Pivot to SWOT?

Science as a career field is unusual in many ways. One example: it's generally advisable to go job hunting a full year before your current position ends. For that reason, back in September, I started looking for a next position and initially focused on planetary science positions. Although I've made some good connections along the way and some of my position applications are still outstanding, I'm now about 6 months out from the end of my current position, and I recently started broadening my focus a bit. In the process, I've found some very exciting possibilities in terrestrial hydrology!

Although my PhD is in Planetary Sciences, my BS was in Geology and much of my work in recent years has focused on Earth, albeit with the ultimate goal of developing techniques to apply on other planets. Toward the end of grad school, I also developed a novel algorithm that can derive a centerline network from the polygonal footprint of a river. That project got me interested in automated descriptions of river geometry on Earth, and it turns out, that's a hot topic right now. In fact, I've had promising chats with three potential advisors looking for a postdoc with exactly that focus.

So, why is river geometry of such interest now? A big reason is one upcoming mission: the Surface Water and Ocean Topography (SWOT) mission, which is a join project of NASA and CNES (the French space agency), in partnership with the Canadian and UK space agencies (CSA and UKSA). It is scheduled to launch in February of 2022. SWOT will use radar altimetry to measure the heights of water, with an accuracy of ~1 cm! One of the most exciting aspects of the mission is that, for the first time, we will be able to measure the elevations of surface water across the entire globe, including all rivers ≥100 m wide and 100,000's of lakes and reservoirs (≥250 m2). From these elevation measurements, values such as reservoir volume and river discharge can be estimated but these estimates require paired description of the surface water geometry, which is where my expertise comes in.

As you probably know, climate change and population growth (among other issues) have strained water resources globally, highlighting the immense potential of SWOT. As examples, SWOT data and analysis can contribute in each of the following ways:

• Assess the impact of climate change on freshwater resources and inform mitigation efforts to avoid the worst impacts on human communities, agriculture, and industry.
• Continuously monitor (11-day revisit time) river discharge in areas that are currently unmonitored (or under-monitored) because of remoteness, political instability, or lack of resources. This monitoring will inform models and provide a critical guide for (1) natural hazard planning, including floods and droughts, and (2) management plans for water use, including urban, industrial, and agricultural.
• Provide vital information on the water resources that are shared by neighboring countries.
• Improve weather and climate forecasting by providing higher-resolution information of ocean conditions and surface hydrology.

I would be excited to apply my skills with computational geometry, computer vision, and modeling to maximize the scientific impact of SWOT data. One such application would be calibrating observed river reach geometries to their instantaneous discharges, while accounting for complicating factors such as slope, climate, recent weather, and soil type. We could then apply these calibrations to decades of Landsat (visible satellite) data to improve estimates of surface hydrology in recent history, effectively extending SWOT data backward in time. (A Landsat mosaic of the Lena River is shown below.) Combined with the documented prevailing climate, those estimates would provide a crucial guide to how future climate change will impact water resources and help to test land water models.