Shuttle Radar Topography Mission Data Research Articles

Land-Use Improvements in the Weather Research and Forecasting Model over Complex Mountainous Terrain and Comparison of Different Grid Sizes

Weather forecasts over mountainous terrain are challenging due to the complex topography that is necessarily smoothed by actual local-area models. As complex mountainous territories represent 20% of the Earth’s surface, accurate forecasts and the numerical resolution of the interaction between the surface and the atmospheric boundary layer are crucial. We present an assessment of the Weather Research and Forecasting model with two different grid spacings (1 km and 0.5 km), using two topography datasets (NASA Shuttle Radar Topography Mission and Global Multi-resolution Terrain Elevation Data 2010, digital elevation models) and four land-cover-description datasets (Corine Land Cover, U.S. Geological Survey land-use, MODIS30 and MODIS15, Moderate Resolution Imaging Spectroradiometer land-use). We investigate the Ortles Cevadale region in the Rhaetian Alps (central Italian Alps), focusing on the upper Forni Glacier proglacial area, where a micrometeorological station operated from 28 August to 11 September 2017. The simulation outputs are compared with observations at this micrometeorological station and four other weather stations distributed around the Forni Glacier with respect to the latent heat, sensible heat and ground heat fluxes, mixing-layer height, soil moisture, 2-m air temperature, and 10-m wind speed. The different model runs make it possible to isolate the contributions of land use, topography, grid spacing, and boundary-layer parametrizations. Among the considered factors, land use proves to have the most significant impact on results.

The use of remotely sensed data to reveal geologic, structural, and hydrologic features and predict potential areas of water resources in arid regions

Egypt’s arid deserts resemble the Sahara. They lack water resources because of climatic conditions, although the high topographic areas receive rainfall during sporadic storms. In this article, integrating radar Advanced Land Observing Satellite (ALOS)/Phased Array type L-band Synthetic Aperture Radar (PALSAR), Landsat-8, Sentinel-2, and Shuttle Radar Topography Mission (SRTM) data reveal the geological, geomorphic, structural, and hydrological features in Wadi Batur (WB), Egypt. This defunct tributary of the Nile basin, in the eastern Egyptian desert, covers approximately 6600 km2. Analysis of the remotely sensed data shows that the northwest–southeast structures control the structures discussed in this study, which are later captured by the east–west trend. A fused ALOS/PALSAR and Landsat-8 image reveals two water outlets for the WB: one extends between the Precambrian and Phanerozoic rocks and drains in a northwestern direction to Wadi Matula in the north, and the second cuts the sedimentary rock and drains to the west, at Idfu. Ten sub-basins were extracted by using SRTM data and arranged by their infiltration properties. Eight evidential maps were combined after assigning a weight to each, and a Geographic Information Systems (GIS) technique was used to predict the groundwater recharge potential zones (GPZs). The results show that the predicted GPZs in the WB fall into six categories, ranging from excellent to bare/absent. Importantly, about 10% of the surface areas in the WB basin are characterized by an excellent recharging potential and represent the most promising zones for future groundwater extraction. Combining various datasets derived from satellite sensors is a substantial tool to detect geological features and explore groundwater resources in arid environments.

Multi criteria analysis for flood hazard mapping using GIS techniques: a case study of Ghaghara River basin in Uttar Pradesh, India

Flooding is one of the major issues in the low lying area of Indo-Gangetic Plain. The Ghaghara basin witnesses the floods every year in Indian sub-continent and has caused loss of numerous lives and land for several decades. It may not be stopped but can be preventive. The present study is an attempt to initiate the flood risk zonation by defining multiple criteria for evaluating this major issue in Ghaghara basin, Uttar Pradesh, India. The work was done using Geographic Information Systems (GIS), Remote sensing (RS) data of (Linear Imaging Self Scanning) LISS III, SRTM (Shuttle Radar Topography Mission) data, and Survey of India (SOI) toposheet. The yearly average interpolated rainfall and multiple themes like slope, micro-watersheds, drainage density, land use/land cover (LULC), soil moisture, and soil surface texture were used to delineate the flood hazard risk zonation map. The study identified promising results for the establishment and categorization of flood risk zones into very low hazard risk zone (4%), low hazard risk zone (8.5%), moderate hazard risk zone (23.6%), high hazard risk zone (42%), and very high risk zones (21.9%). It is estimated on the basis of the study that ~27,490 localities were influenced by floods along the major channels, i.e., Ghaghara, Sarda, and Rapti. The results of this study could allow better relief operations and reduce the risk of flooding.

Integration of remote-sensing data for mapping lithological and structural features in the Esh El-Mallaha area, west Gulf of Suez, Egypt

Esh El-Mallaha west of the Gulf of Suez is a potential area for hydrocarbon resources. In this article, Landsat-8 Operational Land Imager (OLI), Shuttle Radar Topography Mission (SRTM), and Advanced Land Observing Satellite (ALOS) Phased Array Type L‐band Synthetic Aperture Radar (PALSAR) data were utilized to identify the geological and structural features of this area which represents a part of the North Eastern Desert (NED), Egypt. The use of band ratios (BR) and principal component analysis (PCA) allowed characterizing the different varieties of rock units. These approaches allowed discriminating the various rock units e.g., metavolcanics, granitoids including the two phases of the older granites and younger granites along with the third phase which represented by elongated ridges cut the rocks and clearly allowed tracing the contacts of different lithological units of the Neoproterozoic basement and Phanerozoic sedimentary rocks. Applying the fused Landsat-8 OLI and ALOS/PALSAR data improved the structural elements that difficult to reveal by optical images. Combination of Landsat-8 OLI, ALOS/PALSAR, and SRTM data effectively display the structural and lithological contacts. The lineament extraction and interpretation indicated that the area is clearly shaped by the NW-SE graben and controlled by the Gulf of Suez tectonic trend. Such structures allowed the accumulation of thick sediments in the faulted basin that represents the promise area for oil, gas, and water resources. Lineament analysis revealed that the major tectonic trends controlling the area are NW-SE and NE-SW directions with less effect of N-S and E-W trends. The NW-SE sinistral and NE-SW dextral lateral movements are recognized. Overall results revealed that the integration of optical and radar remotely sensed data is an effective tool in deciphering geological and structural features in the arid regions.

Mapping Groundwater Potential Zones Using a Knowledge-Driven Approach and GIS Analysis

Despite the Sahara being one of the most arid regions on Earth, it has experienced rainfall conditions in the past and could hold plentiful groundwater resources. Thus, groundwater is one of the most precious water resources in this region, which suffers from water shortage due to the limited rainfall caused by climatic conditions. This article will assess the knowledge-driven techniques employed to develop a model to integrate the multicriteria derived from geologic, geomorphic, structural, seismic, hydrologic, and remotely sensed data. This model was tested on the defunct Kom Ombo area of Egypt’s Nile river basin in the eastern Sahara, which covers ~28,200 km2, to reveal the promising areas of groundwater resources. To optimize the output map, we updated the model by adding the automated depression resulting from a fill-difference approach and seismic activity layers combined with other evidential maps, including slope, topography, geology, drainage density, lineament density, soil characteristics, rainfall, and morphometric characteristics, after assigning a weight for each using a Geographic Information System (GIS)-based knowledge-driven approach. The paleochannels and soil characteristics were visualized using Advanced Land Observing Satellite (ALOS)/Phased Array type L-band Synthetic Aperture Radar (PALSAR) data. Several hydromorphic characteristics, sinks/depressions, and sub-basin characteristics were extracted using Shuttle Radar Topography Mission (SRTM) data. The results revealed that the assessed groundwater potential zones (GPZs) can be arranged into five distinctive groups, depending on their probability for groundwater, namely very low (6.56%), low (22.62%), moderate (30.75%), high (29.71%), and very high (10.34%). The downstream areas and Wadi Garara have very high recharge and storage potential. Interferometry Synthetic Aperture Radar (InSAR) coherence change detection (CCD) derived from Sentinel-1 data revealed a consistency between areas with high InSAR CCD (low change) that received a plausible amount of surface water and those with very low InSAR CCD values close to 0 (high change). Landsat data validated the areas that received runoff and are of high potentiality. The twenty-nine groundwater well locations overlaid on the GPZs, to assess the predicted model, indicated that about 86.17% of the wells were matched with very good to moderate potential zones.

Incorporation of slope and rainfall variability in channel network extraction from DEM data at basin scale

This work presents an analytical framework that includes slope and rainfall variability with value of the critical area in defining a threshold for channel initiation processes for the whole river basin. The study overcomes the existing limitation of application of constant threshold for extracting channels throughout the basin by proposing slope and rainfall dependent variable threshold. The proposed algorithm successfully captures the spatial variability in drainage patterns at basin-scale characterized by different topographic characteristics. As basin-scale studies are mostly carried out using coarse-resolution digital elevation model (DEM), this methodology has been developed using Shuttle Radar Topography Mission (SRTM) data of 30 m spatial resolution. The resultant drainage pattern was compared with the published map based on field observations, which shows a closer match with field conditions. A front-end application was developed to implement the methods as an end-to-end process to make user interaction simpler.

Integration of remote-sensing, structural, and geochemical data for characterizing granitoid rocks in Um Naggat pluton, Central Eastern Desert, Egypt

Integration of remotely-sensed data, field work in addition to geochemical and mineral chemistry analyses, indicates that the Um Naggat granite pluton (UNP) has distinctive lithologic and structural characteristics. Image transformation techniques of using Landsat-8 Operational Land Imager (OLI) data successfully discriminated lithologic characteristics and highlighted hydrothermally altered areas. Shuttle Radar Topography Mission (SRTM) and OLI data allowed highlighting the structural contacts and revealed that the dominant structural trends are NW-SE, NE-SW, and N-S. Petrographic examination, field, and structural survey results revealed that the (UNP) pluton consists of biotite alkali feldspar granite (BAFG) and alkali granite (AG) in addition to a hybrid granite zone (HGZ). The BAFG phase is dominated by an alkaline suite with composition ranging from granite to alkali feldspar granite and pertains to post-orogenic granite (POG) and within-plate granites (WPG). The AG represents the youngest alkali granite phase of magmatism in the studied pluton. Various enclaves from diorites and microgranites have been recorded within the HGZ. Field relationships confirmed with quantitative analysis of magmatic fabric measurements indicate that the AG granitic phase was emplaced as subparallel-elongated sheets or dike-like masses trending E-W and associated with an extensional regime overprinted by the right-lateral strike-slip regime. This phase of “within plate” hypersolvus granite has excessive of large-ion lithophile (LIL) and high field strength (HFS) elements such as Zr, Nb, and Ga that belongs to A-type granites, being depicted by elevated alkali composition and high Fe2O3t/(Fe2O3t +MgO) ratios, and excessive amount of Zr, Y, Nb, and Ga. Microprobe analysis reveals that the compositions of amphibole mineral in the HGZ extent from magnesio-hornblende to actinolite and the temperature of the plagioclase range from 900 to 1050 °C, while the plagioclase of the BAFG is extremely pure albite in composition.

Assessment of the AERMOD dispersion model in complex terrain with different types of digital elevation data

The AERMET/AERMOD (American Meteorological Society (AMS)/EPA Regulatory Model) dispersion modeling system constitutes a tool recommended by the United States Environmental Protection Agency (U.S. EPA) both for flat and complex terrain in a local scale with a distance of 50 km. This model requires several input data for pollutant prediction. As part of the research, the effectiveness evaluation of the AERMOD model was conducted based on two of the model evaluation databases (Martin’s Creek and Lovett) depending on different available DEM sources. The analysis involved comparison of different modeling results obtained with the application of different DEM datasets, i.e. NED (National Elevation Dataset), ASTER (Aster Global Digital Elevation Model), SRTM (Shuttle Radar Topography Mission) and USDEM (US GeoData Digital Elevation Models). Achieved outcomes indicated, that the use of different elevation datasets did not influence the evaluation results of the AERMOD model in a local scale and complex terrain significantly. Regardless of the field experiment and DEM dataset, for each case the values of FB and FBRHC fell within the range of ± 0.33. The highest values of the model performance measures reached 0.89 – 0.91 for IOA and 0.78 – 0.81 for COE in the case using the NED dataset. Slightly worse model performance was observed for the SRTM data with IOA equal to 0.82 – 0.91 and COE reaching 0.64 – 0.83.

Evaluation of topographic data sources for 2D flood modelling: case study of Kelani basin, Sri Lanka

Frequent flooding in Sri Lanka underscores the necessity of flood modelling as inundation extent and flood depth can easily be identified for implementing flood control measures. Accuracy of flood modelling is primarily influenced by topographic data sources and their resolution. Due to the lack of Light Detection and Ranging (LiDAR) data source in most regions of Sri Lanka, alternative topographic data sources need to be assessed. This paper investigates the accuracy of 2D flood model results in terms of flood depth and inundation extent developed based on open source topographic data sources, namely Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne Thermal Emission (ASTER) with 30 and 90 m resolutions. This study was carried out at the downstream of Kelani river basin as it is prone to frequent flooding. The 1 m resolution LiDAR data were used as the reference data to assess the accuracy of aforesaid data sources, and were resampled to 30 and 90 m to investigate the effect of resolution with SRTM and ASTER data sources. The results show that reduction in the resolution of LiDAR data source does not significantly affect the model accuracy as even 90 m resolution LiDAR data source produced higher accurate results (flood depth, root mean square error of 0.95 m; inundation extent, F-statistic of 70.21%) than the 30 m resolution SRTM and ASTER data sources.

An Innovative Approach for Improving the Accuracy of Digital Elevation Models for Cultivated Land

The redistribution of solar radiation, temperature, soil moisture and heat by topography affects the physical and chemical properties of the soil and the spatial distribution characteristics of crop growth. Analyses of the relationship between topography and these variables may help to improve the accuracy of digital elevation models (DEMs). The purpose of correcting Shuttle Radar Topography Mission (SRTM) data is to obtain high-precision DEM data in cultivated land. A typical black soil area was studied. A high-precision reference DEM was generated from an unmanned aerial vehicle (UAV) and extensive measured ground elevation data. The normalized differential vegetation index (NDVI), perpendicular drought index (PDI) extracted from SPOT-6 remote sensing images and potential solar radiation (PSR) extracted from SRTM. The interactions between topography and NDVI, PDI, and PSR were analyzed. The NDVI, PDI and PSR in June, July, August and September of 2016 and the SRTM were used as independent variables, and the UAV DEM was used as the dependent variable. Linear stepwise regression (LSR) and a back-propagation neural network (BPNN) were used to establish an elevation prediction model. The results indicated that (1) The correlation between topography and NDVI, PSR, PDI was significant at 0.01 level. The PDI and PSR improved the spatial resolution of SRTM data and reduce the vertical error. (2) The BPNN (R21 = 0.98, root mean square error, RMSE1 = 0.54) yielded a higher SRTM accuracy than did the studied linear model (RMSE1 = 1.00, R21 = 0.90). (3) A series of significant improvements in the SRTM were observed when assessed with the reference DEMs for two different areas, with RMSE reductions of 91% (from 14.95 m to 1.23 m) and 93% (from 15.6 m to 0.94 m). The proposed method improved the accuracy of existing DEMs and could provide support for accurate farmland management.

Integration of satellite data and spatial decision models for zoning new urban communities in El-Fayoum Desert

The current study adopts a spatial multidisciplinary approach for applying allocation models in zoning new urban sustainable communities in El-Fayoum Desert. Landsat 8 OLI imageries acquired in 2016, Shuttle Radar Topography Mission data, and thematic maps were utilized. Three spatial multicriteria sub-models were designed to create three criteria themes, namely, land resources, infrastructure, and environmental protection. The analytical hierarchy process and fuzzy sets were used for infrastructure and resources themes. The infrastructure theme was combined using weighted linear combination (WLC). The ordered weighted averaging (OWA) low-risk “AND” was used to combine the resources theme. The environmental protection theme was combined using the Boolean overlay model. The three themes (sub-models) were finally combined using equal weights to produce suitability index maps. OWA model was run on the combined (index) to test the different level of risk and trade-off between the factors. Results reveal that OWA model with minimum risk (AND) resulted in most optimum zones with total area equivalent to 58.33 km2. The WLC model (OWA medium risk) resulted in optimum zones of total area equivalent to 102.77 km2. The OWA maximum risk (OR) resulted in optimum zones with total area equivalent to 329.84 km2. The resultant maps were compared with the zones for new urban communities proposed by the General Organization for Physical Planning in its strategy for sustainable urban development of El-Fayoum. The comparison pointed out a reasonable agreement; in addition, results revealed more suitable locations that are recommended for future urban development.

Aeromagnetic and remote sensing evidence for structural framework of the middle Niger and Sokoto basins, Nigeria

High resolution aeromagnetic and Shuttle Radar Topography Mission data from parts of the N-S axis of the western half of Nigeria that covers the Middle Niger and Sokoto Basins provide a coherent picture for the surface expression of the linear and curvilinear features and the topography of the zone. It equally identifies the boundaries of the sedimentary basins with depths up to 950 m, thereby establishing the controlling architectural framework of the two basins. The relationship between observed structural features and lateral continuity of the Anka–Yauri–Iseyin and Kalangai–Zungeru-Ifewara shear zones and their implication on the mineral deposits in the region has been reinforced. The three-dimensional analytic signal applied to the aeromagnetic data unveiled magnetic structures and depths to magnetic basement were estimated using the source parameter imaging technique. The results identified several E-W, NW-SE, NNE-SSW and ENE-WSW trending structural features, two of which correspond to the NNE-SSW trending Anka–Yauri–Iseyin and Kalangai–Zungeru-Ifewara shear zones formed during the Pan-African orogeny. Additionally, we unravel a sedimentary pile, here called Libata-Auna sub-basin, connecting the Middle Niger and Sokoto Basins. The shred of evidence derived from both methods reveal the potential of the faults system through the crystalline and the sedimentary parts of the studied area for future minerals exploration projects.

Estimating Mangrove Above-Ground Biomass Loss Due to Deforestation in Malaysian Northern Borneo between 2000 and 2015 Using SRTM and Landsat Images

Mangrove forests are highly productive ecosystems and play an important role in the global carbon cycle. We used Shuttle Radar Topography Mission (SRTM) elevation data to estimate mangrove above-ground biomass (AGB) in Sabah, Malaysian northern Borneo. We developed a tree-level approach to deal with the substantial temporal discrepancy between the SRTM data and the mangrove’s field measurements. We predicted the annual growth of diameter at breast height and adjusted the field measurements to the SRTM data acquisition year to estimate the field AGB. A canopy height model (CHM) was derived by correcting the SRTM data with ground elevation. Regression analyses between the estimated AGB and SRTM CHM produced an estimation model (R2: 0.61) with a root mean square error (RMSE) of 8.24 Mg ha−1 (RMSE%: 5.47). We then quantified the mangrove forest loss based on supervised classification of multitemporal Landsat images. More than 25,000 ha of mangrove forest had disappeared between 2000 and 2015. This has resulted in a significant decrease of about 3.96 million Mg of mangrove AGB in Sabah during the study period. As SRTM elevation data has a near-global coverage, this approach can be used to map the historical AGB of mangroves, especially in Southeast Asia, to promote mangrove carbon stock conservation.

Comparative Analysis of Ellipsoidal Height and Shuttle Radar Topographic Mission Elevation

Ellipsoidal elevation represents a precise geospatial data type within the analysis and modelling of various hydrological and ecological phenomenon required in preserving the human environment. Likewise, Shuttle Radar Topographic Mission (SRTM) has created an unparalleled data set of global elevations that are freely available for modelling ubiquitous environmental applications. This research aims to carry out a comparative analysis of ellipsoidal heights and SRTM heights with the following objectives: downloading DEM’s (SRTM) data covering the study area, determining the spot heights within the boundary in conventional method, extract DEM’S heights within the boundary of the study area, and compared the heights in the conventional method with DEM’S heights. South GPS and Leica Total Station were used to acquire data for control extension and spot heightening respectively while the elevation of SRTM data was obtained by transforming the X and Y data from GPS observationto Longitude and Latitude before using ArcGIS 10.6 to extract the elevation of the boundary pillar and all the spot heights which were relatively compared in terms of its products- heights, contour, 3-D wireframe, 3-D surface model, and overlaid of contour on shaded relief. The results of the study showed that vertical difference using conventional method and SRTM dataset ranges between -2.345m to 11.026m. Also, the hypothesis tested using a two-tail student t-test and F-test revealed that one mean is not significantly different from the other at 95% confidence level. The research recommends that the products obtained for the two systems can be used interchangeably.
 Keywords: Shuttle radar topographic mission, Ellipsoidal elevation, contour, 3D wireframe, 3D surface model

Determination of agricultural land suitability with a multiple-criteria decision-making method in Northwestern Turkey.

This study was carried out in the district of Lapseki in Çanakkale, Turkey. The suitability of land in Lapseki for agriculture was evaluated by using an analytic hierarchy process. In the study, the basic parameters were determined by using the soil map and the Shuttle Radar Topography Mission data. Land use capability classes, soil depth, erosion risk and other soil properties (limiting factors) were obtained from the soil map, while slope, elevation and aspect were obtained from the Shuttle Radar Topography Mission data. To determine the weight of the parameters in the analytic hierarchy process, the opinions of the public institutions and experts were obtained. The obtained data were analyzed with the analytic hierarchy process and mapped with geographic information systems techniques, and a land suitability map was generated. The agricultural land suitability map demonstrated that 2.95% (2557 ha) of the lands in the study area were highly suitable; 10.37% (8989 ha) were moderately suitable; 53.47% (46,336 ha) were marginally suitable; and 33.21% (28,775 ha) were not suitable for agricultural use. The data from the agricultural land suitability map were compared with the Coordination of Information on the Environment 2012 data. As a result of comparison, 14.12% (361 ha) of highly suitable lands for agriculture and 2.25% (202 ha) of moderate suitable lands for agriculture are urbanized. It was seen that 45.71% (24,837 ha) of the lands that are marginally suitable for agriculture and 18.76% (5397 ha) of the not suitable lands had current land use for agriculture.

Vulnerability assessment of an aquifer in the basement complex terrain of Nigeria using ‘LAHBUD’ model

We integrated hydrogeological and hydrogeophysical parameters to evaluate aquifer vulnerability to contamination in a basement complex terrain in Nigeria. Aeromagnetic and Shuttle Radar Topography Mission (SRTM) data were used to generate the composite lineament density map. Lithology information was obtained from the existing geological map, while land-use and land-use changes were derived from the Landsat 8 imagery. We also acquired 216 vertical electrical soundings (VES) to estimate the geoelectric parameters including depth to aquifer, hydraulic conductivity, and bedrock relief maps. The information obtained from geoelectric parameters, lithology, lineament density, and land use were used as the parameters in assessing the aquifer vulnerability using multi-criteria decision analysis (MCDA) in the context of the analytical hierarchy process (AHP). The assigned weights for the various aquifer vulnerability indices are 0.4569, 0.2482, 0.1469, 0.0775, 0.0402 and 0.0303 respectively for lithology (L), depth to aquifer (A), hydraulic conductivity (H), bedrock relief (B), land-use (U) and lineament density (D). These values were normalized and used in establishing a consistency ratio of 6.94%, which is lower than 10% (recommended limit). The MCDA was used to develop the aquifer vulnerability (‘LAHBUD’) model which was used to classify the study area into very low, low, moderate, high, and very high aquifer vulnerability zones. Geochemical parameters obtained from water samples were used to validate the ‘LAHBUD’ model, and gave 81% agreement in predicting the risk level of possible contaminant influence with the conceptual model, and thus confirm the reliability of the model adopted for this study.

Segmentation of Sumatran Fault Zone in Tanggamus District, Lampung based on GPS Displacement and SRTM Data

One of sources of earthquakes in Lampung Province is southern segment of Sumatran fault. The fault is used as consideration in generating hazard map which source comes from stress accumulation of crust which can be obtained by measurement of points in surface. Determining fault location is important for sustainable development in Lampung Province. Southern segment of Sumatran fault stretched on Kota Agung – capital of Tanggamus District, one of the cities with the oldest civilization in Lampung Province. The sedimentation of Kota Agung causes the delineation of Sumatran Fault Zone by using Digital Terrain Model conducted on previous research had flaw. GPS Displacement Data, Shuttle Radar Topography Mission (SRTM) Data and seismic activity are used as tools to determine the location of fault. SRTM Data has 30 meter resolution and measured in 2018. Seismic activity used in this research is obtained from USGS from last 100 years and is used as support data to determine whether the fault delineated with SRTM and GPS displacement is active. GPS displacement is derived from GPS coordinates measured periodically from 2006 to 2019. Displacement used in this research is horizontal displacement since Sumatran Fault is known as strike-slip fault that move on horizontal plane. The result resembles previous research. Location that has the highest possibility of Sumatran Fault Zone segmentation is identified as Sumatran Fault Zone segmentation on previous research named as West Semangko Fault, and East Semangko Fault, respectively. The only fault earthquakes occurred on location which is not identified Sumatran Fault Zone segmentation on previous research.

Monitoring Water-Related Ecosystems with Earth Observation Data in Support of Sustainable Development Goal (SDG) 6 Reporting

Lack of national data on water-related ecosystems is a major challenge to achieving the Sustainable Development Goal (SDG) 6 targets by 2030. Monitoring surface water extent, wetlands, and water quality from space can be an important asset for many countries in support of SDG 6 reporting. We demonstrate the potential for Earth observation (EO) data to support country reporting for SDG Indicator 6.6.1, ‘Change in the extent of water-related ecosystems over time’ and identify important considerations for countries using these data for SDG reporting. The spatial extent of water-related ecosystems, and the partial quality of water within these ecosystems is investigated for seven countries. Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 5, 7, and 8 with Shuttle Radar Topography Mission (SRTM) are used to measure surface water extent at 250 m and 30 m spatial resolution, respectively, in Cambodia, Jamaica, Peru, the Philippines, Senegal, Uganda, and Zambia. The extent of mangroves is mapped at 30 m spatial resolution using Landsat 8 Operational Land Imager (OLI), Sentinel-1, and SRTM data for Jamaica, Peru, and Senegal. Using Landsat 8 and Sentinel 2A imagery, total suspended solids and chlorophyll-a are mapped over time for a select number of large surface water bodies in Peru, Senegal, and Zambia. All of the EO datasets used are of global coverage and publicly available at no cost. The temporal consistency and long time-series of many of the datasets enable replicability over time, making reporting of change from baseline values consistent and systematic. We find that statistical comparisons between different surface water data products can help provide some degree of confidence for countries during their validation process and highlight the need for accuracy assessments when using EO-based land change data for SDG reporting. We also raise concern that EO data in the context of SDG Indicator 6.6.1 reporting may be more challenging for some countries, such as small island nations, than others to use in assessing the extent of water-related ecosystems due to scale limitations and climate variability. Country-driven validation of the EO data products remains a priority to ensure successful data integration in support of SDG Indicator 6.6.1 reporting. Multi-country studies such as this one can be valuable tools for helping to guide the evolution of SDG monitoring methodologies and provide a useful resource for countries reporting on water-related ecosystems. The EO data analyses and statistical methods used in this study can be easily replicated for country-driven validation of EO data products in the future.

Use of optical and radar remote sensing satellites for identifying and monitoring active/inactive landforms in the driest desert in Saudi Arabia

Observing Earth from the space is key for monitoring land-surface dynamics and probing near-surface geomorphic and geological features, including those obscured by sand sheets/dunes and human activity. The hyper-arid area of the Arabian Peninsula was selected for detecting and extracting obscure paleohydrological systems and modeling the spatio-temporal dynamics of sand dunes using synthetic aperture radar (SAR) and optical high-resolution remote sensing images. Interferometric synthetic aperture radar (InSAR) coherence change detection (CCD) using Sentinel-1 imagery was performed, revealing subtle changes in the surficial landforms of the study area. These images also discriminated between active and inactive geomorphic features. In addition, low-frequency L-band Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar (ALOS/PALSAR) and Shuttle Radar Topography Mission (SRTM) data revealed the details of paleochannels in the basins that drain into the Arabian Gulf. These ephemeral rivers are the source of sand that was later reshaped into dunes by aeolian processes. The results also revealed that the morphology and extension of dunes were clearly influenced by topography, slope, and wind velocity and direction, rather than human activities. Knowledge gained by exploring desert features is essential for planning settlements and development, and integrated approaches using a variety of remote sensing datasets are key for enhancing Earth observation across a range of spatial and temporal scales.

Impact of glacier shape on the mass balance changes: A case study of Dongkemadi region, central Tibetan Plateau

The morphology of glacier is a key factor impacting the glacier mass redistributions. High-resolution digital elevation models (DEMs) provide a reliable method to explore the vertical characteristics of glacier surface elevation changes in different types. Using topographic maps from 1969 and Shuttle Radar Topography Mission (SRTM) data acquired in 2000, we calculated the surface elevation changes for 18 glaciers to generate vertical profiles of elevation difference (VPED) in the Dongkemadi region, central Tibetan Plateau. The results showed that the VPEDs vary highly among different glacier types. For valley glaciers, surface thinning at middle elevations is less than that at higher and lower elevations; for cirque glaciers, however, the maximum surface decline occurred in the middle section; whereas hanging glaciers experienced progressively less surface lowering with increasing elevation. Glacier geometry directly affects ice dynamics, which in turn dictates the VPEDs of specific glaciers. This regulation of glacier evolution can be applied to project how valley glaciers might eventually assume the VPEDs of cirque and hanging glaciers due to ongoing warming.