Coupling multitemporal remote sensing with geomorphology and hydrological modeling for post flood recovery in the Strymonas dammed river basin (Greece)

Flood detection and monitoring is increasingly important, especially on remote areas such as African tropical river basins, where ground investigations are difficult. We present an experiment aimed at integrating multi-temporal and multi-source data from the Sentinel-1 and ALOS 2 synthetic aperture radar (SAR) sensors, operating in C band, VV polarization, and L band, HH and HV polarizations, respectively. Information from the globally available CORINE land cover dataset, derived over Africa from the Proba V satellite, and available publicly at the resolution of 100 m, is also exploited. Integrated multi-frequency, multi-temporal, and multi-polarizations analysis allows highlighting different drying dynamics for floodwater over various land cover classes, such as herbaceous vegetation, wetlands, and forests. They also enable detection of different scattering mechanisms, such as double bounce interaction of vegetation stems and trunks with underlying floodwater, giving precious information about the distribution of flooded areas among the different ground cover types present on the site. The approach is validated through visual analysis from Google EarthTM imagery. This kind of integrated analysis, exploiting multi-source remote sensing to partially make up for the unavailability of reliable ground truth, is expected to assume increasing importance as constellations of satellites, observing the Earth in different electromagnetic radiation bands, will be available.

Section: Preliminary Analysis-detection Of Open Floodwater As Decreasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Integrating C- and L-Band SAR Imagery for Detailed Flood Monitoring of Remote Vegetated Areas

Refice

Zingaro

D’Addabbo

et al. 2020

“…Generally, the channel response to anthropogenic interventions is rapid and depends not only on the type of intervention but also on the spatial scale. Several studies have demonstrated how variations in land use [3][4][5][6][7], urbanization [8,9], channelization [10,11], dam construction [12][13][14], and sediment mining [15][16][17][18] alter flow and sediment regimes, leading to changes in river dynamics and morphology. Over the past 200 years, the morphological fluvial dynamics of most European and Italian rivers have been mainly modified by human impacts [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…Reconstruction of the fluvial evolutionary dynamics highlights the effects of the influence (natural and anthropogenic) of geomorphological factors on the river system [11,40]. Over time, studies of river dynamics in Italy have received growing attention, as clearly shown by the bibliographical review conducted by [41] for the period 1963-2007.…”

Section: Introductionmentioning

confidence: 99%

Channel Changes and Controlling Factors over the Past 150 Years in the Basento River (Southern Italy)

Musso

Capolongo

Caldara

et al. 2020

Channel changes are receiving growing interest in relation to the relevant implications for river management and restoration. In this kind of analysis, purely qualitative approaches have been gradually replaced by quantitative approaches aimed at reconstructing the temporal variations in parameters (e.g., channel width and depth) to investigate not only the evolutionary trend of the river but also the possible cause-effect connections. This paper investigates the channel dynamics in the Basento River (Basilicata Region, Italy) over the past 150 years, when the river was heavily affected by human activities (e.g., hydraulic interventions and gravel mining) and climate changes. Channel adjustments were analysed with historical maps, aerial photos, and geomorphological surveys. The results show that the channel underwent a strong narrowing during the twentieth century, similar to many rivers in Italy, with the most intense phase from the 1950s to the 1990s (with the width varying from −30% to −80%). The morphology pattern remained almost completely unchanged, apart from a few reaches located in the hilly area that were affected by intense modifications before the 1940s. The causes of channel adjustments were identified as human disturbances (land use variations, channel interventions at the reach scale, sediment mining) from the end of the 1800s to present, as well as natural factors (changes in frequency, duration, and intensity of flood events), whose effects have intensified since the late 1990s.

“…For instance, Wang and Xu assessed channel bar morphologic changes in the highly regulated lower Mississippi River using Landsat imagery and river stage data [10,11]. Capolongo et al coupled multitemporal remote sensing with geomorphology and hydrological modelling for post-flood recovery in the Strymonas dammed river basin [12]. There also have been many studies on the morphodynamic processes of sandbars in the Yangtze River, the channel downstream of the Three Gorges Dam (TGD) in China [13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Long-Term (1986–2018) Evolution of Channel Bars in Response to Combined Effects of Cascade Reservoirs in the Middle Reaches of the Hanjiang River

Zhang

Cai

Yang

et al. 2019

Channel bars are essential landforms and their evolution is crucial to aquatic and riparian biodiversity, river’s water-sediment process, and economic development. With the development of water conservation facilities and hydropower projects, numerous changes have been taken place in hydrological regimes and morphology. There have been many changes on channel bars in the middle reaches of Hanjiang River due to the combined effects of cascade reservoirs. However, little was known about such dynamics and their linkages to cascade dams across the entire downstream area. Using Landsat remote sensing images from 1986–2018 and the threshold binary Otsu extraction method, this study completed comprehensive monitoring of nine mid-channel bars (DX1–DX7, XZ1, and XZ2), and three shoal group (XZ3–XZ5) dynamics. Results showed that the mid-channel bars’ area in the reach from Danjiangkou to Xiangyang (DX) decreased over the past 33 years, with the exception of DX4, while the total area decreased by 23.19%, this channel bars’ area change was mainly influenced by backwater from the Cuijiaying Reservoir with high water level after 2010 (r = −0.93, p < 0.01). The total channel bar area from Xiangyang to Huangzhuang (XZ) decreased by 16.63% from 1986 to 2018. The total channel bar area in XZ had a strong negative correlation with runoff at Huangzhuang hydrologic station (r = −0.79, p < 0.05), which was partly attributed to upstream precipitation according to the high correlation between runoff and precipitation (R2 = 0.65). In general, the DX section was under equilibrium between scouring and deposition compared to downstream Xiangyang, the bars in DX section were mainly affected by water level, and bars in XZ section during 1986–2018 were complicated because it was upstream eroded and downstream deposited. In addition, vegetation cover, revetments, flood events, sand mining, land use, and over-exploitation may cause channel bar area dynamics. Hence, more continuous investigations are suggested to focus on effects of cascade reservoir operation on hydrological regime, as well as the changing morphology of channel bars in the middle reaches of the Hanjiang River.