Monitoring wetland ditch water levels in the North Kent Marshes, UK, using Landsat TM imagery and ground-based measurements

Al-Khudhairy, D. H. A.; Leemhuis, Constanze; Hoffmann, Volker H.; Calaon, R.; Shepherd, IM; Thompson, J. R.; Gavin, Helen; Gasca‐Tucker, David

doi:10.1080/02626660109492852

Cited by 25 publications

(18 citation statements)

References 17 publications

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“…Frohn et al, 2005) and more sophisticated methods (e.g. Al-Khundhairy et al, 2002). In this study, because our interest was simply the presence or absence of open water, histogram manipulation was selected because of its simplicity.…”

Section: Factors Controlling Heterogeneous Vegetation Changementioning

confidence: 99%

Spatially heterogeneous impacts on rangeland after social system change in Mongolia

Okayasu

Muto²,

Jamsran

et al. 2007

Land Degrad Dev

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After the social system in Mongolia changed from socialism to capitalism in the early 1990s, the cooperative system called negdel, which helped to disperse the grazing pressure, collapsed. As a consequence of the collapse, scientists warned that grazing pressure would become concentrated and fixed at particular locations, resulting in land degradation. However, no quantitative studies of such potential local concentration have been performed in Mongolia. In this study, using satellite images and large-scale thematic maps, we analysed the local vegetation change in relation to possible control factors, including open water, roads and settlements. Individual factors had significant impacts on the local vegetation change: particularly prominent were a beltlike decrease in plant density along the main roads and decreases around densely populated areas. In addition, the interaction between these factors negatively affected vegetation, as seen by a decrease around roads and open water near settlements. This interactive effect is likely a consequence of the basic requirements of the nomadic pastoralists, namely quality grassland, water sources and the services provided by settlements. In our study area in Mongolia, the local pattern of vegetation change was determined by the complex process of pastoralists' decision-making. A comprehensive understanding of this process is essential for devising management plans to counteract this vegetation degradation.

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Section: Factors Controlling Heterogeneous Vegetation Changementioning

confidence: 99%

Spatially heterogeneous impacts on rangeland after social system change in Mongolia

Okayasu

Muto²,

Jamsran

et al. 2007

Land Degrad Dev

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“…Xu [38] proposed the mNDWI by replacing the NIR band with SWIR-1 based on the above theory, achieving a satisfied result in suppressing built-up land noise. Due to water bodies having a relatively low reflectance, especially in the NIR to SWIR bands, Al-Khudhairy et al [40] developed the Sum457 using the NIR, SWIR-1, and SWIR-2 bands of the Landsat Thematic Mapper (TM) data to delineate water bodies. Xiao et al [57] developed the LSWI by considering the two bands of NIR and SWIR to estimate water content of the land surface.…”

Section: Water Index-based Approachesmentioning

confidence: 99%

“…Beeri et al [39] put forward a combination of indices of Sum457, ND5723, and ND571 to form a water extraction model. Among the three indices, Sum457 has been proposed and applied for separating water from the surrounding materials by Al-Khudhairy et al [40] in 2002, and the two additional indices introduced (ND5723 and ND571) could further minimize the effects of aerosols and other atmospheric interface if the data has been normalized. Feyisa et al [41] proposed an automated water extraction index (AWEI) in 2013, and furthermore, they used different formats of AWEI for scenes with shadows (AWEIsh) and without shadows (AWEInsh).…”

Section: Introductionmentioning

confidence: 99%

Open Surface Water Mapping Algorithms: A Comparison of Water-Related Spectral Indices and Sensors

Zhou

Dong

Xiao

et al. 2017

Water

182

105

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Open surface water bodies play an important role in agricultural and industrial production, and are susceptible to climate change and human activities. Remote sensing data has been increasingly used to map open surface water bodies at local, regional, and global scales. In addition to image statistics-based supervised and unsupervised classifiers, spectral index-and threshold-based approaches have also been widely used. Many water indices have been proposed to identify surface water bodies; however, the differences in performances of these water indices as well as different sensors on water body mapping are not well documented. In this study, we reviewed and compared existing open surface water body mapping approaches based on six widely-used water indices, including the tasseled cap wetness index (TCW), normalized difference water index (NDWI), modified normalized difference water index (mNDWI), sum of near infrared and two shortwave infrared bands (Sum457), automated water extraction index (AWEI), land surface water index (LSWI), as well as three medium resolution sensors (Landsat 7 ETM+, Landsat 8 OLI, and Sentinel-2 MSI). A case region in the Poyang Lake Basin, China, was selected to examine the accuracies of the open surface water body maps from the 27 combinations of different algorithms and sensors. The results showed that generally all the algorithms had reasonably high accuracies with Kappa Coefficients ranging from 0.77 to 0.92. The NDWI-based algorithms performed slightly better than the algorithms based on other water indices in the study area, which could be related to the pure water body dominance in the region, while the sensitivities of water indices could differ for various water body conditions. The resultant maps from Landsat 8 and Sentinel-2 data had higher overall accuracies than those from Landsat 7. Specifically, all three sensors had similar producer accuracies while Landsat 7 based results had a lower user accuracy. This study demonstrates the improved performance in Landsat 8 and Sentinel-2 for open surface water body mapping efforts.

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“…For another, altimetry is a profiling technique, not an imaging technique; it can only provide a limited footprint of a lake and is unable to depict overall spatial distribution on a regional scale [21,22]. Moreover, there is an indirect method that uses the water level/area relationship to estimate the water level [23,24]. However, the derived relationships between water level and area are essentially empirical, and the transferability from one hydro-geomorphological setting to another has not been proven.…”

Section: Introductionmentioning

confidence: 99%

Combining Multispectral Imagery with in situ Topographic Data Reveals Complex Water Level Variation in China’s Largest Freshwater Lake

Liu

2015

Remote Sensing

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Lake level variation is an important hydrological indicator of water balance, biodiversity and climate change in drainage basins. This paper illustrates the use of moderate-resolution imaging spectroadiometer (MODIS) data to characterize complex water level variation in Poyang Lake, the largest freshwater lake in China. MODIS data were used in conjunction with in situ topographic data, otherwise known as the land-water contact method, to investigate the potential of this hybrid water level spatiotemporal variability measurement technique. An error analysis was conducted to assess the derived water level relative to gauge data. Validation results demonstrated that the land-water contact method can satisfactorily capture spatial patterns and seasonal variations in water level fluctuations. The correlation coefficient ranged from 0.684 to 0.835, the root-mean-square-error from 0.79 m-1.09 m, and the mean absolute bias error from 0.65 m to 0.86 m for five main gauge stations surrounding the lake. Additionally, seasonal and interannual variations in the lake's water level were revealed in the MODIS-based results. These results indicate that the land-water contact method has the potential to be applied in mapping water level changes in Poyang Lake. This study not only provides a foundation for basic hydrological and ecological studies, but is also valuable for the conservation and management of water resources over gauge-sparse regions in Poyang Lake. OPEN ACCESSRemote Sens. 2015, 7 13467

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Monitoring wetland ditch water levels in the North Kent Marshes, UK, using Landsat TM imagery and ground-based measurements

Cited by 25 publications

References 17 publications

Spatially heterogeneous impacts on rangeland after social system change in Mongolia

Spatially heterogeneous impacts on rangeland after social system change in Mongolia

Open Surface Water Mapping Algorithms: A Comparison of Water-Related Spectral Indices and Sensors

Combining Multispectral Imagery with in situ Topographic Data Reveals Complex Water Level Variation in China’s Largest Freshwater Lake

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