CONSIDERING CLIMATIC CONDITION IN BANGLADESH TO PERFORM A PROJECT
The climatic condition is major considering issue to implement an outdoor project- like underground or submarine power transmission cable line in specified time period keeping project cost within a budget frame. Regional weather conditions affect the technology and engineering design, performance of the plant and of course implementing cost and project management.
The intent of this article to consider the climatic condition in Bangladesh particularly implement the high voltage and medium voltage underground and submarine power transmission cable line project in capital city Dhaka and costal city Chittagong.
The presenting the weather condition will help to understand the level of weather impact on time scheduling, risk managing, costing and budgeting the project; professional can use this data to eliminate or reduce the impact of weather.
Climatic Data for Bangladesh
Bangladesh experiences tropical hot, wet and dry climate. Whole the year, distinguished six seasons, but factors will affect for project implements are southwest monsoon with heavy rainfall, tropical storm with heavy thunder and wind, common tornados; also considerable hot & dry, and cold weather for project management.
The area is close to sea level and is in a tropical climate. The ambient temperature variation is between 5oC and 400C with periods of high humidity.
The area is designated a zone of moderate intensity for earthquakes and costal cyclone. The seismic factor is 0.15g.
Atmospheric pollution is mid-level and special insulator design or washing is not required. The area is subject to high winds of typhoon strength. The average climatic conditions in Bangladesh is as below:
Maximum ambient shade temperature : 40o C
Minimum ambient shade temperature : 50 oC
Maximum daily average temperature : 35 oC
Maximum annual average temperature : 25 oC
Maximum wind velocity (3 second gust) : 160 Km/h
Minimum wind velocity for line rating purposes : 1.6/3.2 Km/h (33/132kV)
Solar radiation : 100mW/sq. cm
Rainfall : 2.5 m/annum
Relative humidity, maximum : 100%
Average : 80%
Altitude : less than 150m
(No ice or snow expected)
Atmospheric Pollution : mid-level
Soil type : alluvial
Soil temperature (at 1.1m) : 30 oC
Soil thermal resistivity : 1.50C m/w
Isokeraunic Level (Thunderstorm days) : 80
Southwest Monsoon with Heavy Rain
Southwest Monsoon is main unfaberable season for outdoor works in Bangladesh due to continuous heavy to very heavy rainfall, flash flood and natural calamity etc. This occurs from June to until September.
Most of the rural are goes under water and in urban area authority does not allow to construction work in public space like road cutting for cable trench, sewerage or water line.
Tropical Storms and Heavy Thunder
Tropical summer storms come with heavy strong wind, sometime turns into tornado without any notice. This storms not continue for long time, just for a portion of a day. From April to June this happen each year in Bangladesh.
Outdoor construction works may hamper and some accident may occur by falling or propelling materials due to heavy wind.
To perform an operation in tower or over the land level for hoisting and lifting in the stormy season, necessary arrangement must take to tackle the risk.
Common Tornados in Bangladesh
Tornados are very much common natural disaster in Bangladesh. Long coastal area including Chittagong are affected each year several times by tornadoes and cyclones.
During cyclones most of the coastal area affected by high tides and flash floods, damage to housing and infrastructure from stronger winds and storm surge.
Roads and communication system may shutdown temporarily for some remote area. Due to flood water in low-land, project may need re-scheduling to complete the work.
Hot and Dry Weather
Sometime the summer come with very hot and dry weather that causes very difficult outdoor work for worker and need midday break what major pose for construction work. Hot and dry weather causes of formation hues dust and dirt, equipment and machinery may malfunction or damage.
Sophisticated cable jointing works may become difficult to keep the jointing vicinity dust free, humidity and ambient temperature controlled. Some metallic and electronic measuring equipment and tools may give error in their calibration due to outdoor hot temperature.
In high temperature causes reduce the elasticity of some materials and hardware may show errors in measurement due to expansion for increased temperature.
Due to dry temperature lack of moisture may cause unexpected effect for building or jointing materials.
There is no history to ice or snow in Bangladesh, temperature never goes below 5o C, temperature range in winter from December to February 10oC to 181oC which is very comfortable to outdoor works.
Sometime weather goes foggy in morning that causes bad-traffic in roads and delay to reach workstation.
Engineering and Technology Selection Considering Climatic Parameters
Considering the factors of climate, local weather and variation of its seasonal characteristics, the equipment and tools group selection need picture-perfect. Engineering and technology selection to perform the project implementation, climatic information will leads to seamless economic decision. Bearing the weather conditions and making necessary arrangements always possible to reduce time consuming, loss & injury.
Weather is always around us, we cannot keep it away, but we can manage our project scientifically and technologically that become weather-friendly.