Calibration and Validation of SWAP to Simulate Conjunctive Use of Fresh and Saline Irrigation Waters in Semi-Arid Regions

Soil–Water–Atmosphere–Plant (SWAP) version 2.0 was evaluated for its capability to simulate crop growth and salinity profiles at Agra (India) located in a semi-arid region having deep water table and monsoon climate. The data of 12 conjunctive use treatment combinations simulating cyclic and mixing modes of fresh and saline water for wheat were used to calibrate and validate the model. Absolute deviations between the SWAP simulated and observed relative yields during calibration ranged from 2.5 to 2.9 %. A close agreement in the trend and values of measured and simulated soil salinity profiles was observed. Scenario building simulations carried out with the validated SWAP revealed that the maximum crop yields varied from 97 to 99 % with the best available water (EC 3.6 dS m^?1) while the minimum ranged from 65 to 79 % in the treatment with all saline water. Other than this, the relative yield varied from 80 to 98 % in 10 other cyclic and mixing mode treatments. It was established that notwithstanding the seasonal build-up of salts due to saline water use, there would be no long-term build-up of salts as leaching during the monsoon season would render the soil profile salt free at the time of sowing of rabi (winter) crops. Thus, short-term field observations could be used in conjunction with SWAP to show that there seems to be an assured long-term sustainability when saline water is used in conjunctive mode with fresh water in monsoon climatic conditions with deep water table. These results are in conformity with the observation that many farmers in India are using saline and fresh water in conjunctive mode on a long-term basis.     

Management of hazardous road derived respirable particulates using magnetic properties of tree leaves

The magnetic properties of tree leaves along with their ecological, economical and aesthetic importance can be used to control road derived respirable particulates. Isothermal remanent magnetization (IRM₃₀₀ mT) of three different tree leaves viz. Mango (Mangifera indica), Sisso (Dalbergia sisso) and Banyan (Ficus benghalensis) were determined and IRM₃₀₀ mT normalized for the leaf area. The normalized 2-D magnetization of leaves as shown by results is dominantly controlled by leaf morphology and traffic density. F. benghalensis (Banyan) leaf has highest 2-D magnetization and D. sisso (Sisso) leaf having least 2-D magnetization suggesting greater ability of F. benghalensis (Banyan) tree leaves to reduce magnetic particulates. The particle size of the magnetic grains falls in the category of PM2.5, a particle size hazardous to human health due to its capacity to be inhaled deeply into the lungs.     

Dynamics of traffic noise in a tropical city Varanasi and its abatement through vegetation

Noise level monitoring and its reduction with different width and height of vegetation belt were studied in the Varanasi city. Noise level monitoring of the Varanasi city revealed the fact that area category A (without vegetation) was highly polluted as compare to area category B (with vegetation) having less fluctuation of traffic load. Four plant species Putranjeva roxburghi, Cestrum nocturnum, Hibiscus rosasinensis and Murraya peniculata were tested for noise reduction study at different frequencies. Experiment revealed the fact that H. rosasinensis reduced noise highest at both low and high frequencies (100-500 Hz, 22 dB and 2.5-6.3 KHz 26 dB), followed by M. peniculata (100-500 Hz, 18 dB and 2.5-6.3 KHz 20 dB), P. roxburghi (100-500 Hz 15 dB and 2.5-6.3 KHz 17 dB) and C. nocturnum (100-500 Hz 9 dB and 2.5-6.3 KHz 14 dB). Significance of vegetation belt in noise reduction was established with multiple regression models.     

Environmental studies on river water quality with reference to suitability for agricultural purposes: Mahanadi river estuarine system, India – a case study

Hydrochemistry of surface water (pH, specific conductance, total dissolved solids, sulfate, chloride, nitrate, bicarbonate, hardness, calcium, magnesium, sodium, potassium) in the Mahanadi river estuarine system, India was used to assess the quality of water for agricultural purposes. The samples were studied for 31 different stations during six different seasons in the years 2001-2003. Chemical data were used for mathematical calculations (SAR, Na%, RSC, potential salinity, permeability index, Kelly's index, magnesium hazard, osmotic pressure and salt index) for better understanding the suitability river water quality for agricultural purposes. The river water is free from nitrate-nitrogen hazard and has much less osmotic pressure and RSC values. Further there is no complete precipitation of calcium and magnesium in the study area. The results revealed that waters of some polluted stations like Sambalpur down (D/s of Sambalpur town) and Kathjodi (Cuttack) down (D/s of Cuttack town) are unsuitable up to some extent, where as it is quite unsuitable in case of estuarine samples during the pre-monsoon and post-monsoon seasons. The results were verified by USSL and Wilcox diagrams, which show all the fresh water zone samples (low-medium salinity with low sodium) of the study area are in the 'Excellent to good' category and are suitable to irrigate all soils for semi-tolerant and tolerant as well as sensitive crops.     

Study of the variation and the effect of geo-chemical composition on the external background radiation level

The study to generate the baseline of natural radiation and radioactivity in East and West Khasi Hills District of Meghalaya, India was conducted to determine the different radiation dose in selected stations. Twenty stations were selected in both the district, which include Shillong the capital of Meghalaya and the Domiasiat area, which has been identified as one with a Uranium ore deposit. The dose was measured using a Micro-R-Survey meter and from the measurement it was found out that the absorbed dose in both the districts ranges from 0.04 to 1.66 microGy h(-1). The maximum dose was observed in Kylleng (0.72 microGy h(-1)) and the minimum in Mawphlang (0.06 microGy h(-1)). Average absorbed dose and equivalent dose were found to be higher than the Indian and world average values by several orders. The radiation levels distribution was found to be non-uniform through out the selected study area.     

Color removal from paper mill effluent through adsorption technology

The bagasse fly ash, obtained from the local sugar industry, has been used as an inexpensive and effective adsorbent for the removal of color from pulp and paper industry. Effect of various operating variables, viz., contact time, initial concentration, adsorbent dose and particle size on the removal of color has been studied and discussed. It is found that for optimum removal of color, contact time for adsorption equilibrium equals to 60 min., at dosage of 2 g/l of baggase fly ash. The material exhibits good removal capacity (86%) and follows both the Langmuir and the Freundlich models.     

An assessment of trace element contamination in intertidal sediment cores of Sunderban mangrove wetland, India for evaluating sediment quality guidelines

This paper presents a comprehensive account regarding concentration, distribution and possible sources of trace elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in 20-30 cm sediment cores (<63 microm particle size) collected at the confluence of the Ganges River and Bay of Bengal (Sunderban wetland, India). This work aims to evaluate the fluvio-marine and geochemical processes influencing the metal distribution. The most interesting features are the downward increase of concentrations of majority of the elements reaching overall maximum values at a depth of 10-15 cm observed in station Lot No.8 located along the main stream of the Ganges estuary as well as an overall elevated concentration of all the elements in the lower littoral zone. The interelemental relationship revealed the identical behaviour of elements during its transport in the estuarine environment. The overall variation in concentration can be attributed to differential discharge of effluents originating from industrial and agricultural as well as from domestic sewage. Arsenic exceeded effects range - low (ER - L) concentrations, implying occasional or frequent adverse biological effects. For Cu, Ni and Cr a smaller proportion of samples had exceeded the ER - L values indicating that the dataset would be suitable for future use in evaluating predictive abilities of SQGs.     

Estimation of green house gas emissions from Koteshwar hydropower reservoir,India

The emissions of greenhouse gas (GHG) from soils are of significant importance for global warming. The biological and physico-chemical characteristics of soil affect the GHG emissions from soils of different land use types. Methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂) production rates from six forest and agricultural soil types in the Koteshwar hydropower reservoir catchments located in the Uttarakhand, India, were estimated and their relations with physico-chemical characteristics of soils were examined. The samples of different land use types were flooded and incubated under anaerobic condition at 30 °C for 60 days. The cumulative GHG production rates in reservoir catchment are found as 1.52 ± 0.26, 0.13 ± 0.02, and 0.0004 ± 0.0001 μg g soil^?1 day^?1 for CO₂, CH₄, and N₂O, respectively, which is lower than global reservoirs located in the same eco-region. The significant positive correlation between CO₂ productions and labile organic carbon (LOC), CH₄ and C/N ratio, while N₂O and N/P ratio, while pH of soils is negatively correlated, conforms their key role in GHG emissions. Carbon available as LOC in the reservoir catchment is found as 3–14% of the total ?C” available in soils and 0–23% is retained in the soil after the completion of incubation. The key objective of this study to signify the C, N, and P ratios, LOC, and pH with GHG production rate by creating an incubation experiment (as in the case of benthic soil/sediment) in the lab for 60 days. In summary, the results suggest that carbon, as LOC were more sensitive indicators for CO₂ emissions and significant C, N, and P ratios, affects the GHG emissions. This study is useful for the hydropower industry to know the GHG production rates after the construction of reservoir so that its effect could be minimized by taking care of catchment area treatment plan.