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Forecasting of load is essential for operating power systems. India recently witnessed one of the worst power crisis with the highest ever power demand of 207 GW on April 29, 2022. The demand in the month of May and June 2022 was estimated to reach 215 GW. The peak demand this year 2023, according to the electricity ministry, is predicted to be around 230 GW from April to June. The inability to meet certain fundamental issues as power can take a toll on any country's economy. Proper prediction helps in proper decision making and planning. The main objective of this paper is to predict day ahead electrical load demand for Assam. Statistical and Machine Learning Algorithms has been studied. The study has been carried out using real-time data for the years 2016, 2017 and 2018. The paper presents a detailed analysis of the different hyper parameters of the deep learning models and their effect is seen on the learning efficiency. A novel stacked forecasting model is proposed using neural networks as base learners and CatBoost as the meta-learner. The performance of the proposed model has been evaluated and compared with individual models in terms of training time and accuracy using different error metrics namely MAE, MSE, RMSE, MAPE and R2 score. A comparison of the proposed prediction model with the prediction models available in literature has been presented. The conclusion states that both the statistical and machine learning algorithms used in this study act as useful tools for daily load forecasting with considerable accuracy; yet machine learning algorithm outperforms the statistical methods. The entire work has been done in Google Colaboratory using Python as the programming language. [ABSTRACT FROM AUTHOR]

Road connectivity is among the few factors which trigger the urbanisation and development process in a region. It facilitates trade, transport, social integration, economic development, socio-economic interaction and cultural assimilation. The present paper aims at analyzing the road infrastructure of Assam with special focus on the Central Brahmaputra Valley. The significance of the study area lies in providing smooth accessibility to the East Asian countries, especially in terms of Act East Policy. The study constitutes an investigation of the growth of road length, road density and connectivity in the study area in spatio-temporal context. Here, growth in road infrastructure has been compared with the growth in urban population and towns. Spatial variation in terms of growth can clearly be seen while discussing the growth of road connectivity and urban growth. Morigaon district has experienced the highest growth in terms of both road connectivity and urban population which clearly reveals that a strong positive relationship exists between the growth of road infrastructure and urban growth. The study has the potential of becoming a guideline for the policy makers to implement action plans for increasing the degree of accessibility in the region. [ABSTRACT FROM AUTHOR]

In this paper, we report the results of seasonal variations of indoor radon and thoron concentrations, equilibrium factors for gas progeny, and radiological risks to dwellers in the hilly area of Guwahati City, Assam, India. Twin-cup dosemeters with LR-115 (II) nuclear track detectors were used in this study. The findings show that values vary significantly, with winter having the highest values and summer having the lowest, with spring and autumn having moderate values. In winter, radon concentrations range from 61.6 ± 11.2 Bq m−3 (Mud) to 115.3 ± 34.3 Bq m−3 (AT), with geometric mean values of 69.2 ± 13.8 Bq m−3 and 109.4 ± 27.9 Bq m−3, and in summer, they range from 21.1 ± 5.9 Bq m−3 (Mud) to 28.4 ± 8.3 Bq m−3 (AT), with geometric mean values of 22.7 ± 6.3 Bq m−3 and 26.1 ± 7.1 Bq m−3, whereas thoron concentrations range from 13.1 ± 5.1 Bq m−3 (Mud) to 58.8 ± 12.6 Bq m−3 (AT), with geometric mean values of 27.6 ± 7.0 Bq m−3 and 52.9 ± 10.1 Bq m−3 in winter, respectively, and in summer, from 8.8 ± 2.3 Bq m−3 (Mud) to 13.0 ± 5.5 Bq m−3 (Mud), with a geometric mean value of 1.87 ± 1.29 Bq m−3. Radon and thoron progeny levels are reported to vary from 4.1 ± 0.3 mWL (Mud) to 15.1 ± 4.3 mWL (AT) and 2.6 ± 0.9 mWL (Mud) to 14.3 ± 4.2 mWL (AT) in winter and from 1.5 ± 0.7 mWL (AT) to 3.0 ± 2.5 mWL (Mud) and 0.9 ± 0.3 mWL (AT) to 2.7 ± 0.5 mWL (Mud) in summer, respectively. The equilibrium factors for radon and its progeny have been reported to range from 0.23 ± 0.1 (Mud) to 0.51 ± 0.3 (AT) in winter, whereas from 0.23 ± 0.1 (AT) to 0.48 ± 0.4 (Mud) in summer, respectively. The equilibrium factors for thoron and its progeny have been estimated in the range of 0.02 ± 0.01 (Mud) to 0.09 ± 0.06 (AT) in winter, whereas 0.02 ± 0.02 (AT) to 0.07 ± 0.05 (Mud) in summer, respectively. The inhalation dose rates differed from house to house, having values in the range of 1.2 ± 0.2 mSv year−1 (Mud) to 4.6 ± 1.3 mSv year−1 (AT) in winter, whereas 0.5 ± 0.3 mSv year−1 (AT) to 0.9 ± 0.5 mSv year−1 (Mud) in summer, respectively. The effective doses (EDs) due to the exposure of radon and thoron in the study area have been found to range from 2.5 ± 0.3 mSv (Mud) to 9.1 ± 2.7 mSv (AT) in winter and 0.9 ± 0.4 mSv (AT) to 1.8 ± 1.3 mSv (Mud) in summer, respectively. The levels of radon and thoron in similar types of construction were found to be significantly different from one house to another. The estimated radon and thoron concentrations in the houses of that region during winter are found to be substantially higher than the global averages as reported by UNSCEAR. [ABSTRACT FROM AUTHOR]

This paper presents the groundwater quality assessment of the upper Brahmaputra floodplains of Assam on a seasonal basis. A total of 88 samples were analyzed for the presence of potentially toxic elements in two seasons. In addition, an attempt is made to identify any possible associated health risks to the residents via the drinking water pathway. The study reveals the presence of various potentially toxic elements, in particular, manganese, iron, nickel, and fluoride concentration exceeding the drinking water specifications set by BIS and WHO drinking water standards. The degree of groundwater contamination was assessed using the Water Quality Index, Heavy metal Pollution Index, Heavy metal Evaluation Index, and Degree of Contamination. The spatial distribution maps of groundwater quality were prepared using geographical information system. The non-carcinogenic health risk was evaluated using hazard quotients and hazard index as per the United States Environmental Protection Agency methodology. The hazard quotient of fluoride and manganese have values > 1, which exceeds USEPA recommended benchmark. The health risk assessment identified that the risk was highest during the pre-monsoon season, and the child population is more vulnerable to non-carcinogenic risk than the adults. Findings of cancer risk identified that pre-monsoon groundwater samples from the Golaghat District pose the highest health risks in the upper Brahmaputra floodplains. The risk is highest in the southwest of the study area, followed by the south and then by the north. [ABSTRACT FROM AUTHOR]

Clean and sustainable energy holds preeminent importance from a socio-environmental standpoint and can be achieved through the implementation of a hybrid renewable energy system (HRES). As well as ensuring the stable and reliable operation of power systems amidst the increasing integration of renewable energy sources, precise source forecasting becomes indispensable. Thus, this paper presents a pioneering HRES design incorporating photovoltaic (PV), wind turbine (WT), and biogas generator (Bio) technologies, wherein animal manure is utilized as biomass for the sustainable valorization of animal waste. The preliminary objective of this study is to address the prevailing gaps to attain sustainable energy production that is both cost-optimal and technically efficient. Consequently, this paper investigates source forecasting through time series modeling, and assesses the techno-environmental and economic viability of HRES (both off-grid and on-grid) within the northeastern state of India, specifically focusing on the case study of the Cachar district in Assam state. Moreover, real data analysis is conducted to model and optimize the hybrid system. The findings reveal promising outcomes in terms of cost, emissions, and electrical energy potential, in which the optimal configuration PV/Bio with grid results in a net present cost (NPC) of 0.659 M$, cost of energy (COE) of 0.00684 $/kWh, and CO2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$_2$$\end{document} emission of 2368 kg/yr. For the off-grid, the optimal configuration PV/Bio/Battery obtained with NPC of 2.49 M$, COE of 0.218 $/kWh, and CO2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$_2$$\end{document} emission of 346 kg/yr. The analyzed results of the off-grid case are compared and validated with existing literature on different energy economics with optimum configurations. The obtained optimum system is more cost-effective than the existing systems in the literature. Furthermore, a sensitivity analysis is performed to assess the system’s robustness. Finally, this study endeavors to project a future power system for one of the prominent regions in Assam, an Indian state. [ABSTRACT FROM AUTHOR]

The creation of the National Register of Citizens (NRC) in Assam is indicative of the sharpening tensions surrounding citizenship, belonging and integration in India. Officially aimed at demarcating the "legitimate citizens", its implementation is believed to have resulted in the partial exclusion of the so-called "Doubtful Voters" and denationalisation of the "illegitimate residents". These frictions associated with citizenship identity and rights are nowhere as acute as in the northeastern Indian state of Assam, where measures of retroactive revocation, administrative erasure and withdrawal of citizenship rights have been systematically deployed against religious and linguistic minorities. Using new research with some NRC rejected applicants in western Assam and other materials, this article identifies the central aspects of the implementation gap in the crucial, albeit problematic task of locating the rightful "Assamese-Indian" citizens. Linking our work to the idea of the 'process is the punishment', we conceptualise these conspicuous inconsistencies in the NRC citizenship determination processes and their results as the "punitive gap". We have identified the distinctive contours of this gap in terms of the massive economic costs, intensification of social (including gender and religion-based) inequalities, increased control through social suspicion and unpredictable outcomes for the marginal Miya Muslim community. The article highlights how this punitive gap has constantly eroded key components of due process, of procedural and substantive protections of the rights of individuals, during the NRC determination exercise and after the release of the final draft list. [ABSTRACT FROM AUTHOR]

An environmental geographical study involves the relief aspects of the geographical unit. Relief analysis of a geographical unit includes relative relief, slope gradient, steepness, and drainage characteristics. The study area selected for the study is a part of the upper Jiadhal drainage basin consisting of 370.63 sq. km of area. It is a young river system (6th order) with lots of sediment carrying capacity and intensive flood frequencies. In this study, the relief morphology of the upper Jiadhal basin is undertaken observing its unique characteristic of large sediment supply causing flood problems in lower basin areas. Open source Landsat: L5135041_041200901113_MTL, TA6RFR_A012986-20,190,901 data from Bhuvan (ISRO) was accessed by ArcGIS tools. It focused that the upper catchment is more influential by environmental problems rather than human except deforestation activities, as there is very less settlement due to no communication route to the interior catchments of the basin. The mainstream of Sido occupies forth (4th) order stream, Sika and Siri are of fifth (5th) order and Jia of sixth (6th) order stream contained to drain the lower basin. The results revel that, the landscape is prone to erosion mainly due to physical and climatic factors and prominently dominated by human intervention due to agro-forestry and could be mitigated with certain specific measures on a location basis including structural engineering measures and watershed management techniques in the degraded areas for the sustainability of the basin. The early studies in this region include the lower basin of the river system, due to inaccessibility. The area is newly demarcated to a different administrative district of Arunachal Pradesh (Lower Siang) and thus in near future more anthropogenic activities would active in the upper catchment, which may influence the environment stability. So the upper catchment management would be a prime concern for the environmentalist in near future. [ABSTRACT FROM AUTHOR]

Background: Operational large-scale flood monitoring using publicly available satellite data is possible with the advent of Sentinel-1 microwave data, which enables near-real-time (at 6-day intervals) flood mapping day and night, even in cloudy monsoon seasons. Automated flood inundation area identification in near-real-time involves advanced geospatial data processing platforms, such as Google Earth Engine and robust methodology (Otsu's algorithm). Objectives: The current study employs Sentinel-1 microwave data for flood extent mapping using machine learning (ML) algorithms in Assam State, India. We generated a flood hazard and soil erosion susceptibility map by combining multi-source data on weather conditions and soil and terrain characteristics. Random Forest (RF), Classification and Regression Tool (CART), and Support Vector Machine (SVM) ML algorithms were applied to generate the flood hazard map. Furthermore, we employed the multicriteria evaluation (MCE) analytical hierarchical process (AHP) for soil erosion susceptibility mapping. Summary: The highest prediction accuracy was observed for the RF model (overall accuracy [OA] > 82%), followed by the SVM (OA > 82%) and CART (OA > 81%). Over 26% of the study area indicated high flood hazard-prone areas, and approximately 60% showed high and severe potential for soil erosion due to flooding. The automated flood mapping platform is an essential resource for emergency responders and decision-makers, as it helps to guide relief activities by identifying suitable regions and appropriate logistic route planning and improving the accuracy and timeliness of emergency response efforts. Periodic flood inundation maps will help in long-term planning and policymaking, flood management, soil and biodiversity conservation, land degradation, planning sustainable agriculture interventions, crop insurance, and climate resilience studies. [ABSTRACT FROM AUTHOR]

Preservatives are used to increase the shelf life of any product for a very long time, yet they are extremely detrimental to human health when used in food. The use of preservatives like formaldehyde by fishermen and fish merchants for prolonged preservation of fish during sales and transportation has recently become problematic and threat to human health. Therefore, the goal of the current investigation was to determine the presence of formaldehyde in the fish sold at fish markets in Nagaon, Assam. The present investigation indicates the contamination of fish with formaldehyde in the local fish markets of Nagaon district. The fish that show the presence of formaldehyde are imported (challani) and out of the whole fish sample collection (challani/imported), Labeo rohita, Catla catla indicates the highest positive result, with 35.96% and 48.44% respectively from the 114 Labeo rohita to 64 Catla catla samples. Additionally, the results for Ompok pabda, Pangasius pangasius, Hilsa ilisha, and Piaractus brachypomus are all positive, with Hilsa ilisha showing a positive result of 100% from their whole sample collection. However, the local fish like Labeo gonius, Cirrhinus reba, Ctenopharyngodon idella, Cirrhinus mrigala, and Hypophthalmicthys nobilis fish species have shown 100% negative results for formalin detection, indicating that their samples are formalin-free. Since formaldehyde is harmful to human health, better methods and techniques should be adopted for the preservation of fish for commerce and storage. Strict regulations should be put in place to limit the use of these hazardous chemical substances. [ABSTRACT FROM AUTHOR]

The presence of heavy metals in agricultural soils has become a critical concern in the face of increased environmental scrutiny, highlighting the relationship between human and natural impacts on our land. This study focused on examining heavy metal contamination levels including Copper (Cu), Chromium (Cr), Cobalt (Co), Lead (Pb), Iron (Fe), Zinc (Zn), Nickel (Ni) and Manganese (Mn) conducting an ecological risk assessment in the Morigaon district's paddy fields, which are characterized by disturbed soils. Undisturbed playground soils of the Morigaon district were taken as control. Based on the averages of all locations and the corresponding contamination factor (Cf) for paddy field, it was found that the soil's Cr (0.56 to 0.84), Fe (0.11 to 0.13), Mn (0.38 to 0.78), and Zn (0.35 to 0.65) contamination is low, with Cf < 1 for all seasons. Observed levels of Cu, Ni, and Pb showed moderate contamination throughout seasons, with contamination factors (Cf) ranging from 1 to 3. Meanwhile, Co exhibited a greater amount of contamination in the disturbed soil, with Cf ranging from 3 to 6, indicating significant contamination. Higher degree of contamination (CD) of the sampling sites (10.71 to 14.72) might have been due to metal contamination, especially Co, Ni and Pb. Undisturbed soil showed a comparatively lesser degree of contamination because of an absence of physical or chemical disturbances. In particular, Ni contents of disturbed and undisturbed sites were excessively higher than the worldwide average. Significant variations from global averages were particularly noted for Co and Pb. Conversely, Cr, Mn, and Zn demonstrated minimal variations when compared to these averages. Additionally, metrics such as Enrichment Factors (EF), Potential Ecological Risk Index (PERI) and Ecological Risk Index (Er) were elevated in the disturbed soils relative to their undisturbed counterparts. The findings indicated that anthropogenic activities have significantly negatively influenced the Morigaon district paddy field's soil quality and agriculture. [ABSTRACT FROM AUTHOR]

The Assam lemon is a highly valued Citrus cultivar known for its unique aroma, flavor, and appearance. This study aimed to investigate the morphological, seeding pattern and biochemical variations within 132 populations of Assam lemon from across 22 districts of Assam along with the control samples, with the objective to offer comprehensive understanding that could facilitate the improvement of breeding programs and further improvement of this important cultivar. Clustering based on UPGMA algorithm for morphological and seeding pattern data were analysed at population level, revealed two major clusters, where all the populations of Upper Assam districts were in the same cluster with the original stock (control population). The populations from Tinsukia and Dhemaji districts displayed more close similarities with the control population in comparison to populations of Upper Assam districts. Another interesting observation was regarding flowering patterns, while populations from Upper Assam districts excluding Golaghat district displayed both bisexual and unisexual flowers with less concentration of unisexual flowers, other remaining districts had bisexual and unisexual flowers of almost equal concentration. Unisexual flowers contained only the male reproductive organs with 40 anthers, while bisexual flowers had 36 anthers. Seeding patterns were examined across the districts, and it was found that populations from Tinsukia, Dhemaji, Lakhimpur, Dibrugarh, Jorhat, and the control population exhibited seedless characteristic while populations from other selected districts displayed a combination of seedless and seeded traits. Interestingly, Golaghat district appears as the linking district and showed availability of both seeded and seedless Assam lemon fruit, connecting the regions of Barak valley, Central, Lower, North and Upper Assam. Biochemical analysis showed significant variations across districts, however, the populations from Dhemaji, Tinsukia, Lakhimpur, Dibrugarh, and Jorhat districts displayed similarity with the control population. The study also investigated variability in soil nutrient content revealing substantial variation among the populations studied. This comprehensive investigation provides valuable insights into the morphological, seeding pattern, and biochemical diversity within the Assam lemon cultivar. These findings can be instrumental in breeding programs to enhance the cultivar, particularly in producing high-quality seedless fruits to meet consumer demands. [ABSTRACT FROM AUTHOR]

In this study, spatial–temporal monotonic and non-monotonic trends in Assam, India, have been analyzed for annual precipitation data through the classical and innovative trend analysis (ITA) methodology. The results of the ITA method have been presented with percentile (quartile) intervals. Thus, within the scope of this study, piecewise trends (low; 25% < , medium; 25–75%, and high; 75% > categories) have been objectively analyzed and identified. The annual precipitation data that was measured in twenty stations in the Assam region from 1901 to 2002 is used for the analysis. According to the classical Modified Mann–Kendall (MMK) method results, only in one station of twenty stations, there is an increasing trend contrary to the decreasing trends in five stations; on the other hand, there is no trend in fourteen stations. As regards to the classical Sen's slope (SS) method calculation, a method which is frequently used together with the MMK method to calculate trend slopes, there are paradoxical results between the MMK and SS method. For instance, at the Cachar station, while there is not any significant trend according to the MMK methodology, the result of the SS methodology points out the largest decreasing trend magnitude. Also, the MMK and SS results are incompatible for the Hailakandi, Karimganj, Dhemaji, Nagaon, Barpeta, Golaghat, Kokrajhar, and Lakhimpur stations. On the other hand, there is little incompatibility between the results of the ITA and SS methods. Also, comprehensive information regarding piecewise trends has been obtained through the ITA model graphs with a quartile range. [ABSTRACT FROM AUTHOR]

Petrochemical contamination has been one of the significant causes of pollution all over the world. The upper Assam of Northeast India has been known for its oil industries and their contribution to India's economy. With tremendous oil production, an adequate amount of petroleum contamination is also observed. Several works have been furnished in the oilfields of Assam; however, the knowledge of heavy metal contamination and hydrocarbon pollution in nearby water bodies and soil, along with risk assessment and statistical validation in the vicinity of the Geleky oilfield of Sibsagar district of Assam, is still limited. The study also reveals native potential phytoremediators that can uptake heavy metals and hydrocarbons to help clean the environment through a greener approach. The presence of aromatic hydrocarbon derivatives in water, soil, plants, and sludge samples, including groundwater, is an alarming concern due to their high toxicity to the surrounding ecosystem and potential threat to the groundwater system. The Principal Component Analysis (PCA) further corroborates the significant and common origin of the heavy metals and total petroleum hydrocarbon (TPH), which inclines toward the oil exploration activities in the nearby oilfield. Among all the six plant species studied, Colocasia esculenta proved to be a noteworthy phytoremediator of both heavy metals and TPH, having an uptake efficiency of 78% of Zn, 46% of Pb, and 75% of Fe, and 70% of TPH. The study provides baseline information to help us identify future threats and suitable endemic phytoremediators, which can be advantageous for future remediation. [ABSTRACT FROM AUTHOR]

Microfinance is globally trusted for corroborating the upliftment of the rural vulnerable poor sections. It is looked upon as a means of credit-based poverty alleviation through financial inclusion. India also witnesses the same. In India, the self-help group bank linkage programme (SHG–BLP) is architected by NABARD in 1992 as a pilot project. The programme was mainstreamed in 1996 to link unorganised with the formal financial sector. In Assam, microfinance services are made available through SHG–BLP registered under Deendayal Antyodaya Yojana–National Rural Livelihoods Mission. Central Assam is the epicentre of operative SHG–BLP. This backdrop motivates us to explore the contribution of SHG–BLP in financial and social inclusion of the marginalised rural people of central Assam. Two self-developed indices, viz., financial inclusion index and social exclusion index are constructed by applying Multiple Correspondence Analysis. The impact analysis is facilitated by the Propensity Score Matching method. The study concludes that the SHG–BLP is successful in ensuring financial inclusion and simultaneously also assists in reducing social exclusion among the stakeholders. [ABSTRACT FROM AUTHOR]

This article presents a study of service-based centrality and hierarchical distribution of settlements in a rural district of Assam state in India, namely Dibrugarh. A compound Centrality Index has been constructed using Analytical Hierarchy Process (AHP). The centrality of a settlement (for this study, Gram Panchayat-rural administrative unit) has been computed using the index, which considers the relative importance of the available services and facilities (within the settlement) that the rural people regularly access. AHP, a systematic and reliable tool, has been used to measure the relative importance of the available services and facilities. Ward's method has been implemented for determining the hierarchy of a settlement based on its computed centrality. The results indicate the centrality of the rural settlements varies from moderate to poor, and the spatial distribution of the hierarchy of settlements is unorganised. The study provides an in-depth understanding of the regional development status in Dibrugarh. Policy implications are suggested, and scopes for further studies are identified. [ABSTRACT FROM AUTHOR]

Disaster response operation is required to execute in unforeseen calamitous event. This research has designed a mathematical model for solid transportation problem in disaster response to allocate relief materials in the affected areas. Minimization of total cost for disaster operation and maximization of coverage of number of affected people to serve are two main objective functions of the model. The model is considered in two environments: certain and uncertain. To handle the uncertainty, this model is solved through three different techniques namely decomposition of interval-coefficient, expected value operator and rough chance constraint programming considering the parameters are in rough interval form. To measure the efficiency of proposed model, a real-life problem is performed considering the flood of Assam and a plan is envisaged for large-scale flood. Weighted metric method is used to convert multi-objective problem to single objective problem. The said model in certain environment gives optimal result in crisp form. In uncertain measure, solutions of the model are in the form of rough interval, crisp and interval which help concern authority to make better decision for allocating relief materials in disaster. Eventually, a comparative study is performed. [ABSTRACT FROM AUTHOR]

Crop yield forecasting is the art of predicting yield before harvest and is crucial for sound planning and policy making at various levels. Rapeseed and mustard (R&M) is the predominant oilseed crop in Assam and is very much sensitive to climatic factors compared to other crops grown during rabi season. In the context of recent climate variability observed in the Brahmaputra valley, development of efficient yield forecasting models for R&M based on weather parameters would certainly help the policy makers in formulating appropriate policies and decision-making. The present study was undertaken to develop R&M pre-harvest yield forecast models at F1 (flowering), F2 (siliqua formation) and F3 (siliqua development & maturity) stages for 15 districts of Assam using stepwise multiple linear regression (SMLR) and artificial neural network (ANN) techniques by analysing the yield and weather data for 27 years and to investigate the impact of weather factors in determining the yield of R&M. The results were enumerated based on coefficient of determination (R2), root mean square error (RMSE) and normalized root mean square error (RMSEn) values. ANN models were found to have greater R2 values over SMLR at all the three stages of forecast except in 2–3 districts. Similarly, profound improvement was observed in RMSE and RMSEn values of the forecast models using ANN technique. Analysing the percent error between observed and forecasted yield, ANN weather-based models were found to give more accurate pre-harvest yield prediction of R&M in the Brahmaputra valley of Assam. Temperature and relative humidity were found to be the most significant parameters in affecting R&M yield in most of the districts during all the three stages of forecast. [ABSTRACT FROM AUTHOR]

Water and aquatic insects were collected seasonally from site 1, the low-lying area of the dump near Deepor Beel, and from sites 2 and 3 of the main wetland and analysed. While dissolved oxygen (DO) increased from site 1 to site 3 in each season, electrical conductivity (EC), total dissolved solid (TDS), total alkalinity (TA) and free CO (F-CO) decreased. Pb and Cd were found to exceed the limits set for drinking water in all the sites and seasons. Species richness (SpR) was found highest (23) at site 2 and lowest (14) at site 1. Sensitive species was absent. The Shannon ( H′) values at site 1 were < 1 while at sites 2 and 3 were > 1 in most of the seasons. Biological monitoring scores (Biological Monitoring Working Party and Stream Invertebrate Grade Number-Average Level) in different sites and seasons inferred severely poor to moderate water quality. At site 1, significant negative correlations were seen for Pb and Cr with SpR while Ni and Cu with insect density (ID). At site 2, TA had highly significant positive correlations with SpR and ID while Cu showed negative correlation with SpR. At site 3, ID had significant negative relationships with air temperature, water temperature, depth, TA, F-CO, PO and Cr. Canonical correspondence analysis triplot has clearly separated site 1 associated with tolerant species and highly influenced by TA, TDS, EC, F-CO Cr, Ni, Cd and Zn confirming high anthropogenic activities on that site. Tolerant and semitolerant species were present at site 2 (influenced by depth and transparency) and site 3 (influenced by Pb and WT) both. Results of this study discerned that the dump site is the point source of pollution. [ABSTRACT FROM AUTHOR]

Rainfall is a principal element of the hydrological cycle and its variability is important from both the scientific as well as practical point of view. Wavelet regression (WR) technique is proposed and developed to analyze and predict the rainfall forecast in this study. The WR model is improved combining two methods, discrete wavelet transform and linear regression model. This study uses rainfall data from 21 stations in Assam, India over 102 years from 1901 to 2002. The calibration and validation performance of the models is evaluated with appropriate statistical methods. The root mean square errors (RMSE), N-S index, and correlation coefficient (R) statistics were used for evaluating the accuracy of the WR models. The accuracy of the WR models was then compared with those of the artificial neural networks (ANN) models. The results of monthly rainfall series modeling indicate that the performances of wavelet regression models are found to be more accurate than the ANN models. [ABSTRACT FROM AUTHOR]

Arsenic (As) mobilization to the groundwater of Brahmaputra floodplains was investigated in Titabor, Jorhat District, located in the North Eastern part of India. The groundwater and the aquifer geochemistry were characterized in the study area. The range of As concentration in the groundwater varies from 10 to 440 μg/l with mean concentration 210 μg/l. The groundwaters are characterized by high dissolved Fe, Mn, and HCO and low concentrations of NO and SO indicating the reduced conditions prevailing in the groundwater. In order to understand the actual mobilization processes in the area, six core drilling surrounding the two target tube wells (T1 and T2) with high As concentration (three drill-cores surrounds each tube well closely) was done. The sediment was analyzed its chemical, mineralogical, and elemental compositions. A selective sequential extraction suggested that most of the As in the sediment is bound to Fe oxides fractions (32 to 50 %) and the competition for adsorption site by anions (PO) also accounts to significant fractions of the total arsenic extracted. High variability in the extraction as well as properties of the sediment was observed due to the heterogeneity of the sediment samples with different chemical properties. The SEM and EDX results indicate the presence of Fe, Mn coating along with As for most of the sample, and the presence of As associated minerals were calculated using PHREEQC. The mobilization of As into the groundwater was anticipated to be largely controlled by the reductive dissolution of Fe oxides and partly by the competitive anions viz. PO. [ABSTRACT FROM AUTHOR]

The historical rainfall data of 110 years (1901-2010) of the two neighbouring basins of Brahmaputra and Barak of Assam, Northeast India were analyzed for monthly, seasonal and annual trends. The Mann-Kendall test and Sen's slope model were used to identify the trends and estimate the magnitude of change, respectively. The analysis revealed significant decreasing trend of rainfall during monsoon and post-monsoon seasons in the Barak basin during 1901-2010. Annual as well as monsoon rainfall during the recent 30-year normal period decreased significantly in both the basins. The last decade (2001-10) was the leanest decade in both the basins. Recent rainfall fluctuations with larger amplitudes indicate greater degree of uncertainties of heavy floods or short spell drought events. [ABSTRACT FROM AUTHOR]

The present article discusses an overview on the contamination of non-segregated open municipal solid waste (MSW) in and around a dumping site at Garchuk in Guwahati city, Assam, India. Analysis showed depth-wise variations in the concentrations of selected heavy metals in MSW and their subsequent accumulations with increasing depths. Zinc was the most abundant heavy metal in MSW. Six-step selective sequential extractions revealed that most of the heavy metals in MSW were in the residual phase except zinc. Analysis of the leachate from MSW showed high concentrations of fluoride, chloride, ammonium-nitrogen and the ratio of biological oxygen demand/chemical oxygen demand. Concentrations of all the heavy metals in the leachates were higher than the Indian national effluent standards. High amounts of biological oxygen demand, heavy metals, total and fecal coliforms in water samples from the adjoining water body (Deepor Beel, a Ramsar site) of the MSW dumping site indicated its unsuitability for domestic use. Principle component analysis showed that influence of MSW leachate was the major source of water contamination in Deepor Beel. Though accumulation of heavy metals in different vegetables growing in MSW dumping site did not exceed the recommended maximum intake, it was a significant additional source of heavy metals in cooked human diet. [ABSTRACT FROM AUTHOR]

Traditional homegardens are an important component of the farming systems in many rural communities and have been highlighted considerably due to their sustainability and role in the conservation of biodiversity. However, the functional aspect of the homegardens, which includes the phenological behavior of the dominant tree species in such agroforestry systems, has been undermined till date, and there is a lack of adequate data on this aspect of the traditional homegardens. As a step in this direction the present study was carried out to determine the phenological behavior of important multipurpose trees in the homegardens of the village of Dargakona, Assam, northeast India. The study revealed the dominance of periodic growth deciduous species from a total of 25 tree species selected for phenological observation. The diversity of multipurpose trees in the homegardens is represented by different plant functional types with different phenological behavior which showed significant changes in their responses to inter-annual climatic variations. The diversity of tree species with different phenological behavior has implications for the temporal partitioning of resources, especially during periods of scarcity, thereby resulting in efficient utilization of resources such as water. Also the diverse phenological behavior plays an important role in regulating the food supply for the herbivore population and the year-round availability of products, and such information can be useful in the selection of species for integration into other agroforestry systems which can be sustainable in the long run. [ABSTRACT FROM AUTHOR]

Houttuynia cordata Thunb. is a rhizome-bearing aromatic medicinal herb and is restricted to specialized moist habitats. The plant is collected from natural habitats for local consumption and trade. The status of the species and its variations in physiological performance in different habitats were studied in selected sites of geographically different areas of Brahmaputra valley in eastern India. The surveys were conducted in two different growth stages of the plant during 2005–2007. The sites where the species was encountered were marked and a distribution map was prepared. The frequency and density of the plant was higher in the moist habitats with higher organic carbon (0.85 ± 0.05%). Generally, the density, biomass production and growth had significant (P < 0.05) positive relationship with the soil physicochemical properties (linear curve fit). Soil moisture was the most dependent factor for the plant growth and the optimum growth was recorded at 78 ± 5.6% (r2 = 0.9; P ≤ 0.01). The physiological performance of the plant in all the studied sites were significantly varied (P < 0.05). The growth and development of H. cordata were also different in the flowering and senescence stages. Clay loam soil, average soil pH of 5.9, and 78% soil moisture were the favorable soil characteristics for the better growth of H. cordata and, hence, these data may be considered for conservation of the species. [ABSTRACT FROM AUTHOR]

We present here optical properties and crystallinity index of quartz (SiO2) in natural rocks samples from the Mikir and Khasi hills, Assam, India. Infrared spectroscopy has been used to study the structure of quartz in rock samples and estimate the mining quality of quartz mineral, which is substantiated by calculating the crystallinity index. Systematic investigations of structure have been carried out in between 10 μm (1000 cm-1) and 20 μm (500 cm-1) bands of silicates. Investigation is based on the assignment of infrared bands to certain structural groups of SiO4 tetrahedra. The crystallinity of samples has been ascertained by comparing the ratio of intensity of the characteristic peak at 778 and 695 cm-1 with the corresponding ratio for a standard sample. The crystallinity parameter is calculated by using a standard procedure which can be used to estimate the distribution of quartz in various rocks for mining purpose. The infrared spectroscopic investigation is found to be an ideal tool for structure elucidation and for estimating quartz crystallinity of the natural samples. [ABSTRACT FROM AUTHOR]