Geography


https://sites.google.com/a/gauhati.ac.in/research/geography/#udb03062019 A changing coastline

https://sites.google.com/a/gauhati.ac.in/research/geography/#udb30112018 Glacial Meltwater Study
How are we changing a coastline?

Ujjal Deka Baruah and his fellow researchers report the long & short time changes of the Puri Coastline due to natural and anthropogenic (human) causes using satellite imagery. This research is published in Environmental Earth Sciences.


Authors
from other institutions

Abstract
The coastal regions of India are densely populated and most biological productive ecosystems which are threatened by erosion, natural disaster, and anthropogenic interferences. These threats have made priority in appraisal of shoreline dynamicity as part of sustainable management of coastal zones. The present study assessed the long- to short-term dynamicity of shoreline positions along the coast of Puri district, Odisha, India, during the past 25 years (1990–2015) using open-source multi-temporal satellite images (Landsat TM, ETM+, and OLI) and statistical-based methods (endpoint rate, linear regression rate and weighted linear regression). The long-term assessment during 1990–2015 shows that shoreline accredited at the rate of 0.3 m a−1 with estimated mean accretion and erosional rate of 1.18 m a−1 and 0.64 m a−1, respectively. A significant trend of coastal erosion is primarily observed on the northern side of Puri district coast. A cyclic pattern of accretion (during 1990–1995 and 2000–2004) and erosion (during 1995–2000 and 2009–2015) was observed during the assessment of short-term shoreline change. It exhibited significant correlation with the landfall of severe cyclones and identified cyclic phases after severe cyclonic storms, i.e., phase of erosion, phase of accretion and phase of stabilisation. Overall, the natural processes specifically the landfall of tropical cyclones and anthropogenic activities such as the construction of coastal structures, encroachment and recent construction in the coastal regulatory zone, and construction of dams in upper catchment areas are the major factors accountable for shoreline changes. The output of the research undertaken is not only crucial for monitoring the dynamism of coastal ecosystem boundaries but to enable long- to short-term coastal zone management planning in response to recently reported high erosion along the Puri coast. Moreover, the usage of open-source satellite imageries and statistical-based method provides an opportunity in developing cost-effective spatial data infrastructure for shoreline monitoring and vulnerability mapping along the coastal region.

https://sites.google.com/a/gauhati.ac.in/research/geography/#top 
 



Hydrogeochemical study on glacial meltwater of Manimahesh Glacier in Himachal Pradesh

Ujjal Deka Baruah and his research collaborators have found some interesting facts about glacier meltwater in the Manimahesh Glacier in the Himachal Pradesh region of India. The research findings of this study is published in Proceedings of the National Academy of Sciences, India in the Physical Sciences Section (Section A).




Authors
Virendra Bahadur Singh1, Pritam Chand1, Milap Chand Sharma1, Ujjal Deka Baruah, Manoj Kumar1, Naveen Kumar1, and AL Ramanathan1
1 from other institutions

Abstract
The hydrogeochemical study on glacial meltwater gives important information about the quality of meltwater and weathering processes controlling dissolved ions chemistry in the glacierized area. Anionic abundance in the Manimahesh Glacier meltwater shows a trend of HCO3- > SO42- > Cl- = NO3-, whereas cationic abundance in the meltwater shows a trend of Ca2+ > Mg2+ > K+ > Na+. On the basis of high equivalent ratios of (Ca + Mg) versus (Na + K) and (Ca + Mg) versus TZ+ (total cations) and low equivalent ratio of (Na + K) versus TZ+, carbonate-type weathering has been identified as a major hydrogeochemical process regulating solute chemistry of the Manimahesh Glacier meltwater followed by silicate weathering. About 80% of bicarbonate in the meltwater of investigation area was mainly generated from carbonate weathering, whereas 20% of bicarbonate was produced from silicate weathering. The result of statistical methods (correlation, principal component and cluster analysis) shows that meltwater quality of the Manimahesh Glacier is mainly governed by carbonate and silicate-type weathering, oxidation of pyrite, dissolution of sulphate minerals and atmospheric input. The average value of suspended sediment concentration (SSC) in the glacier meltwater was calculated to be 46 mg/l and 63 mg/l during the month of June and July 2014, respectively, showing higher concentration of SSC during the month of July (peak-flow period) followed by June (low-flow period).