe – Land Use Land
Cover (LULC) Analysis is to provide Lake Tahoe land managers historic LULC classification
data, documented in attachment 1 (Map 1 - 1997) to present, documented in attachment 2 (Map 2 – 2024), to
help land managers plan for and upgrade storm water runoff infrastructure in an
effort to reduce contamination and improve Lake Tahoe's water clarity and to
document the efforts and process of the analysis.
The
process started by creating Map 1. Map 1
was created from the National Land Cover Dataset (NLCD_nad27) from 1992 data
file to include a data image and shape files updated in 1997. Second, a few minor changes were made to
correct feature classifications using techniques learned in lab 1. Lab 1 visual interpretation techniques were
used to view the image by patterns and association and compared with open data
source from Tahoe
Parcels Data | Tahoe Open Data . Lake
Tahoe’s Lake was found to be incorrectly classified, and the lakes attribution
data and symbology was incorrectly placed in the vegetation shape file. To correct the error a new feature class of
lake was created, and Lake Tahoe was placed under the new feature class and
symbology was updated. Third, using
knowledge, concepts and techniques learned in lab 2, Land Use Land Cover (LULC)
and lab 5, Unsupervised and Supervised Classification, a re-coding of the LULC
data re-code was performed to narrow LULC classifications to 5 classifications
and symbology of each recoded feature class was updated. Finally, a map layout of the updated
information was created, providing a historical reference.
Map 2 – was
created using landsat5_July6th2010 provided data set. First the file was uploaded to the ERDAS
software suite, using techniques and tools learned in lab 3, Image Spatial
Enhancement, Multispectral Data and Band Indices, several viewing tools were
used to analyze the image, and meta data was also viewed. Additionally, the masking tool was used to
create a one-layer image of the file, the image was uploaded to ArcGIS pro and
a Composite Band image was created. Next
, the El_Dorado_Parcels Shape file published 5 October 2017 and last updated 1 August 2024, datasets containing updated Lake Tahoe parcel
information, was downloaded from the Tahoe Regional Planning Agency at
URL: Tahoe
Parcels Data | Tahoe Open Data. Next,
a new map and layout was created in ARCGis to include the El_Dorado_Pacels
dataset and common data sets provided from 1997 using same or similar tools and
techniques to create map 1.
