precision. The accuracy in terms of the root-mean-square error (RMSE) was estimated to be 2.71 m when compared to using Ice, Cloud, and Land Elevation Satellite altimetry data. The bare-Earth topography from the InSAR and altimetry data showed a higher accuracy than two other vegetation-bias-corrected DEMs: multi-error-removed 20°36′ 20°48′ 21°00′ 21°12′ improved-terrain (RMSE: 4.95 m) [73] and bare-Earth SRTM (RMSE: 3.32 m) [74]. This method has the advantage of capturing subtle elevation gradients within wetlands and relies on InSAR- and radar-altimetry measurements. Therefore, the failure of either technique could result in data gaps in the obtained topography. 20°36′ 2°12′ 21°00′ 21°12′ 2°12′ 2°00′ 2°00′ km 1°48′ 0 10 20°36′ 20 2°00′ 2°00′ km 1°48′ 20 30 0 21°00′ 0 40 60 (a) 20°48′ 80 21°00′ 10 20 30 21°00′ cm 100 120 -120 -100 -80 -60 -40 -20 (b) 21°12′ 20°36′ 20°48′ 21°00′ cm 20 0 21°12′ 2°12′ 2°12′ 2°00′ 2°00′ km 1°48′ 0 10 2°00′ km 0 30 10 20 30 20°48′ 21°00′ 10 20 30 21°00′ cm 50 40 cm -80 -70 -60 -50 -40 -30 -20 -10 0 (d) (c) 20°36′ 2°00′ 1°48′ 20 21°00′ 0 21°12′ 20°36′ 2°12′ 20°48′ 21°00′ 21°12′ 2°12′ 2°00′ 1°48′ 20°48′ 2°00′ km 0 10 20 10 20 30 (e) 2°00′ km 1°48′ 30 0 21°00′ 0 2°00′ 40 50 cm 60 10 20 30 21°00′ 0 10 20 30 40 50 60 cm 70 (f) FIGURE 8. The multitemporal water-flow direction derived from InSAR and the mass-continuity equation for the Congo wetlands (from [64]). (a) 19 September-20 December 2007. (b) 20 December 2007-21 June 2008. (c) 19 June-4 August 2007. (d) 12 May-27 June 2010. (e) 6 May-21 June 2008. (f) 27 June-27 September 2010. 130 IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE MARCH 2020