Experimental study on the hydrological performance of green roofs in the application of novel biochar

Biochar has the potential to be a soil amendment in green roofs owing to its water retention, nutrient supply, and carbon sequestration application. The combined effects of biochar and vegetated soil on hydraulic performance (e.g., saturated hydraulic conductivity, retention and detention, and runoff delay) are the crucial factor for the application of the novel biochar in green roofs. Recent studies investigated soil water potential (i.e., suction) either on vegetated soil or on biochar-amended soil but rarely focused on their integrated application. With the purpose of investigating the hydraulic performance of green roofs in the application of biochar, the combined effect of biochar and vegetated soil on hydrological processes was explored. Artificial rainfall experiments were conducted on the four types of experimental soil columns, including natural soil, biochar-amended soil, vegetated natural soil, and vegetated biochar-amended soil. The surface ponding, bottom drainage and the volumetric water content were measured during the rainfall test. Simulation method by using HYDRUS-1D was adopted for estimating hydraulic parameters and developing modelling analysis. The results indicated that the saturated hydraulic conductivity of vegetated soil columns were higher than bare soil columns. The addition of biochar decreased the saturated hydraulic conductivity, and the magnitude of decrease was much significant in the case of vegetated soil. The influence of vegetation on permeability is more prominent than biochar. The vegetated biochar-amended soil has the highest retention and detention capacity, and shows a preferable runoff delay effect under heavy rain among the four soil columns. The results from the present study help to understand the hydrological processes in the green roof in the application of biochar, and imply that biochar can be an alternative soil amendment to improve the hydraulic performance.     

Comparative performance evaluation of physicochemical treatment processes for simulated dairy wastewater

In the present study, the effectiveness of physicochemical treatment processes (coagulation and Fenton’s oxidation) was investigated for simulated dairy wastewater (pH = 7.3, chemical oxygen demand (COD) = 3600 mg/l, 5-day biochemical oxygen demand (BOD₅) = 1950 mg/l, total Kjeldahl nitrogen (TKN) = 87 mg/l, and total phosphorous (TP) = 14 mg/l). Plain and ballasted coagulation runs were carried out in a jar apparatus, while Fenton’s oxidation was performed in a three-neck glass reactor. Ballasted coagulation caused an enhancement in the settling rate of sludge though no significant enhancement in the removal of organics was observed. Individually, coagulation and Fenton’s oxidation processes resulted in ~67 and 80 % COD removals, respectively, from the wastewater. The sequential treatment exploring coagulation followed by Fenton’s oxidation showed overall COD, BOD₅, TKN, and TP reductions of ~93, 97, 84, and 70 %, respectively, from the wastewater. However, a biological post-treatment would be required to achieve the effluent discharge standards. The removal of proteins, fats, and amino acids from wastewater was confirmed from Fourier transform infrared analysis of the settled sludge (obtained after coagulation process). Preliminary cost analysis suggested coagulation and the sequential treatment (i.e. coagulation followed by Fenton’s oxidation) as the preferred options.     

Holocene tectono-geomorphic evolution of Haryana plains,Western Ganga plain,India

Haryana plain is the drainage divide between the Ganga plain in the east and the Indus plain in the west. Being a part of the Himalayan foreland, its geomorphology, sedimentation processes, and tectonism are broadly controlled by the Himalayan tectonics. Soil and geomorphological mapping in Haryana plain bring out geomorphic features such as paleochannels, various active drainage patterns, and landforms such as old fluvial plains, floodplains, piedmonts, pediments, terminal fans, and eolian plains. Based on the degree of soil development, and Optical stimulated luminescence (OSL) ages, the soil-geomorphic units were grouped into six members (QIMS-I to VI) (Quaternary Indus Morphostratigraphic Sequence) of a morphostratigraphic sequence: QIMS-VI 9.86–5.38 Ka, QIMS-V 5.38–4.45 Ka, QIMS-IV 4.45–3.60 Ka, QIMS-III 3.60–2.91 Ka, QIMS-II <?2.91–1.52 Ka, and QIMS-I <?1.52 Ka. OSL chronology of different geomorphic features suggests six episodes of tectono-geomorphic evolution in the region since 10 Ka. Neotectonic features such as nine faults, two lineaments, and five fault-bounded tectonic blocks have been identified. Independent tilting and sagging of the blocks in response to neotectonics have resulted in modification of landforms, depositional processes, and hydro-geomorphology of the region. Major rivers like the Yamuna, the Ghaggar, and the Sutlej show different episodes of shifting of their courses. Lineament controlled few extinct channels have been recorded between 20 and 25 m depth below the surface in the ground-penetrating radar (GPR) profiles. These buried channels are aligned along the paleo-course of the Lost Saraswati River interpreted from the existing literature and hence are considered as the course of the lost river. Seven terminal fans have been formed on the downthrown blocks of the associated faults. The Markanda Terminal Fan, the first of such features described, is indeed a splay terminal fan and was formed by a splay distributary system of the Markanda River. Association of three terminal fans of different ages with the Karnal fault indicates the segment-wise development of the fault from west to east. Also, comparison with other such studies in the Ganga plain to further east suggests that the terminal fans formed by streams with distributary drainage pattern occur only in semiarid regions as in the present area and thus are indicators of semiarid climate/paleoclimate. Though the whole region is tectonically active, the region between the Rohtak fault and Hisar fault is most active at present signified by the concentration of earthquake epicenters.     

Static deformation of two welded half-spaces due to very long strike-slip dislocations

Closed form analytic expressions for displacement and stresses at any point of either of the two homogeneous, isotropic, perfectly elastic half-spaces in welded contact due to very long strike-slip dislocations are obtained. Both cases of vertical and horizontal strike-slip dislocations are discussed in detail. Variation of the displacement with horizontal distance from the fault and with vertical distance from the interface for a vertical strike-slip fault is studied numerically.     

Mapping and monitoring of Rann (tidal) ingress in Banni Plains,Kachchh, Gujarat using multi-temporal satellite data

The Rann ingress into the ‘Banni Plains’ of Kachchh district, Gujarat which is famous for the sprawling grasslands supporting significant cattle population is taking place at an alarming rate. This has resulted in the desertion of many villages due to intrusion of Rann waters. In the present investigation multi-date satellite data has been analysed to map and monitor the Rann ingress during the period 1975 to 1989. Detailed analysis has brought out that the inundation is quite rapid affecting about 244 sq. km area during 1960–1989 period. Mapping of the creeks has also been done to understand the possible mechanism of ‘Rann ingress’.     

On pressure-work,viscous dissipation and the energy balance relation for geothermal reservoirs

This article examines the conditions under which the pressure-work and viscous dissipation terms should be retained in the energy balance relation for single (liquid water or vapor) and two-phase (liquid water and vapor) fluid flow through porous media. It is shown that if one wishes to retain the pressure-work term, then one must also keep the viscous dissipation term in the energy balance. Consideration of steady non-isothermal radial flow demonstrates that both pressure-work and viscous dissipation are liable to have negligibly small effects in single phase liquid water and in two-phase liquid-vapor systems. This conclusion is, however, not generally valid for pure vapor systems; in this case, pressure-work and viscous dissipation can produce significant variations in the computed reservoir response.     

Estimation and comparison of leaf area index of agricultural crops using irs liss-III and EO-1 hyperion images

Motivated by the increasingly availability and importance of hyperspectral remote sensing data, this study aims to determine whether current generation narrowband hyperspectral remote sensing data could be used to estimate vegetation Leaf Area Index (LAI) accurately than the traditional broadband multispectral data. A comparative study has been carried out to evaluate the performance of the narrowband Normalized Difference Vegetation Index (NDV1) derived from Hyperion hyperspectral sensor with that of derived from IRS LISS-III for the estimation of LAI of some major agricultural crops (e.g. cotton, sugarcane and rice) in part of Guntur district, India. It has been found that the narrowband NDVI derived from Hyperion has shown better results over its counterpart derived from broadband LISS-III. Linear regression models have been used which with selected subsets of individual Hyperion bands performed better to predict LAI than those based on the broadband datasets, although the potential to overfit models using the large number of available Hyperion bands is a concern for further research.     

Superoxide-mediated reduction of organically complexed iron(III): Impact of pH and competing cations (Ca)

The mechanism and kinetics of superoxide-mediated reduction of a variety of organic iron(III) complexes has been investigated over the pH range 7-9. Our experimental results show that the rate of iron(II) formation is a function of pH, ligand type and ligand concentration with the measured rate varying between 0.44 ± 0.07 and 39.25 ± 1.77 pM s⁻¹ in the systems investigated. Additionally, our results show that the presence of competing cations such as Ca²⁺ have a significant impact on iron(II) formation if the organic ligand is strongly complexed by Ca²⁺. Formation of iron(II) occurs by either (or, in some instances, both) reaction of superoxide with inorganic iron(III) after its dissociation from the complex (dissociative reduction) or by direct reaction of superoxide with the complex (non-dissociative reduction). In the presence of weak ligands, dissociative reduction (DR) dominates; however non-dissociative reduction (NDR) becomes important in the presence of either strongly binding ligands or high concentrations of weakly binding ligands. The major factors contributing to the pH dependence of the iron(II) formation rate are the complexation kinetics of inorganic iron(III) (which controls the DR contribution) and the reduction kinetics of the iron(III) complex (which controls the NDR contribution). The relative NDR contribution increases with increasing superoxide and ligand concentration and decreasing pH for all ligands examined. Since iron(II) formation occurring via NDR results in a significantly larger increase in the proportion of iron in free aquated form than does DR, this non-dissociative pathway of superoxide-mediated iron(III) reduction is particularly effective in increasing the lability of iron in aquatic systems.     

Microwave response of seasonal snow-cover measured by using a ground-based radiometer at 6.93 and 18.7 ghz frequencies and at dual polarization

Snow cover is an important variable for climatic and hydrologic models due to its effects on surface albedo, energy, and moisture budgets. Passive microwave sensors can be used to monitor temporal and spatial variations in large-scale snow cover parameters, avoiding problems of cloud cover and polar nights. In the present study, brightness temperature values were estimated (using calibration curves) for moist snow on natural and blackbody/metal surface. T_B response on snow depth, density, SWE and angular variation from nadir were measured and found that T_B decreases with increase of snow depth and with increase of angle from nadir. Empirical relations were used to estimate emissivity, dielectric constant and dielectric loss factor. It was observed that emissivity decreases with the increase of dielectric constant. The dielectric constant and dielectric loss factor both increases with the increase of density. Experiments were performed during winter of year 2005 at Dhundi and Solang (H.P.), India, using ground based passive microwave radiometer having 6.9 and 18.7 GHz antenna frequencies at dual polarization.     

Flow in an aquifer charged with hot water from a fault zone

Many geothermal anomalies are intersected by vertical fault zones (narrow zones of fractured material with large effective permeability). These conduits are probably responsible for much of the upwelling of hot water from depth. This paper considers a shallow aquifer intersected by a vertical fault. The fluid flow in the aquifer is numerically modeled as a two-dimensional problem. It is observed that the temperature distribution in the aquifer is governed primarily by lateral flow of hot water supplied from the intersecting vertical fault and only secondarily by conduction. The numerical results also provide a possible explanation for the local temperature maxima and inversions occasionally observed in borehole measurements. The present model is an alternative to that based on mushroom-shaped isotherm distributions found in high Rayleigh number large-scale circulation cell calculations.