This fall was my first semester working in Amanda’s lab. I started out by assisting Megan on compiling and analyzing her data from this past summer’s fieldwork in China. It was a great opportunity for me to continue building on the GIS skills that I have. Megan’s objective was to quantify the river’s change in a rural village in Yangjuan, China. She did this by using repeat photography, GPS data, GIS mapping techniques, and traditional surveying methods. She found that parts of the restoration effort of the rural village were relatively effective, but that during a 50-year flood they proved to be largely ineffective in protecting agriculture.
My part in this presentation was helping her to quantify the change by visually analyzing the data in ArcMap. I started out doing this by taking the GPS data she had tracking the left and right banks of the river and transforming the feature vertices to points. After adding surface information and running the Euclidean distance, I was able to quantify the change between the available 2010 data and the 2015 data so that I could measure the change in bank width between that period on both the left and right bank. I also digitized the riverbanks in order to create a simple graphic for Megan, which she could use to display her surveyed area. Lastly, I helped Megan to customize a map that showed the different landform properties of the river in order to help her audience visualize how the river has shifted and affected the land over the past seven years.
If I’d had more time, I would have turned the riverbanks into routes in order to create a longitudinal profile of the river displaying both elevation and distance.
Otherwise, I have spent the semester assisting in running sediment samples, sieving, and have been prepping for my own trip with Amanda to China this January. We will be looking to generate a comprehensive understanding of the fire history in western China. We are hoping to determine the background and long-term erosion rates in the Lower Jin Sha. Additionally, we want to describe the stratigraphy of the river and collect samples for radiocarbon dating. Combined, this data will allow us to figure out how frequent fires were in past years. The information will also inform us as to if large debris flows were related to these events. Ultimately, a greater understanding of how fire use in the Lower Jin Sha region relates to erosion will arise.