Sea Level Variations and Geomorphological Changes in the Coastal Belt of Pakistan

Khan, Taseer Ahmed; Razzaq, D. A.; Chaudhry, Qamar-uz-Zaman; Quadir, Dewan Abdul; Kabir, Anwarul; Sarker, Majajul Alam

doi:10.1080/014904102753516804

Cited by 25 publications

(18 citation statements)

References 2 publications

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“…Regarding climatic factors in the area, historical air and sea surface temperatures (SST) data of Karachi also show increasing trends over the past 35 years, of the order of 0.19°C and 0.3°C per decade for air temperature and mean SST, respectively (Khan et al, 2002).…”

Section: Future Threats and Challengesmentioning

confidence: 99%

Vulnerability of the Indus River Delta of the North Arabian Sea, Pakistan

2016

Global NEST Journal

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Seawater intrusion has been a serious problem in the Indus River Estuary (IRE) for decades. The literature reviews, hydrological and meteorological observations were analyzed to examine and discuss the causes and consequences of seawater intrusion in the IRE. Both sea water intrusion and coastal erosion are having a devastating environmental and social impact and the whole ecosystem of the Indus Delta is facing serious threat. The Indus deltaic region is not only threatened by continuing activities upstream but also by the neighboring sea in the south, due to the impacts of local weather conditions. Observational results suggest that seawater intrusion reaches 84 km upstream in the IRE during the dry season. Extensive field investigations and a high resolution coastal ocean model are urgently needed for future study.

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Section: Future Threats and Challengesmentioning

confidence: 99%

Vulnerability of the Indus River Delta of the North Arabian Sea, Pakistan

2016

Global NEST Journal

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“…The Sindh coastal zone is mixed wave dominated, with continuous accretion and erosion due to waves and tides of up to 3 m in height, modifying the coastal environment [16]. Strong westerly winds prevail during the summer monsoon and influence ocean circulation with the dominant direction of surface water flow [42]. The pre-and post-monsoon periods have long been associated with cyclone development in the Arabian Sea, which increase erosion and move the shoreline landward.…”

Section: Study Areamentioning

confidence: 99%

“…These include four major floods and six historical cyclones, which have damaged the socio-economy of low lying areas within the Sindh coastal region [41]. The coastal belt of the Indus Delta Region is continuously changing due to physical processes such as tidal actions, waves, wind speed, sea level rise, and anthropogenic factors, for example land reclamation and modification [12,16,42,43]. Rising sea levels are contributing to the erosion of less resistant soil in the region.…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, the Intergovernmental Panel on Climate Change (IPCC) predicts that the global mean sea-level will rise from 0.43 m to 0.84 m in the current scenario and 0.61 m to 1.10 m in the worst case scenario by 2100 [45]. It has been reported that the sea level has already risen from 1.1 mm/year to 1.8 mm/year regionally over the past decade [42]. If sea levels rise above the predicted rate, shorelines in the region will experience erosion in both the long-and short-term.…”

Section: Introductionmentioning

confidence: 99%

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Coastline Vulnerability Assessment through Landsat and Cubesats in a Coastal Mega City

et al. 2020

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According to the Intergovernmental Panel on Climate Change (IPCC), global mean sea levels may rise from 0.43 m to 0.84 m by the end of the 21st century. This poses a significant threat to coastal cities around the world. The shoreline of Karachi (a coastal mega city located in Southern Pakistan) is vulnerable mainly due to anthropogenic activities near the coast. Therefore, the present study investigates rates and susceptibility to shoreline change using a 76-year multi-temporal dataset (1942 to 2018) through the Digital Shoreline Analysis System (DSAS). Historical shoreline positions were extracted from the topographic sheets (1:250,000) of 1942 and 1966, the medium spatial resolution (30 m) multi-sensor Landsat images of 1976, 1990, 2002, 2011, and a high spatial resolution (3 m) Planet Scope image from 2018, along the 100 km coast of Karachi. The shoreline was divided into two zones, namely eastern (25 km) and western (29 km) zones, to track changes in development, movement, and dynamics of the shoreline position. The analysis revealed that 95% of transects drawn for the eastern zone underwent accretion (i.e., land reclamation) with a mean rate of 14 m/year indicating that the eastern zone faced rapid shoreline progression, with the highest rates due to the development of coastal areas for urban settlement. Similarly, 74% of transects drawn for the western zone experienced erosion (i.e., land loss) with a mean rate of −1.15 m/year indicating the weathering and erosion of rocky and sandy beaches by marine erosion. Among the 25 km length of the eastern zone, 94% (23.5 km) of the shoreline was found to be highly vulnerable, while the western zone showed much more stable conditions due to anthropogenic inactivity. Seasonal hydrodynamic analysis revealed approximately a 3% increase in the average wave height during the summer monsoon season and a 1% increase for the winter monsoon season during the post-land reclamation era. Coastal protection and management along the Sindh coastal zone should be adopted to defend against natural wave erosion and the government must take measures to stop illegal sea encroachments.Remote Sens. 2020, 12, 749 2 of 24 developments in coastal areas [1,2]. Therefore, shoreline indicators are used for a consistent representation of a shoreline. The most common shoreline indicators are the tidal datum (e.g., a specific elevation at the land-ocean boundary) and visually discernible features (e.g., a revetment structure, an erosion scarp, a previous high-tide high-water level, low-tide low-water level, or dune vegetation line, etc.) [3][4][5][6][7][8]. The shoreline is an indicator of the ecological health of coastal areas [3,[9][10][11]. In past decades, the development of mega-infrastructure projects in coastal areas for urbanization/industrialization has placed more stress on the coastal ecosystem and changed ocean hydrodynamics [12][13][14][15][16]. Unplanned coastal development coupled with the natural action of ocean processes has led to the increasing vulnerability of low lying coasta...

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“…Each coastline computed was assigned five attributes, i.e., date, length, ID, shape, and uncertainty. We selected the 1989 coastline as a benchmark, as 1989 is the start of the data series and the year that the United Nations Environment Programme (UNEP) included Pakistan in the group of countries vulnerable to the impact of rising sea level [29]. Among the three existing methods for baseline demarcation (i.e., creating a baseline from a specific distance of a coastline, using a pre-existing baseline, and buffering method), we adopted the buffering method, as it is considered to be the most reliable and accurate [43].…”

Section: Analysis Of Coastline Changementioning

confidence: 99%

Three Decades of Coastal Changes in Sindh, Pakistan (1989–2018): A Geospatial Assessment

et al. 2019

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Coastal erosion endangers millions living near-shore and puts coastal infrastructure at risk, particularly in low-lying deltaic coasts of developing nations. This study focuses on morphological changes along the~320-km-long Sindh coastline of Pakistan over past three decades. In this study, the Landsat images from 1989 to 2018 at an interval of 10 years are used to analyze the state of coastline erosion. For this purpose, well-known statistical approaches such as end point rate (EPR), least median of squares (LMS), and linear regression rate (LRR) are used to calculate the rates of coastline change. We analyze the erosion trend along with the underlying controlling variables of coastal change. Results show that most areas along the coastline have experienced noteworthy erosion during the study period. It is found that Karachi coastline experienced 2.43 ± 0.45 m/yr of erosion and 8.34 ± 0.45 m/yr of accretion, while erosion on the western and eastern sides of Indus River reached 12.5 ± 0.55 and 19.96 ± 0.65 m/yr on average, respectively. Coastal erosion is widespread along the entire coastline. However, the rate of erosion varies across the study area with a general trend of erosion increasing from west to east in the Indus Delta region (IDR), and the highest average erosion rate is 27.46 m/yr. The interdecadal change during 1989-periods depicted an increasing linear trend (R 2 = 0.78) from Karachi to Indus River (IR) East zone. The spatial trend from west to east is positively correlated with mean sea level rise, which has increased from 1.1 to 1.9 mm/year, and negatively correlated with topographic slope, which is found to be decreasing eastward along the coastline. The findings necessitate appropriate actions and have important implications to better manage coastal areas in Pakistan in the wake of global climate change.

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Sea Level Variations and Geomorphological Changes in the Coastal Belt of Pakistan

Cited by 25 publications

References 2 publications

Vulnerability of the Indus River Delta of the North Arabian Sea, Pakistan

Vulnerability of the Indus River Delta of the North Arabian Sea, Pakistan

Coastline Vulnerability Assessment through Landsat and Cubesats in a Coastal Mega City

Three Decades of Coastal Changes in Sindh, Pakistan (1989–2018): A Geospatial Assessment

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