scholarly journals Origin and evolutionary processes of deep groundwater salinity in southwestern coastal region of the Ganges-Brahmaputra-Meghna Delta, Bangladesh

2021 ◽  
Vol 36 ◽  
pp. 100854
Author(s):  
Masudur Rahman ◽  
Tomochika Tokunaga ◽  
Tsutomu Yamanaka
Keyword(s):  
Coastal Region ◽  
Groundwater Salinity ◽  
Evolutionary Processes ◽  
Deep Groundwater ◽  
The Ganges

scholarly journals Groundwater salinity variation in Upazila Assasuni (southwestern Bangladesh), as steered by surface clay layer thickness, relative elevation and present-day land use

2019 ◽  
Vol 23 (3) ◽  
pp. 1431-1451 ◽  
Author(s):  
Floris Loys Naus ◽  
Paul Schot ◽  
Koos Groen ◽  
Kazi Matin Ahmed ◽  
Jasper Griffioen
Keyword(s):  
Land Use ◽  
Drinking Water ◽  
Coastal Region ◽  
Shallow Depth ◽  
Hydrological Processes ◽  
Groundwater Salinity ◽  
Clay Layer ◽  
Fresh Groundwater ◽  
Salinity Variation ◽  
Clay Layers

Abstract. In the southwestern coastal region of Bangladesh, options for drinking water are limited by groundwater salinity. To protect and improve the drinking water supply, the large variation in groundwater salinity needs to be better understood. This study identifies the palaeo and present-day hydrological processes and their geographical or geological controls that determine variation in groundwater salinity in Upazila Assasuni in southwestern Bangladesh. Our approach involved three steps: a geological reconstruction, based on the literature; fieldwork to collect high-density hydrological and lithological data; and data processing to link the collected data to the geological reconstruction in order to infer the evolution of the groundwater salinity in the study area. Groundwater freshening and salinization patterns were deduced using PHREEQC cation exchange simulations and isotope data were used to derive relevant hydrological processes and water sources. We found that the factor steering the relative importance of palaeo and present-day hydrogeological conditions was the thickness of the Holocene surface clay layer. The groundwater in aquifers under thick surface clay layers is controlled by the palaeohydrological conditions prevailing when the aquifers were buried. The groundwater in aquifers under thin surface clay layers is affected by present-day processes, which vary depending on present-day surface elevation. Slightly higher-lying areas are recharged by rain and rainfed ponds and therefore have fresh groundwater at shallow depth. In contrast, the lower-lying areas with a thin surface clay layer have brackish–saline groundwater at shallow depth because of flooding by marine-influenced water, subsequent infiltration and salinization. Recently, aquaculture ponds in areas with a thin surface clay layer have increased the salinity in the underlying shallow aquifers. We hypothesize that to understand and predict shallow groundwater salinity variation in southwestern Bangladesh, the relative elevation and land use can be used as a first estimate in areas with a thin surface clay layer, while knowledge of palaeohydrogeological conditions is needed in areas with a thick surface clay layer.

scholarly journals Groundwater salinity variation in Upazila Assasuni (southwestern Bangladesh), as steered by surface clay layer thickness, relative elevation and present-day land use

2018 ◽  
Author(s):  
Floris Loys Naus ◽  
Paul Schot ◽  
Koos Groen ◽  
Kazi Matin Ahmed ◽  
Jasper Griffioen
Keyword(s):  
Land Use ◽  
Drinking Water ◽  
Coastal Region ◽  
Shallow Depth ◽  
Hydrological Processes ◽  
Groundwater Salinity ◽  
Clay Layer ◽  
Fresh Groundwater ◽  
Salinity Variation ◽  
Clay Layers

Abstract. In the southwestern coastal region of Bangladesh, options for drinking water are limited by groundwater salinity. To protect and improve the drinking water supply, the large variation in groundwater salinity needs to be better understood. This study identifies the palaeo and present-day hydrological processes and their geographical or geological controls that determine variation in groundwater salinity in Upazila Assasuni in southwestern Bangladesh. Our approach involved three steps: a geological reconstruction, based on the literature; fieldwork to collect high density hydrological and lithological data; and data processing to link the collected data to the geological reconstruction in order to infer the evolution of the groundwater salinity in the study area. Groundwater freshening and salinization patterns were deduced using PHREEQC cation exchange simulations and isotope data was used to derive relevant hydrological processes and water sources. We found that the factor steering the relative importance of palaeo and present-day hydrogeological conditions was the thickness of the Holocene surface clay layer. The groundwater in aquifers under thick surface clay layers is controlled by the palaeohydrological conditions prevailing when the aquifers were buried. The groundwater in aquifers under thin surface clay layers is affected by present-day processes, which vary depending on present-day surface elevation. Slightly higher-lying areas are recharged by rain and rainfed ponds and therefore have fresh groundwater at shallow depth. In contrast, the lower-lying areas with a thin surface clay layer have brackish–saline groundwater at shallow depth because of flooding by marine-influenced water, subsequent infiltration and salinization. Recently, aquaculture ponds in areas with a thin surface clay layer have increased the salinity in the underlying shallow aquifers. We hypothesize that to understand and predict shallow groundwater salinity variation in southwestern Bangladesh, the relative elevation and land use can be used as a first estimate in areas with a thin surface clay layer, while knowledge of palaeohydrogeological conditions is needed in areas with a thick surface clay layer.

Comparison of stable isotopes, ratios of 36Cl/Cl and 129I/127I in brine and deep groundwater from the Pacific coastal region and the eastern margin of the Japan Sea

2012 ◽  
Vol 27 (12) ◽  
pp. 2389-2402 ◽  
Author(s):  
Yasunori Mahara ◽  
Tomoko Ohta ◽  
Tomochika Tokunaga ◽  
Hiroyuki Matsuzaki ◽  
Eiji Nakata ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Coastal Region ◽  
Japan Sea ◽  
Deep Groundwater ◽  
Eastern Margin ◽  
The Pacific ◽  
The Japan Sea

scholarly journals A physical study of the effect of groundwater salinity on the compressibility of the Semarang-Demak aquitard, Java Island

2018 ◽  
Author(s):  
Dwi Sarah ◽  
Lambok M. Hutasoit ◽  
Robert Delinom ◽  
A. Sadisun
Keyword(s):  
Coastal Region ◽  
Clay Mineralogy ◽  
Physical Analysis ◽  
Groundwater Salinity ◽  
Saline Groundwater ◽  
Fabric Analysis ◽  
Physical Study ◽  
Consolidation Rate ◽  
Compression Characteristics

This article is currently under review oin Journal of Geosciences, MDPI. Authors: Dwi Sarah, Lambok Hutasoit, Robert Delinom, Imam A. Sadisun, Taufiq Wirabuana -- Semarang-Demak and other cities along the coast of North Java are vulnerable to land subsidence. The presence of saline groundwater in the coastal region is thought to affect the high subsidence rate, in this case the compressibility of the aquitard layer. We aimed to analyze the effects of groundwater salinity on the compression characteristics of the Semarang-Demak clay using physical analysis. Methods included the determination of groundwater salinity, clay mineralogy and fabrics, and consolidation tests under various salinity conditions. The Semarang-Demak clay is dominated by smectite of high activity and saline clay exists at the depth of 10 to 35 m. Consolidation tests reveals that the increase of salinity increases the average consolidation rate and hydraulic conductivity up to 42% and 37.5%, respectively. Clay fabric analysis showed that the groundwater salinity modified the interconnectivity of pores by changing the fabric into parallel alignments, facilitating faster porewater dissipation, hence the clay is more readily compressed. These findings are useful for explaining the mechanism of the fast-subsiding coastal plains of North Java.

Mālvan—Further Light on the Southern Extension of the Indus Civilization

1970 ◽  
Vol 102 (1) ◽  
pp. 20-28 ◽  
Author(s):  
F. R. Allchin ◽  
J. P. Joshi
Keyword(s):  
Coastal Region ◽  
Single Site ◽  
Archaeological Survey ◽  
The South ◽  
Indus Civilization ◽  
The Past ◽  
The North ◽  
Principal Directions ◽  
Three Stages ◽  
The Ganges

In 1947 partition left India without a single site attributable to the Indus civilization. During the past two decades there has been a considerable extension of our knowledge, due mainly to the explorations and excavations of the Archaeological Survey of India. It now appears as though the Harappan culture spread into India in two principal directions: north-eastwards into the eastern Panjāb and across the Indo-Gangetic divide into the plains that lie between the Ganges and Jamunā rivers; and south-eastwards into Kacch and Kāṭhiāwār, and thence perhaps inland towards southern Rājāsthān and into the coastal region of Gujarāt. In the north the principal sites are at Rūpar in the Panjāb, Alamgīrpur in U.P., and Kālibangan in north Rājāsthān. In the south the principal excavated site is at Lothal on the Gulf of Cambay. In particular the extensive excavations at Kālibangan and Lothal have provided a mass of solid data relating to the Harappan settlements and series of well stratified radio-carbon dates. In 1957 S. R. Rao explored southern Gujarāt and in the light of his discoveries at a number of sites there he proposed a sequence of three stages of “Harappan” and “late Harappan” cultures. These he showed might be related to the sequence revealed by his excavations at Lothal and Rangpur in Saurāṣṭra. Rao's exploration suggested a number of interesting questions.

Sources of deep groundwater salinity in the southwestern zone of Bangladesh

2010 ◽  
Vol 63 (2) ◽  
pp. 363-373 ◽  
Author(s):  
Mirza A. T. M. Tanvir Rahman ◽  
Ratan Kumar Majumder ◽  
Syed Hafizur Rahman ◽  
Md. Abdul Halim
Keyword(s):  
Groundwater Salinity ◽  
Deep Groundwater

Opportunities and risks with early sowing of sunflower in a salt-affected coastal region of the Ganges Delta

2021 ◽  
Vol 41 (3) ◽  
Author(s):  
Priya Lal Chandra Paul ◽  
Richard W. Bell ◽  
Edward G. Barrett-Lennard ◽  
Enamul Kabir ◽  
Donald S. Gaydon
Keyword(s):  
Coastal Region ◽  
Ganges Delta ◽  
The Ganges

scholarly journals Salinity variation of south-western coastal region of Bangladesh in response to discharge from an upstream river

2020 ◽  
Vol 8 (2) ◽  
pp. 173
Author(s):  
Md . Shibly Anwar ◽  
Md. Zakir Hasan ◽  
Kalimur Rahman
Keyword(s):  
River Flow ◽  
High Salinity ◽  
Coastal Region ◽  
Dry Season ◽  
Salinity Level ◽  
Western Region ◽  
The South ◽  
Discharge Data ◽  
The Ganges ◽  
High Salinity Level

Long term variation in upstream water flow through the Ganges−Gorai river are affecting the salinity levels of south-western coastal region of Bangladesh. Salinity data for the Rupsha river was collected for several years to demonstrate the historical changes of salinity level in the south-western coastal region. Furthermore, discharge data of the Ganges and Gorai river were also collected to discuss the effect of upstream discharge on the variation of salinity level. This study also collected water and soil samples from different places of this region to measure the salinity level and compare the values with the standard ones. A decreasing trend in dry season Ganges-Gorai river flow was observed after the initiation of the Farakka barrage in 1975. Consequently, the south-western region underwent high salinity level. The Ganges sharing treaty in 1996 and dredging of the Gorai riverbed (GRRP-I and GRRP-II) in 1999 and in 2012 helped the region to recover from high salinity level for a certain period. The salinity level of the collected water samples was in alarming level but soil sample was not in so frightening condition in 2015. Results suggested that to maintain the salinity level of south-western region within the acceptable limit for drinking, fisheries, and cultivation purposes, approximately 80 m3/s Gorai river discharges required at dry season. To do that, it is necessary to ensure 1200 m3/s discharge through the Ganges river at the Hardinge Bridge point. To protect the vital south-western region, it becomes necessary to optimize flow augmentation in the Ganges-Gorai river and to continue the further phases of restoration project in the future.   

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