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India has abundant water resources, including rivers and snow-covered mountains in the Himalayas, which can supply the country's water needs. In many areas, however, accessible water supplies are depleting due to fast population growth and the need to fulfill rising demands for irrigation, human and industrial consumption. Physico-chemical and microbiological characteristics were stuided of the Asan river water in Doon valley of Uttarakhand, India, that sampled were collected a fourteen water quality parameters at seven locations from October 2018 to March 2019. The water quality index and water quality maps was prepared in the Arc GIS software 10.7 using Inverse distance weighted (IDW) method. The sampled datasets were used to prepare a spatial water quality index map based on Analytical Hierarchy Process. Based on the results the weightage of the pH was found to the maximum (24%), BOD (17%), DO (13.7%), TDS (11.1%), EC (7.8%), TH (4.8%), CH (4.6%), MH (4.5%), WT (3.4%), AT (2.4%), Na (1.9%), K (1.7%), NO3(1.5%) and PO4 (1.3%). The result demonstrates that the water is heavily polluted towards station three caused due to the extensive anthropogenic activities. Thus, there is a need for combined government and non-government measures to enable the Asan rivers to slow their decline and return to their natural, pollutant-free state, which is crucial for the health of their environment. [ABSTRACT FROM AUTHOR]

In a mountainous basin, flash-flood-induced soil erosion and its assessment are of major concern to the researchers. Cloudburst-induced extreme rainfall, undulating terrain, and inadequate water and soil conservation practices aggravate the problem of soil erosion. Alaknanda, a major basin of the upper Ganges in India, has experienced several incidents of flash floods. These have resulted in heavy soil loss, water siltation, and pollution in the basin. This study uses the revised universal soil-loss equation (RUSLE) in the GIS framework to assess the soil loss rate in various sub-basins of the Alaknanda. Further, the study suggests sub-basin prioritisation based on high soil erosion rate and past vulnerability that need attention of the decision-makers. RUSLE, an empirical soil erosion model, is easy to comprehend physically, involves minimum resources, and works on readily available inputs. The parameters used in the assessment include R-Rainfall Erosivity, Cover Management-C, Topographic-LS, Conservation Practice-P, and Soil Erodibility-K. The average R, K, LS, C & P factors for the Alaknanda basis are estimated as 437 MJ mm/ha/yr., 0.07 t ha h MJ-1 ha-1 mm-1, 1.4, 0.7, and 0.62, respectively. The mean annual soil erosion rate in the sub-basins varies from 6 to 27.9 t /ha/year with a mean rate of 13.4 t/ha/year and total erosion of 13.7 Mt/year. The results show that out of the twelve sub-basins, two (WS7 and WS5) fall in the high erosional class (18–30 t/ha/year), nine fall in the moderate erosional class (7–18 t /ha /year) and one basin in the low erosional class (1.0–7.0 t /ha/year). It is hoped that the present study will be helpful to the decision-makers while prioritising the actions to be taken for the water and soil conservation purposes. [ABSTRACT FROM AUTHOR]

To monitor the spread of the novel coronavirus (COVID-19), India, during the last week of March 2020, imposed national restrictions on the movement of its citizens (lockdown). Although India's economy was shut down due to restrictions, the nation observed a sharp decline in particulate matter (PM) concentrations. In recent years, Delhi has experienced rapid economic growth, leading to pollution, especially in urban and industrial areas. In this paper, we explored the linkages between air quality and the nationwide lockdown of the city of Delhi using a geographic information system (GIS)-based approach. Data from 37 stations were monitored from 12 March, 2020 to 2 April, 2020 and it was found that the Air Quality Index for the city was almost reduced by 37% and 46% concerning PM2.5 and PM10, respectively. The study highlights that, in regular conditions, the atmosphere's natural healing rate against anthropogenic activities is lower, as indicated by a higher AQI. However, during the lockdown, this sudden cessation of anthropogenic activities leads to a period in which the natural healing rate is greater than the induced disturbances, resulting in a lower AQI, and thus proving that this pandemic has given a small window for the environment to breathe and helped the districts of Delhi to recover from serious issues related to bad air quality. If such healing windows are incorporated into policy and decision-making, these can prove to be effective measures for controlling air pollution in heavily polluted regions of the World. [ABSTRACT FROM AUTHOR]

Purpose: To determine the prevalence and risk factors for pterygium in geographically diverse regions of India. Methods: A population-based, cross-sectional multicentric study was conducted in adults aged ≥40 years in plains, hilly and coastal regions of India. All participants underwent a detailed questionnaire-based assessment for sun exposure, usage of sun protective measures, exposure to indoor smoke, and smoking. Detailed ocular and systemic examinations were performed. Pterygium was diagnosed and graded clinically by slit-lamp examination. Association of pterygium with sociodemographic, ophthalmological, and systemic parameters was assessed. Physical environmental parameters for the study period were estimated. Results: Of the 12,021 eligible subjects, 9735 (81% response rate) participated in the study. The prevalence of pterygium in any eye was 13.2% (95% CI: 12.5%-13.9%), and bilateral pterygium was 6.7% (95% CI: 6.2–7.2). The prevalence increased with age (<0.001) irrespective of sex and was highest in those aged 60–69 years (15.8%). The prevalence was highest in coastal (20.3%), followed by plains (11.2%) and hilly regions (9.1%). On multi-logistic regression, pterygium was positively associated with coastal location (P<0.001), illiteracy (P = 0.037), increasing lifetime sun exposure (P<0.001), and negatively associated with BMI ≥25 kg/m2 (P = 0.009). Conclusion: Pterygium prevalence is high in the rural Indian population. The association of pterygium with several potentially modifiable risk factors reflects its multifactorial etiology and provides targets for preventive measures. [ABSTRACT FROM AUTHOR]

In view of an exponential increase in the negative impacts of flash-floods globally, the present work aims at the identification of flash-floods-prone river reaches in the Beas river basin, Himachal Pradesh, India using a multi-criteria indexing technique. The flood hazard index (FHI) was computed by implementing analytical hierarchy process (AHP) model on 6 hydrologic parameters influencing flood hazard, namely rainfall intensity, curve number (CN) grid, time of travel, slope, Manning's roughness coefficient and drainage density. The CN grid (empirical parameter to estimate direct surface runoff) was used as one of the parameters which depend upon the land use, hydrologic soil group and hydrologic conditions. It is imperative to mention that remote sensing and geographical information system (GIS) techniques played a crucial role in the preparation of these 6 parameter layers. The AHP model calculates the normalized weights for each parameter using pair-wise comparison matrices. The rainfall intensity and curve number were the factors having the highest normalized weight of 34.52 each. Subsequently, the estimated weights of the parameters and hazard level-wise rating scores were used in a GIS environment to generate FHI. The generated FHI raster was masked using floodplain layer within geomorphology map and river buffer to identify flash-floods-affected river reaches. The generated flash-floods map was validated by historical flash-floods ground points, field observations and remote sensing data. The results depicted that the river reaches in the north and east of the Beas basin are susceptible to flash-floods which are mainly governed by heavy rainfall intensity and high runoff characteristics. The river stretches namely Bahang–Manali (Beas), Kullu–Bhuntar (Beas) and Manikaran–Kheer-Ganga (Parvati) have been categorized into very high and high flash-floods zones. Decreasing trend of normalized differential vegetation index (NDVI) was observed for river reaches falling within the very high and high zones indicating the vegetation loss post successive flash-floods events. The river order 2 lies in the very high and high flash-floods zones, indicating the fact that the contribution of tributaries is significant to flood events. Flash-floods map will serve as catastrophic product, which will help policymakers to take suitable measures to reduce the risk of flash-floods. [ABSTRACT FROM AUTHOR]

Purpose: To determine the prevalence of cataract and its association with sun exposure and other environmental risk factors in three different geographically diverse populations of India. Design: Population based cross sectional study during 2010–2016 Participants: People aged ≥ 40 years residing in randomly sampled villages were enumerated (12021) and 9735 (81%) underwent ophthalmic evaluation from plains, hilly and coastal regions (3595, 3231, 2909 respectively) Methods: A detailed questionnaire-based interview about outdoor activity in present, past and remote past, usage of sun protective measures, exposure to smoke, and detailed ophthalmic examination including assessment of uncorrected and best corrected visual acuity, measurement of intraocular pressure, slit lamp examination, lens opacities categorization using LOCS III and posterior segment evaluation was done. Lifetime effective sun exposure was calculated using Melbourne formula and expressed as quintiles. These were supplemented with physical environmental measurements. Main outcome measures: Lifetime sun exposure hours, smoking, indoor kitchen smoke exposure and their association with cataract and subtypes. Prevalence of cataract calculated based on lens opacities or evidence of cataract surgery. Results: Cataract was identified in 3231 (33.3%) participants. Prevalence of cataract in males (32.3%) and females (34.1%) was similar. Nuclear cataract was the commonest sub-type identified in 94.7% of affected eyes. Sun exposure had a significant association with cataract with odds ratio (OR) increasing from 1.6 (95% Confidence Intervals [CI]: 1.4, 1.9) in 3rd quintile, to 2.6 (CI: 2.2, 3.1) in 4th quintile and 9.4 (CI: 7.9, 11.2) in 5th quintile (p<0.0001). Cataract also showed a significant association with smoking (OR: 1.4, CI: 1.2, 1.6) and indoor kitchen smoke exposure (OR: 1.2, CI: 1.0–1.4). Nuclear cataract showed a positive association with increasing sun exposure in 3rd (β coefficient 0.5, CI:0.2–0.7), 4th (β: 0.9, CI: 0.7–1.1) and 5th (β: 2.1, CI:1.8–2.4) quintiles of sun exposure, smoking (β: 0.4, CI: 0.2–0.6) and indoor kitchen smoke exposure (β: 0.3, CI: 01–0.5) while cortical cataract showed a positive association with sun exposure only in 5th quintile (β: 2.6, CI:1.0–4.2). Posterior subcapsular cataract was not associated with any of the risk factors. Conclusion: Cataract is associated with increasing level of sun exposure, smoking and exposure to indoor kitchen smoke. [ABSTRACT FROM AUTHOR]

Aerosol direct radiative effect (DRE) in India is mostly reported for the clear sky conditions. Here, we quantify the modulation of aerosol DRE in the presence of clouds using 2 years (2007–2008) of measured aerosol chemical composition data at megacity Delhi in the Indo-Gangetic Basin. Mean (± 1σ) seasonal top-of-the-atmosphere (TOA) aerosol DRE for the most probable mixing states in the presence of water and ice clouds are 7.3 ± 4.3 and 3.7 ± 1.8 W m−2 in the pre-monsoon, − 0.3 ± 3.7 and − 2.1 ± 4.4 W m−2 in the monsoon, 18.9 ± 15.9 W m−2 in the post-monsoon (no ice cloud is present in this season) and 11.8 ± 6.2 and 6.9 W m−2 in the winter seasons, respectively. The corresponding values for surface DRE are − 20.7 ± 5.5 and − 17.9 ± 8.4 W m−2, − 20.8 ± 8.1 and − 18.0 ± 9.4 W m−2, − 70.9 ± 11.7 W m−2, and − 55.7 ± 1.4 and − 49.8 W m−2 in the four seasons, respectively. Solar radiation reflected by water clouds interacts with aerosol layer aloft, enhancing TOA warming, while ice clouds reflect back a fraction of radiation supposed to interact with the aerosol layer beneath, thereby reducing TOA warming. We observe a reduction in the surface aerosol DRE in the presence of clouds by a larger magnitude relative to the change in TOA DRE. The aerosol DRE in the presence of water and ice clouds leads to a net decrease in atmospheric heating by 7.6% and 28.7% in the pre-monsoon, 21.5% and 39.1% in the monsoon, 0.6% (no discernable ice clouds) in the post-monsoon, and 9.5% and 24.0% in the winter seasons, respectively, for the most probable mixing state cases. Our results imply that under cloudy-sky condition, the aerosol-induced atmospheric heating in India is overestimated if the aerosol mixing state deviates (e.g., core-shell mixing) from the usually assumed external mixing. [ABSTRACT FROM AUTHOR]

Introduction: The present work is aimed to understand direct radiation effects due to aerosols over Delhi in the Indo-Gangetic Basin (IGB) region, using detailed chemical analysis of surface measured aerosols during the year 2007. Methods: An optically equivalent aerosol model was formulated on the basis of measured aerosol chemical compositions along with the ambient meteorological parameters to derive radiatively important aerosol optical parameters. The derived aerosol parameters were then used to estimate the aerosol direct radiative forcing at the top of the atmosphere, surface, and in the atmosphere. Results: The anthropogenic components measured at Delhi were found to be contributing ∼72% to the composite aerosol optical depth (AOD ∼0.84). The estimated mean surface and atmospheric forcing for composite aerosols over Delhi were found to be about −69, −85, and −78 W m and about +78, +98, and +79 W m during the winter, summer, and post-monsoon periods, respectively. The anthropogenic aerosols contribute ∼90%, 53%, and 84% to the total aerosol surface forcing and ∼93%, 54%, and 88% to the total aerosol atmospheric forcing during the above respective periods. The mean (±SD) surface and atmospheric forcing for composite aerosols was about −79 (±15) and +87 (±26) W m over Delhi with respective anthropogenic contributions of ∼71% and 75% during the overall period of observation. Conclusions: Aerosol induced large surface cooling, which was relatively higher during summer as compared to the winter suggesting an increase in dust loading over the station. The total atmospheric heating rate at Delhi averaged during the observation was found to be 2.42 ± 0.72 K day, of which the anthropogenic fraction contributed as much as ∼73%. [ABSTRACT FROM AUTHOR]

Abstract: Aerosol characteristics were studied over Delhi, a typical urban station in the Ganga basin in Northern India, during two contrasting weather conditions: winter and summer, to explain the changes in columnar and surface aerosol characteristics with the help of ground based measurements and CALIPSO satellite data. The near-surface mean aerosol mass concentrations of PM10 and PM2.5 (±standard deviation) were observed to be ∼200 (±24) and 118 (±33)μgm−3, respectively, during the winter and ∼168 (±31) and 55 (±12)μgm−3, respectively, during the summer. PM2.5 was found to be about two times higher than the PM10 concentration during the winter period. Aerosol mass size distribution showed bi-modal nature during both the periods, with relative dominance of fine-particle mass concentrations during the winter, having low R eff value (0.63±0.05μm) and coarse-particle mass concentrations during the summer, having large R eff value (1.52±0.60μm). The concurrent measurement of columnar aerosol optical depth (AOD) showed high values (>0.60 at 500nm) during both the periods. The Ångström exponent (α) over the station, however, also suggests relatively large contribution of fine-mode particles during the winter (α∼1.02) and coarse-mode dust particles during the summer (α∼0.51). The observed features in the surface and columnar measured aerosol characteristics during two different seasons are explained using the vertical winds coupled with the vertical profile of aerosols. [Copyright &y& Elsevier]

The impact of long-range transported dust aerosols, originating from the Thar Desert region, to a high-altitude station in the central Himalayas was studied with the help of micro-pulse lidar (MPL) observations. A drastic change in lidar back-scatter profile was observed on a dust day as compared with that on a pre-dust day. The back-scatter coefficient on a dust day revealed that the dust layer peaked at an altitude ∼1300 m above ground level (AGL) and extended up to ∼3000 m AGL, with maximum value ∼3 × 10–5 m–1 sr–1. Aerosol Index (AI) and air mass back-trajectory analysis substantiate the transport of dust aerosols from the far-off Thar Desert region to the experimental site. A significant effect of dust aerosols was also observed over the station on the spectral aerosol optical depths (AODs), measured using a Microtops-II Sunphotometer. It showed significantly different spectral behaviour of AOD on a dust day as compared with that on a pre-dust day. The Ångström exponent (α) showed a marked decrease from 0.42 to 0.04 from the pre-dust day to the dust day. The aerosol radiative forcing estimated using the Santa Barbara DISORT (discrete ordinate radiative transfer) atmospheric radiative transfer (SBDART) model, in conjunction with the optical properties of aerosol and cloud (OPAC) model, showed values of about –30, –45 and +15 W m–2, respectively, at top-of-atmosphere (TOA), surface and in the atmosphere on the dust day. The positive atmosphere forcing caused an estimated heating of the lower atmosphere by ∼0.4 K day–1. [ABSTRACT FROM AUTHOR]

Simultaneous measurements of aerosol black carbon (BC) mass concentration using an Aethalometer Model AE-42 and mixing layer height (MLH) using a monostatic sonic detection and ranging (SODAR) system were carried out from January 2006 to January 2007 at the mega-city Delhi. The BC concentration generally had a typical diurnal variation with morning and late-afternoon/night peaks. The average BC concentration during the whole period of observation was fairly high at 14.75 μg m−3. The BC concentration nearly doubled during cloudy-sky conditions compared to that during clear-sky conditions. The seasonal variation showed a maximum average concentration during the winter (25.5 μg m−3) and a minimum during the monsoon season (7.7 μg m−3), with post- and pre-monsoon values at 13.7 and 9.4 μg m−3, respectively. The average BC concentrations were strongly affected by the ventilation coefficient, a product of average wind speed (WS) and average MLH, and were found to be strongly anticorrelated. A simple model of BC concentration along with the MLH and WS was applied to estimate the average BC emission, which was found to vary in the range 11 000–17 000 kg of BC per day. The maximum emission during the day averaged every hour for different months lay in the range 1000–2100 kg h−1. The mean monthly emission varied in the range 0.35–0.52 Gg per month, giving rise to an annual estimated emission of 4.86 Gg in the year 2006 over Delhi. [ABSTRACT FROM AUTHOR]

Abstract: Simultaneous measurements of aerosol absorption and scattering coefficients for the PM2.5 aerosols particles were done at Delhi during April 2008–March 2009 to estimate the aerosol single scattering albedo (SSA) and the Angstrom absorption exponents at the surface. The annual average SSA at 0.55 μm was found to be 0.70 ± 0.07 with only slight variations during the four seasons, summer (0.63 ± 0.06), monsoon (0.69 ± 0.07), winter (0.74 ± 0.03) and spring (0.72 ± 0.04). However, large variations in average absorption and scattering coefficients were seen during these four seasons. The average absorption coefficients during summer, monsoon, winter and spring were found to be 62.47 ± 21.27, 50.95 ± 43.61, 189.65 ± 85.94 and 90.65 ± 33.06 Mm−1 respectively. The corresponding scattering coefficients were 110.46 ± 36.15, 95.34 ± 49.46, 565.59 ± 274.59 and 236.56 ± 96.25 Mm−1. The Angstrom absorption exponent (ασ(abs)) remained close to unity throughout the year averaging at 1.02 ± 0.08, 1.02 ± 0.10, 1.04 ± 0.11, and 1.03 ± 0.05 during summer, monsoon, winter and spring seasons respectively, strongly indicating that the absorption at Delhi aerosol is mainly due to the abundance of black carbon of fossil fuel origin. [ABSTRACT FROM AUTHOR]

The concentrations of PM10, PM2.5 and their water-soluble ionic species were determined for the samples collected during January to December, 2007 at New Delhi (28.63° N, 77.18° E), India. The annual mean PM10 and PM2.5 concentrations (± standard deviation) were about 219 (± 84) and 97 (±56) µgm−3 respectively, about twice the prescribed Indian National Ambient Air Quality Standards values. The monthly average ratio of PM2.5/PM10 varied between 0.18 (June) and 0.86 (February) with an annual mean of ∼0.48 (±0.2), suggesting the dominance of coarser in summer and fine size particles in winter. The difference between the concentrations of PM10 and PM2.5, is deemed as the contribution of the coarse fraction (PM10−2.5). The analyzed coarse fractions mainly composed of secondary inorganic aerosols species (16.0 µgm−3, 13.07%), mineral matter (12.32 µgm−3, 10.06%) and salt particles (4.92 µgm−3, 4.02%). PM2.5 are mainly made up of undetermined fractions (39.46 µgm−3, 40.9%), secondary inorganic aerosols (26.15 µgm−3, 27.1%), salt aerosols (22.48 µgm−3, 23.3%) and mineral matter (8.41 µgm−3, 8.7%). The black carbon aerosols concentrations measured at a nearby (∼300 m) location to aerosol sampling site, registered an annual mean of ∼14 (±12) µgm−3, which is significantly large compared to those observed at other locations in India. The source identifications are made for the ionic species in PM10 and PM2.5. The results are discussed by way of correlations and factor analyses. The significant correlations of Cl−, SO, K+, Na+, Ca2+, NO and Mg2+ with PM2.5 on one hand and Mg2+ with PM10 on the other suggest the dominance of anthropogenic and soil origin aerosols in Delhi. [ABSTRACT FROM AUTHOR]

Abstract: Indo-Gangetic (IG) alluvial plains, one of the largest river basins in the world, suffers from the long range transport of mineral dust from the western arid and desert regions of Africa, Arabia and Rajasthan during the summer (pre-monsoon season, April–June). These dust storms influence the aerosol optical depth (AOD) across the IG plains. The Kanpur AERONET (Aerosol Robotic Network) station and Moderate Resolution Imaging Spectro-radiometer (MODIS) data show pronounced effect on the aerosol optical properties and aerosol size distribution during major dust storm events over the IG plains that have significant effect on the aerosol radiative forcing (ARF). The multi-band AOD, from AERONET and MODIS, show contrasting changes in wavelength dependency over dust affected regions. A time collocated (±30min) validation of AERONET AOD with MODIS Terra (level 2 swath product) over Kanpur, at a common wavelength of 550nm for the period 2001–2005 show moderate correlation (R 2∼0.6) during the summer season. The average surface forcing is found to change by −23Wm−2 during dust events and the top of the atmosphere (TOA) forcing change by −11Wm−2 as compared to the non-dusty clear-sky days. A strong correlation is found between AOD at 500nm and the ARF. At surface, the correlation coefficient between AOD and ARF is found to be high (R 2=0.925) and is found to be moderate (R 2=0.628) at the TOA. The slope of the regression line gives the aerosol forcing efficiency at 500nm of about −46±2.6Wm−2 and −17±2.5Wm−2 at the surface and the TOA, respectively. The ARF is found to increase with the advance of the dry season in conjunction with the gradual rise in AOD (at 500nm) from April (0.4–0.5) to June (0.6–0.7) over the IG plains. [Copyright &y& Elsevier]

Abstract: We present the ground-based, clear-sky daytime measurements of column aerosol optical depths (AODs) at different wavelengths and the mixing height of atmospheric boundary layers at various locations, conducted during ISRO-GBP aerosol-radiation-trace gases measurements campaign in the central Indian region (17.3–28.6°N and 77.2°–78.2°E) from Delhi to Hyderabad and back, in the month of February 2004. The measurements show AOD variation at 500nm in the range of 0.2–0.5 and Angstrom exponent in the range of 1.0–1.4 throughout the region. The entire experimental region has been classified into four categories depending upon their locations and surroundings, viz., forest, rural, semi-urban, and rural-dusty. The volume size distribution of the aerosol particles at all these categories showed a bi-modal distribution with fine mode dominating around 0.23μm effective radius and the coarse mode dominating around 1μm. The forest site showed minimum AOD and α values with an equal contribution of aerosol particles in the fine and coarse mode. As the fine-mode particle concentration relatively increased at other regions, the α value also went on increasing, along with the increase in AOD. The AOD also showed a latitudinal variation with a minimum occurring at about 23.5°N. During the whole campaign, the average mixing height of planetary boundary layer (PBL) during the daytime was found to be between 650 and 950m. [Copyright &y& Elsevier]

Aerosol scattering and absorption characteristics were investigated at an urban megacity Delhi in the western Indo-Gangetic Basin (IGB) during the period from October 2011 to September 2012 using different in-situ measurements. The scattering coefficient (σ sp at 550 nm) varied between 71 and 3014 Mm −1 (mean ~710 ± 615 Mm −1 ) during the entire study period, which was about ten times higher than the absorption coefficient (σ abs at 550 nm ~67 ± 40 Mm −1 ). Seasonally, σ sp and σ abs were substantially higher during the winter/post-monsoon periods, which also gave rise to single scattering albedo (SSA) by ~5%. The magnitude of SSA (at 550 nm) varied between 0.81 and 0.94 (mean: 0.89 ± 0.05). Further, the magnitude of scattering Ångström exponent (SAE) and back-scattering Ångström exponent (BAE) showed a wide range from −1.20 to 1.57 and −1.13 to 0.87, respectively which suggests large variability in aerosol sizes and emission sources. Relatively higher aerosol backscatter fraction ( b at 550 nm) during the monsoon (0.25 ± 0.10) suggests more inhomogeneous scattering, associated with the coarser dust particles. However, lower value of b during winter (0.13 ± 0.02) is associated with more isotropic scattering due to dominance of smaller size particles. This is further confirmed with the estimated asymmetry parameter (AP at 550 nm), which exhibits opposite trend with b . The aerosol optical parameters were used in a radiative transfer model to estimate aerosol radiative forcing. A mean radiative forcing of −61 ± 22 W m −2 (ranging from −111 to −40 W m −2 ) was observed at the surface and 42 ± 24 W m −2 (ranging from 18 to 87 W m −2 ) into the atmosphere, which can give rise to the mean atmospheric heating rate of 1.18 K day −1 . [ABSTRACT FROM AUTHOR]

The flash flood-induced erosion is the primary contributor to soil loss within the Indian Himalayan Region (IHR). This phenomenon is exacerbated by a confluence of factors, including extreme precipitation events, undulating topographical features, and suboptimal soil and water conservation practices. Over the past few decades, several flash flood events have led to the significant degradation of pedosphere strata, which in turn has caused landslides along with fluvial sedimentation in the IHR. Researchers have advocated morphometric, hydrologic, and semi-empirical methods for assessing flash flood-induced soil erosion in hilly watersheds. This study critically examines these methods and their applicability in the Alaknanda River basin of the Indian Himalayan Region. The entire basin is delineated into 12 sub-watersheds, and 13 morphometric parameters are analyzed for each sub-watershed. Thereafter, the ranking of sub-watersheds vulnerability is assigned using the Principal Component Analysis (PCA), compounding method (CM), Geomorphological Instantaneous Unit Hydrograph (GIUH), and Revised Universal Soil Loss Equations (RUSLE) approaches. While the CM method uses all 13 parameters, the PCA approach suggests that the first four principal components are the most important ones, accounting for approximately 89.7% of the total variance observed within the dataset. The GIUH approach highlights the hydrological response of the catchment, incorporating dynamic velocity and instantaneous peak magnifying the flash flood susceptibility, lag time, and the time to peak for each sub-watershed. The RUSLE approach incorporates mathematical equations for estimating annual soil loss utilizing rainfall-runoff erosivity, soil erodibility, topographic, cover management, and supporting practice factors. The variations in vulnerability rankings across various methods indicate that each method captures distinct aspects of the sub-watersheds. The decision-maker can use the weighted average to assign the overall vulnerability to each sub-watershed, aggregating the values from various methods. This study considers an equal weight to the morphometric, hydrological GIUH, and semi-empirical RUSLE techniques to assess the integrated ranking of various sub-watersheds. Vulnerability to flash flood-induced landslides in various sub-watersheds is categorized into three classes. Category I (high-priority) necessitates immediate erosion control measures and slope stabilization. Category II (moderate attention), where rainwater harvesting and sustainable agricultural practices are beneficial. Category III (regular monitoring) suggests periodic community-led soil assessments and afforestation. Sub-watersheds WS11, WS8, WS5, and WS12 are identified under category I, WS7, WS4, WS9, and WS6 under category II, and WS1, WS3, WS2, and WS10 under category III. The occurrence of landslides and flash-flood events and field observations validates the prioritization of sub-watersheds, indicating the need for targeted interventions and regular monitoring activities to mitigate environmental risks and safeguard surrounding ecosystems and communities., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To estimate the prevalence and determine risk factors for dry eye disease (DED) in geographically diverse regions of India., Method: A population based cross-sectional study was conducted on people aged ≥40 years in plain, hilly and coastal areas. Dry eye assessment by objective [tear film break-up time (TBUT), Schirmer I, corneal staining] and subjective [Ocular Surface Disease Index (OSDI)] parameters was performed with questionnaire-based assessment of exposure to sunlight, cigarette smoke, indoor smoke. The prevalence of DED with age, sex, occupation, location, smoking, exposure to sunlight, indoor smoke, diabetes, hypertension, was subjected to logistic regression analysis., Results: 9,735 people (age 54.5 ± 0.1 years; range 40-99, males 45.5%) were included. The prevalence of DED was 26.2%, was higher in plains (41.3%) compared to hilly (24.0%) and coastal area (9.9%) (p < 0.001) and increased with age (p < 0.001), female gender (p < 0.001), smoking (p < 0.001), indoor smoke (p < 0.001), diabetes (p-0.02), hypertension (0.001), occupations with predominant outdoor activity (p-0.013) and increasing exposure to sunlight (trend). Multi-logistic regression showed a positive association with female sex (OR-1.2, CI-1.01, 1.4), exposure to indoor smoke (OR-1.3, CI-1.1, 1.5), smoking (OR-1.2; CI-1.03, 1.3), prolonged exposure to sunlight (OR-1.8, CI-1.5, 2.2), hypertension (OR 1.3, CI-1.2, 1.4), diabetes (OR-1.2, CI-1, 1.5) and negative association with region - hilly (OR-0.5, CI-0.4, 0.6) and coastal (OR-0.2; CI-0.1, 0.2), and BMI (OR-0.8, CI-0.7, 0.9)., Conclusion: DED is common in population ≥40 years of age. Its prevalence is affected by extrinsic (geographic location, exposure to sunlight, smoking, indoor smoke) and intrinsic (age, sex, hypertension, diabetes, BMI) factors., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The higher altitude regions of Himalayas and Tibetan Plateau are influenced by the dust and black carbon (BC) aerosols from the emissions and long-range transport from the adjoining areas. In this study, we present impacts of advection of polluted air masses of natural and anthropogenic emissions, on aerosol optical and radiative properties at Manora Peak (~2000 m amsl) in central Himalaya over a period of more than two years (February 2006-May 2008). We used the most updated and comprehensive data of chemical and optical properties available in one of the most climatically sensitive region, the Himalaya, to estimate atmospheric radiative forcing and heating rate. Aerosol optical depth (AOD) was found to vary from 0.04 to 0.45 with significantly higher values in summer mainly due to an increase in mineral dust and biomass burning aerosols due to transport. In contrast, single scattering albedo (SSA) varied from 0.74 to 0.88 with relatively lower values during summer, suggesting an increase in absorbing BC and mineral dust aerosols. As a result, a large positive atmospheric radiative forcing (about 28 ± 5 Wm(-2)) and high values of corresponding heating rate (0.80 ± 0.14 Kday(-1)) has been found during summer. During the entire observation period, radiative forcing at the top of the atmosphere varied from -2 to +14 Wm(-2) and from -3 to -50 Wm(-2) at the surface whereas atmospheric forcing was in the range of 3 to 65 Wm(-2) resulting in a heating rate of 0.1-1.8 Kday(-1)., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Aerosol measurements over an urban site at Delhi in the western Ganga basin, northern India, were carried out during 2009 using a ground-based automatic sun/sky radiometer to identify their different types and to understand their possible radiative implications. Differentiation of aerosol types over the station was made using the appropriate thresholds for size-distribution of aerosols (i.e. fine-mode fraction, FMF at 500 nm) and radiation absorptivity (i.e. single scattering albedo, SSA at 440 nm). Four different aerosol types were identified, viz., polluted dust (PD), polluted continent (PC), mostly black carbon (MBC) and mostly organic carbon (MOC), which contributed ~48%, 32%, 11% and 9%, respectively to the total aerosols. Interestingly, the optical properties for these aerosol types differed considerably, which were further used, for the first time, to quantify their radiative implications over this station. The highest atmospheric forcing was observed for PC aerosol type (about +40 W m(-2), along with the corresponding atmospheric heating rate of 1.10 K day(-1)); whereas the lowest was for MBC aerosol type (about +25 W m(-2), along with the corresponding atmospheric heating rate of 0.69 K day(-1))., (Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.)