Surface Water Changes Research Articles

Monitoring Surface Water Change in Northeast China in 1999–2020: Evidence from Satellite Observation and Refined Classification

Monitoring Surface Water Change in Northeast China in 1999–2020: Evidence from Satellite Observation and Refined Classification

Quantifying the availability of seasonal surface water and identifying the drivers of change within tropical forests in Cambodia.

Surface freshwater is a vital resource that is declining globally, predominantly due to climate and land use changes. Cambodia is no exception and the loss threatens many species, such as the giant ibis a Critically Endangered waterbird. We aimed to quantify the spatial and temporal (2000-2020) change of surface water availability across northern and eastern Cambodia and to assess the impact of this on the giant ibis. We used a Random Forest Classifier to determine the changes and we tested the impact of land use and geographical covariates using spatially explicit regression models. We found an overall reduction of surface water availability of 4.16%. This was predominantly driven by the presence of Economic Land Concessions and roads which increased the probability of extreme drying and flooding events. The presence of protected areas reduced these probabilities. We found changes in precipitation patterns over the wider landscape did not correlate with changes in surface water availability, supporting the overriding influence of land use change. 98% of giant ibis nests recorded during the time period were found within 25m of surface water during the dry season, highlighting their dependency on surface water. The overall surface water decline resulted in a 25% reduction in dry season suitable habitat for the giant ibis. Although absolute changes in surface water over the whole area were relatively small, the impact on the highest quality habitat for ibis is disproportionate and therefore threatens its populations. Defining the threats to such an endangered species is crucial for effective management.

Long-term spatiotemporal surface water dynamics using Google Earth Engine in southeastern Morocco

Monitoring changes in water areas within arid regions is vital for directing water resource development and ensuring efficient use, and addressing the impacts of drought and climate change. Thus, in this research, we examined the annual changes in surface water at the El Mansour Eddahbi (EME) dam (southeastern Morocco) from 1984 to 2023. To achieve this, we exploited the Google Earth Engine’s potential and applied four water indices – MNDWI, EWI, NWI, and AWEI – to Landsat satellite images. Subsequently, for each year, a supervised classification utilizing random forest was implemented to accurately extract and identify water areas. The findings revealed that the EME dam’s water surface area fluctuates substantially on an inter-annual basis. Besides, Pearson’s analysis demonstrates that the EME dam’s water surface area has a strong positive correlation with drought indices such as SPI-12 and SPEI-12. This highlights the link between changing surface water, drought, and the need for adaptive water management under climate change.

Application of GIS and RS in Petroleum Exploration

As the world’s demand for energy continues to increase, the efficiency and accuracy of exploration and exploitation of oil and gas resources have become increasingly important. The development of GIS and RS technologies has provided unprecedented convenience and opportunities for the exploitation of oil and gas resources. GIS and RS technologies have played a revolutionary role in pinpointing potential oil and gas fields, evaluating exploration risks, and monitoring the environmental impacts of exploitation activities. This paper focuses on the application of GIS and RS technologies in the field of oil exploration, focusing on the application of novel data sources such as LiDAR, high-resolution remote sensing imagery, UAV, and satellite remote sensing technologies, and the role of these technologies in assessing the environmental impacts of oil exploitation. This paper concludes that GIS and RS technologies not only enhance the accuracy of oil and gas field detection but also play a non-negligible role in environmental protection. Accurately detecting changes in surface water and groundwater helps to identify and prevent the occurrence of pollution that may be caused by exploration activities at an early stage. The significance of this paper is not only to improve the efficiency and accuracy of oil exploration but also to promote environmental protection and sustainable development.

The circular economy of water across the six continents.

Water is our most valuable and precious resource, yet it is only available in a limited amount. Sustainable use of water can therefore only operate in a circular way; nonetheless, still today depletion of water resources proceeds at an accelerated pace. Here, we quantitatively assess the water circular economy and the status of water management across 132 countries distributed over six continents by introducing the water circular economy index, WCEI, based on the three pillars of water circular economy, i.e., decreasing, optimising, and retaining. This index relies on eight indicators such as water stress, tap water price, water use efficiency, the degree of water resource management, proportion of safely treated wastewater, population with access to safe drinking water, drinking water quality, and surface water changes in hydrological basins. It allows ranking 132 countries, and most importantly to identify criticalities and bottlenecks in the sustainable use of water resources across the six continents, pointing at possible directions and actions towards a fully circular economy of water.

2000–2020年丹江口水库（河南部分）水体面积数据集

Danjiangkou Reservoir serves as the water source of the South-to-North Water Diversion Project. The long-term monitoring of changes of surface water for the reservoir using the remote sensing images is of great significance in ensuring the water transfer volume of the South-to-North Water Diversion. In this study, we used multi-temporal Landsat remote sensing images to obtain a long-time series of spatial surface water datasets for Danjiangkou Reservoir (Henan ) based on Google Earth engine cloud platform through the relationship among modified Normalized Difference Water Index (mNDWI), Enhanced Vegetation Index (EVI) and Normalized Difference Vegetation Index (NDVI). This dataset includes the surface water of Danjiangkou Reservoir from 2000 to 2020. It can provide a basis for exploring the spatiotemporal changes of the surface water and ecological environment changes in Danjiangkou Reservoir.

Mapping multi-decadal wetland loss: Comparative analysis of linear and nonlinear spatiotemporal characterization

Wetlands provide critical habitat for birds and endangered species, and can be influenced by shifts in water availability and land use. The Landsat image archive can help both document historical wetland change and monitor current dynamics, but multi-decadal retrospective studies face two important challenges: 1) many important ecohydrological processes occur at scales finer than the field of view of a 30 m Landsat pixel, and 2) ecologically meaningful wetland response units frequently exhibit spatiotemporal complexity in both vegetation and surface water which may not be well-represented by a simple study area spatial mean. Here we explore a novel method for contending with these challenges with application to the rapidly changing Andrade Mesa wetlands along the US-Mexico border. Using a 26-year (1995–2021) Landsat image time series, we track changes in surface water and vegetation using green vegetation (V) and dark (D) fractions estimated from spectral mixture analysis (SMA). Spatiotemporal dynamics in both V and D fractions were characterized using two techniques: linear Principal Component Analysis (PCA) and nonlinear manifold learning (via Uniform Manifold Approximation and Projection; UMAP). Bounding temporal endmembers were identified from PCA and used to construct a temporal mixture model which quantified total area of surface water and vegetation loss, including an uncertainty estimate. UMAP clearly distinguished areas with differing onset of vegetation and water loss which were not identifiable using PCA. Change maps were then associated with different mechanisms and outcomes, including possible mechanical clearing of vegetation and unexpected greening of woody vegetation. The overall timing of surface water and vegetation decline follows the lining of the All-American Canal, suggesting a potential cross-border hydrologic association between loss of a wetland in Mexico and water efficiency measures implemented in the United States.

Comprehensive Landsat-Based Analysis of Long-Term Surface Water Dynamics over Wetlands and Waterbodies in North America

Wetlands are considered one of the most valuable ecosystems around the world and provide numerous environmental services, including water purification, flood protection, and habitat for a variety of species. Wetlands loss is an increasing trend due to anthropogenic activities and natural processes. As such, spatial knowledge regarding the extent and dynamics of surface water is demanding for wetland conservation and protection. The Landsat program, with five decades of historical Earth observation data, has a unique advantage for monitoring wetland surface water changes and dynamics with 30 m spatial resolution. We monitored 266 Ramsar wetland sites in North America for the past 40 years using the open-access Landsat data within the Google Earth Engine cloud computing platform. Landsat Collection 2 Level-2 surface reflectance products were preprocessed and cloud-screened, and a time series of spectral bands and indices were created. The unsupervised Dynamic Surface Water Extent method classified each image into water classes with different confidence levels. An average overall agreement of 92,97% and an average F-score of 96.31% were achieved in this study. Water occurrence maps, in addition to inundation class and change maps, were created for the entire North America, and quantified spatial information was calculated for Ramsar wetland sites.

Climate-induced surface water variability at Monte San Nicola type-section (Sicily, southern Italy): New data across the Gelasian GSSP

We present the first high-resolution results on planktonic foraminiferal stable oxygen isotopes and calcareous plankton assemblages at the Monte San Nicola GSSP section (near Gela, Sicily), the type-section for the Lower Pleistocene Gelasian Stage. The oxygen isotope profile is remarkably similar to the Eastern Mediterranean oxygen isotope record and indicates that the studied section, extending from marine isotope stage (MIS) G4 to MIS 103, clearly records glacial-interglacial variability. Cyclic changes of calcareous plankton assemblages (calcareous nannofossils and foraminifera) indicate that warmer and stratified surface waters occurred during interglacials, while cooler and unstable conditions developed during glacial phases. Signatures of further increase in surface water stratification are also captured by our surface water proxies and are coeval with enhanced monsoon run-off, developed during precession minima/insolation maxima. The surface water changes recorded at the Monte San Nicola section are in phase with North Atlantic climate variability, even at suborbital scale, and reveal evidence of the first significant southward migration of the Subarctic Front in the mid-latitudes during MIS 104, slightly below the GSSP. The overall dataset provides precise alignment of the Gelasian GSSP within MIS 103 as well as new climatostratigraphic constraints, close to the GSSP, thus improving its correlation potential outside the type-area.

Cyprus Surface Water Area Variation Based on the 1984–2021 Time Series Built from Remote Sensing Products

Cyprus experiences the highest level of water stress among European Union countries due to several interplaying factors such as rainfall variability and increasing water demand. These instigate the nation to build dams on almost all rivers of the island to satisfy the requirements for drinking water and irrigation. Many studies have been primarily conducted on assessing water availability for various uses, particularly for drinking water supply and irrigation. However, there is still a gap/less explored area in terms of a better understanding of changes in surface water over time. Thus, this study aims to evaluate the water surface area variation in Cyprus over the past four decades based on remote sensing products, timeseries analysis and trend detection. The result reveals a statistically significant increasing trend (p < 0.05) in water surface area between 1984–2021. However, following the completion of the final reservoir in 2010, a statistically significant decreasing trend (p < 0.05) was observed in the permanent water surface area. This decline is related to both climatic variability and increased water demands. We observed cycles of 6, 8, and 11 years in permanent water. These cycles indicate a recurring pattern of water scarcity, with severe implication already observed on both economic activity and agriculture. The recent decade has witnessed a decline in rainfall, and this is evident through the decrease in vegetation greenness in rainfed agricultural regions, highlighting its impact. Therefore, the findings of this study underscore not only the necessity for the development of infrastructure aimed at conserving water, but also reinforces the need to discuss water use priorities in Cyprus.

Mapping surface water dynamics (1985–2021) in the Hudson Bay Lowlands, Canada using sub-pixel Landsat analysis

The fate of the carbon stored in frozen peatlands in Canada's Hudson Bay Lowlands (HBL) depends strongly on water, with wetter conditions favoring long-term storage. Dynamic surface water products generated from historical Landsat data exist to inform surface water trends in the HBL based on binary classifications of land vs water at 30 m spatial resolution. However, the HBL contains many water features smaller than 30 m, including streams and patterned fens that require a sub-pixel mapping approach to fully capture their dynamics. In this paper, we leverage an existing binary dynamic surface water product to generate a spatially and temporally comprehensive Landsat sub-pixel surface water time-series over the HBL. We first generate Landsat Red, NIR and SWIR composites from 1985 to 2021 and evaluate data-driven machine learning and physical models to derive sub-30 m water fractions across the entire mapping domain. Data-driven models were calibrated on 30 m water fractions obtained from 16 of 17 WorldView scene water fraction maps and assessed on the 17th held-out scene in a jackknife validation. Data-driven models were also calibrated by relating scaled Landsat reflectance to water fractions obtained from binary water masks at corresponding scales from 90 to 270 m. Physical models involved simple linear unmixing using a new approach that samples land endmembers in the vicinity of each pixel to represent land reflectance, and a global water endmember sampled beneath permanent water in each image. The assumption of linear scaling was verified at sub-30 m to 270 m resolution for NIR, SWIR and NDVI, which were all highly correlated with water fraction and had no significant differences among water fraction – spectral feature relationships across the full range of scales. Each of 11 different methods and input spectral features were evaluated against WorldView water fractions and ranked based on nine criteria. We found that machine learning using all spectral features including local NIR land endmembers performed best among data-driven approaches, and linear unmixing of the NIR band using local land endmembers performed best among physical. Both best-performing methods were applied to the entire time-series and surface water area trends were calculated and compared with trends obtained from binary water masks. All three methods agree on the direction of surface water change towards wetting, with sub-pixel inter-annual variation agreeing with stream discharge noted in other studies.

Tributaries protect the water quality of central lake in an artificial spiderweb-structured water system, from the perspective of runoff pollution control

Urban lakes are often disconnected to the surrounding rivers, and they are affected by rainfall runoff pollution. This study focused on an artificial lake-river system in Shanghai featuring a spiderweb-structure, it is expected to detect whether the tributaries in such a system made a protective and buffering effect on the lake under the impact of rainfall runoff. A hydrodynamic model was established using MIKE 21, one of the most widely used software which can conduct two-dimensional modeling of water quality changes in surface water, to simulate the changes of total nitrogen (TN) and total phosphorus (TP), the key indicators causing lake eutrophication, under different rainfall events. The results showed that, under various conditions, storm events almost have no first or final effect on the central lake, TN and TP in the lake were improved by 5%–18% and 1%–12% among monitoring stations. However, Obvious negative effects were displayed in the water quality of radial – circular tributaries, and the first effects in circular tributaries were more serious than those on the radial because their difference in hydrological condition. With the increase of rainfall intensity, the peak value of the pollutant concentration in circular rivers increased 63%–185% as compared with the initial. As to final effects, some circular rivers were significantly impacted, and the pollutant concentration increased by approximately 40% in the seventh day as rainfall started. It was deduced that tributaries played as protective buffer against pollutants in this spiderweb water system, in that pollutants would be degraded in such dense spiderweb-structured river systems before entering the central lake, and rainfall runoff would also accelerate the flow in rivers and lakes. Therefore, the paper hold that, the central lake could not be separated from the radial – circular tributaries, and the officially planned pumps and sluices in the river estuaries would not be recommended. This study would provide technical support for the planning, construction and ecological protection of artificial urban lake-river system in similar areas.

Monitoring spatiotemporal changes of urban surface water based on satellite imagery and Google Earth Engine platform in Dhaka City from 1990 to 2021

BackgroundThis study focuses on Dhaka City and its impact on urban surface water. Cities, ecosystems, and agriculture need surface water. It is crucial for water resource planning and environmental preservation. The primary aim is to study how urbanization has affected surface water in Dhaka City over 30 years using satellite imagery.MethodsThe study analyzed three decades of urban surface water shifts using Landsat 5 TM and Landsat 8 OLI/TIRS satellite imagery and Google Earth Engine (GEE) with JavaScript code for water ratio index detection. To investigate water level changes, field observation surveys and secondary data analysis were conducted. This integrated methodology simplified surface water data extraction and analysis, making remote sensing easier and allowing cloud-based satellite data processing.ResultsThe study demonstrates that the amount of surface water in cities is going down, from 36.23 km2 in 1990 to 5.83 km2 in 2021, which is an enormous decrease. This means that about 20 square kilometers, or 45 percent of the water's surface, have been lost in the last 30 years. The main reasons for the drop are unplanned expansion of cities, accelerated real estate development, and more trade and economic activities in the study area.ConclusionsThe GEE algorithms provide useful insights into surface water's maximum and minimum extent, enabling appropriate planning and management. These findings aid Dhaka City's water resource management and environmental protection.

Microbiological Treatment of Nitrate and Selenate from Coal Mine-Affected Water in a Subsurface,Semi-Passive, and in situ Water Treatment Facility

Metallurgical coal mining generates significant amounts of waste rock, which can release nitrate and selenate upon atmospheric exposure, with resulting changes in surface water and ground water quality. Microorganisms residing on waste rock in the local subsurface have the metabolic potential to denitrifyand reduce selenium to treat mine-affected waters and stabilize waste rock. To support these processes, waste rock facilities have been designed to inject nutrients (e.g., methanol and phosphoric acid) in semi-passive water treatment of mine-impacted waters. Microbial community data regularly collected fromsubsurface semi-passive reactors throughout the startup and operations phases showed that native heterotrophic denitrifying bacteria and selenium reducing bacteria were enriched as a result of nutrient amendment. The microbial community was stable while the source water and geochemical parameters remained unchanged; however, a significant shift in the microbial community coincided with changes in the source of water treated. Metagenomic sequencing of microbial communities within the active treatment zone revealed multiple biochemical pathways of nitrate reduction. Geochemical and water quality data indicate near complete selenate reduction, yet a low abundance of in known selenate reduction genes were recovered. This may suggest that biologically mediated selenium reduction may be more widespread, both functionally and taxonomically. Further research into these pathways and mechanisms for nitrate and selenium reduction will help to strengthen our understanding of selenium reduction mechanisms and their application in mine water waste management.

Detecting long-term Arctic surface water changes

Detecting long-term Arctic surface water changes

Reply to: Detecting long-term Arctic surface water changes

Reply to: Detecting long-term Arctic surface water changes

Evaluating Habitat Suitability and Tidal Wetland Restoration Actions With ECOSTRESS

AbstractAs temperatures rise, it is increasingly important to monitor changes in habitat conditions for aquatic species and mitigate emerging stressors. The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument provides temperature products at a spatial and temporal scale not previously available. Here, we utilize ECOSTRESS temperature products to assess fluctuations in thermal habitat suitability for an endangered fish species and we also demonstrate the utility of the data set to assess water surface and bulk temperature changes following completion of two tidal wetland restoration efforts in the San Francisco Estuary and Sacramento–San Joaquin River Delta (Bay Delta). During all hours of the day throughout the 2018–2022 study period, key Delta Smelt habitat areas including Honker Bay, West Suisun Bay, and Mid Suisun Bay had greater than 75% of their areas suitable; there were several instances during which less than 25% of the area was thermally suitable generally coinciding with heatwave events. Overall, midday hours are less frequently suitable than morning and evening hours. Early evidence from ECOSTRESS indicates that there may be a decrease in surface water temperature of up to several degrees in tidal restoration areas, but more data is needed to show statistically significant outcomes. The ECOSTRESS record began in summer of 2018, and a longer record is needed to fully capture temperature changes associated with wetland processes and restoration efforts. Future applications of ECOSTRESS products can the capacity to help further understand ecosystem conditions and how restoration efforts affect water temperature, informing decisions that benefit Delta Smelt and other at‐risk aquatic species.

Assessing environmental change associated with early Eocene hyperthermals in the Atlantic Coastal Plain, USA

Abstract. Eocene transient global warming events (hyperthermals) can provide insight into a future warmer world. While much research has focused on the Paleocene–Eocene Thermal Maximum (PETM), hyperthermals of a smaller magnitude can be used to characterize climatic responses over different magnitudes of forcing. This study identifies two events, namely the Eocene Thermal Maximum 2 (ETM2 and H2), in shallow marine sediments of the Eocene-aged Salisbury Embayment of Maryland, based on magnetostratigraphy, calcareous nannofossil, and dinocyst biostratigraphy, as well as the recognition of negative stable carbon isotope excursions (CIEs) in biogenic calcite. We assess local environmental change in the Salisbury Embayment, utilizing clay mineralogy, marine palynology, δ18O of biogenic calcite, and biomarker paleothermometry (TEX86). Paleotemperature proxies show broad agreement between surface water and bottom water temperature changes. However, the timing of the warming does not correspond to the CIE of the ETM2 as expected from other records, and the highest values are observed during H2, suggesting factors in addition to pCO2 forcing have influenced temperature changes in the region. The ETM2 interval exhibits a shift in clay mineralogy from smectite-dominated facies to illite-rich facies, suggesting hydroclimatic changes but with a rather dampened weathering response relative to that of the PETM in the same region. Organic walled dinoflagellate cyst assemblages show large fluctuations throughout the studied section, none of which seem systematically related to CIE warming. These observations are contrary to the typical tight correspondence between climate change and assemblages across the PETM, regionally and globally, and ETM2 in the Arctic Ocean. The data do indicate very warm and (seasonally) stratified conditions, likely salinity-driven, across H2. The absence of evidence for strong perturbations in local hydrology and nutrient supply during ETM2 and H2, compared to the PETM, is consistent with the less extreme forcing and the warmer pre-event baseline, as well as the non-linear response in hydroclimates to greenhouse forcing.

Introducing ICEDAP: An ‘Iterative Coastal Embayment Delineation and Analysis Process’ with Applications for the Management of Coastal Change

Coastal embayments provide vital benefits to both nature and humans alike in the form of ecosystem services, access to waterways, and general aesthetic appeal. These coastal interfaces are therefore often subject to human development and modifications, with estuarine embayments especially likely to have been anthropogenically altered. Frequent alterations include damming to eliminate tidal influx, backfilling to create new land, and development for the sake of economic gain, which may cause profound damage to local habitats. By providing a record of transitions in surface waters over time, satellite imagery is essential to monitoring these coastal changes, especially on regional to global scales. However, prior work has not provided a straightforward way to use these satellite-derived datasets to specifically delineate embayed waters, limiting researchers’ ability to focus their analyses on this ecologically and economically important subset of coastal waters. Here, we created ICEDAP, a geometry-based ArcGIS toolbox to automatically delineate coastal embayments and quantify coastal surface water change. We then applied ICEDAP to the coast of South Korea, and found that coastal habitat change was particularly profound within embayed regions identified using an 8 km epsilon convexity setting (denoting a moderate distance from the coast and degree of enclosure by surrounding land areas). In the mapped coastal embayments, more than 1400 km2 of coastal habitats were lost during the past 38 years, primarily due to human modification such as large-scale land reclamation projects and the construction of impoundments. Our results suggest that anthropogenic alterations have resulted in the widespread loss of more than USD 70 million of valuable coastal ecosystem services. Together, ICEDAP provides a new innovative tool for both coastal scientists and managers to automatically identify hotspots of coastal change over large spatial and temporal scales in an epoch where anthropogenic and climate-driven changes commonly threaten the stability of coastal habitats.

Variations in water storage of Bosten Lake, China, over the last two decades based on multi-source satellite data

Study regionBosten Lake (Xinjiang, China). Study focusThis paper mainly focuses on quantifying changes in water storage of Bosten Lake using multi-mission satellite data. From Landsat images, we firstly extracted the lake area changes between 2003 and 2022 with the help of the modified normalized difference water index (MNDWI); Secondly, we used ICESat-1, CryoSat-2, and ICESat-2 altimetry data to draw the information of the water surface changes of the lake; Finally, the factors influencing the changes of the water volume of Bosten Lake were analyzed using meteorological and human activity data. New hydrological insights for the regionThe findings indicate that the area of Bosten Lake has reduced from 1037.9 km2 to 1015.77 km2, the water level has fallen by 0.58 m, and the volume of water has lost by 1.07 km3 between 2003 and 2022. During this period, the temperature and precipitation changes did not significantly correlate with the lake changes. In fact, lake change has obvious relationship with ecological water transfer and agricultural activities in the area. This paper is meaning in strengthening the understanding of the variation of freshwater lakes in arid areas under the background of global warming and its role in the regional water system. It also correctly assessed the impact of climate change and human activities on lakes as well as provide technical support for the sustainable development of ecological environment.