Abstract:
This research work was undertaken to do the preliminary survey for the study of shore erosion and siltation along the coast of Karachi.
A stretch of about twenty miles, starting from Manora and in the West upto about 25 miles ahead of paradise point was selected for the study. Six different location in this area were selected for taking observation and they were named Station No.1 to Station No.6.
From these stations weekly data from sea surface temperature, air temperature, direction of wind, directions of waves and time period of wave was recorded. Beside this, photographs of coast line on both sides (East and West) were taken after every two weeks to study the changes in coast line. Also samples of sand and water were collected after every week.
In the laboratory the samples of sand are being dried and sorted out with the help of sieving machine. Water samples were analyzed for determining salinity and suspended mass in the sea water.
From this study it is concluded that the coastal zone which we studied under the influence of SW monsoon varies due to erosion and siltation and the quantity of medium sand increases from station No.4 to station No.6 indicating progressive siltation to the east. This could be considered as movement of sea bed material along the coast in the easterly direction due to wave activity.
The average surface salinity of sea water of the coast at Hawk’s Bay (neglecting the probable mining of fresh water due to outfall of Layri and Hub rivers and torrential rain) is 35.80% which is in conformity with overall average value of salinity in Northern Arabian Sea.
