Damodar Basin Research Articles

Identification of spatially distributed hotspots for soil loss and erosion potential in mining areas of Upper Damodar Basin – India

Limited measurements of soil erosion, sediment transport and deposition due to coal mining activities hamper the planning for soil and water management in large coalfields. Management of erosion in these areas requires the identification of vulnerable zones. In this study, a modified Universal Soil Loss Equation model coupled with Analytic Hierarchy Process has been used to develop an Erosion Potential Index (EPI) to identify probable zones of soil erosion in the Upper Damodar Basin (UDB). The Damodar river valley has been subjected to severe environmental contamination over the years due to large scale mining and industrial activities. The results revealed that north-western and the central part of the UDB lied in the high EPI zone. Revised Universal Soil Loss Equation (RUSLE) model was used to estimate the soil loss for the UDB. The results of the RUSLE model revealed that the soil loss in the study area varied from a minimum of 0 to a maximum of 91.34 t ha−1 yr−1 in some areas. The spatial distribution of soil loss in the UDB was classified into 5 categories (Very Slight, Slight, Moderate, Severe and Extremely Severe). From results it was observed that about 959.9 km2 or 22% of the total study area lied in the severe soil loss zone i.e., soil losses in these areas ranged between 20 and 40 t ha−1 yr−1. Most of these areas were located in the vicinity of coal mining areas. Although, the lack of available data may impair the prediction accuracy of the proposed model at such a large watershed scale. However, the results of the proposed approach indicate usefulness in identifying erosion hotspots in large distributed watersheds with limited data.

Comparative study on sorption characteristics of coal seams from Barakar and Raniganj formations of Damodar Valley Basin, India

The methane retention mechanism in coal seams is markedly different from those of conventional gas reservoirs. Methane remains mainly as physically adsorbed molecules on micropore surface. Chemical and petrographic compositions of coal are the measures of maturity and type of organic matter that control the methane sorption characteristics of the coal. 99% of Indian coal occurrences are contributed by lower Gondwana sequences housed in two major geologic formations, younger Raniganj and older Barakar. The Raniganj Formation is best exposed in Raniganj Sub-basin and Barakar Formation is best exposed in Jharia Sub-basin of Damodar Valley. Present work attempts a systematic investigation on comparative account of methane sorption characteristics of coals from Raniganj Formation of Raniganj Sub-basin and Barakar Formations of Jharia Sub-basin in relation to their chemical composition and petrographic makeup. Chemical analyses shows that moisture, ash, volatile matter and fixed carbon varies between 2.5 and 4.6%, 10.0–27.2%, 38.8–40.2% (dmmf) and 59.8–61.2% (dmmf), respectively for Raniganj coals and, 0.5–1.1%, 16.7–32.9%, 20.7–22.0% (dmmf) and 78.0–79.3% (dmmf), respectively for Barakar coals. Carbon content is distinct for the suites of coal, 79.2–85.4% and 85.6–92.0% for Raniganj and Barakar coals, respectively. The vitrinite reflectance for the Raniganj coals ranges 0.53–0.72% and the Barakar coals ranges 1.09–1.23%. Based on the chemical composition and vitrinite reflectance value Raniganj coals belongs to high volatile bituminous type, whereas Barakar coals belongs to high to medium volatile bituminous type. Such variation in composition and maturity is mainly attributed to the variation in precursor organic matter as well as the basinal and thermal history of the sub-basins under consideration.H/C atomic ratio of the Raniganj and Barakar coals varies between 0.65 and 0.80 and 0.51–0.72 and O/C atomic ratio varies between 0.05 and 0.13 and 0.01–0.07, respectively. Coals of both the Raniganj and Barakar formations are mostly of kerogen Type-III with Raniganj coals falling in wet gas maturity stage approaching early-thermogenic methane generation whereas Barakar coals falling in condensate gas stage approaching peak-thermogenic methane generation. The Langmuir volume ranges from 9.3–21.8 cc/g (daf) for Raniganj coals and 21.1–29.1 cc/g (daf) for Barakar coals. Sorption capacity for the set of coals shows a strong rank dependency and increase with corresponding increase in rank down the stratigraphic column. Methane sorption capacity shows positive relationship with carbon content and vitrinite reflectance, and negative relationship with moisture content, ash and volatile matter. Moisture effect is more prominent in low rank Raniganj coals. The adsorption capacity shows a strong positive relation with vitrinite content and a moderate negative relation with inertinite content for both the Raniganj and Barakar coals, which may be attributed to dominancy of micropores in vitrinites with rank enhancement. The multiple regression analysis shows that the moisture is the main predictor of the VL, and the interaction of moisture with ash and reflectance mainly control the sorption capacity. A predictive model equation is developed for determination of sorption for Damodar basin coals from carbon, ash and moisture data.

Floral diversity and environment during the early Permian: a case study from Jarangdih Colliery, East Bokaro Coalfield, Damodar Basin, India

Macro and miofloral analyses of coal-bearing sequences of the Jarangdih coal mine, Damodar Basin, were carried out to infer the floral diversity, age assessment, and the palaeoenvironment during the deposition of the Barakar Formation in this area. Damodar Basin, one of the five major Gondwana basins in India, is considered as the reference basin for inter-basinal age correlations. The Barakar strata of this colliery have yielded a diverse macroflora consisting of the groups Glossopteridales (Glossopteris, Vertebraria, Gangamopteris, fructifications, and stem casts) and Equisetales (Phyllotheca indica, Schizoneura gondwanensis, and Paracalamites sp.). The genus Glossopteris dominates the assemblage with 16 species viz. G. arberi, G. communis, G. churiensis, G. giridihensis, G. indica, G. intermedia, G. intermittens, G. leptoneura, G. linearis, G. mohudaensis, G. recurva, G. searsolensis, G. stenoneura, G. taenensis, G. tenuifolia, and G. tenuinervis. The leaves of Glossopteris leptoneura have impressions of male sporangia adhered on them. The groups Lycopodiales, Coniferales, Sphenophyllales, and Filicales are not represented as macrofloral remains; however, their presence is recorded in the palynoassemblage. The palynological analysis has revealed only one palynoassemblage characterised by the dominance of striate bisaccate palynomorphs mainly Faunipollenites and non-striate bisaccate pollen—Scheuringipollenites. The other stratigraphically significant palynotaxa are Striatopodocarpites, Verticipollenites, Crescentipollenites, Striatites, and Arcuatipollenites. The recovered palyno- and megafloral assemblages suggest the late early Permian (Kungurian) age to the Barakar strata of Jarangdih coal mine and prevalence of moderately warm climate during their deposition.

A comprehensive study on correlation of gastropod diversity with some hydroenvironmental parameters of selected waterbodies of lower Damodar basin, West Bengal, India

Gastropods, an important group of mollusc, inhabitants of sediment-rich bottom zone have evidentiary role in freshwater ecosystem. Their community structure has been influenced by the water and soil quality parameters. Under the scenario of intensive agricultural practice and fast urbanization waterbodies particularly the ponds of lower Damodar basin in Howrah district, West Bengal, India are badly affected by growing pollution load. In current study, three lentic waterbodies i.e Shiberjala pond, Nayachak Wetland and Dhasa Waterbody were chosen to assess the gastropod diversity. Selected physico-chemical parameters including Temperature, Dissolved Oxygen, pH, Free Carbon di oxide, Nitrate and Phosphate of all three waterbodies were determined also. Dhasa Waterbody containing 7 species, exhibited highest species richness. The density and species richness showed spatial variation among study sites. Bellamya bengalensis was the dominant species found at all study sites. Melanoides tuberculata in spite of their absence in Shiberjala pond, appeared to be the second most dominant species. Brotia sp and Bithynia sp was the least abundant species. Gastropod species richness showed significant negative correlation with DO level(r=-0.705, P<0.05).Nitrate level was significantly positively correlated(r=0.474, P<0.05) with gastropod species richness and density. Phosphate level (r=0.33) also positively correlated with gastropod richness.

Palynology and palaeoenvironment of Late Permian Sawang OCM, East Bokaro Coalfield, Damodar Basin, India

Palynodating of Sawang Open Cast Mine (OCM) section from East Bokaro Coalfield, Damodar Basin has been done. Recovered palynofossils are characterized by the dominance of Striatopodocarpites–Faunipollenites complex. The other stratigraphically significant taxa recorded from this section are Guttulapollenites hannonicus, Crescentipollenites fuscus, Rhizomaspora indica, R. triassica, Distriatites sp., Weylandites lucifer, Microfoveolatispora gondwanensis, Dictyotriletes invisus, Indotriradites spp., Arcuatipollenites pellucidus, Alisporites indicus and Klausipollenites schaubergeri. Other rare palynotaxa include Parasaccites, Corrisaccites, Dicapipollenites, Striomonosaccites, Barakarites, Plicatipollenites, Scheuringipollenites, Densipollenites, Callumispora, Tiwariasporis, Praecolpatites and Distriatites. On the basis of the total palynocomposition, the studied section has been dated as Late Permian age. This age correlation also gets support from comparative studies with similar palynoassemblages known from other coalfields of Indian Gondwana basins such as Damodar, Son–Mahanadi, Rajmahal, Wardha–Godavari and Satpura basins of India and from known Gondwanan continents. Palynofossil evidences indicate prevalence of warm and humid conditions. The dominance of conifers and subdominance of Glossopterids, cordaites and low percentage of triletes (filicopsids and lycopsids) suggests that the Inland Sawang OCM was deposited under freshwater environment.

Late Permian palynomorphs from the West Bokaro Coalfield, Damodar Basin, Jharkhand, India

Palynological studies were carried out for samples collected from the Bokaro River section near Danea area from West Bokaro Coalfield, Damodar Basin. The recovered palynomorphs are characterized by the dominance of monosaccate pollen mainly Densipollenites (D. magnicorpus, D. invisus, D. indicus and D. densus) and subdominance of Faunipollenites spp.–Striatopodocarpites spp. complex. The other stratigraphically significant taxa recorded from this section are Guttulapollenites hannonicus, Crescentipollenites fuscus, Arcuatipollenites (A. pellucidus, A. ovatus and A. damudicus), Alisporites asansolensis, Verticipollenites gibbosus, Striatites rhombicus, Platysaccus densicorpus, Chordasporites sp., Parasaccites (P. perfectus and P. densicorpus) and Horriditriletes sp. On the basis of the total palynocomposition, the studied section has been dated as late Permian in age. This age correlation also gets support from comparative studies with similar palynoassemblages known from other coalfields of Indian Gondwana basins such as Damodar, Satpura, Son–Mahanadi, Rajmahal and Wardha–Godavari basins. The dominance of Cordaites and subdominance of conifers of Glossopterids suggests that the deposition of the sedimentary sequences took under freshwater environment.

Permian macro- and miofloral diversity, palynodating and palaeoclimate implications deduced from the coal-bearing sequences of Singrauli coalfield, Son–Mahanadi Basin, central India

The coal-bearing sequences of Barakar and Raniganj formations exposed in Bina and Jhingurdah open-cast collieries, respectively, are analysed for their macro- and miofloral content. The sediment successions primarily comprise of sandstones, shales, claystones and coal seams. In addition to the diverse glossopterid assemblage, four palynoassemblage zones, namely Zones I and II in Bina Colliery and Zones III and IV in Jhingurdah Colliery, have also been recorded in the present study. The megafossil assemblage from the Barakar strata of Bina Colliery comprises of three genera, namely Gangamopteris, Glossopteris and cf. Noeggerathiopsis. Palynoassemblage-I is characterised by the dominance of non-striate bisaccate pollen genus Scheuringipollenites and subdominance of striate bisaccate Faunipollenites and infers these strata to be of Early Permian (Artinskian) age (Lower Barakar Formation). The palynoassemblage has also yielded a large number of naked fossil spore tetrads, which is the first record of spore tetrads from any Artinskian strata in the world and has a significant bearing on the climatic conditions. The palynoassemblage-II is characterised with the dominance of Faunipollenites over Scheuringipollenites and is indicative of Kungurian age (Upper Barakar Formation). The megafossil assemblage from the Raniganj Formation of Jhingurdah Colliery comprises of five genera with 26 species representing four orders, viz., Equisetales, Cordaitales, Cycadales and Glossopteridales. The order Glossopteridales is highly diversified with 23 taxa and the genus Glossopteris, with 22 species, dominates the flora. The mioflora of this colliery is represented by two distinct palynoassemblages. The palynoassemblage-III is correlatable with the palynoflora of Early Permian (Artinskian) Lower Barakar Formation. The assemblage suggests the continuity of older biozones into the younger ones. The palynoassemblage-IV equates the beds with composition V: Striatopodocarpites–Faunipollenites–Gondisporites assemblage zone of Tiwari and Tripathi (1992) of Late Permian (Lopingian) Raniganj Formation in Damodar Basin. The FAD’s of Alisporites, Klausipollenites, Falcisporites, Arcuatipollenites pellucidus and Playfordiaspora cancellosa palynotaxa in this assemblage enhance the end Permian level of the Jhingurdah Top seam, as these elements are the key species to mark the transition of Permian into the Lower Triassic.

Late Permian palynoassemblage from Borehole No. WG-22 near Sekapur, Wardha District, Maharashtra, India

The present paper deals with the palynological investigation of the Lower Gondwana sequence intersected in Borehole No. WG–22, drilled near Sekapur Village, in Wardha District, Maharashtra. The study divulges the incidence in significant proportion and with consistency of striate bisaccate palynomorphs, viz. Striatopodocarpites and Faunipollenites and non–striate genus Scheuringipollenites. The associated genera recorded include, Weylandites, Tiwariasporis, Densipollenites, Verticipollenites and Klausipollenites, though with meagre distribution. This palynoassemblage has been dated as Late Permian and affiliate closely with the palynofloral assemblages known from the basal part Raniganj Formation of East and West Bokaro coalfields, Damodar Basin, Makardhokada area of Nagpur District and vast areas of Godavari Valley. The study indicates that almost similar vegetational pattern existed in the Nagpur, Wardha–Godavari and Damodar basins however, there existed regional variations in the generic composition of the vegetation in Satpura Basin as suggested by their palynofloral contents. The mega– and microfloral studies of the Wardha Basin with particular reference to Sekapur area suggests prevalence of warm and temperate climate in this region.

Early Triassic Palynomorphs from Kuraloi Block, Belphar Area, Ib-River Coalfield, Mahanadi Basin, Odisha

Abstract: A rich assemblage of palynomorphs including miospores and megaspores has been recorded from the bore core no. IBKAN-2 drilled at a depth of 17.80m in Kuraloi Block-A, south-west part of the Ib-River Coalfield, Jharsuguda district, Odisha. The miofloral assemblage recovered shows prominence of cingulate, zonate, taeniate, non-striate and non saccate palynotaxa which indicate an early Triassic age and is comparable with the palynoassemblages of the same age known from the Damodar basin, India. The megaspore assemblage includes eight genera and fifteen species namely, Banksisporites karanpuraensis, B. indicus, B. utkalensis, Banksisporites sp., Barakarella pantii, Barakarella sp., Biharisporites spinosus, Biharisporites sp., Erlansonisporites triassicus, Erlansonisporites cf. erlansonii, Erlansonisporites sp. Jhariatriletes sp., Singhisporites sp., Ramispinatispora sp. and Talchirella trivedii. Records of megaspores are sparse in the early Triassic of Gondwana basins of India. The present study records the first occurrence of miospores and megaspores from the early Triassic of Mahanadi basin besides substantiating the earlier data.

Palyno-petrographical Facet and Depositional Account of Gondwana Sediments from East Bokaro Coalfield, Jharkhand

Abstract: Palynological and petrological studies have been undertaken on the Gondwana coal and associated lithologies encountered in borehole EBM-2 of East Bokaro coalfield of Damodar Basin, India. The palynological investigation resulted in the recognition of Assemblage –III (Densipollenites, 27.9 m – 214.30 m), Assemblage – II (Striatopodocarpites + Faunipollenites, 225.00 m – 297.60 m) and Assemblage – I (Faunipollenites + Scheuringipollenites, 307.00m – 433.00 m). Lithofacies study was also done for better understanding of the preservation and abundance/paucity of the spores and pollen in different lithologies as the current borehole has significant thickness of mudstones, shales and siltstone. Palynofacies study and Petrographical studies of coal samples encountered in the borehole were used to determine the depositional environment of the coal precursor peat swamp. Palynological data has revealed the presence of younger Raniganj palynoflora between 27.00-214.30 m depth that is lithologically defined as Barren Measures Formation. This spore pollen study has proved that these sediments were deposited during late early Permian to late Permian period. Further the maceral analysis of organic sediments as well as the Thermal Alteration Index (TAI) has revealed that the coaly shale at 336.5 m depth has hydrocarbon generation potential.

Dam-induced changes in flood hydrology and flood frequency of tropical river: a study in Damodar River of West Bengal, India

The Damodar River of West Bengal is popularized as ‘Sorrow of Bengal’ due to massive unpredictable destruction in the monsoonal floods, recorded since 1665. After establishment of Damodar Valley Corporation (DVC) of India in 1948, Tilaiya, Tenughat, Konar, Maithon and Panchet dams (Jharkhand) and Durgapur barrage (West Bengal) are built to regulate flood flow to a certain limit. But, as the floods were unpredictable in pre-dam phase, even now, lower Damodar Basin is not secure from the monsoonal floods. To assess the flood risk and nature of flood discharge, we have focused here to fit extreme value distribution (EVD) to the annual peak flow of the Damodar River using mainly Gumbel and log Pearson type III distributions. Pre-dam (1934–1957) and post-dam (1958–2007) flood frequency analysis has significantly projected maximum probable flood discharge of Damodar at Rhondia with a certain return period of occurrence, and it provides an idea about future flood risk in lower Damodar Basin.

Organic Matter Characterization of Carbonaceous Shales from Raniganj Coalfields and its Implications on Depositional Condition: A Palynofacies and Petrographic Overview

Abstract The present work deals with the palaeoenvironment and depositional setting of the subsurface sediments from bore hole RT-4 of Tamra block from Raniganj coalfield of Damodar Basin, India. Nineteen shale samples were subjected to palynological and coal petrographical analyses. On the basis of botanical affinity between the miospores and the parent plants as well as the different plant groups, each coal plant assemblage was determined. The dominance of bisaccates such as Scheuringipollenites, Faunipollenites (=Protohaploxypinus), Striatopodocarpites and presence of monosaccates such as Densipollenites, Parasaccites reflect a peat forming community composed mainly of gymnosperms. Subordinate trilete spores derived from filicopsids (Cyclogranisporites, Horriditriletes, Brevitirletes, Callumispora, Microbaculsispora, Microfoveolatispora, Cyclobaculisporites), lycopsids (Indotriradites, Gondispoirtes and Didecitriletes) and sphenopsids (Laevigatosporites) are less abundant occurring in variable proportions reflecting a hypautocthonous taphocenose. Presence of Botryococccus algae has been recorded. Palynofacies and petrographic analyses suggest deposition in open mires in a Limnic to limno-telmatic conditions with intermittent flooding of the site.

Latest Permian palynomorphs from Jharia Coalfield, Damodar Basin, India and their potential for biostratigraphic correlation

The objective of the present work is to palynologically date the samples collected from Jharia Coalfield. The samples have been collected from an outcrop section exposed across the Damodar river near NH 32 enroute from Bokaro to Dhanbad (23° 43′06.93″N and 86° 12′06.90″E) near Jharia Coalfield of Damodar Basin. Palynological analysis of the samples has revealed that the palynomorph assemblage is characterized by high incidence of Densipollenites spp. in association with dominance of striate bisaccates chiefly Striatopodocarpites spp. and Faunipollenites spp. The other stratigraphically significant taxa recorded in the section are Guttulapollenites hannonicus, Klausipollenites schaubergeri, Alisporites spp. Falcisporites spp. and Lunatisporites spp. On the basis of the palynocomposition the section has been assigned a latest Permian age. Age determination for the section has been inferred by comparison with coeval assemblages from previous Gondwana studies from India and across Gondwana which were compared to the biostratigraphically dated palynological records from Australia (oldest APP6 Zone) as it is one of the few areas in Gondwana where the palynological records have been calibrated against adequately dated marine invertebrate zones. However, comparison with the westernmost portion of Gondwana was difficult due to its mid latitudinal position (c. 20°S) during the Lopingian (late Permian) which lead to an early transition from coal-bearing strata to red-bed and evaporitic deposits in some parts.

Organic richness and gas generation potential of Permian Barren Measures from Raniganj field, West Bengal, India

The organic geochemistry of shales in terms of its organic richness, hydrocarbon source potential, thermal maturity, depositional environment, etc., are essential stipulations for shale gas resources assessment. In this study, a total of 32 core samples of Permian Barren Measures from four boreholes in Raniganj field of Damodar Basin were analysed to evaluate their gas generation potential using Rock–Eval pyrolysis techniques. Petrographic analysis brings out the lithofacies of Barren Measures as carbonaceous silty shale, iron rich claystone and sand-shale intercalation. The total organic content (TOC) of the shale units of Barren Measures ranges from 3.75 to 20.9 wt%, whereas hydrogen index (HI) ranges from 58.45 to 125.34 mg HC/g TOC. Present study suggests early to late maturated (0.6–1%) organic matters in Barren Measures with gas prone type III kerogen. The study analysed the effect of burial history on the preservation and maturation of organic matters. The organic richness, kerogen type, thermal maturity and petrographic properties of Barren Measures signify fair to excellent gas generation potential.

Microstructure and pore system analysis of Barren Measures shale of Raniganj field, India

The parameters of shales in terms of its organic richness, thermal maturity, porosity, permeability, pore & fracture network, orientation of microfractures etc. are the crucial requisites for shale gas exploration and exploitation. In this study, Permian Barren Measures of Raniganj field in Damodar Basin were analysed using thin section petrography, scanning electron microscopy, helium porosimetry, micro computer tomography and x-ray Diffractometer, to assess their petrographic and reservoir characteristics. The Total Organic Content (TOC) of the shale units of Barren Measures ranges from 3.75 to 20.9 wt% with more than 50% quartz content. Carbonaceous silty shales have been analysed using Micro Computed Tomography (μ CT) system to evaluate pore system, fracture network, fabric anisotropy and mineral component of the shale and verified that allocations of pores and mineral grains in Barren Measure shales are highly anisotropic. A porosity range of 3%–5% are achieved by μ CT, where pores are mostly nanopores, micropores, mesopores and macropores. Presence of scattered and pore filling organic matters are analysed in both thin section and SEM images, the morphology and sizes of pores behave a wide range from <10 nm to >100 μm.

Advent and decline of the genus Glossopteris Brongniart in the Talcher Coalfield, Mahanadi Basin, Odisha, India

The paper deals with the distribution of the genus Glossopteris and its fructifications in different Lower Gondwana formations of Talcher Coalfield of Odisha State. We demonstrate how this taxon appeared in this basin in the earliest Permian Talchir Formation and evolved and diversified through the Karharbari, Barakar, Barren Measures and lower part of Kamthi formations and ultimately vanished in the early Triassic in the upper part of Kamthi Formation. Amongst fifty-one species of the genus Glossopteris recorded in all, one species each has been found in the Talchir and upper part of Kamthi formations and two, sixteen and forty-seven species respectively are represented in Karharbari, Barakar and the lower part of Kamthi formations. Barren Measures Formation is devoid of any megaplant fossil. Similarly, out of twenty-seven taxa of fertile organs belonging to the Glossopteris, two each are found in the Talchir and Barakar formations respectively, whereas twenty-four are recorded from the lower part of Kamthi Formation. It is observed that Glossopteris is less diversified in Early Permian Karharbari Formation. However, it diversified and proliferated during Barakar and Late Permian lower part of Kamthi formations. Further, it shows declination in the Early Triassic upper part of Kamthi Formation. The study shows that the lower part of Kamthi Formation of Talcher Coalfield has the maximum diversity of Glossopteris (forty-seven species) among all the known localities of this formation exposed in Indian Gondwana.&#x0D; The existence of meagre Glossopteris species against many Gangamopteris species in the needle shale confirms its association with the lower floral zone of Talchir Formation instead of the upper floral zone established by previous workers in this basin. Very low diversity of Glossopteris in the upper part of Kamthi Formation of Talcher Basin demonstrates that this palaeogeographic area would have experienced more arid conditions in early–middle Triassic period as compared to the mellowing climatic conditions prevailing during the same time period in the Panchet Formation (=Upper Kamthi Formation) of other areas of Son–Mahanadi Basin and the Damodar Basin.

Analysing the effect of land-use/cover changes at sub-catchment levels on downstream flood peaks: A semi-distributed modelling approach with sparse data

This paper aims to evaluate how varying degrees of land-use/cover (LULC) changes across sub-catchments affect a flood peak at the catchment outlet. The study site was the Konar catchment, a part of the upper Damodar Basin in eastern India. A HEC-HMS model was set up to simulate rainfall–runoff processes for two LULC scenarios three decades apart. Because of sparse data availability at the study site, we used the Natural Resource Conservation Service (NRCS) curve number (CN) approach to account for the effect of LULC and soil on the hydrologic response of the catchment. Although a weak (r=0.53) but statistically significant positive linear correlation was found between sub-catchment wise LULC changes and the magnitude of the flood peak at the catchment outlet, a number of sub-catchments showed marked deviations from this relationship. The varying timing of flow convergence at different stream orders due to localised LULC changes makes it difficult to upscale the conventional land-use and runoff relationship, evident at the plot scale, to a large basin. However, a simple modelling framework is provided based on easily accessible input data and a freely available and widely used hydrological model (HEC-HMS) to check the possible effect of LULC changes at a particular sub-catchment on the hydrograph at the basin outlet.

Further contribution to the mega- and microfossil assemblages from the Johilla-Ganjra Nala confluence, South Rewa Gondwana Basin, Madhya Pradesh, India

The present paper deals with mega- and microfossils recovered from the Early Permian sediments of the Johilla-Ganjra Nala confluence of Johilla Coalfield, Madhya Pradesh. Megafossils include Gangamopteris major, G. cyclopteroides, Glossopteris indica, G. gigas, G. conspicua, G. mohudaensis, Noeggerathiopsis hislopii, Samaropsis goraiensis, Cordaicarpus zeilleri, Alatocarpus indicus, few platyspermic seeds and Equisetalean axes. The palynological studies reveal that coal-bearing beds contain dominance of monosaccate pollen (Parasaccites, Plicatipollenites and Pachysaccus) in association with Callumispora gretensis, Crucisaccites monoletus, Barakarites indicus, Faunipollenites varius, Lunatisporites diffusus and Crescentipollenites fuscus indicating an Early Permian age to the coal beds exposed near the confluence of Johilla River and Ganjra Nala. The mega- and microflora recorded from these beds indicate a transitional zone of the Upper Karharbari and Lower Barakar formations. The study further suggests that the climatic conditions of Son Valley were cooler than the Damodar Basin.

Late Permian Palynology and depositional environment of Chintalapudi sub basin, Pranhita–Godavari basin, Andhra Pradesh, India

The present study deals with the palynological dating, correlation and depositional setting of the sediments from bore cores MGP-11 and MGP-4 from Gauridevipet area of Chintalapudi sub-basin of Godavari master basin, south India. On the basis of palynological studies, three palynoassemblages have been identified, one in bore core MGP-11 a Faunipollenites (=Protohaploxypinus) and Striasulcites assemblage and two in bore core MGP-4; one is characterized by the dominance of striate bisaccates and Densipollenites and the other by Striatopodocarpites and Cresentipollenites palynoassemblages. The other stratigraphically significant taxa include Guttulapollenites hannonicus, Lunatisporites noviaulensis, Lunatisporites pellucidus, Densoisporites contactus, Chordasporites australiensis, Goubinispora spp., Lundbladispora microconata, Lundbladispora raniganjensis and Klausipollenites schaubergeri. The recovered taxa suggest a Late Permian, Lopingian age for these rocks. This interpretation is based on the correlation of the assemblages with similar assemblages from previous Gondwana studies chiefly Densipollenites magnicorpus Zone of Damodar Basin, India and Late Permian palynoassemblages from Africa, Antarctica, Australia and South America. On the basis of palaeobotanical affinity of the identified microflora it has been inferred that the peat forming plant community was composed mainly of gymnosperm pollen attributable to glossopterids, that includes striate and non-striate bisaccates and paucity of cordaites which includes monosaccates. Spores are subordinate and are derived from lycopsids (Lundbladispora, Densoisporites), sphenopsids (Latosporites) and filicopsids (Horriditriletes, Lophotriletes, Verrucosisporites, Osmundacidites, Leiotriletes, Callumispora, Brevitriletes and Microbaculispora) occurring in variable proportions. The dominance of subarborescent/arborescent vegetation suggests a development in a forest swamp probably in a small distant marginal part of the mire or periods of standing water. This flooding environment favoured the growth of herbaceous lycopsids, filicopsids and sphenopsids in the palaeomire. More or less similar environments of deposition have been deduced for both the sedimentary sequences on the basis of palynofacies analysis. Anaerobic, reducing, water logged peat-forming conditions have been inferred based on the abundance of phytoclasts. The relative abundance of structured organic matter implies the existence of a fairly dense vegetation cover in the hinterland. The charcoal fragments recovered from the present study area reflects a possible wildfire in the accumulated swamps or a wildfire in the hinterland after which the sediments were flushed by fluvial systems into the swamps.

Palaeoenvironmental significance of fluvial facies and archives of Late Quaternary deposits in the floodplain of Damodar River, India

Statigraphic exposures, fluvial archives and borehole data have been allowed to reconstruct the alluvial history of Late Pleistocene to Early Holocene and climate changes in the monsoonal wet–dry region of lower Damodar Basin (West Bengal, India). The facies architectures and climate proxies suggest that five to six climate changes occurred in between ∼14 and 6 kiloannum (ka). Supporting evidence from the floodplain of Damodar River demonstrates that the successive phases of aggradation and incision were linked to the south-west monsoonal variability of Late Quaternary period. The onset of semi-arid climate was associated with caliches, pond and backswamp deposits of waning low-energy floods. The relatively warm-humid climate was associated with sandy bedforms, valley fills, slack water deposits and ferruginous nodules. This paper presents a synthesis of the available palaeoclimatic records from the lower Ganga Basin and the rivers of western and central India for the palaeoenvironmental significance of Late Quaternary deposits and discusses the influence of palaeoclimatic controls on the fluvial architectures and archives that developed below the floodplain of Damodar River. We have taken some representative studies from the region to reveal the spatial variability in fluvial successions in response to climate changes during this period.