Time Series Analyses of Changes in Surface Area of South Korean Estuaries from 1985-2015: Developing New Tools and Protocols Using Global Surface Water Datasets Within Google Earth Engine and ArcGIS

Abstract

Estuaries play key roles in both marine and fluvial ecological health, as they house some of the largest biodiversity in the world, provide important marine habitat, including nursery grounds for both fin and shellfish, and act as filters and buffers between saltwater and freshwater. They are also important for geologic stability, as they stabilize shorelines and protect coastal areas from large tidal events, storm surge and coastal flooding. However, many estuaries as well as drainage basins, globally, have been heavily altered over time, due to the expansion of urban areas, flood water controls, freshwater retention, storm surge and tsunami mitigation and the implementation of intensified agricultural practices. Given the variety of estuarine types and settings as well as the high degree of coastal modification, it can be difficult to examine changes over time. One way many researchers study estuaries is through aerial images and datasets. This project will use a Global Surface Water Dataset (GSWD) and display it in both Google Earth Engine and ArcGIS in order to delineate estuaries and compare their changes in surface area across a time series of images (1985-2015) in South Korea. Within South Korea, there are 463 identified estuaries, 49% of these estuaries have been closed with estuarine dams. In addition, the vast majority all of the Korean estuaries (both with and without estuarine dams) have been modified by land reclamation and seawalls. Natural morphodynamic feedbacks to these alterations have led to further alteration of the systems. To quantify these changes across the time series, Geospatial Methodology will be developed and implemented, including clipping the GSW dataset to South Korea, buffering shoreline datasets, using stream datasets to intersect with the GSW dataset to locate major estuaries, and examining the change in size of individual estuaries. This project will establish a set of tools that can be used for estuarine delineation and quantification of change detection within these estuaries.