Vulnerability to watershed erosion and coastal deposition in the tropics

Abstract

Over half of the global population is projected to live in the tropics by 2050. Sustainable land development will be challenged by enhanced sediment erosion and deposition, which can negatively impact water quality and ecosystem services in inland and coastal waterways. Existing erosion assessments treat watersheds and coastal zones separately, but we connect them in a two-part vulnerability index to watershed erosion and coastal deposition at 0.0004° (~ 45 m) resolution throughout the tropics. We use open-source datasets and a simple, GIS-based method geared toward tropical, novice end-users. Part 1 of the index reveals a majority of the tropics is vulnerable to erosion. Vulnerability is highest where there are co-occurrences of earthquakes, steep slopes, and high precipitation such as the Caribbean and Southeast Asia. In Part 2, we assess erosion vulnerability at 4 watersheds and include their coastal systems, which can enhance or diminish vulnerability of the entire system to coastal deposition.

Erosion and deposition vulnerability of small (<5,000 km2) tropical islands

“…We assess vulnerability to erosion and deposition on St. John using locally or regionally collected high-resolution datasets input into the EVI-EDVI method described in Browning and Sawyer [ 47 ]. Step-by-step instructions on the analysis are shown in Appendix A.…”

“…A new method developed by Browning and Sawyer [ 47 ] connects watershed erosion to coastal deposition across the tropics, termed the Erosion Vulnerability Index (EVI) and the coupled Erosion and Deposition Vulnerability Index (EDVI). This method focuses on land use change and open-source datasets in order to assess vulnerability to erosion and deposition across the entirety of the tropics.…”

“…St. John is representative to other small tropical islands vulnerable to erosion given its size (50 km 2 ), mountainous topography, concentrated rainfall, and rapid development. Furthermore, the wealth of data on St. John allows for testing the performance of a global erosion vulnerability index [ 47 ]. The lack of perennial streams allows for a very accurate estimation of sediment flux and deposition rates around the island.…”

“…This means that erosion and terrigenous deposition are driven by rainfall and thus the terrestrial signal is easy to identify, which aid in validating our qualitative results. We present results for all of St. John’s land area, including site-specific analysis of 2 watersheds using the low-resolution datasets from Browning and Sawyer [ 47 ] and new high-resolution field collected datasets.…”

Spatial pattern of the ecological environment in Yunnan Province

“…Scholars are interested in environmental sustainability [ 51 ], ecological environment quality [ 52 ], ecological environment carrying capacity [ 53 , 54 ], ecological footprint [ 55 , 56 ], environmental capacity, fragility, significance, and natural disaster risk. These assessments are used to examine the major areas: environmental resource management, biodiversity conservation amid development and social change; climate change adaptation, natural hazards, vulnerability, and resilience; urban environmental systems; multiscale deforestation and reforestation; food, agriculture, environment, and health; and energy and society transitions [ 35 – 57 ].…”