Hydroclimatology of the 2001 Lena River Flooding: An analysis and geophysical data framework for pan-Arctic environmetal studies

Factors contributing to the historic flooding along the Lena River in May 2001 are examined using a collection of geophysical data sets for the pan-Arctic region. This framework of geophysical data, model simulations, and analytic tools has been developed to study the regional- and continental-scale Arctic hydrology in an effort to quantify the flux of freshwater to the Arctic Ocean. Contributing factors in this catastrophic flooding were the anomalously high snowfall in the southern part of the basin following a winter of extreme cold. Rapid warming in early May, with air temperatures of over 20°C early in the melt season produced excessive snowmelt and runoff in the southern headwaters of the basin.Ice jams, with anomalously high ice thicknesses following the extreme cold exacerbated the rise in water stage near the cities of Lensk and Yakutsk. Recently obtained discharge records for several subbasins with the most severe flooding are compared with modeled values from the pan-Arctic Water Balance Model. Areas most susceptible to flooding are determined by utilizing landscape slope as a proxy for channel and floodplain morphology. Our analysis illustrates the convergence of hydroclimatic and landscape factors that led to extreme flooding across parts of this region. This study also sheds light on our ability to produce accurate estimates of the land-to-ocean freshwater fluxes