Unprecedented satellite survey of global surface water and ocean topography

2017 ◽  
Vol 76 (22) ◽  
Author(s):  
Anne Marie de Grosbois
Author(s):  
Edward Salameh ◽  
Frédéric Frappart ◽  
Damien Desroches ◽  
Imen Turki ◽  
Denis Carbonne ◽  
...  

Author(s):  
Elizabeth H. Altenau ◽  
Tamlin M. Pavelsky ◽  
Michael T. Durand ◽  
Xiao Yang ◽  
Renato Prata de Moraes Frasson ◽  
...  

Author(s):  
Paul D. Bates ◽  
Jefferey C. Neal ◽  
Douglas Alsdorf ◽  
Guy J.-P. Schumann

2020 ◽  
Vol 12 (17) ◽  
pp. 2675
Author(s):  
Qianqian Han ◽  
Zhenguo Niu

Inland surface water is highly dynamic, seasonally and inter-annually, limiting the representativity of the water coverage information that is usually obtained at any single date. The long-term dynamic water extent products with high spatial and temporal resolution are particularly important to analyze the surface water change but unavailable up to now. In this paper, we construct a global water Normalized Difference Vegetation Index (NDVI) spatio-temporal parameter set based on the Moderate-resolution Imaging Spectroradiometer (MODIS) NDVI. Employing the Google Earth Engine, we construct a new Global Surface Water Extent Dataset (GSWED) with coverage from 2000 to 2018, having an eight-day temporal resolution and a spatial resolution of 250 m. The results show that: (1) the MODIS NDVI-based surface water mapping has better performance compared to other water extraction methods, such as the normalized difference water index, the modified normalized difference water index, and the OTSU (maximal between-cluster variance method). In addition, the water-NDVI spatio-temporal parameter set can be used to update surface water extent datasets after 2018 as soon as the MODIS data are updated. (2) We validated the GSWED using random water samples from the Global Surface Water (GSW) dataset and achieved an overall accuracy of 96% with a kappa coefficient of 0.9. The producer’s accuracy and user’s accuracy were 97% and 90%, respectively. The validated comparisons in four regions (Qinghai Lake, Selin Co Lake, Utah Lake, and Dead Sea) show a good consistency with a correlation value of above 0.9. (3) The maximum global water area reached 2.41 million km2 between 2000 and 2018, and the global water showed a decreasing trend with a significance of P = 0.0898. (4) Analysis of different types of water area change regions (Selin Co Lake, Urmia Lake, Aral Sea, Chiquita Lake, and Dongting Lake) showed that the GSWED can not only identify the seasonal changes of the surface water area and abrupt changes of hydrological events but also reflect the long-term trend of the water changes. In addition, GSWED has better performance in wetland areas and shallow areas. The GSWED can be used for regional studies and global studies of hydrology, biogeochemistry, and climate models.


2019 ◽  
Vol 7 ◽  
Author(s):  
Theodore Langhorst ◽  
Tamlin M. Pavelsky ◽  
Renato Prata de Moraes Frasson ◽  
Rui Wei ◽  
Alessio Domeneghetti ◽  
...  

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 69
Author(s):  
Zahra Kalantari ◽  
Sonia Borja ◽  
Georgia Destouni

Spatial and temporal characteristics of surface water resources (e.g., extension, connectivity, seasonality) are key elements in water allocation, climate and hydrological regulation, ecosystem functioning, and the food-energy-water nexus. Changes in surface water area due to losses/gains to land could strongly affect these processes on different scales. Previous findings on changes in the Earth’s surface water area are contradictory. Based on water–land year classification datasets, we estimated global surface water area changes between 1985–2000 and 2001–2015. We found a net global gain in surface water of 100,454 km2, attributable to a large net gain in seasonal water (83,329 km2) and a small net gain in permanent water (17,125 km2). In general, net changes were highly heterogeneous in space, with local exceptions of clear drying and wetting trends, e.g., the Aral Sea and Quill Lakes, respectively. These findings raise multiple questions as to why seasonal water gains dominate and how different intertwined drivers (e.g., hydroclimate and human-induced water–land use changes) shape the distribution of the Earth’s surface water. Understanding these long-term changes is essential to predicting water-related pressures and prioritizing management decisions.


2017 ◽  
Vol 53 (10) ◽  
pp. 8164-8186 ◽  
Author(s):  
Renato Prata de Moraes Frasson ◽  
Rui Wei ◽  
Michael Durand ◽  
J. Toby Minear ◽  
Alessio Domeneghetti ◽  
...  

Author(s):  
Lee-Lueng Fu ◽  
Lee-Lueng Fu ◽  
Lee-Lueng Fu ◽  
Lee-Lueng Fu ◽  
Lee-Lueng Fu ◽  
...  

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