[A-CG45] 陸域〜沿岸域における⽔・⼟砂動態

[ACG45-11] Infrastructure and algorithm preparations for integrating lakes and reservoirs to SWOT’s river discharge estimations

★Invited Papers

*Jida Wang¹、Md Safat Sikder¹、George H Allen²、Ryan Riggs²、Yongwei Sheng³、Dai Yamazaki⁴、Jean-François Crétaux⁵、Tamlin Pavelsky⁶ (1.Kansas State University、2.Texas A&M University、3.University of California, Los Angeles、4.The University of Tokyo、5.Laboratoire d'Études en Géophysique et Océanographie Spatiales (LEGOS), Centre National d'Études Spatiales (CNES)、6.University of North Carolina, Chapel Hill)

キーワード：Lake, River, Surface Water and Ocean Topography (SWOT) mission, Reservoir, discharge algorithm, infrastructure database

Lakes and reservoirs are integral components of the global drainage system. Although typically considered as surface water stores, lakes and reservoirs function as “virtual gauges” on the river network, with their storage variation reflecting and affecting discharge changes between the connecting rivers. Despite this inherent interconnection, lakes and rivers are currently treated as two separate domains by the product team of the Surface Water and Ocean Topography (SWOT) satellite mission. Integration of these two components has become increasingly necessary to facilitate a synergistic use of both SWOT’s lake and river products. This presentation will review two aspects of ongoing progress from the SWOT Science Team on this critical integration. The first aspect emphasizes “infrastructure” database construction. Specifically, we are leveraging the SWOT a Priori Lake Database (PLD) and the SWOT River Database (SWORD), in combination with the high-resolution MERIT Hydro hydrography dataset, to produce a harmonized a priori global lake-river database. This harmonized database offers reliable connectivity and drainage relations among lakes and rivers, and in principle, allows us to track how each SWOT-visible lake may drain to a SWOT-visible river reach either directly or through SWOT-invisible reaches. The second aspect applies the harmonized a priori database to improving discharge algorithms. While existing SWOT discharge algorithms focus on free-flowing river reaches, we introduce the concept and preliminary results of “Lakeflow”, an algorithm tailored to discharge estimates at the lake-river interface. In brief, Lakeflow exploits the potential of lake-river mass conservation, and uses SWOT-observed lake storage changes as a primary constraint to optimize the flow-law parameters of the inflow and outflow river channels. We will then discuss about our collaborative efforts of integrating Lakeflow to the open-source SWOT software “Confluence”, and how it may complement other algorithms to benefit the monitoring of discharge-storage dynamics, particularly in ungagged and lake-dense regions. The importance of lake-river integration will also be discussed on the context of broader hydrological community such as limnology and hydrodynamic modeling.