Coastal Hypoxia Analysis and Risk Tracking (CHART) through Remote Sensing and Process-based Modeling in South and Southeast Asia: Review of Research Strategy and Results

Abstract:

ABSTRACT: Land-based nutrient sources from anthropogenic sources are driving increases in eutrophic conditions of inland and coastal waters around the globe. Loss of floodplains and wetlands along rivers and coasts reduces the capacity of systems to prevent or mitigate such threats. Our focus in this NASA InterDiscipinary Science project is South and Southeast Asia (SSEA), a region with rapid environmental change driven by urbanization, upland and wetland ecosystem change, and agricultural intensification. The project utilizes contemporary and archival optical and radar remote sensing to study how, where, and when watershed disruption has occurred in the SSEA region, and to assess changing coastal hypoxia risk associated with these land-based factors. Change detection using multi-sensor remote sensing of terrestrial watersheds and coastal zones help to identify key factors along the land-to-ocean continuum (as disrupted by human actions like dam/reservoir construction), which can then be related to eutrophication and development of hypoxia in offshore waters. We focus on 8 large SSEA watersheds, with detailed high-resolution modeling and multi-sensor ocean color data in two sub-domains: the Mekong Delta and the Krishna/Godavari deltas, and their respective coastal oceans. This talk summarizes our strategy to develop risk and threat indicators, their mapping, and interpretation as potential determinants of changes in coastal receiving waters, which have been observed through ocean color remote sensing and simulation. It also provides an overview of our key research findings. These include reconciliation of multi-sensor detection of wetland state and trends, hydrologically-mediated mobilization of chemical constituents from the uplands to the coasts, and the use of high resolution coastal ocean color remote sensing together with coastal ocean simulation to jointly detect changes in the physical and chemical character of associated river plumes.