Sep 17, 2011

Demand Forecasting for Dhaka City

Dhaka is a huge city. It has a large number of population. Water is the basic need. At present 75% city area is under Dhaka Water Supply & Sewerage Authority (DWASA) water supply coverage, out of which 82% is from groundwater sources tapping through 411 Deep Tubewells (DTW); the remaining 18% of the water is supplied from the two major water treatment plants situated at Saidabad, Chadnighat and two smaller units in Narayanganj. The population of Dhaka city, Narayanganj and Tongi is presently more than 10 million and the growth trend indicates that by the year 2010 it would be about 13.4 million. The increase of population would create further water supply demand of additional 120% of present production, which has to be met either from the surface water sources or by sinking additional DTW. 

Sep 16, 2011

Dhaka City Drainage: Cause & Scenario

In the last 3 decades, Dhaka has grown radically at a great pace. It had been a provincial capital in the pre-independence era transforming into the capital of independent Bangladesh in 1971. Presently Dhaka has become the nerve center of the entire country. All activities related to economy, culture, politics, administration, education, health and society as a whole are centered based on Dhaka. The city has witnessed major growth in population over the last 3 decades; this is mainly due to migration from the countryside and townships. Since 1971, the population of the city has grown from about 1 million to more than 12 million in 2004. In another 20 years, Dhaka will be among the 10 most densely populated mega cities of the world with about 20 million people. The city area has also expanded. The total area of Dhaka, its satellite town Narayanganj and suburban areas (including Keraniganj, Tongi and Savar) is around 792 sq. km. Between 1990 and 2000, the built-up area has increased by around 46% (JICA Baseline Study, 2000). The city expansion occurred both horizontally and vertically. 

Sep 1, 2011

What is a Rubber Dam?

A rubber dam is a rubber membrane filled with water or air, attached to the concrete sill. In the upright – full position it serves as a barrier which impounds water. It functions as a barrier in the river where we want to use running water as a drive for a hydroelectric power plant or we want to use the river for field irrigation. Rubber dams are cylindrical rubber fabrics placed across channels, streams and weir or dam crests to raise the upstream water level when inflated. The membrane is a multi-layer fabric made of synthetic fiber (usually nylon)and rubberized on one or both sides. The fabric is quite flexible and yet exhibits good wear-resistance characteristics. A layer of stainless steel mesh or ceramic chips can be embedded in the surface layer to reduce or prevent vandal damage.