Political economy of the energy-groundwater nexus in India: exploring issues and assessing policy options

Indian agriculture is trapped in a complex nexus of groundwater depletion and energy subsidies. This nexus is the product of past public policy choices that initially offered opportunities to India’s small-holder-based irrigation economy but has now generated in its wake myriad economic, social, and environmental distortions. Conventional ‘getting-the-price-right’ solutions to reduce these distortions have consistently been undermined by the invidious political economy that the nexus has created. The historical evolution of the nexus is outlined, the nature and scale of the distortions it has created are explored, and alternative approaches which Indian policy makers can use to limit, if not eliminate, the damaging impacts of the distortions, are analysed.     

Geometric Integration of Aerial and High-Resolution Satellite Imagery and Application in Shoreline Mapping

This paper investigates the geopositioning accuracy achievable from integrating IKONOS and QuickBird satellite stereo image pairs with aerial images acquired over a region at Tampa Bay, Florida. The results showed that the accuracy is related to a few factors of imaging geometry. For example, the geopositioning accuracy of a stereo pair of IKONOS or QuickBird images can be improved by integrating a set of aerial images, even just a single aerial image or a stereo pair of aerial images. Shorelines derived from the IKONOS and QuickBird stereo images, particularly the vertical positions, are compared with the corresponding observations of water-penetrating LiDAR and water gauge stations and proved that differences are within the limit of the geopositioning uncertainty of the satellite images.     

Urban base flow with low impact development

A novel form of urbanization, low impact development (LID), aims to engineer systems that replicate natural hydrologic functioning, in part by infiltrating stormwater close to the impervious surfaces that generate it. We sought to statistically evaluate changes in a base flow regime because of urbanization with LID, specifically changes in base flow magnitude, seasonality, and rate of change. We used a case study watershed in Clarksburg, Maryland, in which streamflow was monitored during whole‐watershed urbanization from forest and agricultural to suburban residential development using LID. The 1.11‐km² watershed contains 73 infiltration‐focused stormwater facilities, including bioretention facilities, dry wells, and dry swales. We examined annual and monthly flow during and after urbanization (2004–2014) and compared alterations to nearby forested and urban control watersheds. We show that total streamflow and base flow increased in the LID watershed during urbanization as compared with control watersheds. The LID watershed had more gradual storm recessions after urbanization and attenuated seasonality in base flow. These flow regime changes may be because of a reduction in evapotranspiration because of the overall decrease in vegetative cover with urbanization and the increase in point sources of recharge. Precipitation that may once have infiltrated soil, been stored in soil moisture to be eventually transpired in a forested landscape, may now be recharged and become base flow. The transfer of evapotranspiration to base flow is an unintended consequence to the water balance of LID. © 2016 The Authors Hydrological Processes Published by John Wiley & Sons Ltd.     

Determination of linear polarization and faraday rotation of pulsar signals from spectral intensity modulation

Most of the known pulsars are sources of highly linearly polarized radiation. Faraday rotation in the intervening medium rotates the plane of the linear polarization as the signals propagate through the medium. The Rotation Measure (RM), which quantifies the amount of such rotation as a function of wavelength, is useful in studying the properties of the medium and in recovering the intrinsic polarization characteristics of the pulsar signal. Conventional methods for polarization measurements use telescopes equipped with dual orthogonally polarized feeds that allow estimation of all 4 Stokes parameters. Some telescopes (such as the Ooty Radio Telescope) that offer high sensitivity for pulsar observations may however be receptive to only a single linear polarization. In such a case, the apparent spectral intensity modulation, resulting from differential Faraday rotation of the linearly polarized signal component within the observing bandwidth, can be exploited to estimate the RM as well as to study the linear polarization properties of the source. In this paper, we present two improved procedures by which these observables can be estimated reliably from the intensity modulation over large bandwidths, particularly at low radio frequencies. We also highlight some other applications where such measurements and procedures would be useful.     

Estimation of probable maximum precipitation for catchments in eastern India by a generalized method

Summary A generalized method to estimate the probable maximum precipitation (PMP) has been developed for catchments in eastern India (80° E, 18° N) by pooling together all the major rainstorms that have occurred in this area. The areal raindepths of these storms are normalized for factors such as storm dew point temperature, distance of the storm from the coast, topographic effects and any intervening mountain barriers between the storm area and the moisture source. The normalized values are then applied, with appropriate adjustment factors in estimating PMP raindepths, to the Subarnarekha river catchment (upto the Chandil dam site) with an area of 5663 km². The PMP rainfall for 1, 2 and 3 days were found to be roughly 53 cm, 78 cm and 98 cm, respectively. It is expected that the application of the generalized method proposed here will give more reliable estimates of PMP for different duration rainfall events.With 5 Figures     

Stormwater management network effectiveness and implications for urban watershed function: A critical review

Deleterious effects of urban stormwater are widely recognized. In several countries, regulations have been put into place to improve the conditions of receiving water bodies, but planning and engineering of stormwater control is typically carried out at smaller scales. Quantifying cumulative effectiveness of many stormwater control measures on a watershed scale is critical to understanding how small‐scale practices translate to urban river health. We review 100 empirical and modelling studies of stormwater management effectiveness at the watershed scale in diverse physiographic settings. Effects of networks with stormwater control measures (SCMs) that promote infiltration and harvest have been more intensively studied than have detention‐based SCM networks. Studies of peak flows and flow volumes are common, whereas baseflow, groundwater recharge, and evapotranspiration have received comparatively little attention. Export of nutrients and suspended sediments have been the primary water quality focus in the United States, whereas metals, particularly those associated with sediments, have received greater attention in Europe and Australia. Often, quantifying cumulative effects of stormwater management is complicated by needing to separate its signal from the signal of urbanization itself, innate watershed characteristics that lead to a range of hydrologic and water quality responses, and the varying functions of multiple types of SCMs. Biases in geographic distribution of study areas, and size and impervious surface cover of watersheds studied also limit our understanding of responses. We propose hysteretic trajectories for how watershed function responds to increasing imperviousness and stormwater management. Even where impervious area is treated with SCMs, watershed function may not be restored to its predevelopment condition because of the lack of treatment of all stormwater generated from impervious surfaces; non‐additive effects of individual SCMs; and persistence of urban effects beyond impervious surfaces. In most cases, pollutant load decreases largely result from run‐off reductions rather than lowered solute or particulate concentrations. Understanding interactions between natural and built landscapes, including stormwater management strategies, is critical for successfully managing detrimental impacts of stormwater at the watershed scale.     

On the variability timescales and magnetic field in OJ 287

The continuum spectrum of OJ 287, like most other BL Lac objects, is featureless- no emission or absorption lines are observed. However, OJ 287 shows variations at different timescales in flux and polarization at various wavelength bands. Using the available variability data one can estimate the sizes of the emission regions in the source from light travel time arguments. We assume the emission mechanism to be synchrotron radiation by high energy electrons with single power law energy distribution. Theoretical synchrotron spectrum in the frequency range 10¹¹–10¹⁷ H _z is compared with the observed spectral shape, obtained from new multifrequency quasi-simultaneous observations, to estimate the lower and upper cut off frequencies. These frequencies are used to obtain theoretical values of the variability timescales and magnetic field in the emission region. We obtain a value of 0.93 G for the magnetic field and 5.184×10⁴ sec for the cooling time from the quiescent continuum spectrum. The shock-in-jet model explains the spectrum where shocks accelerate the particles and amplify the magnetic field in the jet. This timescale is compared with the one obtained from observed short timescale variability (20 minutes) with proper beaming correction. The short timescale variations (200 minutes in the source frame), possibly caused by an additional, flaring, component of the source, are also used to calculate compressed magnetic field. The observed and theoretically estimated variability timescales and the shape of the spectrum suggest that there are more than one emission components in OJ 287.     

Improving pulsar distances by modelling interstellar scattering

In this paper we propose a scenario for the formation of a population of baryon-rich, dark-matter-deficient dwarf galaxies at high redshift from the mass swept out in the intergalactic medium (IGM) by energetic outflows from luminous quasars. We predict the intrinsic properties of these galaxies, and examine the prospects for their observational detection in the optical, X-ray and radio wavebands. Detectable thermal Sunyaev–Zel'dovich decrements on arcminute scales in the cosmic microwave background radiation maps are expected during the shock-heated expanding phase from these hot bubbles. We conclude that the optimal detection strategy for these dwarfs is via narrow-band Lyman-α imaging of regions around high-redshift quasars. A scaled-down (in the energetics) version of the same model is speculated upon as a possible mechanism for forming pre-galactic globular clusters.     

Origin of high fluoride in groundwater in the North Gujarat-Cambay region, India

This paper reports on the origin of high fluoride in a regional alluvial aquifer system under water stress in the North Gujarat-Cambay (NGC) region in western India. This region is severely affected by endemic fluorosis due to ingestion of groundwater containing excessive fluoride. With an objective to understand factors controlling high fluoride concentration in groundwater of this region, 225 groundwater samples have been analysed for various chemical parameters. Samples were collected from different depth zones tapping shallow dug wells, geothermal springs, hand-pumps and tubewells, including free flowing artesian wells up to 450 m depth from the aquifers in the Quaternary alluvial formation covering most of the study area. No relation was found between fluoride concentration and depth of sampled groundwater. However, certain sub-aquifer zones have been identified within the Cambay Basin where groundwater contains relatively high fluoride concentration. In general, areas of high fluoride overlap areas with high electrical conductivity (EC). On the west flank of the Cambay Basin in the low lying belt linking Little Rann of Kachchh-Nalsarovar-Gulf of Khambhat (LRK-NS-GK), high fluoride and EC in shallow aquifers originate from evaporative enrichment. On the east flank of Cambay Basin, some high fluoride pockets are observed which are probably due to preferential dissolution of high fluoride bearing minerals. On this flank high fluoride is also associated with thermal springs. Within the Cambay Basin, alternating belts of low and high fluoride concentrations are ascribed to groundwater recharge during the past wet and arid climatic phases, respectively. This is based on groundwater radiocarbon age contours of ~20 ka overlapping the high fluoride belt.

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Resumen Este artículo reporta sobre el origen de altas concentraciones de flúor en un sistema regional de acuíferos bajo presión hídrica en la región del norte de Gujarat-Cambay (NGC) del occidente de India. Esta región está afectada severamente por fluorosis endémica debido a la ingestión de agua subterránea que contiene exceso de flúor. Se tomaron 225 muestras de agua subterránea las cuales fueron analizadas por varios parámetros químicos con el objetivo de entender los factores que controlan las elevadas concentraciones de flúor en esta región. Las muestras se colectaron a diferentes profundidades en pozos someros, manantiales geotermales, pozos con bombas de mano, y pozos entubados incluyendo pozos artesianos de flujo libre de hasta 450 m de profundidad emplazados en los acuíferos de la formación aluvial Cuaternaria que cubre la mayor parte del área de estudio. No se encontró ninguna relación entre la concentración de flúor y la profundidad de las muestras de agua subterránea. Sin embargo, se identificaron dentro de la cuenca Cambay algunas zonas sub-acuíferas donde el agua subterránea contiene concentraciones relativamente altas de flúor. En general, las áreas con elevada concentración de flúor están sobrepuestas a áreas de alta conductividad eléctrica (CE). Sobre el flanco occidental de la cuenca Cambay, en la faja baja que une Little Rann con Kachchh-Nalsarovar-Golfo de Khamhat (LRK-NS-GK), las altas concentraciones de flúor y altas CE en acuíferos someros se derivan de enriquecimiento por evaporitas. Sobre el flanco oriental de la cuenca Cambay se observaron algunos cuerpos con alta concentración de flúor los cuales se deben probablemente a la disolución preferencial de minerales con alto contenido de flúor. En este flanco el alto contenido de flúor también se asocia con manantiales termales. Dentro de la cuenca Cambay existen fajas alternantes, con concentraciones altas y bajas de flúor, las cuales se atribuyen a recarga de agua subterránea durante las fases climáticas pasadas, húmedas y áridas, respectivamente. Este planteamiento se basa en contornos de edades de ~20 ka de radiocarbono que están sobrepuestos a la faja alta en flúor.

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Résumé Cet article étudie lorigine des teneurs élevées en Fluorure dans un système aquifère alluvial régional, soumis à un stress hydrique dans le Nord Gujarat–région Cambay (NGC) à lOuest de lInde. Cette région est sévèrement affectée par une fluorose endémique, due à lingestion deau souterraine très riche en fluor. Avec pour objectif de comprendre les paramètres contrôlant les fortes teneurs en fluor, 225 échantillons deau souterraine ont été analysés sur différents paramètres. Les échantillons ont été pris à différentes profondeurs : puits de surface, sources géothermiques, pompes à main, forages artésiens jaillissant dont la profondeur avoisine les 450 m dans les formations alluviales quaternaire recouvrant la plus grande partie de la région étudiée. Il ny a pas de relation entre la profondeur et les teneurs en fluorure. Néanmoins, certaines zones sub-aquifères ont été identifiées dans le Basin de Cambay où leau souterraine présentait des concentrations relativement élevées en fluorure. En général les zones de hautes concentrations en fluorure recouvrent les zones à fortes conductivité électrique (abréviation en anglais: EC). Sur le flanc Ouest du bassin de Cambay dans le mince lit reliant Little Ran de Kachchh-Nalsarovar au golfe de Khambhat (LRK-NS-GK), les fortes teneurs en fluorure et les EC dans la nappe phréatique proviennent de lenrichissement par les évaporites. Sur le flanc Est du bassin, des poches de teneurs élevées en fluorures ont été observées, probablement dues à des dissolutions préférentielles de minéraux fluorés. Sur ce flanc des teneurs sont également associées à la présence de sources géothermales. Dans le bassin de Cambay, les alternances de couches lits à fortes teneurs et de lits à faibles teneurs sont expliquées par la recharge durant les périodes climatiques humides et les périodes climatiques plus sèches. Ceci est corroboré par les datations au radiocarbone (environ 20.000 an) au dessus du lit riche en fluorure.

     

Solar X-ray Spectrometer (Soxs) Mission on Board GSAT2 Indian Spacecraft: The Low-Energy Payload

The first space-borne solar astronomy experiment of India, namely Solar X-ray Spectrometer (SOXS), was successfully launched on 08 May 2003 on board geostationary satellite GSAT-2 of India. The SOXS is composed of two independent payloads, viz. SOXS Low-Energy Detector (SLD) Payload and SOXS High-Energy Detector (SHD) Payload. The SOXS aims to study the full-disk integrated X-ray emission in the energy range from 4 keV to 10 MeV. In this paper we present the first report on the SLD instrumentation and its in-orbit performance. The SLD payload was designed and developed at the Physical Research Laboratory in collaboration with various centers of Indian Space Research Organisation (ISRO). The basic scientific aim of the SLD payload is to study solar flares in the energy range from 4 to 60 keV with high spectral and temporal resolution. To meet these requirements, the SLD payload employs state-of-the-art solid state detectors, the first time for a solar astronomy experiment, viz. Si PIN (4 –25 keV), and cadmium–zinc–telluride (4 –60 keV). With their superb high-energy resolution characteristics, SLD can observe iron and iron–nickel complex lines that are visible only during solar flares. In view of its 3.4 FOV, the detector package is mounted on a Sun Aspect System, for the first time, to get uninterrupted observations in a geostationary orbit. The SLD payload configuration, its in-flight operation, and the response of the detectors are presented. We also present the first observations of solar flares made by the SLD payload and briefly describe their temporal and spectral mode results.