Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data

Abstract

Abstract. Quantification of surface water storage in extensive floodplains and their dynamics are crucial for a better understanding of global hydrological and biogeochemical cycles. In this study, we present estimates of both surface water extent and storage combining multi-mission remotely sensed observations and their temporal evolution over more than 15 years in the Mackenzie Delta. The Mackenzie Delta is located in the northwest of Canada and is the second largest delta in the Arctic Ocean. The delta is frozen from October to May and the recurrent ice break-up provokes an increase in the river's flows. Thus, this phenomenon causes intensive floods along the delta every year, with dramatic environmental impacts. In this study, the dynamics of surface water extent and volume are analysed from 2000 to 2015 by combining multi-satellite information from MODIS multispectral images at 500 m spatial resolution and river stages derived from ERS-2 (1995ERS-2 ( -2003, ENVISAT (2002ENVISAT ( -2010 and SARAL (since 2013) altimetry data. The surface water extent (permanent water and flooded area) peaked in June with an area of 9600 km 2 (±200 km 2 ) on average, representing approximately 70 % of the delta's total surface. Altimetrybased water levels exhibit annual amplitudes ranging from 4 m in the downstream part to more than 10 m in the upstream part of the Mackenzie Delta. A high overall correlation between the satellite-derived and in situ water heights (R > 0.84) is found for the three altimetry missions. Finally, using altimetry-based water levels and MODIS-derived surface water extents, maps of interpolated water heights over the surface water extents are produced. Results indicate a high variability of the water height magnitude that can reach 10 m compared to the lowest water height in the upstream part of the delta during the flood peak in June. Furthermore, the total surface water volume is estimated and shows an annual variation of approximately 8.5 km 3 during the whole study period, with a maximum of 14.4 km 3 observed in 2006. The good agreement between the total surface water volume retrievals and in situ river discharges (R = 0.66) allows for validation of this innovative multi-mission approach and highlights the high potential to study the surface water extent dynamics.

Variations of Surface and Subsurface Water Storage in the Lower Mekong Basin (Vietnam and Cambodia) from Multisatellite Observations

“…Then, linear interpolation was applied to estimate monthly surface-water height maps at similar spatial and temporal resolution as MODIS-derived surface-water extent maps. Finally, monthly variation of the SWS in the region was estimated as the product of the variations of the surface-water extent and surface-water height, following the approach described in References [18,30,35,40]. The variation of the SWS was validated by comparing with the variation of in situ discharge of the Mekong River and the variation of the TWS derived from GRACE data, showing very high linear temporal correlation of 96%, and 95%, respectively.…”

“…In the present study, our goal is to apply this multisatellite technique over the LMB located in Vietnam and Cambodia, to quantify the variations of the SWS and SSWS in the hydrological cycle, and estimate their contribution to TWS. To this end, surface-water extent maps derived from MODIS imagery at 500 m spatial resolution are combined with surface-water level variations maps estimated using ENVISAT altimetry data, similar to what was recently proposed by [34] and [35]. The study area was limited to latitude lower than the 13.5°( black rectangle in Figure 1-left) where ENVISAT altimetry data were good enough for extraction of surface-water height.…”

“…Monthly maps of surface-water level of the study area can be estimated by combining monthly satellite altimetry data at all 45 ENVISAT VSs and MODIS-derived inundated maps. At a given month, satellite altimetry data at the VSs are linearly interpolated over the inundated areas (from the corresponding MODIS-derived surface water extent map described in Section 3.1) to estimate the surface-water level at each grid point of 500 m spatial resolution following the approach developed by [33], and applied to MODIS-based inundation products [34,35]. Monthly maps of surface-water level of the study area at 500 m spatial resolution can be constructed for the 2003-2009 period.…”

Identifying Flood Events over the Poyang Lake Basin Using Multiple Satellite Remote Sensing Observations, Hydrological Models and In Situ Data

“…To assess the accuracy of MODIS-derived inundated area, the concurrent higher-resolution satellite imageries are always included for comparison [5,54]. In this study, the cloud-free Landsat-8 OLI (Operational Land Imager) image collected on 5 October 2013 is analyzed and compared with MODIS observations on 7 October 2013.…”

On the Feasibility of Water Surface Mapping with Single Photon LiDAR

“…Precise knowledge of area-wide water surface heights is inevitable for many disciplines such as hydrology, hydraulic engineering, flood risk management, ecology, climate change, etc. [1][2][3][4]. In hydro sciences, continuous water level heights are required as ground truth for calibrating and validating rainfall-runoff models [5] and multidimensional hydrodynamic-numerical models, also referred to as computational fluid dynamic (CFD) models.…”