scholarly journals Monitoring Lake Levels From Space: Preliminary Analysis With SWOT

2021 ◽  
Vol 3 ◽  
Author(s):  
Akhilesh S. Nair ◽  
Nitish Kumar ◽  
J. Indu ◽  
B. Vivek
Keyword(s):  
Surface Water ◽  
Temporal Resolution ◽  
Anthropogenic Activities ◽  
Rapid Change ◽  
Water Storage ◽  
Water Levels ◽  
Study Region ◽  
Volume Calculation ◽  
Spatial Coverage

Lakes are an essential component of biogeochemical processes, and variations in lake level are regarded as indicators of climate change. For more than a decade, satellite altimetry has successfully monitored variation in water levels over inland seas, lakes, rivers, and wetlands. Through altimetry, the surface water levels are measured at varying temporal scales depending on the orbit cycle of the satellite. The futuristic mission of Surface Water and Ocean Topography (SWOT) scheduled to be launched in year 2022 shall offer the spatial coverage and resolution suitable for water level estimation and volume calculation in small water bodies like lakes worldwide. With a radar interferometer in Ka-band, SWOT proposes to provide two-dimensional maps of water heights 21 days repeat orbit configuration. Cycle average SWOT datasets for land will be developed with higher temporal resolution, with temporal resolution varying geographically. This work assesses the potential of SWOT for monitoring water volumes over a case study lake by analyzing SWOT like synthetic data produced using the SWOT simulator developed by the Centre National d'Etudes Spatiales (CNES). With SWOT relying on a novel technology, the initial 90 days of this mission after launch shall focus on an extensive calibration and validation. Firsthand results of SWOT-simulated water levels and volumes are presented over a case study region in the tropical band, namely, Pookode Lake, in the ecologically fragile district of Wayanad, Kerala, India. It is the second-largest freshwater lake in Kerala that is being affected by anthropogenic activities, causing huge depletion in lake water storage in the last four decades. Our analysis indicated that the lake region is subjected to a rise in temperature of 0.018°C per year. We further assess the potential of remote sensing and SWOT data to monitor water storage of Pookode Lake, which is undergoing a rapid change. Results show that the proxy water surface elevations have immense potential in scientific studies pertaining to lake monitoring across the world. Overall, the study shows the potential of SWOT for monitoring the variability of water levels and volumes in this region.

scholarly journals Assessing the Potential Impacts of the Grand Ethiopian Renaissance Dam on Water Resources and Soil Salinity in the Nile Delta, Egypt

2019 ◽  
Vol 11 (24) ◽  
pp. 7050 ◽  
Author(s):  
Sherien Abdel Aziz ◽  
Martina Zeleňáková ◽  
Peter Mésároš ◽  
Pavol Purcz ◽  
Hany Abd-Elhamid
Keyword(s):  
Surface Water ◽  
Water Resources ◽  
Soil Salinity ◽  
Crop Yields ◽  
Nile Delta ◽  
National Income ◽  
Water Levels ◽  
Groundwater Levels ◽  
Deep Aquifers

Several studies have reported that the construction of the Grand Ethiopian Renaissance Dam (GERD) could have severe effects on the water resources in downstream countries, especially Egypt. These effects include changes in surface water level, groundwater levels in shallow and deep aquifers, saltwater intrusion, and increases in soil salinity, which could affect crop yields. This paper assesses the potential impacts of the GERD on the Nile Delta, Egypt. It includes the effects of reducing surface water levels (SWL) and changing the crop patterns at the groundwater levels (GWL), in addition to the effect of cultivating crops that consume less water on soil salinity. A pilot area is selected in the east of the Nile Delta for the assessment. The results of the study revealed that GWL is directly proportional to SWL. Comparing the case study of 2012, when SWL was reduced by 50%, the GWL decreased from 5.0 m to 2.0 m. After adjustment, the crop patterns from rice to other crops decreased the GWL to 1.30 m. Additionally, the results showed that there is a significant relationship between soil salinity and crop patterns. Soil salinity increased during the cultivation of the Delta with non-rice crops, such as grapes. Salinity increased from 0.45 S/m after 10 years of simulation to 0.48 S/m. This estimation highlights the undesirable effects of the GERD on Egypt’s water resources, soil salinity, crop yields, and national income.

scholarly journals Interannual variations of the terrestrial water storage in the Lower Ob' Basin from a multisatellite approach

2010 ◽  
Vol 14 (12) ◽  
pp. 2443-2453 ◽  
Author(s):  
F. Frappart ◽  
F. Papa ◽  
A. Güntner ◽  
S. Werth ◽  
G. Ramillien ◽  
...  
Keyword(s):  
Surface Water ◽  
Root Zone ◽  
Water Storage ◽  
Temporal Variations ◽  
Water Levels ◽  
The Arctic ◽  
Water Volume ◽  
Hydrological Models ◽  
Radar Altimetry ◽  
Terrestrial Water

Abstract. Temporal variations of surface water volume over inundated areas of the Lower Ob' Basin in Siberia, one of the largest contributor of freshwater to the Arctic Ocean, are estimated using combined observations from a multisatellite inundation dataset and water levels over rivers and floodplains derived from the TOPEX/POSEIDON (T/P) radar altimetry. We computed time-series of monthly maps of surface water volume over the common period of available T/P and multisatellite data (1993–2004). The results exhibit interannual variabilities similar to precipitation estimates and river discharge observations. This study also presents monthly estimates of groundwater and permafrost mass anomalies during 2003–2004 based on a synergistic analysis of multisatellite observations and hydrological models. Water stored in the soil is isolated from the total water storage measured by GRACE when removing the contributions of both the surface reservoir, derived from satellite imagery and radar altimetry, and the snow estimated by inversion of GRACE measurements. The time variations of groundwater and permafrost are then obtained when removing the water content of the root zone reservoir simulated by hydrological models.

scholarly journals The 2019–2020 Rise in Lake Victoria Monitored from Space: Exploiting the State-of-the-Art GRACE-FO and the Newly Released ERA-5 Reanalysis Products

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4304
Author(s):  
Mehdi Khaki ◽  
Joseph Awange
Keyword(s):  
Lake Victoria ◽  
Water Discharge ◽  
Water Storage ◽  
The State ◽  
Water Levels ◽  
Subsurface Water ◽  
Surface Model ◽  
The Past ◽  
Short Rainy Season ◽  
Spatial Coverage

During the period 2019–2020, Lake Victoria water levels rose at an alarming rate that has caused various problems in the region. The influence of this phenomena on surface and subsurface water resources has not yet been investigated, largely due to lack of enough in situ measurements compounded by the spatial coverage of the lake’s basin, incomplete/inconsistent hydrometeorological data, and unavailable governmental data. Within the framework of joint data assimilation into a land surface model from multi-mission satellite remote sensing, this study employs the state-of-art Gravity Recovery and Climate Experiment follow-on (GRACE-FO) time-variable terrestrial water storage (TWS), newly released ERA-5 reanalysis, and satellite radar altimetry products to understand the cause of the rise of Lake Victoria on the one hand, and the associated impacts of the rise on the total water storage compartments (surface and groundwater) triggered by the extreme climatic event on the other hand. In addition, the study investigates the impacts of large-scale ocean–atmosphere indices on the water storage changes. The results indicate a considerable increase in water storage over the past two years, with multiple subsequent positive trends mainly induced by the Indian Ocean Dipole (IOD). Significant storage increase is also quantified in various water components such as surface water and water discharge, where the results show the lake’s water level rose by ∼1.4 m, leading to approximately 1750 gigatonne volume increase. Multiple positive trends are observed in the past two years in the lake’s water storage increase with two major events in April–May 2019 and December 2019–January 2020, with the rainfall occurring during the short rainy season of September to November (SON) having had a dominant effect on the lake’s rise.

scholarly journals Determination of Ground Water Stressed Regions of Visakhapatnam District using Arc Map

2019 ◽  
Vol 8 (4) ◽  
pp. 11546-11549
Keyword(s):  
Surface Water ◽  
Ground Water ◽  
Water Conservation ◽  
Human Life ◽  
Scale Up ◽  
Temporal Variations ◽  
Water Levels ◽  
Efficient Design ◽  
Study Region ◽  
Visakhapatnam District

Water is essential for human life, which is vastly used for basic needs like drinking and other domestic, irrigational and industrial purposes etc. The main sources of water are classified as surface and sub-surface sources. The surface water resources are varied like rivers, ponds, lakes etc. but the sub-surface resources are only water bearing aquifers. Day by day the sub surface water is degrading due to many reasons like pollution, climate change etc. Therefore, studies on conservation of ground water is important. For the present study, data of ground water levels for eleven years (2007-2017) at 69 locations of various mandals (zones) in Visakhapatnam district (Andhra Pradesh, India) was obtained from the A.P. Ground Water and Water Audit Department, Visakhapatnam. By using ArcMap of ArcGIS and the spatial and temporal variations were mapped onto the base map of Visakhapatnam. The results indicated ‘water stressed areas’ in the study region. It was observed that the ground water levels dwindled drastically in the years 2016 and 2017. The results of the study highlighted the immediate necessity to scale up the ground water conservation measures and efficient design of the ground water resource systems in the area.

scholarly journals Automatic Detection of Inland Water Bodies along Altimetry Tracks for Estimating Surface Water Storage Variations in the Congo Basin

2021 ◽  
Vol 13 (19) ◽  
pp. 3804
Author(s):  
Frédéric Frappart ◽  
Pierre Zeiger ◽  
Julie Betbeder ◽  
Valéry Gond ◽  
Régis Bellot ◽  
...  
Keyword(s):  
Time Series ◽  
Surface Water ◽  
Water Storage ◽  
Temporal Variations ◽  
Water Levels ◽  
Congo Basin ◽  
Radar Altimetry ◽  
Surface Water Storage ◽  
Cuvette Centrale ◽  
Good Agreement

Surface water storage in floodplains and wetlands is poorly known from regional to global scales, in spite of its importance in the hydrological and the carbon balances, as the wet areas are an important water compartment which delays water transfer, modifies the sediment transport through sedimentation and erosion processes, and are a source for greenhouse gases. Remote sensing is a powerful tool for monitoring temporal variations in both the extent, level, and volume, of water using the synergy between satellite images and radar altimetry. Estimating water levels over flooded area using radar altimetry observation is difficult. In this study, an unsupervised classification approach is applied on the radar altimetry backscattering coefficients to discriminate between flooded and non-flooded areas in the Cuvette Centrale of Congo. Good detection of water (open water, permanent and seasonal inundation) is above 0.9 using radar altimetry backscattering from ENVISAT and Jason-2. Based on these results, the time series of water levels were automatically produced. They exhibit temporal variations in good agreement with the hydrological regime of the Cuvette Centrale. Comparisons against a manually generated time series of water levels from the same missions at the same locations show a very good agreement between the two processes (i.e., RMSE ≤ 0.25 m in more than 80%/90% of the cases and R ≥ 0.95 in more than 95%/75% of the cases for ENVISAT and Jason-2, respectively). The use of the time series of water levels over rivers and wetlands improves the spatial pattern of the annual amplitude of water storage in the Cuvette Centrale. It also leads to a decrease by a factor of four for the surface water estimates in this area, compared with a case where only time series over rivers are considered.

scholarly journals Comparing global and regional maps of intactness in the boreal region of North America: Implications for conservation planning in one of the world’s remaining wilderness areas

2020 ◽  
Author(s):  
Pierre Vernier ◽  
Shawn Leroux ◽  
Steve Cumming ◽  
Kim Lisgo ◽  
Alberto Suarez Esteban ◽  
...  
Keyword(s):  
North America ◽  
Boreal Forest ◽  
Conservation Planning ◽  
Anthropogenic Activities ◽  
Rapid Change ◽  
Model Assessment ◽  
Human Influence ◽  
Boreal Region ◽  
Human Footprint ◽  
Spatial Coverage

AbstractThough North America’s boreal forest contains some of the largest remaining intact and wild ecosystems in the world, human activities are systematically reducing its extent. Consequently, forest intactness and human influence maps are increasingly used for monitoring and conservation planning in the boreal region. We compare eight forest intactness and human impact maps to provide a multi-model assessment of intactness in the boreal region. All maps are global in extent except for Global Forest Watch Canada’s Human Access (2000) and Intact Forest Landscapes (2000, 2013) maps, although some global maps are restricted to areas that were at least 20% treed. As a function of each map’s spatial coverage in North America, the area identified as intact ranged from 55% to 79% in Canada and from 32% to 96% in Alaska. Likewise, the similarity between pairs of datasets in the Canadian boreal ranged from 0.58 to 0.86 on a scale of 0-1. In total, 45% of the region was identified as intact by the seven most recent datasets. There was also variation in the ability of the datasets to account for anthropogenic disturbances that are increasingly common in the boreal region, such as those associated with resource extraction. In comparison to a recently developed high resolution regional disturbance dataset, the four human influence datasets (Human Footprint, Global Human Modification, Large Intact Areas, and Anthropogenic Biomes), in particular, omitted 59-85% of all linear disturbances and 54-89% of all polygonal disturbances. In contrast, the global IFL, Canadian IFL, and Human Access maps omitted 2-7% of linear disturbances and 0.1-5% of polygonal disturbances. Several differences in map characteristics, including input datasets and methods used to develop the maps may help explain these differences. Ultimately, the decision on which dataset to use will depend on the objectives of each specific conservation planning project, but we recommend using datasets that 1) incorporate regional anthropogenic activities, 2) are updated regularly, 3) provide detailed information of the methods and input data used, and 4) can be replicated and adapted for local use. This is especially important in landscapes that are undergoing rapid change due to development, such as the boreal forest of North America.

scholarly journals Potential and Limitations of Satellite Altimetry Constellations for Monitoring Surface Water Storage Changes—A Case Study in the Mississippi Basin

2020 ◽  
Vol 12 (20) ◽  
pp. 3320
Author(s):  
Denise Dettmering ◽  
Laura Ellenbeck ◽  
Daniel Scherer ◽  
Christian Schwatke ◽  
Christoph Niemann
Keyword(s):  
Surface Water ◽  
Mississippi River ◽  
Satellite Altimetry ◽  
Remote Sensing Data ◽  
Water Area ◽  
Water Levels ◽  
In Situ Data ◽  
Ocean Topography

Remote sensing data are essential for monitoring the Earth’s surface waters, especially since the amount of publicly available in-situ data is declining. Satellite altimetry provides valuable information on the water levels and variations of lakes, reservoirs and rivers. In combination with satellite imagery, the derived time series allow the monitoring of lake storage changes and river discharge. However, satellite altimetry is limited in terms of its spatial resolution due to its measurement geometry, only providing information in the nadir direction beneath the satellite’s orbit. In a case study in the Mississippi River Basin (MRB), this study investigates the potential and limitations of past and current satellite missions for the monitoring of basin-wide storage changes. For that purpose, an automated target detection is developed and the extracted lake surfaces are merged with the satellites’ tracks. This reveals that the current altimeter configuration misses about 80% of all lakes larger than 0.1 km2 in the MRB and 20% of lakes larger than 10 km2, corresponding to 30% and 7% of the total water area, respectively. Past altimetry configurations perform even more poorly. From the larger water bodies represented by a global hydrology model, at least 91% of targets and 98% of storage changes are captured by the current altimeter configuration. This will improve significantly with the launch of the planned Surface Water and Ocean Topography (SWOT) mission.

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