Soft-sediment deformation structures in the Late Quaternary sediments of Ladakh: Evidence for multiple phases of seismic tremors in the North western Himalayan Region

The exposed Quaternary sections of Ladakh show evidence of seismicity during the late Quaternary. Multiple levels of soft-sediment deformation structures (seismites) are recorded from the Quaternary sediments of the Spituk-Leh, along Indus Suture Zone (ISZ) and the Khalsar palaeolakes, along Shyok Suture Zone (SSZ) and Karakoraum Fault (KF). The studied sections are a part of two major tectonically formed palaeolakes at 35,000 yr BP. Nine levels of seismites from Spituk-Leh and eight levels from Khalsar sections are recorded. The deformed sediments comprise of clay, silts and sand and are restricted to a single stratigraphic layers bounded by undeformed beds suggesting synsedimentary deformation. The various deformational structures identified are simple and complex convolutes, pinch and swell bedding, microfolds and microfaults, flame-like structures, pseudonodules, clay diapirs, ball and pillow structures, pillar structures, sedimentary dykes and mud lenses. The release of stress along the ISZ, SSZ and KF, may have been responsible for inducing seismicity in the area during the late Quaternary times which may have caused liquefaction as a direct consequence of permanent deformation of ground surface due to earthquakes of large magnitudes (>5 intensity). The chronological data suggests release of stresses along ISZ, SSZ and KF in the form of earthquakes between 35,000 yr BP to approximately the Last Glacial Maxima (LGM) as evident form the available chronology.     

How green was my valley: forest canopy density in relation to topography and anthropogenic effects in Manipur valley,India

Forest canopy density (FCD) is a major factor in the evaluation of forest status and is an important indicator of possible management interventions. The study uses the FCD model with Landsat TM and Landsat 8 OLI images to assess canopy density in India’s Manipur valley and surrounding hills. Normalized difference built-up index (NDBI) was used to extract built-up areas and population density was retrieved from LandScan data, while elevation and slope were obtained from ASTER DEMs (30 m). Four types of canopy density were delineated with crown cover above 71%, 41–70%, 11–40%, below 10% and areas with no canopy cover, that is 0%. A sharp decline in forest area occurred during 1989–2016 at a rate of loss of 2.9 % year-1 with an average rate of deforestation of 3051 ha year-1. Dense forests exhibited remarkable degradation, especially towards the central valley. The variation in the topographical (elevation and slope) gradient resulted in significant differences in the canopy density over the study area barring some hill slopes. Population pressure and various developmental activities in recent decades led to forest degradation in this fragile yet rich Eastern Himalaya biodiversity hotspot.     

Drainage Analysis in a Part of the Brahmaputra Valley in Sivasagar District, Assam, India, to Detect the Role of Neotectonic Activity

An analysis of the drainage network of a part of Sivasagar district, Assam, India, is undertaken to reveal the role of neotectonic activity of the area. A number of fluvial geomorphic anomalies have been identified in the area. A prominent annular drainage anomaly is displayed by the major rivers—the Dikhu, Jhanzi, Namdang, Dorika and Disang, whose courses are carved in response to the ongoing tectonic deformation in the area. This study reveals that the development of topography and drainage system of the study area have been influenced by active subsurface geological structures. Formation of paleochannels, compressed meanders, reticulate streams, swamps, sagging of grounds, stream alignments, lineaments, knick points and abandonment of rivers as well as development of smaller drainage anomalies also substantiate the active nature of the subsurface structures.     

Atmospheric correction to IRS-P6 AWiFS data and its validation with ground measurements: A study over the semi-arid region

In this study, we have implemented a fast atmospheric correction algorithm to IRS-P6 advanced wide field sensor (AWiFS) satellite data for retrieving surface reflectance under different atmospheric and surface conditions. The algorithm is based on MODIS climatology products and simplified use of Second Simulation of Satellite Signal in Solar Spectrum (6S) radiative transfer code. The algorithm requires information on aerosol optical depth (AOD) for correcting the satellite dataset. The atmospheric correction algorithm has been tested for IRS-P6 AWiFS False colour composites covering the International Crops Research Institute for the Semi-Arid Tropics Farm, Patancheru, Hyderabad, India, under varying atmospheric conditions. Ground measurements of surface reflectance representing different land use/land cover, i.e. red soil, chick pea, groundnut and pigeon pea crops were conducted to validate the algorithm. Terra MODIS AOD₅₅₀ validated with Microtops-II sun photometer–derived AOD₅₀₀ over the urban region of Hyderabad exhibited very good correlation of ～0.92, suggesting possible use of satellite-derived AOD for atmospheric correction.     

Computerized Database of Salt Affected Soils for Agro‐climatic Regions in the Indo–Gangetic Plain of India Using GIS

Abstract

Indo_Gangetic Plain (IGP) of India that stretched from the foothills of Himalayas near the Punjab State to the Gangetic delta in West Bengal State was known for highly fertile soil and favorable climatic condition for highest production of rice‐wheat. Appearance of soil salinity in large areas of IGP caused a major concern due to loss of productivity. The salt affected soils maps of India (NRSA 1997) showed vast areas of salt affected soils distributed along the Gangetic Plain covering the States of Haryana, Punjab, Uttar Pradesh, Bihar and West Bengal. In the analogue form, these maps contain voluminous data were difficult to handle without messing the whole dataset. An attempt was made to prepare a digitized database of salt affected soils to facilitate easy access, retrieval and map calculations required for reclamation and management of salt affected soil. The salt affected soils maps on 1:250, 000 scale were digitized for the States of Punjab, Haryana, Uttar Pradesh, Bihar and West Bengal using ILWIS. GIS. The Survey of India topomap was used for geo‐referencing and basemap preparation overlaying thematic layers for administrative and political boundaries, infrastructure, irrigation and drainage and settlements. The attribute data on physiography and the soil characteristics were stored in an attribute table and linked with the digitized polygons to prepare a relational database. Combining geo‐referenced (State) maps of Haryana, Punjab, Uttar Pradesh, Bihar and West Bengal using GIS, a composite map for Indo‐Gangetic plain was prepared. Four Agroclimatic regions (ACRs) and seventeen Agroclimatic zones (ACZs) were identified in the Indo‐Gangetic Plain (The Planning Commission of India) for planning and development of natural resources at regional level. The boundaries of ACZs and ACRs were delineated from the primary (master) database of IGP using ILWIS.GIS. The distribution of SAS polygons at regional and zonal level was delineated superimposing digitized boundaries of ACRs and ACZs over the master database of IGP. The state‐wise, region‐wise and zone‐wise extent of SAS was calculated. Soils were essentially saline at Lower‐ and Middle Gangetic Plain regions but highly variable and complex saline‐sodic in the Upper‐ and Trans‐Gangetic Plain regions. The area statistics showed that maximum SAS area occurred in ACR V (Upper Gangetic Plain) in Uttar Pradesh (UP) followed by ACR IV (Middle Gangetic Plain) in UP and Bihar, ACR III (Lower Gangetic Plain) in West Bengal and ACR VI (Trans‐Gangetic Plain) of Haryana and Punjab. Such database in digital format provides geo‐referenced, easy to access and retrievable, relational database comprising of thematic and attribute information of salt affected soils at state, regional and zonal level to facilitate overlay and map calculation of related data such as water quality, climatic, landform etc, useful for planning and decision making in reclamation and management of salt affected soils in IGP and other similar regions.     

Characterizing wetland dynamics: a post-classification change detection analysis of the East Kolkata Wetlands using open source satellite data

The East Kolkata Wetlands is a unique resource recovery system. The Ramsar Convention recognized it as a ‘Wetland of International Importance’ in August 2002. However, the long-term resource exploitation and land use changes in the dynamic ecosystem have resulted in non-linear environmental responses. This is an attempt using open source remote sensing datasets to capture the spatio-temporal transformation of the wetland resulting from various anthropogenic activities. Landsat MSS and TM imageries of 1973, 1980, 1989, 2001 and 2010 were classified using Maximum Likelihood Classifier to monitor the wetland change; however, to study wetland dynamics, the post-classification wetland change detection maps have been generated for two temporal phases, i.e. 1973–1989 and 1989–2010. This study finds that the area under wetlands has reduced comprehensively in the past 40 years due to the conversion of wetlands into various other uses such as urban expansion of the Kolkata metropolitan city.     

Computerized database on salt affected soils in western and central India using GIS

Salt affected soils occupy significant areas in western and central India manifested by the arid and semiarid climate, sandy/clayey soil texture, absence of natural drainage, and inadequate infrastructure and irrigation development. These soils are productive following reclamation and appropriate management. The National Remote Sensing Agency, Hyderabad (India) published state-wise maps of salt affected soils in India on 1:250,000 scale using a legend that includes physiography, soil characteristics, and the aerial extent of the mapping units. In the analogue form, voluminous data contained in such maps were difficult to handle by users of varied backgrounds. An attempt was made to prepare a computerized database of salt affected soils for easy access, retrieval, and manipulation of spatial and attribute data useful for management of salt affected soils. The salt affected soils maps were prepared, for Rajasthan, Gujarat, Madhya Pradesh, and Maharashtra states, overlaying digitized layers of SAS polygons and the Survey of India basemap using the ILWIS (Integrated Land and Water Information System) software. GIS was used to prepare a composite (master) database of western and central India that showed the extent and distribution of salt affected soils. A relational database was prepared combining the digitized polygons with soil characteristics such as nature and degree of salinity (presence of higher concentration of neutral salts and neutral soil reaction), sodicity (presence of higher concentration of basic salts and alkaline reaction) and ground coverage. The regional and zonal databases of salt affected soils were prepared at a suitable scale overlaying agro-climatic regions agro-climatic zones. Spatial relation of salt affected soils with physiography, climate, geology, and agro-eco-sub-regions were evaluated employing map calculations in GIS. Saline soils were prevalent in Gujarat, and Rajasthan while sodic soils were dominant in Maharashtra and Madhya Pradesh. These were distributed primarily in the arid (B) plain of Rajasthan, alluvial (A) and coastal (D) plains of Gujarat, and peninsular plain (F) of Maharashtra and Madhya Pradesh. It occupied 2,596,942 ha (78%) in the western (Rajasthan and Gujarat) and 733,608 ha (22%) in the central (Madhya Pradesh and Maharashtra) regions. The SAS occupied 3.3 million ha in the western and central region constituting 50% of the total salt affected soils in India. The saline and sodic soils occupied 2,069,285 ha (62%) and 1,261,266 ha (38%), respectively.     

Seasonal characteristics and sources of carbonaceous components and elements of PM10 (2010–2019) in Delhi,India

In this study we present the seasonal chemical characteristics and potential sources of PM₁₀ at an urban location of Delhi, India during 2010?2019. The concentrations of carbonaceous aerosols [organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) and water insoluble organic carbon (WIOC)] and elements (Al, Fe, Ti, Cu, Zn, Mn, Pb, Cr, F, Cl, Br, P, S, K, As, Na, Mg, Ca, B, Ni, Mo, V, Sr, Zr and Rb) in PM₁₀ were estimated to explore their possible sources. The annual average concentration (2010–2019) of PM₁₀ was computed as 227?±?97 µg m^?3 with a range of 34?734 µg m^?3. The total carbonaceous aerosols in PM₁₀ was accounted for 22.5% of PM₁₀ mass concentration, whereas elements contribution to PM₁₀ was estimated to be 17% of PM₁₀. The statistical analysis of OC vs. EC and OC vs. WSOC of PM₁₀ reveals their common sources (biomass burning and/or fossil fuel combustion) during all the seasons. Enrichment factors (EFs) of the elements and the relationship of Al with other crustal metals (Fe, Ca, Mg and Ti) of PM₁₀ indicates the abundance of mineral dust over Delhi. Principal component analysis (PCA) extracted the five major sources [industrial emission (IE), biomass burning?+?fossil fuel combustion (BB?+?FFC), soil dust, vehicular emissions (VE) and sodium and magnesium salts (SMS)] of PM₁₀ in Delhi, India. Back trajectory and cluster analysis of airmass parcel indicate that the pollutants approaching to Delhi are mainly from Pakistan, IGP region, Arabian Sea and Bay of Bengal.

     

Soil chemical changes resulting from irrigating with petrochemical effluents

Irrigating food crops with treated wastewater is a popular management option in India. This study evaluated the impacts of land application of treated petrochemical effluent on soil chemical properties. Soil samples were collected from different depths from sites irrigated with petrochemical effluent for 2?years and from control sites. The effluent collected was analysed for different physic?Cchemical properties and its impact on Lagenaria siceraria (Bottle gourd) growth. 100% concentrated effluent was used for the study and compared with the control. It was observed that application of effluent significantly increased the major cations and anions in the field. On the basis of the study, it may be suggested that treated petrochemical effluent can be used as an alternate source for irrigating crops as it increases the nutrient content of the soil. The overall application indicates a lavishing growth of L. siceraria crop in petrochemical irrigated soil than control sites. This study provides information for better understanding of changes in soil properties due to land application of petrochemical effluent. These changes must be considered in developing possible criteria for preserving delicate ecosystems.