scholarly journals Extracting urban water bodies from high-resolution radar images: Measuring the urban surface morphology to control for radar’s double-bounce effect

2020 ◽  
Vol 85 ◽  
pp. 102003 ◽  
Author(s):  
Hao-Yu Liao ◽  
Tzai-Hung Wen
Keyword(s):  
High Resolution ◽  
Surface Morphology ◽  
Water Bodies ◽  
Urban Surface ◽  
Urban Water ◽  
Radar Images ◽  
High Resolution Radar

scholarly journals Two-Step Urban Water Index (TSUWI): A New Technique for High-Resolution Mapping of Urban Surface Water

2018 ◽  
Vol 10 (11) ◽  
pp. 1704 ◽  
Author(s):  
Wei Wu ◽  
Qiangzi Li ◽  
Yuan Zhang ◽  
Xin Du ◽  
Hongyan Wang
Keyword(s):  
Surface Water ◽  
High Resolution ◽  
Urban Surface ◽  
Mapping Technique ◽  
Support Vector ◽  
Svm Classifier ◽  
P Value ◽  
Urban Water ◽  
Water Index ◽  
Water Mapping

Urban surface water mapping is essential for studying its role in urban ecosystems and local microclimates. However, fast and accurate extraction of urban water remains a great challenge due to the limitations of conventional water indexes and the presence of shadows. Therefore, we proposed a new urban water mapping technique named the Two-Step Urban Water Index (TSUWI), which combines an Urban Water Index (UWI) and an Urban Shadow Index (USI). These two subindexes were established based on spectral analysis and linear Support Vector Machine (SVM) training of pure pixels from eight training sites across China. The performance of the TSUWI was compared with that of the Normalized Difference Water Index (NDWI), High Resolution Water Index (HRWI) and SVM classifier at twelve test sites. The results showed that this method consistently achieved good performance with a mean Kappa Coefficient (KC) of 0.97 and a mean total error (TE) of 2.28%. Overall, classification accuracy of TSUWI was significantly higher than that of the NDWI, HRWI, and SVM (p-value < 0.01). At most test sites, TSUWI improved accuracy by decreasing the TEs by more than 45% compared to NDWI and HRWI, and by more than 15% compared to SVM. In addition, both UWI and USI were shown to have more stable optimal thresholds that are close to 0 and maintain better performance near their optimum thresholds. Therefore, TSUWI can be used as a simple yet robust method for urban water mapping with high accuracy.

scholarly journals Reliable Orientation Estimation of Vehicles in High-Resolution Radar Images

2016 ◽  
Vol 64 (9) ◽  
pp. 2986-2993 ◽  
Author(s):  
Fabian Roos ◽  
Dominik Kellner ◽  
Jurgen Dickmann ◽  
Christian Waldschmidt
Keyword(s):  
High Resolution ◽  
Orientation Estimation ◽  
Radar Images ◽  
High Resolution Radar

scholarly journals River Discharge Simulation in the High Andes of Southern Ecuador Using High-Resolution Radar Observations and Meteorological Station Data

2019 ◽  
Vol 11 (23) ◽  
pp. 2804 ◽  
Author(s):  
Diego Mejía-Veintimilla ◽  
Pablo Ochoa-Cueva ◽  
Natalia Samaniego-Rojas ◽  
Ricardo Félix ◽  
Juan Arteaga ◽  
...  
Keyword(s):  
High Resolution ◽  
River Discharge ◽  
Water Resource Management ◽  
Meteorological Station ◽  
Hydrological Simulation ◽  
Radar Observations ◽  
Radar Images ◽  
Extreme Precipitation Events ◽  
Station Data ◽  
High Resolution Radar

The prediction of river discharge using hydrological models (HMs) is of utmost importance, especially in basins that provide drinking water or serve as recreation areas, to mitigate damage to civil structures and to prevent the loss of human lives. Therefore, different HMs must be tested to determine their accuracy and usefulness as early warning tools, especially for extreme precipitation events. This study simulated the river discharge in an Andean watershed, for which the distributed HM Runoff Prediction Model (RPM) and the semi-distributed HM Hydrologic Modelling System (HEC-HMS) were applied. As precipitation input data for the RPM model, high-resolution radar observations were used, whereas the HEC-HMS model used the available meteorological station data. The obtained simulations were compared to measured discharges at the outlet of the watershed. The results highlighted the advantages of distributed HM (RPM) in combination with high-resolution radar images, which estimated accurately the discharges in magnitude and time. The statistical analysis showed good to very good accordance between observed and simulated discharge for the RPM model (R2: 0.85–0.92; NSE: 0.77–0.82), whereas for the HEC-HMS model accuracies were lower (R2: 0.68–0.86; NSE: 0.26–0.78). This was not only due to the application of means values for the watershed (HEC-HMS), but also to limited rain gauge information. Generally, station network density in tropical mountain regions is poor, for which reason the high spatiotemporal precipitation variability cannot be detected. For hydrological simulation and forecasting flash floods, as well as for environmental investigations and water resource management, meteorological radars are the better choice. The greater availability of cost-effective systems at the present time also reduces implementation and maintenance costs of dense meteorological station networks.

scholarly journals Peering Beneath the Powder: Using Radar to Understand Avalanches

Eos ◽  
2018 ◽  
Vol 99 ◽  
Author(s):  
Terri Cook
Keyword(s):  
High Resolution ◽  
Experimental Test ◽  
Test Site ◽  
Radar Images ◽  
Avalanche Behavior ◽  
Key Factor ◽  
High Resolution Radar ◽  
Snow Temperature

High-resolution radar images from Switzerland’s experimental test site show that snow temperature is a key factor in classifying avalanche behavior.

scholarly journals Extraction of Urban Water Bodies from High-Resolution Remote-Sensing Imagery Using Deep Learning

Water ◽  
2018 ◽  
Vol 10 (5) ◽  
pp. 585 ◽  
Author(s):  
Yang Chen ◽  
Rongshuang Fan ◽  
Xiucheng Yang ◽  
Jingxue Wang ◽  
Aamir Latif
Keyword(s):  
Remote Sensing ◽  
Deep Learning ◽  
High Resolution ◽  
Water Bodies ◽  
Urban Water ◽  
Remote Sensing Imagery

scholarly journals Mapping Paleohydrology of the Ephemeral Kuiseb River, Namibia, from Radar Remote Sensing

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1441
Author(s):  
Philippe Paillou ◽  
Sylvia Lopez ◽  
Eugene Marais ◽  
Klaus Scipal
Keyword(s):  
High Resolution ◽  
Drainage System ◽  
Climatic Conditions ◽  
Radar Images ◽  
The North ◽  
Digital Elevation ◽  
Ephemeral Rivers ◽  
High Resolution Radar ◽  
Northern Edge ◽  
Ground Penetrating

The Kuiseb River is one of the major ephemeral rivers of Western Namibia, setting the northern limit of the Namib Sand Sea and outflowing in the Atlantic Ocean at Walvis Bay. Such ephemeral rivers are of the highest importance for the country since they are related both to recent past climatic conditions and to potential water resources. Using high-resolution radar images from the Japanese ALOS-2 satellite, we mapped for the first time the numerous channels hidden under the surface aeolian sediments: while the non-permanent tributaries of the Kuiseb River appear north of its present-day bed, a wide paleochannel system running westward, assumed by previous studies, could be clearly observed in the interdune valleys in the south. Radar-detected channels were studied during fieldwork in May 2019, which produced both subsurface ground-penetrating radar profiles and high-resolution drone-generated digital elevation models. It allowed us to confirm the existence of the “Paleo–Kuiseb” drainage system, a remnant of the Holocene history of the Kuiseb River, moving northward under the progression of the Namib Sand Sea. Our observations also contribute to the explanation of the young age of the linear dunes at the northern edge of the Namib Sand Sea, which are currently active and are pushing the Kuiseb River course toward the north.

scholarly journals Estimation of the orientation of vehicles in high-resolution radar images

2015 ◽  
Author(s):  
Fabian Roos ◽  
Dominik Kellner ◽  
Jens Klappstein ◽  
Juergen Dickmann ◽  
Klaus Dietmayer ◽  
...  
Keyword(s):  
High Resolution ◽  
Radar Images ◽  
High Resolution Radar
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