Using remote sensing technologies to enhance resource conservation and agricultural productivity in underutilized lands of South Asia

Satisfying the food demands of an ever-increasing population, preserving the natural resource base, and improving livelihoods are major challenges for South Asia. A large area of land in the Middle and Lower Gangetic Plains of South Asia remains either uncultivated or underused following the rice harvest in the kharif (wet) season. The area includes “rice-fallow,” estimated at 6.7 million ha, flood-prone riversides (“diara lands,” 2.4 million ha), waterlogged areas (4.9 million ha), and salt-affected soils (2.3 million ha). Bringing these lands under production could substantially improve the food supply and enhance livelihoods in the region. This paper describes a methodological case study that targeted resource-conserving technologies in underused lands of the Ballia District of eastern Uttar Pradesh (India) using multispectral remote-sensing images. Classification of temporal satellite data IRS-P6 in combination with Spot VGT 2 permitted the identification of all major categories of underused land during the post-rainy rabi/winter season, with an average accuracy of 89%. Based on three-year averages of field demonstrations, farmers gained an additional income of $63 ha⁻¹ by introducing raised beds in salt-affected soils; $140 and $800 ha⁻¹ by introducing deepwater rice varieties (monsoon) and boro rice (winter) in waterlogged areas; and $581 ha⁻¹ by introducing zero-till lentil (winter) in rain-fed fallow lowland. Timely wheat planting through zero-tillage implies an additional income of $147 ha⁻¹ and could increase wheat production by 35,000-65,000 tons in the district. The methodologies and technologies suggested in the study are applicable to more than 15 million ha of underutilized lands of the Indo-Gangetic Plains of South Asia. If the technologies are precisely applied, they can result in more than 3000 million US $ of additional income every year to these poverty prone areas.     

Geochemical assessment of groundwater around Macherla-Karempudi area,Guntur district,Andhra Pradesh

Groundwater in Palnad sub-basin is alkaline in nature and Na⁺-Cl⁻-HCO₃⁻ type around Macherla-Karempudi area in Guntur district, Andhra Pradesh. Total dissolved solids (TDS) show strong positive correlation with Cl⁻, Na⁺, Ca²⁺ and Mg²⁺, and positive correlation with SO₄²⁻, K⁺ and HCO₃⁻. Calcareous Narji Formation is the dominant aquifer lithology, and water-rock interaction controls the groundwater chemistry of the area. Chloro-alkaline indices (CAI) are positive at Miriyala, Adigopula, Mutukuru, Macherla and Durgi suggesting replacement of Na⁺ and K⁺ ions from water by Mg⁺⁺ and Ca⁺⁺ ions from country rock through base exchange reactions. Negative CAI values are recorded at Terala, Rayavaram and Nehrunagar, which indicate exchange of Na⁺ and K⁺ from the rock as cation-anion exchange reaction (chloro-alkaline disequilibrium). TDS range from 91 to 7100 ppm (Avg. 835 ppm) and exceed the prescribed limit of drinking water around Mutukuru, Durgi, Rayavaram, Khambampadu and Ammanizamalmadaka areas. Scanty rainfall and insufficient groundwater recharge are the prime factors responsible for high salinity in the area. Fluoride content ranges from <1 to 3.8 ppm and contaminated areas were identified around Macherla (1 sq km; 3.8ppm), Mandadi (1 sq km, 2.1ppm) and Adigopula (2 sq km, <1 to 3.7 ppm). The % Na⁺ content varies from 17 to 85 with the mean value of 57, and eighty (80) samples showed higher %Na⁺ in comparison to the prescribed limit of 60 for irrigation water. Sodium Adsorption Ratio (SAR) and % Na⁺ in relation to total salt concentration indicate that groundwater (51%) mostly falls under doubtful to poor quality for irrigation purpose. Groundwater of Adigopula village is fluoride contaminated and remedial measures are suggested to improve the water quality.     

Dynamic groundwater resources of National Capital Territory,Delhi: assessment,development and management options

Groundwater is one of the important source of water supply to meet the requirements of National Capital Territory (NCT) of Delhi, India which is a fast developing urban conglomeration. An assessment of dynamic groundwater resources of NCT Delhi has been attempted based on the methodology known as Ground Water Resources Estimation Methodology—1997. The methodology includes assessment of annual replenishable groundwater resources using water level fluctuation approach and empirical norms, estimation of the annual quantity of groundwater withdrawal and categorization of the assessment units based on the status of groundwater utilization and water level trend. Annual replenishable groundwater resources of NCT Delhi is about 297 million cubic meter (mcm) while the annual groundwater draft is about 480 mcm. This is because of over-exploitation of replenishable resources in seven out of nine districts of the Capital Territory. Based on the assessment of dynamic groundwater resources, a broad groundwater management plan has been proposed in this paper. This include augmentation of groundwater resources through rain water harvesting schemes to be implemented on a large scale, regulation on groundwater withdrawal in vulnerable areas, development of Yamuna flood plain aquifer and declaration of Delhi ridge as groundwater sanctuary.     

Metal contamination of agricultural soils in the copper mining areas of Singhbhum shear zone in India

The study was intended to investigate the heavy metal contamination in the agricultural soils of the copper mining areas in Singhbhum shear zone, India. The total concentrations of the metals were determined by inductively coupled plasma-mass spectrometer (ICPMS). Pollution levels were assessed by calculating enrichment factor (EF), geo-accumulation index (\(I_\mathrm{geo}\)), contamination factors (CF), pollution load index (PLI), Nemerow index and ecological risk index (\(R_{I}\)). The metal concentrations in the soil samples exceeded the average shale values for almost all the metals. Principal component analysis resulted in extraction of three factors explaining 82.6% of the data variability and indicated anthropogenic contribution of Cu, Ni, Co, Cr, Mn and Pb. The EF and \(I_\mathrm{geo}\) values indicated very high contamination with respect to Cu followed by As and Zn in the agricultural soils. The values of PLI, \(R_{I}\) and Nemerow index, which considered the overall effect of all the studied metals on the soils, revealed that 50% of the locations were highly polluted with respect to metals. The pollution levels varied with the proximity to the copper mining and processing units. Consequently, the results advocate the necessity of periodic monitoring of the agricultural soils of the area and development of proper management strategies to reduce the metal pollution.     

Square Kilometre Array: The radio telescope of the XXI century

The Square Kilometre Array (SKA) will be the world’s largest and most sensitive radio telescope. It will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of theUniverse, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. This project envisages the construction of 133 15-m antennas in South Africa and 131072 log-periodic antennas in Australia, together with the associated infrastructure in the two desert sites. In addition, the SKA is an exemplar Big Data project, with data rates of over 10 Tbps being transported from the telescope to HPC/HTC facilities.     

Secondary dynamical spectra of pulsars as indicators of inhomogeneities in the interstellar plasma

Observations of ten bright pulsars were obtained on the Giant Meter-wavelength Radio Telescope (GMRT, India) in order to study the effects of scattering of their radio waves by contructing and analyzing secondary dynamical spectra. The observations were conducted at 610 and 1420 MHz using a digital spectral analyzer operating in a real-time regime. The frequency resolution was 32.5 or 65.1 kHz, and the readout time was from 61.44 to 512 μs. Archival data for five pulsars at 327 MHz were also used. Procedures for normalizing the spectra and for constructing the secondary dynamical spectra were developed. Parabolic arcs were found in the secondary spectra of four pulsars (B1642-03, B1556-44, B2154+40, and B2021+51). The curvature of these arcs can be used to determine the distance to the effective scattering screen. In all cases, these screens are located relatively near the pulsars themselves.     

Evidence for plunging river plume deposits in the Pahrump Hills member of the Murray formation,Gale crater,Mars

Recent robotic missions to Mars have offered new insights into the extent, diversity and habitability of the Martian sedimentary rock record. Since the Curiosity rover landed in Gale crater in August 2012, the Mars Science Laboratory Science Team has explored the origins and habitability of ancient fluvial, deltaic, lacustrine and aeolian deposits preserved within the crater. This study describes the sedimentology of a ca 13 m thick succession named the Pahrump Hills member of the Murray formation, the first thick fine‐grained deposit discovered in situ on Mars. This work evaluates the depositional processes responsible for its formation and reconstructs its palaeoenvironmental setting. The Pahrump Hills succession can be sub‐divided into four distinct sedimentary facies: (i) thinly laminated mudstone; (ii) low‐angle cross‐stratified mudstone; (iii) cross‐stratified sandstone; and (iv) thickly laminated mudstone–sandstone. The very fine grain size of the mudstone facies and abundant millimetre‐scale and sub‐millimetre‐scale laminations exhibiting quasi‐uniform thickness throughout the Pahrump Hills succession are most consistent with lacustrine deposition. Low‐angle geometric discordances in the mudstone facies are interpreted as ‘scour and drape’ structures and suggest the action of currents, such as those associated with hyperpycnal river‐generated plumes plunging into a lake. Observation of an overall upward coarsening in grain size and thickening of laminae throughout the Pahrump Hills succession is consistent with deposition from basinward progradation of a fluvial‐deltaic system derived from the northern crater rim into the Gale crater lake. Palaeohydraulic modelling constrains the salinity of the ancient lake in Gale crater: assuming river sediment concentrations typical of floods on Earth, plunging river plumes and sedimentary structures like those observed at Pahrump Hills would have required lake densities near freshwater to form. The depositional model for the Pahrump Hills member presented here implies the presence of an ancient sustained, habitable freshwater lake in Gale crater for at least ca 10³ to 10⁷ Earth years.     

Spatial homogeneity of extreme precipitation indices using fuzzy clustering over northeast India

Natural Hazards - Regionalization on the basis of the properties of hydro-meteorological data helps in identifying the regions reflecting the similar characteristics which could be useful in...     

Magnetotelluric investigation of lithospheric electrical structure beneath the Dharwar Craton in south India:Evidence for mantle suture and plume-continental interaction

Broad-band and long period magnetotelluric measurements made at 63 locations along ～500 km long Chikmagalur-Kavali profile,that cut across the Dharwar craton(DC)and Eastern Ghat Mobile Belt(EGMB)in south India,is modelled to examine the lithosphere architecture of the cratonic domain and define tectonic boundaries.The 2-D resistivity model shows moderately conductive features that intersperse a highly resistive background of crystalline rocks and spatially connect to the exposed schist belts or granitic intrusions in the DC.These features are therefore interpreted as images of fossil pathways of the volcanic emplacements associated with the greenstone belt and granite suite formation exposed in the region.A near vertical conductive feature in the upper mantle under the Chitradurga Shear Zone represents the Archean suture between the western and eastern blocks of DC.Although thick(～200 km)cratonic(highly resistive)lithosphere is preserved,significant part of the cratonic lithosphere below the western DC is modified due to plume-continental lithosphere interactions during the Cretaceous—Tertiary period.A west-verging moderately conductive feature imaged beneath EGMB lithosphere is interpreted as the remnant of the Proterozoic collision process between the Indian land mass and East Antarctica.Thin(～120 km)lithosphere is seen below the EGMB,which form the exterior margin of the India shield subsequent to its separation from East Antarctica through rifting and opening of the Indian Ocean in the Cretaceous.