Ground-truth Fields Research Articles

Geomorphic Evolution of Chambal River Origin in Madhya Pradesh using Remote Sensing and GIS

The Fluvial geomorphology of Chambal River basin is so vast in terminology; therefore remote sensing and GIS application and technique to analyzing the whole Chambal geomorphology in interval of space and time has been used. Chambal River is a perennial river and carries large quantity of water and sediment load to transportation. Chambal River is famous for the past prehistoric and as unpolluted river. Chambal origin considered from the Janapav valley (Janapav Shiv Temple) at Malwa ridge surrounded by Manpur Reserve Forest, Madhya Pradesh, India. The source of Chambal water is considered from seepage of groundwater from the Basaltic columnar joint rock (Malwa Ridge) where the water flows from the weak columnar joints of Basalts and follows gradient slop facing in Northward direction. Chambal River has Deccan trap Basalt as river bedded rock, Mesozoic age formation with dendritic drainage pattern at Malwa region. Chambal River origin lies at an elevation of 840.6 meter with Latitude 22 0 27′36.5″N and Longitude 75 0 41′14.4″E (source by: ground truth field data) . Physiographically the area to the North of Chambal is characterized by moderately dissected plateau and formed undulating topography. However, to determine the changes in flow, meandering, and geomorphic landforms development in the Chambal river origin, primarily the toposheet no 46N, 46M and Landsat imagery ETM+ data are used for geomorphic evolution maps and digitization and georeferencing has done by using ArcGIS v10 software. Identification of geomorphological landforms with their specific geomorphological processes either erosional or depositional in the fluvial system of the Chambal River will certainly help in assessing the environmental and hydrological problems in this Malwa region.

Full-physics 3-D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice

AbstractIn this paper we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell’s equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water as a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as ‘null lines’. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.

Airborne synthetic-aperture radar (SAR) imaging to help assess impacts of stationary fishing gear on the north Brazilian mangrove coast

Abstract Assessing artisanal fishing effort and catches in remote tropical coastal areas is a continuous challenge for fisheries data collection. This is the first spatio-temporal analysis of the large tidal weir (LTW) fishery operating on intertidal sand banks along the world’s longest mangrove coast, north Brazil. Airborne synthetic-aperture radar (SAR) images and aerial photos were integrated with field sampling to investigate catch and discard compositions of seven LTW during the main fishing season. LTW measurements on the SAR images were used to generate estimates on daily catch, wood extraction, and sand accumulation. In a coastal stretch of 67 km, 793 LTW were identified on SAR images from 2004, including 573 active LTW. The number of active LTW in Taperaçú Bay and Caeté Bay had increased from 87 in 1998 to 132 in 2004 (52% increase), and from 92 to 202 (106% increase), respectively. Sixty-five fish species from 24 families were captured in the LTW. Ariidae, Sciaenidae, Haemulidae, and Carangidae accounted for 45, 20, 10, and 7% of the total sampled catch weight of 3441 kg, respectively. The mean daily catch per LTW was 110 kg ± 9 SE. Total discards in outer estuarine LTW were >3 times higher than in inner estuarine LTW. All Aspredinidae, Belonidae, Tetraodontidae, and Trichiuridae, and >75% of Auchenipteridae, Clupeidae, Engraulidae, Ephippidae, Loricariidae, Scombridae, and Soleidae were discarded. The LTW fishery apparently practices balanced harvesting; however, the massive LTW increase suggests fishing effort reduction to moderate levels. Mangrove wood extraction for LTW construction (22 835 m3 or 855 390 trees) and sand accumulation (144 802 m3) likely have only local scale effects, negligible for the overall ecosystem dynamics. The study highlights the potential of SAR images for use in fisheries data collection and management of tropical coasts, emphasizing the need for integration with ground-truthing field studies.

Mapping agricultural wetlands in the Sacramento Valley, USA with satellite remote sensing

Information on rice paddy practices and rice habitat is required by decision makers and monitoring protocol to manage the agricultural wetlands of the Sacramento Valley, California. Satellite remote sensing imagery have been able to support these needs with accurate maps of rice extent and delineation of winter flooding. However, delineation of rice and habitat, paddy hydroperiod, and spatiotemporal dynamics have not been thoroughly carried out in the region. The objective of this research application was to evaluate cost-efficient synthetic aperture radar and optical imagery for mapping agricultural wetlands and hydroperiod management. Ground-truth field data from the Glenn-Colusa Irrigation District was used to test a suite of remote sensing indices to differentiate among agricultural wetland types and irrigation practices. A Classification And Regression Tree approach that utilized the random forest algorithm was built to map the agricultural wetlands of the Sacramento Valley. Results show optical indices sensitive to vegetative development and surface water (Landsat NDVI and LSWI) along with Synthetic Aperture Radar backscatter values (PALSAR HH sigma nought σ° dB) were the most useful for mapping hydroperiod across habitats. Overpass timing and irrigation management were key factors in sensor and index selection. Nearly 93 % (185,494 ha) of rice paddies in the Valley underwent wet seeding practices and half (90,168 ha) of actively cultivated rice area was flooded during the winter. Eight percent (16,420 ha) of rice habitat received at least one irrigation application during the crop season. The most challenging habitat types to separate were fallow rice paddies that underwent different frequencies of inundation management due to permitting policies and duck habitat promotion. Overall, the results emphasize the utility of satellite remote sensing for rice decision making and as cost-effective tools for supporting Monitoring, Reporting, and Verification protocol.

Modeling site location patterns amongst late-prehistoric villages in the Wind River Range, Wyoming

The recent discovery of six high-altitude villages and their noticeably similar microenvironments suggest potential site location patterning in Wyoming's high mountains. This pattern, centered upon abundant Whitebark Pine stands further suggests that initial village locations were targeted specifically for the optimal procurement of pine nuts. Through the GIS analysis of topographical, arboreal, and spatial variables accompanied by two ground-truthing field surveys, this project interpreted potential causalities of the locational pattern amongst these villages and, based on the hypothesized model, successfully predicted the locations of 13 new cut-and-fill lodge villages above 10,000 feet in Wyoming's Wind River Range.

A Geospatial Appraisal of Ecological and Geomorphic Change on Diego Garcia Atoll, Chagos Islands (British Indian OceanTerritory)

This study compiled a wide range of modern and historic geospatial datasets to examine ecological and geomorphic change at Diego Garcia Atoll across a 38-year period (1967–2005). This remarkable collection of spatially referenced information offered an opportunity to advance our understanding of the nature and extent of environmental change that has taken place with the construction of the military airbase at Diego Garcia. Changes assessed included movements of the lagoon rim shorelines, changes in the terrestrial vegetation on the lagoon rim and amendments to the bathymetry of the lagoon basin through dredging activities. Data compiled included detailed shoreline and vegetation maps produced as part of the H.M.S. Vidal Indian Ocean Expedition (1967), three Ikonos satellite images acquired in 2005 that collectively covered the complete Atoll area, a ground truthing field dataset collected in the northern section of the lagoon for the purpose of seafloor mapping (2005), observational evidence of shoreline erosion including photographs and descriptions of seawater inundations and bathymetric soundings from five independent surveys of the lagoon floor (1967, 1985, 1987, 1988 and 1997). Results indicated that much of the change along the lagoon rim is associated with the expansion of the inner lagoon shoreline as a result of the construction of the military airbase, with an estimated increase in land area of 3.01 km2 in this portion of the atoll rim. Comparisons of 69 rim width transects measured from 1967 and 2005 indicated that shorelines are both eroding (26 transects) and accreting (43 transects). Within a total vegetated area of 24 km2, there was a notable transition from Cocos Woodland to Broadleaf Woodland for a land area of 5.6 km2. From the hydrographic surveys, it was estimated that approximately 0.55 km3 of carbonate sediment material has been removed from the northwest quadrant of the lagoon, particularly in the vicinity of the Main Passage. As no previous record of benthic character exists, a complete benthic habitat map of the atoll was derived through classification of the three IKONOS satellite images. Management implications arising from this overall appraisal of geomorphic and ecological change at Diego Garcia included the need for ongoing monitoring of shoreline change at a representative set of sites around the atoll rim, monitoring of the water flow regime through the northern channels between the open ocean and the lagoon basin and an ongoing mapping campaign to record periodic changes in the character of the benthic surface ecology.

Rice monitoring with multi-temporal and dual-polarimetric TerraSAR-X data

This study assesses the use of TerraSAR-X data for monitoring rice cultivation in the Sanjiang Plain in Heilongjiang Province, Northeast China. The main objective is the understanding of the coherent co-polarized X-band backscattering signature of rice at different phenological stages in order to retrieve growth status.For this, multi-temporal dual polarimetric TerraSAR-X High Resolution SpotLight data (HH/VV) as well as single polarized StripMap (VV) data were acquired over the test site. In conjunction with the satellite data acquisition, a ground truth field campaign was carried out.The backscattering coefficients at HH and VV of the observed fields were extracted on the different dates and analysed as a function of rice phenology to provide a physical interpretation for the co-polarized backscatter response in a temporal and spatial manner. Then, a correlation analysis was carried out between TerraSAR-X backscattering signal and rice biomass of stem, leaf and head to evaluate the relationship with different vertical layers within the rice vegetation.HH and VV signatures show two phases of backscatter increase, one at the beginning up to 46 days after transplanting and a second one from 80 days after transplanting onwards. The first increase is related to increasing double bounce reflection from the surface–stem interaction. Then, a decreasing trend of both polarizations can be observed due to signal attenuation by increasing leaf density. A second slight increase is observed during senescence. Correlation analysis showed a significant relationship with different vertical layers at different phenological stages which prove the physical interpretation of X-band backscatter of rice. The seasonal backscatter coefficient showed that X-band is highly sensitive to changes in size, orientation and density of the dominant elements in the upper canopy.

Identifying Potential Rainwater Harvesting Sites of a Semi-arid, Basaltic Region of Western India, Using SCS-CN Method

Upper Karha watershed from semi-arid part of Deccan Volcanic Province, India was investigated to identify the potential sites to construct rainwater harvesting structures with the help of remote sensing and geographical information system. Attempt was made to understand the basaltic terrain in spatial context to find out the rainwater harvesting structures like farm ponds, percolation tank, check dams and gully plugs deriving from thematic layers, such as landuse/landcover, slope, soil, drainage and runoff from Landsat Thematic Mapper imagery and other collateral data. Subsequently, these layers were processed to derive runoff from Soil Conservation Service Curve Number (SCS-CN) method using Arc-CN runoff tool. The SCS-CN method shows that the high runoff potential is from water-body, agriculture land (including harvested land) and followed by settlement, open scrub, dense scrub and low for the open forest, dense forest area. Parameters like hydro-geomorphology, geology were considered as per Integrated Mission for Sustainable Development specifications for identification of the structures. The thematic layers overlaid using intersection based on these specifications. Derived sites were investigated for its suitability and implementation by ground truth field verification. In conclusion, the method adopted in present study deciphers the more precise, accurate and ability to process large catchment area than other methods.

Development of a time–frequency approach to quantify railroad ballast fouling condition using ultra-wide band ground-penetrating radar data

This paper discusses the use of ground-penetrating radar (GPR) to assess railroad track substructure conditions. An ultra-wide band (UWB) GPR system, having a centre frequency at or higher than 2 GHz, can be used to detect the scattering pattern and to predict air void volume in railroad ballast. A time–frequency technique was implemented to characterise the signal in time and frequency domains simultaneously. Because electromagnetic energy attenuation is highly frequency dependent, the frequency sub-bands of the reflected UWB GPR signal can be analysed separately to quantify the fouling material and quantify moisture content. Additionally, to validate the GPR system capability, a ground truth field survey was conducted. Using ballast samples collected from the field for validation, this paper shows that a time–frequency analysis may provide a new method to measure the thickness of clean ballast, detect the trapped water and assess the ballast fouling and moisture content along the track.

Red List assessment of nine Aegilops species in Armenia

The aims of this study are to determine the geographical and ecological distribution of nine Aegilops species in Republic of Armenia and to make an assessment of their IUCN Red List status, using the IUCN Red list categories and criteria, in order to develop an in situ conservation strategy for wild relatives of wheat in Armenia. Ecogeographic sur- veys of nine Aegilops species were undertaken over 2 years in Armenia. They included a herbarium survey followed by extensive ground-truthing field surveys where targeted Aegilops species occur. The study showed that of the nine Aegilops species studied, four are threatened and of these, Ae. mutica and Ae. crassa are critically endangered. The latter species may even be extinct in Armenia. Ae. neglecta and A. biuncialis are endangered. Additional stud- ies are required to assess the threat status of Ae. umbellulata. Ae. columnaris was assessed as near threatened, while the remaining species (Ae. triun- cialis, Ae. cylindrica and Ae. tauschii) are of least concern. There has been a dramatic decline in the genetic resources of Aegilops species during recent years in Armenia as a result of adverse human impacts such as expansion of agriculture, urbaniza- tion and uncontrolled grazing. Several species, espe- cially Ae. mutica and Ae. crassa, should be prioritized in conservation activities in Armenia. Efforts should be made to conserve genetic diversity of crop wild relative species both in situ and ex situ, bearing in mind that their germplasm carries potentially valu- able information (traits) that can improve adaptability and productivity of cultivated wheat varieties.

3-hourly quantitative precipitation estimation over Central and Northern Europe from rain gauge and radar data

Continental-scale 3-hourly precipitation fields have been analysed from operational CERAD (Central European Radar) and BALTRAD (Baltic Radar) networks and adjusted with daily precipitation measurements from about 10,000 synoptic and climate stations. Here we focus on the application of CERAD and BALTRAD for quantitative precipitation estimation (QPE) that is the choice of quality control methods, the impact of input radar data quality on the analysis results and the analysis algorithm. The quality of the radar derived precipitation fields has been estimated by comparison with ground truth fields at the spatio-temporal scale of the ELDAS (European Land Data Assimilation System) project grid (0.2°/daily). Additionally, statistics on the availability of CERAD and BALTRAD data for the entire ELDAS period from Oct. 1999 to Dec. 2000 have been compiled. The final ELDAS precipitation product covers the whole of Europe and is available in GRIB format from the ECMWF MARS archive.

Polarimetric synthetic aperture radar (SAR) and geodynamic applications: An overview of a new Earth system observation concept

Space-borne Earth observation technique is one of the most cost effective and rapidly advancing Earth science technological research tools today and the micro-wave radar applications have been leading the discipline. The new Earth observation satellites ENVISAT (launched on March 1 2002, specifically for Earth environment observation), ALOS (planned for launching in 2004 and stands for Advanced Land Observation Satellite), and RADARSAT-II (planned for lauching in 2004) all have synthetic aperture radar (SAR) onboard, which all have partial or fully polarimetric imaging capabilities. In addition to the radar altimeter and scatterometer, these new types of polarimetric imaging radars are opening up completely new possibilities in Earth system science research. The main advantage of a SAR system is the all weather imaging capability without Sun light and the newly developed interferometric capabilities, utilizing the phase information in SAR data further extends the observation capabilities of directional surface covers and neotectonic surface displacements. In addition, if one can utilize the newly available multiple frequency polarimetric information, the new generation of spaceborne SAR systems is the future research tool for Earth observation and global environmental, change monitoring investigation. In preparation of the up-coming new generation of satellites ENVISAT, ALOS, and RADARSAT-II, the Korean scientists and engineers planned the PACRIM-II experiment with NASA(JPL) AIRSAR/MASTER team and carried out multi-disciplinary experiments in the fall of 2000, followed by extensive ground truth field work. The main sensors being utilized included the fully polarimetric SAR systems capable of routine imaging as well as both coss- and along-track interferometry, selectively in three frequencies (C-, L-, and P-bands). The newly added MASTER simulator was a hyperspectral optical imaging system with spectral windows duplicating the MODIS and ASTER multispectral imaging systems. The participating science and engineering disciplines include EM engineering, communication technology, image processing, meteorology, forestry, archeology, geology, environment, natural disaster monitoring and management, geohydrology, agriculture, fishery, coastal changes and oceanography. The geodynamic applications being investigated with the multiple frequency fully polarimetric AIRSAR data include precise generation of digital elevation model (DEM), development of multi-temporal differential crosstrack SAR interferometry, and surface geological mapping without look-direction bias.

Spatial rainfall estimation by linear and non-linear co-kriging of radar-rainfall and raingage data

The feasibility of linear and nonlinear geostatistical estimation techniques for optimal merging of rainfall data from raingage and radar observations is investigated in this study by use of controlled numerical experiments. Synthetic radar and raingage data are generated with their hypothetical error structures that explicitly account for sampling characteristics of the two sensors. Numerically simulated rainfall fields considered to be ground-truth fields on 4×4 km grids are used in the generation of radar and raingage observations. Ground-truth rainfall fields consist of generated rainfall fields with various climatic characteristics that preserve the space-time covariance function of rainfall events in extratropical cyclonic storms. Optimal mean areal precipitation estimates are obtained based on the minimum variance, unbiased property of kriging techniques under the second order homogeneity assumption of rainfall fields. The evaluation of estimated rainfall fields is done based on the refinement of spatial predictability over what would be provided from each sensor individually. Attention is mainly given to removal of measurement error and bias that are synthetically introduced to radar measurements. The influence of raingage network density on estimated rainfall fields is also examined.

A Spectral Approach to the Unification of Satellite and Conventional Temperature Data

A method for combining temperature soundings derived from VISSR Atmospheric Sounder (VAS) radiance observations with conventional data is presented. Using data from the Atmospheric Variability Experiment/VAS Ground Truth Field Experiment, temperature profiles from rawinsonde and VAS observations were represented by Fourier cosine series, with harmonic-by-harmonic comparisons performed for collocated pairs as well as the spatial variations of harmonic coefficients. The zeroth and first harmonics in the VAS temperature soundings were combined with higher harmonics determined from conventional data to form a unified dataset. The quality of the unified data was examined by comparing the vertical motion fields derived from a linear balance model with satellite observations of cloud systems. Case studies at 1200 UTC on August 22, 23, and 24, 1983 over the western Atlantic gave good results.

Some aspects of geomorphic processes along the Goa coast through remote sensing

This paper deals with the processes operating on the beaches of Goa, interpreted from imagery, followed by ground-truth collection and field checks. Studies on Landsat imagery bring out two distinct coastal geomorphological features, one north and the other south of Vasco-da-Gama. The beaches to the south indicate the prograding shoreline with deposition being the dominant phenomenon. The beaches to the north of Vasco-da-Gama reveal a retrograding shoreline where erosion is dominant.

Rawinsonde network tested

The AVE/VAS (Atmospheric Variability Experiment/Visible and Infrared Spin‐Scan Radiometer (VISSR) Atmospheric Sounder) (VAS) Ground Truth Field Experiment was conducted in cooperation with the Operational Satellite Improvement Program and NASA's Severe Storm and Local Weather Research Program. The AVE/VAS experiment was important to the VAS demonstration because it provided, via a special mesoscale rawinsonde network, a fundamental data set upon which the VAS sounding assessment and evaluation will be made. The experiment was managed by the Marshall Space Flight Center and supports NASA's Severe Storm Program as well as the VAS demonstration conducted by NASA and managed by Goddard Space Flight Center.