Browsing by Author "Pavelsky, Tamlin M."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Advancing Field-Based GNSS Surveying for Validation of Remotely Sensed Water Surface Elevation ProductsPitcher, Lincoln H.; Smith, Laurence C.; Cooley, Sarah W.; Zaino, Annie; Carlson, Robert; Pettit, Joseph; Gleason, Colin J.; Minear, J. Toby; Fayne, Jessica V.; Willis, Michael J.; Hansen, Jasmine S.; Easterday, Kelly J.; Harlan, Merritt E.; Langhorst, Theodore; Topp, Simon N.; Dolan, Wayana; Kyzivat, Ethan D.; Pietroniro, Al; Marsh, Philip; Yang, Daqing; Carter, Tom; Onclin, Cuyler; Hosseini, Nasim; Wilcox, Evan; Moreira, Daniel; Berge-Nguyen, Muriel; Cretaux, Jean-Francois; Pavelsky, Tamlin M. (Frontiers, 2020-11-23)To advance monitoring of surface water resources, new remote sensing technologies including the forthcoming Surface Water and Ocean Topography (SWOT) satellite (expected launch 2022) and its experimental airborne prototype AirSWOT are being developed to repeatedly map water surface elevation (WSE) and slope (WSS) of the world’s rivers, lakes, and reservoirs. However, the vertical accuracies of these novel technologies are largely unverified; thus, standard and repeatable field procedures to validate remotely sensed WSE and WSS are needed. To that end, we designed, engineered, and operationalized a Water Surface Profiler (WaSP) system that efficiently and accurately surveys WSE and WSS in a variety of surface water environments using Global Navigation Satellite Systems (GNSS) time-averaged measurements with Precise Point Positioning corrections. Here, we present WaSP construction, deployment, and a data processing workflow. We demonstrate WaSP data collections from repeat field deployments in the North Saskatchewan River and three prairie pothole lakes near Saskatoon, Saskatchewan, Canada. We find that WaSP reproducibly measures WSE and WSS with vertical accuracies similar to standard field survey methods [WSE root mean squared difference (RMSD) ∼8 cm, WSS RMSD ∼1.3 cm/km] and that repeat WaSP deployments accurately quantify water level changes (RMSD ∼3 cm). Collectively, these results suggest that WaSP is an easily deployed, self-contained system with sufficient accuracy for validating the decimeter-level expected accuracies of SWOT and AirSWOT. We conclude by discussing the utility of WaSP for validating airborne and spaceborne WSE mappings, present 63 WaSP in situ lake WSE measurements collected in support of NASA’s Arctic-Boreal and Vulnerability Experiment, highlight routine deployment in support of the Lake Observation by Citizen Scientists and Satellites project, and explore WaSP utility for validating a novel GNSS interferometric reflectometry LArge Wave Warning System.
- Extending global river gauge records using satellite observationsRiggs, Ryan M.; Allen, George H.; Wang, Jida; Pavelsky, Tamlin M.; Gleason, Colin J.; David, Cedric H.; Durand, Michael (IOP, 2023-05-26)Long-term, continuous, and real-time streamflow records are essential for understanding and managing freshwater resources. However, we find that 37% of publicly available global gauge records (N = 45 837) are discontinuous and 77% of gauge records do not contain real-time data. Historical periods of social upheaval are associated with declines in gauge data availability. Using river width observations from Landsat and Sentinel-2 satellites, we fill in missing records at 2168 gauge locations worldwide with more than 275 000 daily discharge estimates. This task is accomplished with a river width-based rating curve technique that optimizes measurement location and rating function (median relative bias = 1.4%, median Kling-Gupta efficiency = 0.46). The rating curves presented here can be used to generate near real-time discharge measurements as new satellite images are acquired, improving our capabilities for monitoring and managing river resources.
- A Framework for Estimating Global River Discharge From the Surface Water and Ocean Topography Satellite MissionDurand, Michael; Gleason, Colin J.; Pavelsky, Tamlin M.; Frasson, Renato Prata de Moraes D. M.; Turmon, Michael; David, Cedric H.; Altenau, Elizabeth H.; Tebaldi, Nikki; Larnier, Kevin; Monnier, Jerome; Malaterre, Pierre Olivier; Oubanas, Hind; Allen, George H.; Astifan, Brian; Brinkerhoff, Craig; Bates, Paul D.; Bjerklie, David; Coss, Stephen; Dudley, Robert; Fenoglio, Luciana; Garambois, Pierre-Andre; Getirana, Augusto; Lin, Peirong; Margulis, Steven A.; Matte, Pascal; Minear, J. Toby; Muhebwa, Aggrey; Pan, Ming; Peters, Daniel; Riggs, Ryan; Sikder, Md Safat; Simmons, Travis; Stuurman, Cassie; Taneja, Jay; Tarpanelli, Angelica; Schulze, Kerstin; Tourian, Mohammad J.; Wang, Jida (American Geophysical Union, 2023-04-06)The Surface Water and Ocean Topography (SWOT) mission will vastly expand measurements of global rivers, providing critical new data sets for both gaged and ungaged basins. SWOT discharge products (available approximately 1 year after launch) will provide discharge for all river that reaches wider than 100 m. In this paper, we describe how SWOT discharge produced and archived by the US and French space agencies will be computed from measurements of river water surface elevation, width, and slope and ancillary data, along with expected discharge accuracy. We present for the first time a complete estimate of the SWOT discharge uncertainty budget, with separate terms for random (standard error) and systematic (bias) uncertainty components in river discharge time series. We expect that discharge uncertainty will be less than 30% for two-thirds of global reaches and will be dominated by bias. Separate river discharge estimates will combine both SWOT and in situ data; these “gage-constrained” discharge estimates can be expected to have lower systematic uncertainty. Temporal variations in river discharge time series will be dominated by random error and are expected to be estimated within 15% for nearly all reaches, allowing accurate inference of event flow dynamics globally, including in ungaged basins. We believe this level of accuracy lays the groundwork for SWOT to enable breakthroughs in global hydrologic science.
- Lake-TopoCat: a global lake drainage topology and catchment databaseSikder, Md Safat; Wang, Jida; Allen, George H.; Sheng, Yongwei; Yamazaki, Dai; Song, Chunqiao; Ding, Meng; Cretaux, Jean-Francois; Pavelsky, Tamlin M. (Copernicus, 2023-08-08)Lakes and reservoirs are ubiquitous across global landscapes, functioning as the largest repository of liquid surface freshwater, hotspots of carbon cycling, and sentinels of climate change. Although typically considered lentic (hydrologically stationary) environments, lakes are an integral part of global drainage networks. Through perennial and intermittent hydrological connections, lakes often interact with each other, and these connections actively affect water mass, quality, and energy balances in both lacustrine and fluvial systems. Deciphering how global lakes are hydrologically interconnected (or the so-called "lake drainage topology") is not only important for lake change attribution but also increasingly critical for discharge, sediment, and carbon modeling. Despite the proliferation of river hydrography data, lakes remain poorly represented in routing models, partially because there has been no global-scale hydrography dataset tailored to lake drainage basins and networks. Here, we introduce the global Lake drainage Topology and Catchment database (Lake-TopoCat), which reveals detailed lake hydrography information with careful consideration of possible multifurcation. Lake-TopoCat contains the outlet(s) and catchment(s) of each lake; the interconnecting reaches among lakes; and a wide suite of attributes depicting lake drainage topology such as upstream and downstream relationship, drainage distance between lakes, and a priori drainage type and connectivity with river networks. Using the HydroLAKES v1.0 (Messager et al., 2016) global lake mask, Lake-TopoCat identifies ĝ1/4ĝ1.46 million outlets for ĝ1/4ĝ1.43 million lakes larger than 10ĝha and delineates 77.5×106ĝkm2 of lake catchments covering 57ĝ% of the Earth's landmass except Antarctica. The global lakes are interconnected by ĝ1/4ĝ3 million reaches, derived from MERIT Hydro v1.0.1 (Yamazaki et al., 2019), stretching a total distance of ĝ1/410×106ĝkm, of which ĝ1/4ĝ80ĝ% are shorter than 10ĝkm. With such unprecedented lake hydrography details, Lake-TopoCat contributes towards a globally coupled lake-river routing model. It may also facilitate a variety of limnological applications such as attributing water quality from lake scale to basin scale, tracing inter-lake fish migration due to changing climate, monitoring fluvial-lacustrine connectivity, and improving estimates of terrestrial carbon fluxes. Lake-TopoCat is freely accessible at 10.5281/zenodo.7916729 (Sikder et al., 2023).
- Satellites reveal hotspots of global river extent changeWu, Qianhan; Ke, Linghong; Wang, Jida; Pavelsky, Tamlin M.; Allen, George H.; Sheng, Yongwei; Duan, Xuejun; Zhu, Yunqiang; Wu, Jin; Wang, Lei; Liu, Kai; Chen, Tan; Zhang, Wensong; Fan, Chenyu; Yong, Bin; Song, Chunqiao (Nature Portfolio, 2023-03-22)Rivers are among the most diverse, dynamic, and productive ecosystems on Earth. River flow regimes are constantly changing, but characterizing and understanding such changes have been challenging from a long-term and global perspective. By analyzing water extent variations observed from four-decade Landsat imagery, we here provide a global attribution of the recent changes in river regime to morphological dynamics (e.g., channel shifting and anabranching), expansion induced by new dams, and hydrological signals of widening and narrowing. Morphological dynamics prevailed in ~20% of the global river area. Booming reservoir constructions, mostly skewed in Asia and South America, contributed to ~32% of the river widening. The remaining hydrological signals were characterized by contrasting hotspots, including prominent river widening in alpine and pan-Arctic regions and narrowing in the arid/semi-arid continental interiors, driven by varying trends in climate forcing, cryospheric response to warming, and human water management. Our findings suggest that the recent river extent dynamics diverge based on hydroclimate and socio-economic conditions, and besides reflecting ongoing morphodynamical processes, river extent changes show close connections with external forcings, including climate change and anthropogenic interference.