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Monitoring Lakes Water Based on Multisource Remote Sensing and Novel...
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Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "New Sensors, New Technologies and Machine Learning in Water Sciences".

Deadline for manuscript submissions: closed (20 July 2022) | Viewed by 26000

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Fei Zhang

E-Mail Website1 Website2
Guest Editor
College of Geography and Remote sensing Sciences, Xinjiang University, Urumqi, China
Interests: remote sensing; water environment; landscape pattern; land use/land cover; modelling building; data reconstruction; image fusion
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Ngai Weng Chan

E-Mail Website
Guest Editor
Geography Section, School of Humanities, Universiti Sains Malaysia, Penang, Malaysia
Interests: environmental hazard management; flood management; climate change adaptation; water resource management; sustainable development
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Xinguo LI

E-Mail Website
Guest Editor
College of Geographic Sciences and Tourism, Xinjiang Normal University, Urumqi, China
Interests: changes of soil and water in arid areas
Dr. Xiaoping Wang

E-Mail Website
Guest Editor
College of Natural Resources and Environment, Northwest A&F University, Yangling, China
Interests: terrestrial water–carbon cycle; water quality monitoring and management
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Inland lakes are indicators of climate change and environmental deterioration. As a unique ecosystem unit, inland lake is one of the basic places for human survival and development. In recent years, with the rapid development of regional society and economy, the ecological environment of inland lakes has been continuously disturbed by human activities under the influence of large-scale water and soil exploitation activities, which have affected the ecological environment of lakes. Therefore, lake ecological restoration and water quality monitoring under the coupling effect of climate change and human activities are the key to lake protection and management. In recent years, remote sensing has played an increasingly important role in the monitoring of the terrestrial water cycle. Remote sensing technology has been applied in many fields, such as water storage, water quality, water level, and hydrodynamics. Furthermore, the explosive growth of remote sensing data applications is driven by the coupling of multisource remote sensing data and the expansion of new modeling technology.

This Special Issue aims to present reviews and recent advances of general interest in the use of remote sensing and GIS on inland lakes. Manuscripts can be related to any use of remote sensing and/or GIS for any application to inland lakes. They can be focused on the monitoring of inland lakes (e.g., water storage, water quality, water level, and hydrodynamics) or flux (e.g., CO2, evapotranspiration) at any scale, as well as on the management of water resources. Observations taking into account spatial and temporal variability are needed to calibrate models and control their forecasts. Remote sensing now provides access to useful factors in inland lake monitoring.

Prof. Dr. Fei Zhang
Prof. Dr. Ngai Weng Chan
Prof. Dr. Xinguo LI
Dr. Xiaoping Wang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • water environment
  • remote sensing
  • modeling
  • lake
  • water resource management

Published Papers (12 papers)

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Editorial

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4 pages, 185 KiB  
Editorial
Monitoring Lakes Water Using Multisource Remote Sensing and Novel Modeling Techniques
by Xiaoping Wang, Fei Zhang, Ngai Weng Chan and Xinguo Li
Water 2022, 14(23), 3904; https://doi.org/10.3390/w14233904 - 1 Dec 2022
Viewed by 1521
Abstract
Inland lakes are indicators of climate change and environmental deterioration [...] Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)

Research

Jump to: Editorial

11 pages, 4528 KiB  
Article
Evaluation of Grand Ethiopian Renaissance Dam Lake Using Remote Sensing Data and GIS
by Asem Salama, Mohamed ElGabry, Gad El-Qady and Hesham Hussein Moussa
Water 2022, 14(19), 3033; https://doi.org/10.3390/w14193033 - 27 Sep 2022
Cited by 5 | Viewed by 5197
Abstract
Ethiopia began constructing the Grand Ethiopian Renaissance Dam (GERD) in 2011 on the Blue Nile near the borders of Sudan for electricity production. The dam was constructed as a roller-compacted concrete (RCC) gravity-type dam, comprising two power stations, three spillways, and the Saddle [...] Read more.
Ethiopia began constructing the Grand Ethiopian Renaissance Dam (GERD) in 2011 on the Blue Nile near the borders of Sudan for electricity production. The dam was constructed as a roller-compacted concrete (RCC) gravity-type dam, comprising two power stations, three spillways, and the Saddle Dam. The main dam is expected to be 145 m high and 1780 m long. After filling of the dam, the estimated volume of Nile water to be bounded is about 74 billion m3. The first filling of the dam reservoir started in July 2020. It is crucial to monitor the newly impounded lake and its size for the water security balance for the Nile countries. We used remote sensing techniques and a geographic information system to analyze different satellite images, including multi-looking Sentinel-2, Landsat-9, and Sentinel-1 (SAR), to monitor the changes in the volume of water from 21 July 2020 to 28 August 2022. The volume of Nile water during and after the first, second, and third filling was estimated for the Grand Ethiopian Renaissance Dam (GERD) Reservoir Lake and compared for future hazards and environmental impacts. The proposed monitoring and early warning system of the Nile Basin lakes is essential to act as a confidence-building measure and provide an opportunity for cooperation between the Nile Basin countries. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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20 pages, 3706 KiB  
Article
Estimations of Water Volume and External Loading Based on DYRESM Hydrodynamic Model at Lake Dianchi
by Rufeng Zhang, Liancong Luo, Min Pan, Feng He, Chunliang Luo, Di Meng, Huiyun Li, Jialong Li, Falu Gong, Guizhu Wu, Lan Chen, Jian Zhang and Ting Sun
Water 2022, 14(18), 2832; https://doi.org/10.3390/w14182832 - 12 Sep 2022
Cited by 5 | Viewed by 1840
Abstract
There are many rivers flowing from complex paths into Lake Dianchi. At present, there is a lack of inflow and water quality monitoring data for some rivers, resulting in limited accuracy of statistical results regarding water volume and external loading estimations. In this [...] Read more.
There are many rivers flowing from complex paths into Lake Dianchi. At present, there is a lack of inflow and water quality monitoring data for some rivers, resulting in limited accuracy of statistical results regarding water volume and external loading estimations. In this study, we used DYRESM to estimate the water volume entering Waihai of Lake Dianchi from 2007 to 2019 without historical hydrological observation data. Then, we combined this information with the monthly monitoring data of water quality to calculate the annual external loading. Our results showed that: (1) DYRESM could effectively capture the extreme changes of water level at Waihai, showing its reliable applicability to Lake Dianchi. (2) The average annual inflow of rivers entering Waihai was about 6.69 × 108 m3. The fitting relationship between river inflow and precipitation was significant on annual scale (r = 0.74), with a higher inner-annual fitting coefficient between them (r = 0.98), thus suggesting that precipitation and its caused river inflows are the main water source for Waihai. (3) From 2007 to 2010, the river loadings remained at a high level. They decreased to 2445.44 t (total nitrogen, TN) and 106.53 t (total phosphorus, TP) due to a followed drought in 2011. (4) The river loading had annual variation characteristics. The contribution rates of TN and TP loading in the rainy season were 63% and 67% respectively. (5) Panlong River, Daqing River, Jinjia River, Xinbaoxiang River, Cailian River and Hai River were the main inflow rivers. Their loadings accounted for 81.3% (TN) and 80.3% (TP) of the total inputs. (6) River loadings have gradually reduced and the water quality of Waihai has continually improved. However, Pearson analysis results showed that the water quality parameters were not significantly correlated with their corresponding external loading at Waihai, indicating that there might be other factors influencing the water quality. (7) The contribution rates of internal release to the total loads of TN and TP at Waihai were estimated to be 7.6% and 8.9% respectively, suggesting that the reductions of both external and internal loading should be considered in order to significantly improve the water quality at Waihai of Lake Dianchi. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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17 pages, 8612 KiB  
Article
High Precision Extraction of Surface Water from Complex Terrain in Bosten Lake Basin Based on Water Index and Slope Mask Data
by Xingyou Li, Fei Zhang, Ngai Weng Chan, Jinchao Shi, Changjiang Liu and Daosheng Chen
Water 2022, 14(18), 2809; https://doi.org/10.3390/w14182809 - 9 Sep 2022
Cited by 9 | Viewed by 9004
Abstract
The surface water extraction algorithm based on satellite remote sensing images is advantageous as it is able to obtain surface water information in a relatively short time. However, when it is used to extract information on surface water in large-scale, long-time series and [...] Read more.
The surface water extraction algorithm based on satellite remote sensing images is advantageous as it is able to obtain surface water information in a relatively short time. However, when it is used to extract information on surface water in large-scale, long-time series and complex terrain areas, there will be a large number of misclassified pixels, and a large amount of image preprocessing work is required. The accuracy verification is time-consuming and laborious, and the results may not be accurate. The complex climatic and topographic conditions in Bosten Lake Basin make it more difficult to monitor and control surface water bodies. Therefore, based on the GEE (Google Earth Engine) cloud platform, and the studies of the effect of nine kinds of water indexes on the surface water extraction in Bosten Lake Basin, this paper adds a slope mask to remove misclassified pixels and finds the best extraction method of surface water extraction in the basin by means of accuracy verification and visual discrimination through continuous iteration of index threshold and slope mask threshold. The results show that when the threshold value is −0.25 and the slope mask is 8 degrees, the index WI2019 has the best effect on the surface water information extraction of Bosten Lake Basin, effectively eliminating the interference of shadow and snow. The effect of water extraction in the long-time series is discussed and it was found that the precision of water extraction in the long-time series is also better than other indexes. The effects of various indexes on surface water extraction under complex terrain are compared. It can quickly and accurately realize the long-time series of surface water extraction under large-area complex terrain and provides useful guiding significance for water resources management and allocation as well as a water resources ecological assessment of Bosten Lake Basin. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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19 pages, 4462 KiB  
Article
Modeling the Effects of Climate Change and Land Use/Land Cover Change on Sediment Yield in a Large Reservoir Basin in the East Asian Monsoonal Region
by Huiyun Li, Chuanguan Yu, Boqiang Qin, Yuan Li, Junliang Jin, Liancong Luo, Zhixu Wu, Kun Shi and Guangwei Zhu
Water 2022, 14(15), 2346; https://doi.org/10.3390/w14152346 - 29 Jul 2022
Cited by 7 | Viewed by 2607
Abstract
This research addresses the separate and combined impacts of changes in climate and land use/land cover on the hydrological processes and sediment yield in the Xin’anjiang Reservoir Basin (XRB) in the southeast of China by using the soil and water assessment tool (SWAT) [...] Read more.
This research addresses the separate and combined impacts of changes in climate and land use/land cover on the hydrological processes and sediment yield in the Xin’anjiang Reservoir Basin (XRB) in the southeast of China by using the soil and water assessment tool (SWAT) hydrological model in combination with the downscaled general circulation model (GCM) projection outputs. The SWAT model was run under a variety of prescribed scenarios including three climate changes, two land use changes, and three combined changes for the future period (2068–2100). The uncertainty and attribution of the sediment yield variations to the climate and land use/land cover changes at the monthly and annual scale were analyzed. The responses of the sediment yield to changes in climate and land use/land cover were considered. The results showed that all scenarios of climate changes, land use/land cover alterations, and combined changes projected an increase in sediment yield in the basin. Under three representative concentration pathways (RCP), climate change significantly increased the annual sediment yield (by 41.03–54.88%), and deforestation may also increase the annual sediment yield (by 1.1–1.2%) in the future. The comprehensive influence of changes in climate and land use/land cover on sediment yield was 97.33–98.05% (attributed to climate change) and 1.95–2.67% (attributed to land use/land cover change) at the annual scale, respectively. This means that during the 2068–2100 period, climate change will exert a much larger influence on the sediment yield than land use/land cover alteration in XRB if the future land use/land cover remains unchanged after 2015. Moreover, climate change impacts alone on the spatial distribution of sediment yield alterations are projected consistently with those of changes in the precipitation and water yield. At the intra-annual scale, the mean monthly transported sediment exhibits a significant increase in March–May, but a slight decrease in June–August in the future. Therefore, the adaptation to climate change and land use/land cover change should be considered when planning and managing water environmental resources of the reservoirs and catchments. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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12 pages, 1797 KiB  
Communication
The Feasibility of Monitoring Great Plains Playa Inundation with the Sentinel 2A/B Satellites for Ecological and Hydrological Applications
by Hannah L. Tripp, Erik T. Crosman, James B. Johnson, William J. Rogers and Nathan L. Howell
Water 2022, 14(15), 2314; https://doi.org/10.3390/w14152314 - 26 Jul 2022
Cited by 3 | Viewed by 2112
Abstract
Playas are ecologically and hydrologically important ephemeral wetlands found in arid and semi-arid regions of the world. Urbanization, changes in agricultural land use and irrigation practices, and climate change all threaten playas. While variations in playa inundation on the Great Plains of North [...] Read more.
Playas are ecologically and hydrologically important ephemeral wetlands found in arid and semi-arid regions of the world. Urbanization, changes in agricultural land use and irrigation practices, and climate change all threaten playas. While variations in playa inundation on the Great Plains of North America have been previously analyzed by satellite using annual and decadal time scales, no study to our knowledge has monitored the Great Plains playa inundation area using sub-monthly time scales. Thousands of playas smaller than ~50 m in diameter, which were not previously identified by the Landsat satellite platform, can now be captured by higher resolution satellite data. In this preliminary study, we demonstrate monitoring spatial and temporal changes in the playa water inundation area on sub-monthly times scales between September 2018 and February 2019 over a region in West Texas, USA, using 10 m spatial resolution imagery from the Sentinel-2A/B satellites. We also demonstrate the feasibility and potential benefits of using the Sentinel-2A/B satellite retrievals, in combination with precipitation and evaporation data, to monitor playas for environmental, ecological, groundwater recharge, and hydrological applications. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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17 pages, 2556 KiB  
Article
Surface Water Quality Assessment and Contamination Source Identification Using Multivariate Statistical Techniques: A Case Study of the Nanxi River in the Taihu Watershed, China
by Zhi-Min Zhang, Fei Zhang, Jing-Long Du and De-Chao Chen
Water 2022, 14(5), 778; https://doi.org/10.3390/w14050778 - 1 Mar 2022
Cited by 19 | Viewed by 3356
Abstract
Understanding the spatiotemporal patterns of water quality is crucial because it provides essential information for water pollution control. The spatiotemporal variations in water quality for the Nanxi River in the Taihu watershed of China were evaluated by a water quality index (WQI) and [...] Read more.
Understanding the spatiotemporal patterns of water quality is crucial because it provides essential information for water pollution control. The spatiotemporal variations in water quality for the Nanxi River in the Taihu watershed of China were evaluated by a water quality index (WQI) and multivariate statistical techniques; additionally, the potential sources of contamination were identified. The data set included 22 water quality parameters collected during the monitoring period from 2015 to 2020 for 14 monitoring stations. WQI assessment revealed that approximately 85% of monitoring stations were classified as “medium-low” water quality, and most showed continuous improvement in water quality. Cluster analysis divided the 14 monitoring stations into three clusters (low contamination, medium contamination and high contamination). Discriminant analysis identified pH, petroleum, volatile phenol, chemical oxygen demand, total phosphorus, F, S, fecal coliform, SO4, Cl, NO3-N, total hardness, NO2-N and NH3 as important parameters affecting spatial variations. Factor analysis identified four potential contamination source types: nutrient, organics, feces and oil. This study demonstrated the usefulness of multivariate statistical techniques in assessing large data sets, identifying contamination source types, and better understanding spatiotemporal variations in water quality to restore and protect water resources. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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16 pages, 4230 KiB  
Article
Long-Term 10 m Resolution Water Dynamics of Qinghai Lake and the Driving Factors
by Qianqian Chen, Wanqing Liu and Chang Huang
Water 2022, 14(4), 671; https://doi.org/10.3390/w14040671 - 21 Feb 2022
Cited by 13 | Viewed by 2610
Abstract
As the largest inland saltwater lake in China, Qinghai Lake plays an important role in regional sustainable development and ecological environment protection. In this study, we adopted a spatial downscaling model for mapping lake water at 10 m resolution through integrating Sentinel-2 and [...] Read more.
As the largest inland saltwater lake in China, Qinghai Lake plays an important role in regional sustainable development and ecological environment protection. In this study, we adopted a spatial downscaling model for mapping lake water at 10 m resolution through integrating Sentinel-2 and Landsat data, which was applied to map the water extent of Qinghai Lake from 1991 to 2020. This was further combined with the Hydroweb water level dataset to establish an area-level relationship to acquire the 30-year water level and water volume. Then, the driving factors of its water dynamics were analyzed based on the grey system theory. It was found that the lake area, water level, and water volume decreased from 1991 to 2004, but then showed an increasing trend afterwards. The lake area ranges from 4199.23 to 4494.99 km2. The water level decreased with a speed of ~0.05 m/a before 2004 and then increased with a speed of 0.22 m/a thereafter. Correspondingly, the water volume declined by 5.29 km3 in the first 13 years, and rapidly increased by 15.57 km3 thereafter. The correlation between climatic factors and the water volume of Qinghai Lake is significant. Precipitation has the greatest positive impact on the water volume variation with the relational grade of 0.912, while evaporation has a negative impact. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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12 pages, 1795 KiB  
Article
A Novel Early Warning System (EWS) for Water Quality, Integrating a High-Frequency Monitoring Database with Efficient Data Quality Control Technology at a Large and Deep Lake (Lake Qiandao), China
by Liancong Luo, Jia Lan, Yucheng Wang, Huiyun Li, Zhixu Wu, Chrisopher McBridge, Hong Zhou, Fenglong Liu, Rufeng Zhang, Falu Gong, Jialong Li, Lan Chen and Guizhu Wu
Water 2022, 14(4), 602; https://doi.org/10.3390/w14040602 - 16 Feb 2022
Cited by 6 | Viewed by 3166
Abstract
To assess water quality (WQ) online for assuring the safety of drinking water, a novel early warning system integrating a high-frequency monitoring system (HFMS) and data quality control (QC) was developed at Lake Qiandao. The HFMS was designed for monitoring water quality, nutrient [...] Read more.
To assess water quality (WQ) online for assuring the safety of drinking water, a novel early warning system integrating a high-frequency monitoring system (HFMS) and data quality control (QC) was developed at Lake Qiandao. The HFMS was designed for monitoring water quality, nutrient inputs by main tributaries, water currents and meteorology at different sites at Lake Qiandao. The EWS focused on data availability, a QC method, a statistical analysis method and data applications instead of technological aspects for sondes, wireless data transfer and interface software development. QC was implemented before use to delete the abnormal values of outliers, to detect change points, to analyse the change trend, to interpolate discrete missing measurements, and find continuous missing or wrong observations caused by technical problems with the sonde. For demonstrating advantages and data availability, surface and profiling measurements at two sites were plotted. The plots show obvious seasonal and diel variations, demonstrating the success of integration of the system with advanced automated technology and good QC. This successfully developed system is now not only giving early warning signals, but also providing critical WQ information for the security of drinking water diverted to Hangzhou city through a tunnel of 110 km length. The automatic monitoring data with QC is also being used to produce initial conditions for WQ prediction based on a three dimensional hydrodynamic-ecosystem model. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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22 pages, 26404 KiB  
Article
Remote Analysis of the Chlorophyll-a Concentration Using Sentinel-2 MSI Images in a Semiarid Environment in Northeastern Brazil
by Thaís R. Benevides T. Aranha, Jean-Michel Martinez, Enio P. Souza, Mário U. G. Barros and Eduardo Sávio P. R. Martins
Water 2022, 14(3), 451; https://doi.org/10.3390/w14030451 - 2 Feb 2022
Cited by 14 | Viewed by 3440
Abstract
In this paper, the authors use remote-sensing images to monitor the water quality of reservoirs located in the semiarid region of Northeast Brazil. Sentinel-2 MSI TOA Level 1C reflectance images were used to remotely estimate the concentration of chlorophyll-a (chl-a), the main indicator [...] Read more.
In this paper, the authors use remote-sensing images to monitor the water quality of reservoirs located in the semiarid region of Northeast Brazil. Sentinel-2 MSI TOA Level 1C reflectance images were used to remotely estimate the concentration of chlorophyll-a (chl-a), the main indicator of the trophic state of aquatic environments, in five reservoirs in the state of Ceará, Brazil. A three-spectral band retrieval model was calibrated using 171 water samples, collected from November 2015 through July 2018 in 5 reservoirs. For validation, 71 additional samples, collected from August 2018 through December 2019, were used to ensure a robust accuracy assessment. The TOA Level 1C products performed very well, achieving a relative RMSE of 28% and R2 = 0.80. Data on wind direction and speed, solar radiation and reservoir volume were used to generate a conceptual model to analyze the behavior of chl-a in the surface waters of the Castanhão reservoir. During 2019, the reservoir water quality showed strong variation, with concentration fluctuating from 30 to 95 µg/L We showed that the end of the dry season is marked by strong eutrophic conditions corresponding to very low water inflows into the reservoir. During the rainy season there is a large decrease in the chl-a concentration following the increase of the lake water storage. During the following dry season, satellite data show a progressive improvement of the trophic state controlled by wind intensity that promotes a better mixing of the reservoir waters and inhibiting the development of most phytoplankton. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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16 pages, 6014 KiB  
Article
Dynamics of Mid-Channel Bar during Different Impoundment Periods of the Three Gorges Reservoir Area in China
by Qingqing Tang, Daming Tan, Yongyue Ji, Lingyun Yan, Sidong Zeng, Qiao Chen, Shengjun Wu and Jilong Chen
Water 2021, 13(23), 3427; https://doi.org/10.3390/w13233427 - 3 Dec 2021
Cited by 3 | Viewed by 1923
Abstract
The dynamics of the mid-channel bars (MCBs) in the Three Gorges Reservoir (TGR) were substantially impacted by the large water-level changes due to the impoundments of the TGR. However, it is still not clear how the morphology of the MCBs changed under the [...] Read more.
The dynamics of the mid-channel bars (MCBs) in the Three Gorges Reservoir (TGR) were substantially impacted by the large water-level changes due to the impoundments of the TGR. However, it is still not clear how the morphology of the MCBs changed under the influence of water level and hydrological regime changes induced by the impoundments and operation of the TGR. In this work, the MCBs in the TGR were retrieved using Landsat remote sensing images from 1989 to 2019, and the spatio-temporal variations in the number, area, morphology and location of the MCBs during different impoundment periods were investigated. The results showed that the number and area of MCBs changed dramatically with water-level changes, and the changes were dominated by MCBs with an area less than 0.03 km2 and larger than 1 km2. The area of MCBs decreased progressively with the rising water level, and the number generally showed a decreasing trend, with the minimum number occurring at the third stage when the water level reached 139 m, resulting in the maximum average area at this period. The ratio of length to width of the MCBs generally decreased with the changes in hydrological and sediment regimes, leading to a shape adjustment from narrow–long to relatively short–round with the rising of the water level. The water impoundments of the TGR led to the migration of the dominant area from the upper section to the middle section of the TGR and resulted in a more even distribution of MCBs in the TGR. The results improve our understanding of the mechanisms of the development of MCBs in the TGR under the influence of water impoundment coupled with the annually cyclic hydrological regime and longer periods of inundation and exposure. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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17 pages, 4090 KiB  
Article
Water Quality Index (WQI) as a Potential Proxy for Remote Sensing Evaluation of Water Quality in Arid Areas
by Fei Zhang, Ngai Weng Chan, Changjiang Liu, Xiaoping Wang, Jingchao Shi, Hsiang-Te Kung, Xinguo Li, Tao Guo, Weiwei Wang and Naixin Cao
Water 2021, 13(22), 3250; https://doi.org/10.3390/w13223250 - 17 Nov 2021
Cited by 12 | Viewed by 3845
Abstract
Water Resource Sustainability Management plays a vitally important role in ensuring sustainable development, especially in water-stressed arid regions throughout the world. In order to achieve sustainable development, it is necessary to study and monitor the water quality in the arid region of Central [...] Read more.
Water Resource Sustainability Management plays a vitally important role in ensuring sustainable development, especially in water-stressed arid regions throughout the world. In order to achieve sustainable development, it is necessary to study and monitor the water quality in the arid region of Central Asia, an area that is increasingly affected by climate change. In recent decades, the rapid deterioration of water quality in the Ebinur Lake basin in Xinjiang (China) has severely threatened sustainable economic development. This study selected the Ebinur Lake basin as the study target, with the purpose of revealing the response between the water quality index and water body reflectivity, and to describe the relationship between the water quality index and water reflectivity. The methodology employed remote sensing techniques that establish a water quality index monitoring model to monitor water quality. The results of our study include: (1) the Water Quality Index (WQI) that was used to evaluate the water environment in Ebinur Lake indicates a lower water quality of Ebinur Lake, with a WQI value as high as 4000; (2) an introduction of the spectral derivative method that realizes the extraction of spectral information from a water body to better mine the information of spectral data through remote sensing, and the results also prove that the spectral derivative method can improve the relationship between the water body spectral and WQI, whereby R2 is 0.6 at the most sensitive wavelengths; (3) the correlation between the spectral sensitivity index and WQI was greater than 0.6 at the significance level of 0.01 when multi-source spectral data were integrated with the spectral index (DI, RI and NDI) and fluorescence baseline; and (4) the distribution map of WQI in Ebinur Lake was obtained by the optimal model, which was constructed based on the third derivative data of Sentinel 2 data. We concluded that the water quality in the northwest of Ebinur Lake was the lowest in the region. In conclusion, we found that remote sensing techniques were highly effective and laid a foundation for water quality detection in arid areas. Full article
(This article belongs to the Special Issue Monitoring Lakes Water Based on Multisource Remote Sensing and Novel Modeling Techniques)
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