Journal of Geography, Environment and Earth Science International

The ability of a water body to self-purify itself is dependent on its re-aeration rate (K_a). This rate is necessary to calculate the dissolved oxygen content in the waterbody. This rate also depends on some variables that include the stream velocity, stream bed slope, cross section area, water depth, frictional velocity, discharge rate, Froude’s number and a number of other things. For the purpose of this study, thirteen empirical equations are considered when evaluating the performance of the re-aeration rates. This is done with respect to the size of the Tungabhadra river. Observation of the re-aeration rate for this study was done using mass balance approach. The data needed for this was gotten from field investigation data obtained from 288 separate samples (6 different sites) between the period March, 2017 to December, 2018. The performance evaluation of the re-aeration equation was done via the implementation of least square techniques. The following statistical error methods were applied in due course; standard error, normal mean method and mean multiplicative method. The results of the methods are 0.16, -0.0006 and 2.75. The coefficient of correlation for this was 0.91 and by interpretation, it shows an efficient outcome.

Coastal zone across the world is typified with intensive multiple human activities. Historic maps and multi-temporal satellite images are helpful in detecting the change in land use over the years. An attempt is made to evaluate the land use/land cover change along the coastal zone of Thiruvananthapuram using Geographic Information System (GIS) and Remote Sensing techniques. Landuse scenarios for 1988, 2000 and 2010 have been generated using Survey of India Topographical Sheets, Landsat ETM+ Image and Quickbird Image respectively. ERDAS software is used for image processing and land-use change is analysed using ArcGis 10.2.1 Software. The reasons and implications of landuse change in the coast are also studied through field investigation and valid conclusions are drawn. Agricultural land, clustered settlement area, a settlement with vegetation, sandy area and rocky area is the broad landuse categories delineated in the coastal zone. The analysis shows that the agricultural land area has decreased from 9.34% to 3.89% while the area under clustered settlement increased from 5.75 % to 25.65% during 1988-2010. This study can provide base information on land use scenario of the coast while framing out the ICZM plan.

Proportion of area under different crops and change therein remains a concern before policymakers, researcher, public policy analysts and, academia like geographers. As cropping pattern determines food security, internal consumption demand and export of crops, sustainable cropping arrangement is essential to follow. The paper examined the pattern and extent of cropping across land size categories at block level in Malda district of West Bengal. The change in cropping pattern from 1995-96 to 2015-16 has been assessed through secondary sources of data. The data for 2015-16 is extrapolated based on previous years (2005-06 and 2015-16) interpolated data. Data were processed in Excel spread sheets and results are shown through maps and tables. The maps were prepared in QGIS 2.18. The findings of the study show that gross cropped area under cereals, pulses and vegetables indicated negative growth while fibres, oilseeds and fruits area increased across land size classes but gain is maximum under marginal land size class. Total area under food crops decreased substantially over non-food crops. The study suggests policy intervention measure to boost up economically profitable crops for the sake of the development of Malda district.

The present study area, occupying a major south-central part of the Jadukata river basin of the West Khasi Hills District of Meghalaya, predominantly comprises two contrasting litho-units viz., the Precambrian gneissic unit (PGU) towards the north of the study area and the Mahadek Formation constituted of sedimentary rocks (MFS) in the south. Derived areal and relief morphometric parameters have been analysed on five sub-basins two of which are in the PGU (Umlang and Umkyrtha) and the other three (Umsophew, Wah-Phodthra, and Khandow) predominantly in the MFS. The drainage density (Dd) and stream frequency (Fs) values are relatively lower for the sub-basins of PGU suggesting higher overland flow. This is substantiated by higher values of the constant of channel maintenance (C) and length of overland flow (Lg). The relief ratio (Rr) and ruggedness number (Rn) are higher for the sub-basins of MFS implying more dissection. High hypsometric integral (HI) and pseudo-hypsometric integral (PHI) suggest youthful stage and neotectonic rejuvenation with a tilt towards the west as indicated by asymmetry factor (AF) and topographic profile. Association of distinct knickpoints of longitudinal profiles with prominent lineaments indicates active fault. Preferred orientation of lower order streams in the PGU sub-basins suggests neotectonism. Deep incision by Umsophew, Wah-Phodthra, and Khandow rivers, forming V-shaped valleys through the MFS is the result of neotectonic uplift which has been further substantiated by very low valley floor-to-height ratio (Vf) at nearby locations of the confluence of these rivers with the Kynshi.

Selected composited samples from Lewumeji (0-111m) and Idogun (0- 54m) wells,  from Abeokuta Group, Eastern Dahomey Basin, Nigeria, were subjected to detailed lithologic and palynological studies. The studies aimed at determining the lithological sequence, relative age, palynological zone and paleoenvironments of deposition. The core samples were subjected to lithological description and palynological analysis using standard procedure in order to determine palynomorphs contents such as pollen, spore and dinoflagellates. The lithologies from both wells consist of reddish to brown clay, reddish to brown colour, rounded to sub rounded sandstone, dark grey shale denoting  possibly fluvial, brackish, lagoonal and marine environments. A total of 31 well preserved low to moderate diverse palynomorphs were recovered from the studied area. The palynomorphs frequency percentage distribution shows that both wells have a higher ratio of land-derived pollen and spores to the marine dinoflagellates; (75%, 25% and 61%, 39%) for Lewumeji and Idogun wells respectively. The microfloral assemblages include abundant Cyathidites sp., Cyathidites minor, Tubistephanocolpites cylindricus, Proteacidites sp., Trilete spore, Foveotriletes margaritae, Monocolpites marginatus, Monoporites annulatus, Pteris sp, Distaverrusporites simplex and Laevigatosporites sp. The dinoflagellates recovered were characterized by the likes of Leiosphaeridia sp., Senegalinium sp., Oligosphaeridinium sp., Paleocytodinium sp., Cerodinium sp. and Subtilisphaera sp.  The wells fall within Cyathidites Minor zone, characterized by the diagnostic occurrence of Cyathidites minor, Cyathidites sp. and Monocolpites marginatus dated Upper Maastrichtian to early Paleocene. Paleoenvironmental interpretations based on the abundance of freshwater swamps pollen and Spores, diagnostic dinoflagellates cyst and the Palynomorphs Marine Index (PMI) are suggestive of environmental settings that vary from continental to brackish water and shallow marine.