Time series analysis of optical remote sensing data for the mapping of temporary surface water bodies in sub-Saharan western Africa

Haas, Eva; Bartholomé, Étienne; Combal, B.

doi:10.1016/j.jhydrol.2009.02.052

Cited by 104 publications

(60 citation statements)

References 27 publications

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“…Moreover, some ponds, like Ebang Mallam, split into several small ponds, which size may be smaller than the spatial resolution of MODIS. This is in line with previous studies using moderate and low resolution sensors (Verdin et al, 1996;Gond et al, 2004;Haas et al, 2009), which concluded that surface estimation is accurate above a given threshold of a few ha or tens of ha, allowing pure pixels to be present. Ponds' size at the end of the wet season, typically from September to November, is therefore preferred to carry out the analysis of the long term changes of the flood in ponds.…”

Section: Assessments Of the Classificationssupporting

confidence: 92%

“…To date, attempts have been made to map the pond floods and to estimate flooded areas either at one date, at a relatively high spatial resolution on the basis of one LAND-SAT or SPOT-HRV image (Liebe et al, 2005;Lacaux et al, 2007) or at a lower resolution using time series of NOAA-AVHRR, SPOT-VGT or MODIS data (e.g. Gond et al, 2004;Haas et al, 2009;Verdin et al, 1996). Beside, the spectral response of surface water has received relatively little attention so far in this region, with a few exceptions like Lacaux et al (2007).…”

Section: Introductionmentioning

confidence: 99%

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Less rain, more water in ponds: a remote sensing study of the dynamics of surface waters from 1950 to present in pastoral Sahel (Gourma region, Mali)

Gardelle

Hiernaux

Kergoat

et al. 2010

Hydrol. Earth Syst. Sci.

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Abstract. Changes in the flooded area of ponds in the Gourma region from 1950 to present are studied by remote sensing, in the general context of the current multi-decennial Sahel drought. The seasonal and interannual variations of the areas covered by surface water are assessed using multidate and multi-sensor satellite images (SPOT, FORMOSAT, LANDSAT-MSS, -TM, and -ETM, CORONA, and MODIS) and aerial photographs (IGN). Water body classification is adapted to each type of spectral resolution, with or without a middle-infrared band, and each spatial resolution, using linear unmixing for mixed pixels of MODIS data. The high-frequency MODIS data document the seasonal cycle of flooded areas, with an abrupt rise early in wet season and a progressive decrease in the dry season. They also provide a base to study the inter-annual variability of the flooded areas, with sharp contrasts between dry years such as 2004 (low and early maximal area) and wetter years such as 2001 and 2002 (respectively high and late maximal area).The highest flooded area reached annually greatly depends on the volume, intensity and timing of rain events. However, the overall reduction by 20% of annual rains during the last 40 years is concomitant with an apparently paradoxical large increase in the area of surface water, starting from the 1970's and accelerating in the mid 1980's. Spectacular for the two study cases of Agoufou and Ebang Mallam, for which time series covering the 1954 to present period exist, this increase is also diagnosed at the regional scale from LANDSAT data spanning 1972-2007. It reaches 108% between September 1975 and 2002 for 91 ponds identified in central Gourma. Ponds with turbid waters and no aquatic vegetation are mostly reCorrespondence to: P. Hiernaux (pierre.hiernaux@cesbio.cnes.fr) sponsible for this increase, more pronounced in the centre and north of the study zone. Possible causes of the differential changes in flooded areas are discussed in relation with the specifics in topography, soil texture and vegetation cover over the watersheds that feed each of the ponds. Changes in rain pattern and in ponds sedimentation are ruled out, and the impact of changes in land use, limited in the area, is found secondary, as opposed to what has often been advocated for in southern Sahel. Instead, major responsibility is attributed to increased runoff triggered by the lasting impact of the 1970-1980's droughts on the vegetation and on the runoff system over the shallow soils prevailing over a third of the landscape.

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Section: Assessments Of the Classificationssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Less rain, more water in ponds: a remote sensing study of the dynamics of surface waters from 1950 to present in pastoral Sahel (Gourma region, Mali)

Gardelle

Hiernaux

Kergoat

et al. 2010

Hydrol. Earth Syst. Sci.

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“…The Agoufou Lake, which is the main target of this study, has been monitored since 2007 for water depth [5] and since 2014 for SPM and turbidity. Due to the size of Sahelian inland waters and to the strong seasonal cycle of most ponds and lakes surface and volume [4,32,33], combining high frequency MODIS (daily) and high spatial resolution Landsat images (30 m) is particularly important to monitor water bodies in this region.…”

Section: Study Areamentioning

confidence: 99%

Analysis of Suspended Particulate Matter and Its Drivers in Sahelian Ponds and Lakes by Remote Sensing (Landsat and MODIS): Gourma Region, Mali

Robert

Kergoat

Soumaguel³

et al. 2017

Remote Sensing

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Abstract:The Sahelian region is characterized by significant variations in precipitation, impacting water quantity and quality. Suspended particulate matter (SPM) dynamics has a significant impact on inland water ecology and water resource management. In-situ data in this region are scarce and, consequently, the environmental factors triggering SPM variability are yet to be understood. This study addresses these issues using remote sensing optical data. Turbidity and SPM of the Agoufou Lake in Sahelian Mali were measured from October 2014 to present, providing a large range of 'values (SPM ranging from 106 to 4178 mg/L). These data are compared to satellite reflectance from Landsat (ETM+, OLI) and MODIS (MOD09GQ, MYD09GQ). For each of these sensors, a spectral band in the near infrared region is found to be well suited to retrieve turbidity and SPM, up to very high values (R 2 = 0.70) seldom addressed by remote sensing studies. The satellite estimates are then employed to assess the SPM dynamics in the main lakes and ponds of the Gourma region and its links to environmental and anthropogenic factors. The main SPM seasonal peak is observed in the rainy season (June to September) in relation to precipitation and sediment transport. A second important peak occurs during the dry season, highlighting the importance of resuspension mechanisms in maintaining high values of SPM. Three different periods are observed: first, a relatively low winds period in the early dry season, when SPM decreases rapidly due to deposition; then, a period of wind-driven resuspension in January-March; and lastly, an SPM deposition period in April-May, when the monsoon replaces the winter trade wind. Overall, a significant increase of 27% in SPM values is observed between 2000 and 2016 in the Agoufou Lake. The significant spatio-temporal variability in SPM revealed by this study highlights the importance of high resolution optical sensors for continuous monitoring of water quality in these poorly instrumented regions.

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“…Spatial dynamics and up-to-date information on surface water resources are essential for understanding water resource-related issues in these areas. Temporal water bodies that provide habitats for plant and animal communities in these areas have rarely been included in global datasets, such as the Global Lakes and Wetlands Database (GLWD) [4,5] and Vector Map Level 0 (VMAP0) [6].…”

Section: Introductionmentioning

confidence: 99%

MODIS-Derived Spatiotemporal Changes of Major Lake Surface Areas in Arid Xinjiang, China, 2000–2014

Wang

et al. 2015

Water

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Inland water bodies, which are critical freshwater resources for arid and semi-arid areas, are very sensitive to climate change and human disturbance. In this paper, we derived a time series of major lake surface areas across Xinjiang Uygur Autonomous Region (XUAR), China, based on an eight-day MODIS time series in 500 m resolution from 2000 to 2014. A classification approach based on water index and dynamic threshold selection was first developed to accommodate varied spectral features of water pixels at different temporal steps. The overall classification accuracy for a MODIS-derived water body is 97% compared to a water body derived using Landsat imagery. Then, monthly composites of water bodies were derived for the months of April, July, and September to identify seasonal patterns and inter-annual dynamics of 10 major lakes (>100 km 2 ) in XUAR. Our results indicate that the changing trends of surface area of major lakes varied across the region. The surface areas of the Ebinur and Bosten Lakes showed a significant shrinking trend. The Ulungur-Jili Lake remained relatively stable during the entire period. OPEN ACCESSWater 2015, 7 5732For mountain lakes, the Barkol Lake showed a decreasing trend in April and July, but the Sayram Lake showed a significant expanding trend in September. The four plateau lakes exhibited significant expanding trends in all three seasons except for Arkatag Lake in July. The shrinking of major lakes reflects severe anthropogenic impacts due to agricultural and industrial needs, in addition to the impact of climate change. The pattern of lake changes across the XUAR can provide insight into the impact of climate change and human activities on regional water resources in this arid and semi-arid region.

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Time series analysis of optical remote sensing data for the mapping of temporary surface water bodies in sub-Saharan western Africa

Cited by 104 publications

References 27 publications

Less rain, more water in ponds: a remote sensing study of the dynamics of surface waters from 1950 to present in pastoral Sahel (Gourma region, Mali)

Less rain, more water in ponds: a remote sensing study of the dynamics of surface waters from 1950 to present in pastoral Sahel (Gourma region, Mali)

Analysis of Suspended Particulate Matter and Its Drivers in Sahelian Ponds and Lakes by Remote Sensing (Landsat and MODIS): Gourma Region, Mali

MODIS-Derived Spatiotemporal Changes of Major Lake Surface Areas in Arid Xinjiang, China, 2000–2014

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