Future Scenarios of Environmental Vulnerability Mapping Using Grey Analytic Hierarchy Process

Any sustainable resource utilization plan requires evaluation of the present and future environmental impact. The present research focuses on future scenario generation of environmental vulnerability zones based on grey analytic hierarchy process (grey-AHP). Grey-AHP combines the advantages of grey clustering method and the classical analytic hierarchy process (AHP). Environmental vulnerability index (EVI) considers twenty-five natural, environmental and anthropogenic parameters, e.g. soil, geology, aspect, elevation, slope, rainfall, maximum and minimum temperature, normalized difference vegetation index, drainage density, groundwater recharge, groundwater level, groundwater potential, water yield, evapotranspiration, land use/land cover, soil moisture, sediment yield, water stress, water quality, storage capacity, land suitability, population density, road density and normalized difference built-up index. Nine futuristic parameters were used for EVI calculation from the Dynamic Conversion of Land-Use and its Effects, Model for Interdisciplinary Research on Climate 5 and Soil and Water Assessment Tool. The resulting maps were classified into three classes: “high”, “moderate” and “low”. The result shows that the upstream portion of the river basin comes under the high vulnerability zone for the years 2010 and 2030, 2050. The effectiveness of zonation approach was between “better” and “common” classes. Sensitivity analysis was performed for EVI. Field-based soil moisture point data were utilized for validation purpose. The resulting maps provide a guideline for planning of detailed hydrogeological studies.

     

Greatest observed one-day point and areal rainfall of India

The greatest one-day rain amounts recorded at individual stations in the country during the last 41-year period from 1940 onwards were examined for all observatories as well as State rain-gauge stations in an attempt to bring out up-to-date information on the greatest recorded point rainfall for the duration of one day. Outstanding one-day point rainfall amounts recorded prior to 1940 were also examined and have been included in this note along with their date and year of occurrence by way of comparison. A generalized chart has been prepared based on the percentage ratios of the greatest one-day rainfall to the mean annual rainfall of about 300 observatory stations distributed uniformly over the entire country. On the basis of Depth-Area-Duration (DAD) analyses of the most severe rainstorms which occurred over different plain areas of the country, it has been found that the 2 July, 1941, rainstorm gave the highest areal rain depths in the country for different areas. Comparison with similar areal rain depths of the tropical USA has shown that rain depths of the July, 1941, rainstorm were higher for all areas excepting the areas of 500 sq. miles (1295 sq. km) and 1000 sq. miles (2590 sq. km).     

Hydrometeorological Aspects of Floods in India

The Indian sub-continent being located in the heart of the summermonsoon belt, receives in most parts more than 75% of its annual rainfall during the fourmonsoon months of June to September. As the bulk of summer monsoon rainfall occurs withina period of four months, naturally majority of floods occur in Indian rivers during thisseason only. The ground conditions also help in generating high percentage of run-offbecause of the antecedent wet conditions caused by rainy spells occurring within the monsoonperiod itself. Besides mentioning different weather systems, which cause heavy rainfall and consequentfloods, a detailed discussion of 15 years' floods in different river systems has alsobeen given in the article. This study has shown that the flood problem in India is mostly confinedto the states located in the Indo-Gangetic plains, northeast India and occasionally in therivers of Central India.     

Velocity of small-scale auroral ionospheric current systems over Indian Antarctic station Maitri

The Indian Antarctic station Maitri (geog. 70‡45’S, 11‡45’E, geom. 66‡.03S, 53‡.21E) occupies a sub-auroral location during magnetically quiet conditions(Σκρ < 10), but attains an auroral position when the auroral oval shifts equatorwards with increasing strength of magnetic disturbance. At the latter times, triangulation with 3 fluxgate magnetometers located at the vertices of a suitable triangle provides a means of monitoring mobile auroral ionospheric current systems over Maitri. The spacing between the magnetometers is typically kept at 75–200 km, keeping in mind the scale-sizes of ∼ 100 km for these mobile current systems. This work reports the results of two triangulation experiments carried out around Maitri in January 1992 and January 1995, both during Antarctic summer. The velocities estimated for pulsations of the Pc4 and Pc5 type were about 0.59 km/sec in the direction 102‡.7 east of due north, in the first case, and about 1–3 km/sec in the second case in the east-west direction. While several magnetometer arrays exist in the northern auroral regions (e.g., the Alberta array in Canada, the Alaskan array in the U.S. and the IMS Scandinavian array), there is no report in literature of triangulation through arrays in Antarctica, except for a one-day study by Neudegget al 1995 for ULF pulsations of the Pc1 and Pc2 type. The velocities obtained for the Pi3 type of irregular pulsations over Antarctica in the present study tally well with those obtained for northern auroral locations.     

Hydrological modelling of the Kangsabati river under changed climate scenario: case study in India

India is a large developing country with nearly two‐thirds of the population depending directly on the climate‐sensitive sectors such as agriculture, fisheries and forests. A very well‐calibrated Soil and Water Assessment Tool (R² = 0·9968, NSE = 0·91) was exercised over the Kangsabati river watershed in Bankura district of West Bengal, India, for a year including monsoon and non‐monsoon period in order to evaluate projected parameters for agricultural activities. Evapotranspiration, transmission losses, potential evapotranspiration and lateral flow to reach are evaluated from the years 2041–2050 in order to generate a picture for sustainable development of the river basin and its inhabitants. The projected climate change under various scenarios is likely to have implications on food production, water supply, biodiversity and livelihoods. India has a significant stake in scientific advancement as well as an international understanding to promote mitigation and adaptation. This requires improved scientific understanding, capacity building, networking and broad consultation processes. This paper is a commitment towards the planning, management and development of the water resources of the Kangsabati river by presenting detailed future scenarios of the Kangsabati river basin over the mentioned time period. The major findings of this paper were that of all the chosen projected parameters, transmission losses, soil water content, potential evapotranspiration, evapotranspiration and lateral flow to reach, display an increasing trend over the time period of years 2041–2050. Copyright © 2009 John Wiley & Sons, Ltd.     

Geochemical and hydrogeological contrasts between shallow and deeper aquifers in two villages of Araihazar, Bangladesh: Implications for deeper aquifers as drinking water sources

Sediment and groundwater profiles were compared in two villages of Bangladesh to understand the geochemical and hydrogeological factors that regulate dissolved As concentrations in groundwater. In both villages, fine-grained sediment layers separate shallow aquifers (< 28 m) high in As from deeper aquifers (40-90 m) containing < 10 μg/L As. In one village (Dari), radiocarbon dating indicates deposition of the deeper aquifer sediments > 50 ka ago and a groundwater age of thousands of years. In the other village (Bay), the sediment is < 20 ka old down to 90 m and the deeper aquifer groundwater is younger, on the order of hundreds of years. The shallow aquifers in both villages that are high in As contain bomb-³H and bomb-¹⁴C, indicating recent recharge. The major and minor ion compositions of the shallow and deeper aquifers also differ significantly. Deeper aquifer water is of the Na⁺-HCO₃^- type, with relatively little dissolved NH₄⁺ (76 ± 192 μmol/L), Fe (27 ± 43 μmol/L) and Mn (3 ± 2 μmol/L). In contrast, shallow aquifer water is of the Ca²⁺-Mg²⁺-HCO₃^- type, with elevated concentrations of dissolved NH₄⁺ (306 ± 355 μmol/L), Fe (191 ± 73 μmol/L), and Mn (27 ± 43 μmol/L). In both villages, the quantity of As extractable from deeper aquifer sands with a 1 mol/L phosphate solution (0.2 ± 0.3 mg/kg, n = 12; 0.1 ± 0.1 mg/kg, n = 5) is 1 order of magnitude lower than P-extractable As from shallow deposits (1.7 ± 1.2 mg/kg, n = 9; 1.4 ± 2.0 mg/kg, n = 11). The differences suggest that the concentration of P-extractable As in the sediment is a factor controlling the concentration of As in groundwater. Low P-extractable As levels are observed in both deeper aquifers that are low in As, even though there is a large difference in the time of deposition of these aquifers in the two villages. The geochemical data and hydrographs presented in this study suggest that both Holocene and Pleistocene deeper aquifers that are low in As should be a viable source of drinking water as long as withdrawals do not exceed recharge rates of ∼1 cm/yr.     

Food security and dietary diversity of tea workers of two tea gardens in greater Sylhet district of Bangladesh

The study analyzed the food security and dietary diversity of tea workers in Lakkatura Tea Garden and Ootterbhag Tea garden in greater Sylhet district of Bangladesh. A total of 200 respondents (100 from each tea estate) were interviewed to evaluate the food security and dietary diversity. The study found that average daily per capita calorie intake by tea workers was 2095.96 kcal. In addition, around 85.30% of the total calorie intake was received from the rice consumption. Average per capita daily intake of rice was estimated at 538.51 gm which is higher than the national average. It was also observed that 71.7 and 65.0% households were food secure in Lakkatura and Ootterbhag Tea garden, respectively. In Lakkatura Tea Garden, 61.67% tea workers have medium dietary diversity and in Ootterbhag Tea Estate 49.47% tea workers have low dietary diversity. Using the logit model analysis, this study provides food consumption patterns of tea workers and determine the factors responsible for food security. Household size, farm income and daily calorie intake were found having significant influence on households’ food security. For improving socioeconomic conditions of tea workers, educational institution should be set up to improve their educational status and government should give loans for them at a low interest rate and create alternative job opportunity in off season.