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Located within the Altiplano at 3,686 m above sea level, Lake Poopo is remarkably shallow and very sensitive to hydrologic recharge. Progressive drying has been observed in the entire Titicaca-Poopo-Desaguadero-Salar de Coipasa (TPDS) system during the last decade, causing dramatic changes to Lake Poopo's surface and its regional water supplies. Ou...
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Context 1
... MODIS surfaces ( Figure 5) are linked to bathymetry through the Landsat/MODIS calibration curve ( Figure 6) and a correlation coefficient of R 2 = 0.97 was obtained. A top and inclined view of the final bathymetry is presented in Figure 7a,b. Table 2 shows relations between isolines vertical elevation, the elevation standard deviation (SD) and the number of profiles used for the calculation. ...
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Citations
... To overcome the disadvantages of existing bathymetry derivation techniques, several studies either integrate waterlines obtained from a series of images with a spatial interpolation of geocoded heights [150]- [152] or combine multisatellite observations for deriving bathymetry (e.g., optical imagery, radar, and laser altimetry) [153]- [155]. For example, Abileah and Vignudelli [156] proposed the combination of radar altimetry and multitemporal Landsat data to calculate bathymetry in Lake Nasser. ...
Surface water, which refers to water stored in rivers, streams, lakes, reservoirs, ponds, and wetlands, is a precious resource in terms of biodiversity, ecology, water management, and economics. As a significant hydrological parameter, surface water storage (SWS) influences the exchange of water and energy between the land/water surface and atmosphere. The quantification of SWS and its dynamics is crucial for a better understanding of global hydrological and biogeochemical processes. For more than 30 years, Earth observation (EO) technology has shown that SWS can be measured to some degree, and a variety of techniques have been proposed to facilitate this purpose.
... Satellite scenes from Synthetic Aperture Radars (SAR) are being used for wetland characterization and monitoring (Hess et al., 2003;Salvia et al., 2009;Arsen et al., 2013). These images provide information about the geometric and dielectric characteristics of the observed target. ...
With the launch of the Sentinel-1 mission, for the first time, multitemporal and dual-polarization C-band SAR data with a short revisit time is freely available. How can we use this data to generate accurate vegetation cover maps on a local scale? Our main objective was to assess the use of multitemporal C-Band Sentinel-1 data to generate wetland vegetation maps. We considered a portion of the Lower Delta of the Paraná River wetland (Argentina). Seventy-four images were acquired and 90 datasets were created with them, each one addressing a combination of seasons (spring, autumn, winter, summer, complete set), polarization (VV, HV, both), and texture measures (included or not). For each dataset, a Random Forest classifier was trained. Then, the kappa index values (κ) obtained by the 90 classifications made were compared. Considering the datasets formed by the intensity values, for the winter dates the achieved kappa index values (κ) were higher than 0.8, while all summer datasets achieved κ up to 0.76. Including feature textures based on the GLCM showed improvements in the classifications: for the summer datasets, the κ improvements were between 9% and 22% and for winter datasets improvements were up to 15%. Our results suggest that for the analyzed context, winter is the most informative season. Moreover, for dates associated with high biomass, the textures provide complementary information.
... Combined with Landsat series and Sentinel-2 satellite images, the functional relationship between the water level and water storage capacity is constructed, and Ngoring Lake has been continuously monitored for nearly 30 years, including the changes in water level, lake area, and water storage capacity. Compared with previous studies [16][17][18], the data and methods used in this paper are novel and have a longer observation time. It is of great benefit to the follow-up study of lakes. ...
Mastering the fluctuation of water levels and the water storage capacity of plateau lakes is greatly important for monitoring the water balance of the Tibetan Plateau and predicting regional and global climate change. The water level of plateau lakes is difficult to measure, and the ground measured data of long-time series are difficult to obtain. Ngoring Lake is considered in this study, using spaceborne single-photon lidar ICESat-2/ATL13 inland lake standard data products, the water level values provided by Hydroweb laboratory, and the image data of an optical remote sensing satellite. A new method is proposed in the absence of measured data. The method uses multisource remote sensing data to estimate the long-term changes in the water levels, surface area, and water storage capacity of Ngoring Lake in the past three decades. The results show that the water level values of ICESat-2 and Hydroweb on overlapping observation days are highly correlated, with R2 = 0.9776, MAE = 0.420 m, RMSE = 0.077 m, and the average absolute height difference is 0.049 m. The fusion of multiple altimetry data can obtain more continuous long-time series water-level observation results. From 1992 to 2021, the water body information of Ngoring Lake basin fluctuated greatly and showed different variation characteristics in different time periods. The lowest water level in January 1997 was approximately 4268.49 m, and it rose to its highest in October 2009, approximately 4272.44 m. The change in the water level in the basin was mainly affected by natural factors, such as precipitation, air temperature, and human activities. The analysis shows that ICESat-2 can be combined with other remote sensing data to realize the long-time series dynamic monitoring of plateau lakes, showing great advantages in the comprehensive observation of plateau lakes in no man’s land.
... The Normalized Difference Water Index (NDWI) and its alternations, e.g., modified NDWI, or other approaches such as support vector machines, are used to estimate from satellite data the water area of inland waters [5,[18][19][20][21][22]. Regarding the water level detection, altimetry satellite missions, including ICESat-1 and ICESat-2, SARAL, Sentinel-3, etc., are utilized either with ready-to-use products or with sophisticated procedures, regarding the correction of atmospheric, geoid, and instrument parameters of satellite measurements [2,17,18,[23][24][25][26]. Water level and water area can effectively be combined in order to estimate the water volume change (variation) of a lake or the water storage of a reservoir. Moreover, additional approaches have been developed to monitor the bathymetry of lakes and reservoirs but cannot yet be sufficiently applied in all types of lakes and reservoirs, especially deeper ones [27][28][29][30]. Regarding the abovementioned approaches of the remote sensing of inland water, the majority applied are specific case studies. ...
Inland water resources are facing increasing quantitative and qualitative pressures, deriving from anthropogenic causes and the ongoing climate change. The monitoring of reservoirs is essential for sustainable management and preparation against water scarcity and extreme events, such as droughts. This research, relying on the Sentinel-2 and 3 missions, attempts to demonstrate the efficiency of combining remotely sensed water level and water area estimations, in order to estimate the water storage variation of Yliki reservoir. The case study is conducted in one of the few sufficiently monitored reservoirs in Greece, enabling a direct comparison of the proposed methodology results
with in situ observations. Moreover, this research work proposes a weekly time interval for pairing level and area estimations, instead of shorter time intervals. The results strongly demonstrate the efficiency of remote sensing in the production of empirical level–area–storage (L–A–S) curves. Correlation to in situ monitored storage- and satellite-derived water level, area stand for 98.81% and 99.27% respectively. Water storage variation is estimated and compared to the observed time series, resulting in an RMSE of 1.28% of the reservoir capacity and a correlation of 96.14%. The empirical L–S relationship underestimates storage, while the A–S relationship overestimates storage when
compared to the existing L–A–S curve.
... Satellite images are able to detect water bodies and, using spectral indices and classification algorithms, calculate their extent. The extent of water can also be useful for characterizing the geometry of lakes in combination with satellite altimetry (Arsen et al., 2014;Baup et al., 2014) and in situ water levels (Collischon & Clarke, 2016). Other approaches have been tested in Northeast Brazil using a combination of satellite imagery and field surveys (Lopes & Araújo, 2019), digital elevation models derived from synthetic aperture radar (SAR) images (Zhang et al., 2016), and supervised classification of maximum likelihood (Toledo et al., 2014). ...
... On the other hand, the results encourage the application of the ISODATA method for the calculation of CAVs in other reservoirs in the Northeast semiarid region. Unsupervised methods such as ISODATA do not need to determine the threshold to classify water, as verified in applications using spectral indices (NDVI, NDWI, MNDWI, among others) (Arsen et al., 2014, Feyisa et al., 2014, Schwatke et al., 2019. The results obtained with the ISODATA in the Poço da Cruz reservoir, for example, were better than the application of NDWI carried out by Costa (2019) and had a reduced tendency to underestimate the surface area. ...
Reservoirs are the primary source of water supply in the semiarid region of Pernambuco state, Brazil, because of the constant water scarcity affecting this region. Knowledge of the amount of water available is essential for the effective management of water resources. The volume of water stored in the reservoirs is calculated using the depth-area-volume relationship. However, in most reservoirs in the semiarid region, this relationship is currently out of date. Therefore, the objective of this study was to explore the potential and limitations of the application of the ISODATA unsupervised classification method to calculate the depth-area-volume relationships of reservoirs in the semiarid region of Pernambuco, Brazil. The application of the ISODATA method was evaluated in three reservoirs in the state of Pernambuco, i.e., Poço da Cruz, Barra do Juá, and Jucazinho. The results were compared with the updated curves of reservoirs obtained from bathymetry and recent LiDAR surveys. The ISODATA method presented satisfactory results for the three reservoirs analyzed. The mean absolute error of the volume in Poço da Cruz and Barra do Juá was lower than 1% of the maximum capacity. The use of the ISODATA method meant that the surface area underestimation tendency in the Poço da Cruz reservoir was less than when spectral indices were used.
... Yet when the altimeter manages to acquire the lake or river signals, the estimation is very valuable as demonstrated early in the literature [23] [14] [5] [24] [16]. With the initial Low-Resolution Mode of altimeters (LRM), the accuracy of the estimations is around few cms above very large lakes, such as great Lakes, USA [23] and at decimeter level for smaller lakes [24] [25]. ...
Access to fresh water is a key issue for the next decades in the context of the Global Warming. The water level of lakes is a fundamental variable which needs to be monitored for this purpose. The radar altimetry constellation brings a worldwide means to this question. Recent advances in radar altimeter on-board tracking modes have allowed in monitoring thousands of lakes and rivers. Now, measurements are widely available with better resolution: it is time to drastically improve the processing. The altimetry waveforms over lakes are difficult to analyze, and very different from the ocean ones. We face a large variety of signals due to surface roughness, lake geometry and environment. The inversion process, named retracking, shall be able to describe all these components. We propose here a retracking based on physical simulations taking as inputs the lake contour and the instrument characteristics. Fitting the simulation on the waveforms gives the water surface height. The algorithm has been tested on the Sentinel-3A and Sentinel-3B time series over Occitan reservoirs (France) and Swiss lakes and compared to in-situ references. Over small Occitan reservoirs (few ha to few km2), the UnBiased Root Mean-Square Error (ub-rmse) is better than 14 cm. Over the medium size Swiss lakes, the ub-rmse is better than 10 cm for most of them.
... The advantage of this technique is the possibility of addressing wide spatial gradients (e.g., from global to local scales and across different geographies) spanning several decades at a low cost without instrumental records (Shugar et al., 2020). Satellite image analysis has been used to estimate changes in physical and biological properties on terrestrial and aquatic ecosystems (Crisman et al., 2014;Arsen et al., 2014;Yao et al., 2019). Numerous studies based on satellite images have established the changes in lake water dynamics, volume (e.g., Lu et al., 2013;Baup et al., 2014), morphometry (e.g., Ovakoglou et al., 2016), and surface area (e.g., Gao, 2015;Yao et al., 2019). ...
Study region
Andes central Chile (32ºS-36ºS) / Lakes
Study focus
Mountain lakes play a key role in the terrestrial freshwater reservoir, both for storage of snow melt and precipitation. Although lakes are sensitive to climate variability, the effect of global warming on water availability remains uncertain. Semiarid regions are especially sensitive to relatively small changes in temperature and precipitation as these have disproportionately large impacts on lake hydrologic budgets. Here, we mapped 12 lakes from the Andes of central Chile (32º-36ºS) using Landsat mission and Sentinel-2 satellites images from 1984 to 2020 and compared these results with the available climate data (precipitation, temperature, and evaporation).
New hydrological insights for the region
This approach provides a high-resolution temporal and spatial analysis for changes in lake surface over the last 36 years. Our results indicate that the number of lakes and respective surface area decrease latitudinally from south to north across central Chile, which is consistent the present-day rainfall gradient. Over the study period, lake surface areas decreased significantly between 7% and 25% during the so-called ‘megadrought’ (2010–2020). As lakes continue to dry up, the implications for freshwater availability are of considerable societal and environmental importance. Our results can assist with water management decisions and improve our understanding of future water availability across the region.
... In Titicaca, measured water levels for the modeling period 1980-2015 are also available, which were used in the calibration process. In Poopó there are no measured lake level data, only estimated data based on remote sensing products (Arsen et al., 2014) available on the Hydroweb website (http:// hydroweb.theia-land.fr/). ...
... Third, calibration of the catchments was performed with measurement at the Chuquiña station. Finally, the results of the modeling in Lake Poopó were compared with water levels estimated by previous studies based on water balance methods (Pillco Zola and Bengtsson, 2006) and remote sensing data (Arsen et al., 2014). The SMM calibration process included adjusting the irrigation threshold and the PWD, as a proxy for the specific unknown irrigation management practices carried out in the system. ...
... In the case of Desaguadero Calacoto and Ulloma there is an underestimation of the simulated flows (Fig. 5) which is directly related to the discharge flows from Lake Titicaca, since between 2003-2007 there is an underestimation of the simulated water levels of up to 0.94 m (Fig. 6), which also results in an underestimation of the discharge flows. In Lake Poopó for the validation period there are data generated by Arsen et al. (2014), the simulated levels compared to that data source show a good correspondence (Fig. 6). ...
Study region
The catchment area of Lakes Titicaca and Poopó is located in the Peruvian-Bolivian Altiplano in the central Andes of South America.
Study focus
We quantified the impact of irrigation and climate variability on the range of fluctuation of water levels in Lakes Titicaca and Poopó by applying the WEAP model to dynamically represents the hydrology of the catchment area, irrigation and water storage in the lakes. The model is implemented with observed climate datasets for the region, processed at a monthly time step for the historical period 1980–2015.
New hydrological insights for the region
Fluctuations in water levels are mainly controlled by climate variability. Irrigation withdrawals aggravate unfavorable conditions, thus amplifying water level fluctuations. In Lake Titicaca the climate explains about 80 % of the fluctuation range and the remaining ∼20 % is due to irrigation. In Lake Poopó the role of climate also prevails with a contribution of about 65 %, while the remaining 35 % is attributed to irrigation. The difference in the relative contribution of irrigation between the lakes is due to the fact that the net inputs in Lake Poopó depend mostly on regional flows and on the contributions of Lake Titicaca; while in the much larger Lake Titicaca, there are net inputs due to precipitation on the lake surface in addition to the contributions of the tributaries.
... It should also be emphasised that the availability of bathymetric maps permits the determination of the primary morphometric properties of lakes, and is important for the calculation of the water, thermal, and chemical balances of these elements of the hydrosphere [13]. Therefore, knowledge concerning lake bottom relief is a frequently discussed issue in hydrological research [14][15][16][17][18]. In this context, studies concerning changes in isobaths reflecting the transformations of bottom topography should be considered scarce [19][20][21]. ...
The historical effects of land development on water management currently require a new approach, in many cases involving attempts at the restoration of the quasi-natural state. This is evident in reference to many regions in Poland, where the hydrographic network has been diminishing over the centuries, among others in favour of obtaining new agricultural land. Such activities overlap with natural processes causing transformations of the hydrosphere. The most serious problems currently include water deficits resulting from climate change and human activity. This paper employed archival bathymetric maps from the beginning of the 20th century for the determination of the scale of changes in the morphometric parameters of six lakes in western Poland. It was determined that over a period of more than a hundred years, the surface area (12.2%) and original volume of water bodies (13.9%) were largely reduced. This situation was caused by both natural (overgrowing and shallowing) and anthropogenic (change in water level) factors. The obtained information points to the need of an inventory of historical bathymetric maps of lakes. In combination with modern research, this will allow for the determination of changes in the water resources of lakes and, in a longer-term perspective, potential possibilities of their renaturisation. This knowledge is important in the context of the reconstruction of water resources in the territory of Poland, where their deficits are recorded increasingly frequently. It should also be emphasised that the restoration of the natural capacity of water retention in lakes is a more economical solution and, most importantly, it is not invasive for the environment.
... The subsatellite point footprints of the major altimetry satellites are approximately 2 km and did not cover all lakes. Research has proven that satellite altimetry is suitable for monitoring dynamic changes in the water levels of large lakes [50]. (2) Lake water volume changes are analyzed based on lake water level change monitoring data and satellite remote sensing imaging of lake area changes [51,52]. ...
Obtaining the water volume of small-and medium-sized lakes in enclosed watersheds with scarce data is a global focus of research. River flow into a lake is an important factor affecting the water volume. However, most river flow measurement methods involve long cycles, low efficiency , and transdisciplinary expertise, making rapid assessments in ungauged basins impossible. This paper proposes a remote sensing flow estimation method based on multi-source remote sensing data, which quickly assesses river flow and provides important input data for lake water volume simulation. The cross-section flow was estimated by extracting the river width. The calculated results were consistent with the measured data, with accuracy greater than 90%. The results compared with daily data measured at hydrological stations, and the Nash coefficient was greater than 0.9. Additionally, the simulation method for lake area, water volume, and water level was constructed using river inflow input data, greatly reducing the parameters required by the conventional lake water volume simulation method. Based on the remote sensing discharge estimation method, we quickly and conveniently obtained changes in river flow into the lake, simulated lake water volume, and provided the basis for water resource management in terminal lake basins with scarce data.
