Assessment of Land use/land cover Change in the North-West District of Delhi Using Remote Sensing and GIS Techniques

Land is one of the prime natural resources. A city grows not only by population but also by changes in spatial dimensions. Urban population growth and urban sprawl induced land use changes and land transformation. The land transformation is a natural process and cannot be stopped but it can be regulated. Many geographical changes at the urban periphery are associated with the transfer of land from rural to urban purpose. There is an urgent need for fast growing areas like Delhi, which can be easily done by high-resolution remote sensing data. Land use/land cover of North West of Delhi has been analyzed for the time period of 1972?C2003. The remote sensing data used in study is Aster image of 2003 with a spatial resolution of 15?m and other data of 1972 Survey of India (SOI) toposheet at the scale of 1:50,000. Supervised digital classification using maximum likelihood classifier was applied for preparing land use/land cover. A change detection model was applied in ERDAS Imagine to find out the land use/land cover during 1972 to 2003. Eight land use classes was identified but main dominated classes were built up and agricultural land. A drastic change has been recorded during 30 years of time i. e. (1972-2003). In 1972, 92.06% of the land was under agricultural practice, which reduced to 64.71% in 2003. This shows 27.35% decrease in agricultural land in three decades. On the other hand built up area was 6.31% in 1972, which increased to 34% in 2003. One of the main cause of this land use change is the population growth due to the migration in the district from small cities and rural areas of Delhi.     

An approach to digitize analog form of accelerograms recorded at Tarbela—Pakistan

Pakistan has a long history of seismological activity. The devastation caused by Kashmir earthquake has been administered all over the world. In Pakistan first seismological network, consisting of analog accelerograms and seismographs, was setup in early 1969 at Tarbela, where the largest water reservoir of the country is located. An approach to convert analog ground motion records into digital form is explained using a simple technique. The digitized data was compared with the original analog record and found in good agreement. The data has been used to plot response spectra. The digitized data will be available for seismic response analysis of structures and seismic risk analysis of the region.     

Assessment of flood hazard,vulnerability and risk of mid-eastern Dhaka using DEM and 1D hydrodynamic model

Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map for mid-eastern Dhaka (37.16 km²) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography Mission and the hydrologic field-observed data for 32 years (1972–2004). As the topography of the area has been considerably changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future.     

Dissipative cylindrical fast magnetoacoustic waves in planetary magnetospheres

Nonlinear cylindrical fast magnetoacoustic waves are investigated in a dissipative magnetoplasma comprising of electrons, positrons, and ions. In this regard, cylindrical Kadomtsev-Petviashvili-Burgers (CKPB) equation is derived using the small amplitude perturbation expansion method. Furthermore, cylindrical Burgers-Kadomtsev-Petviashvili (Cyl Burgers-KP) for a fast magnetoacoustic wave is derived, for the first time, for spatial scales larger than the electron/positron skin depths, c/ω _p(e,p). Using the tangent hyperbolic method, the solutions of both planar KPB and Burgers-KP equations are obtained and then subsequently used as an initial profile to solve their respective counterparts in the cylindrical geometry. The effect of positron concentration, kinematic viscosity, and plasma β are explored both for the KPB and the Burgers-KP shock waves and the differences between the two are highlighted. The temporal evolution of the cylindrical fast magnetoacoustic wave is also numerically investigated. The present study may be beneficial to study the propagation characteristics of nonlinear electromagnetic shock waves in planetary magnetospheres.     

Obliquely propagating quasi one dimensional electrostatic solitary structures in dense magnetoplasmas with trapped electrons

In the present investigation, we have studied the linear and nonlinear propagation of electrostatic waves in a dense magnetoplasma with trapped electrons. Using the small amplitude approximation, formation of solitary structures has been studied both for fully and partially degenerate plasmas. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs. The present work may be beneficial to understand the propagation of solitary structures with weak transverse perturbation with special reference to white dwarf asteroseismology.     

Drift solitary structures in inhomogeneous degenerate quantum plasmas with trapped electrons

In the present work, we have considered the nonlinear effects due to trapped electrons in an inhomogeneous degenerate quantum plasma. The formation of drift solitary structures has been investigated for both fully and partially degenerate plasmas. The Sagdeev potential approach has been employed to obtain arbitrary amplitude solitary structures. Interestingly, for a fixed value of density, not only compressive but rarefactive solitary structures have been obtained for a certain temperature range. Furthermore, it has been observed that the drift solitary structures exist only for the case when the drift velocity is smaller than the velocity of the nonlinear structure. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs and the relevance of the results with regard to white dwarf asteroseismology is also pointed out.     

Geochemical and mineralogical characteristics of recent clastic sediments from lower Godavari river: Implications of source rock weathering

The major, trace and rare earth elements geochemistry and clay mineral compositions in the river bed sediments from lower reaches of Godavari river suggest that they are derived from weathering of felsic rocks. Trace and rare earth elemental compositions indicate evidence of sedimentary sorting during transportation and deposition. Lower concentrations of transition elements, such as V, Ni and Cr imply enrichment of felsic minerals in these bed sediments. The REE pattern in lower Godavari sediments is influenced by the degree of source rock weathering. The light rare earth elements (LREE) content are indicating greater fractionation compared to the heavy rare earth elements (HREE). A striking relationship is observed between TiO₂ and gZREE content suggesting a strong control by LREE-enriched titaniferous minerals on REE chemistry. Shale-normalized REE pattern demonstrate a positive Eu anomaly, suggesting weathering of feldspar and their secondary products, which are enriched in Eu. Chondrite-normalised REE pattern is characteristic of felsic volcanic, granites and gnessic source rocks. Trace elemental compositions in sediments located near urban areas suggest influence of anthropogenic activity. Chemical Index of Alteration (CIA) is high (avg. 65.76), suggesting a moderate chemical weathering environment. X-ray diffraction analysis of clay fraction shows predominance of clay minerals that are formed because of the chemical weathering of felsic rocks.     

Sheared ion flow driven nonlinear coherent structures in inhomogeneous electron-positron-ion quantum magnetoplasmas

Nonlinear equations governing the dynamics of finite amplitude drift-acoustic-waves are derived by taking into account sheared ion flow perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons, positrons, and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a counter-rotating vortex for a particular choice of the equilibrium profile. The counter rotating vortices are, however, observed to form on very short scales i.e., of the order of ion Larmor radius ρ _i in quantum plasmas. It is observed that the scalelengths over which these structures form get modified in the presence of quantum statistical and Bohm potential terms as well as the positron concentration. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.     

Structural Investigations of Afghanistan Deduced from Remote Sensing and Potential Field Data

This study integrates potential gravity and magnetic field data with remotely sensed images and geological data in an effort to understand the subsurface major geological structures in Afghanistan. Integrated analysis of Landsat SRTM data was applied for extraction of geological lineaments. The potential field data were analyzed using gradient interpretation techniques, such as analytic signal (AS), tilt derivative (TDR), horizontal gradient of the tilt derivative (HG-TDR), Euler Deconvolution (ED) and power spectrum methods, and results were correlated with known geological structures.The analysis of remote sensing data and potential field data reveals the regional geological structural characteristics of Afghanistan. The power spectrum analysis of magnetic and gravity data suggests shallow basement rocks at around 1 to 1.5 km depth. The results of TDR of potential field data are in agreement with the location of the major regional fault structures and also the location of the basins and swells, except in the Helmand region (SW Afghanistan) where many high potential field anomalies are observed and attributed to batholiths and near-surface volcanic rocks intrusions.A high-resolution airborne geophysical survey in the data sparse region of eastern Afghanistan is recommended in order to have a complete image of the potential field anomalies.