The study was undertaken for understanding the potential of deep aquifers as a source of safe drinking water and for assessing the status of groundwater aquifer near Madunaghat area, Chattogram. The specific issues ar...The study was undertaken for understanding the potential of deep aquifers as a source of safe drinking water and for assessing the status of groundwater aquifer near Madunaghat area, Chattogram. The specific issues are salinity, interconnectivity of the shallow and deep aquifers, mixing of groundwater with the adjacent Halda river water, recharge condition and groundwater age. The isotopic data suggest that most of the groundwater results from a mixture between recent recharge and an older component recharge under climatic conditions cooler than at present. The interconnectivity between shallow aquifers and river waters are mostly found in the line wells installed particularly in shallow depth (16 m) close to Halda river as evidenced from the similar tritium values of sampled line well water with that of the Halda river water. The groundwater in Madunaghat well field area is not affected by salinity, as it is evidenced by higher values of Na/Cl ratio of the groundwater samples compared to the sea water fresh water mixing line. The geochemistry of intermediate and deep groundwater is dominated by Na-Mg-HCO<sub>3</sub> and Na-HCO<sub>3</sub> type waters. Even the relationship between chloride and oxygen-18 (Cl-<em>δ</em><sup>18</sup>O) depicts that the waters from the deep, intermediate and shallow wells do not fall on the seawater mixing line. The Carbon-14 contents of intermediate to deep groundwater samples vary from 16.2 to 59.3 pMC indicating the residence time in the range of 4300 to 15,000 years BP, <em>i.e.</em>, the sourced water recharged the aquifers a long time ago. The intermediate and deep wells have water with arsenic concentrations less than the detection limit of 3.0 μg/L. Only a few shallow wells have arsenic concentrations greater than the detection limit varying from 13.7 - 47.4 μg/L, which is less than the DoE permissible limit (50 μg/L) implying that the groundwater at Madunaghat area is not affected by Arsenic contamination.展开更多
Dhaka, Bangladesh’s capital, already has a congestion problem to handle the ever-growing demand for traffic. The usage of private cars cannot be stopped by charging and the town is not encouraged by quality public tr...Dhaka, Bangladesh’s capital, already has a congestion problem to handle the ever-growing demand for traffic. The usage of private cars cannot be stopped by charging and the town is not encouraged by quality public transport. It is impossible to enforce congestion prices here in line with traditional cordon pricing systems since the region uses unusual land patterns. However, the </span><span style="font-family:Verdana;">current project Mass Rapid Transit (MRT) Line 6, which will be built by </span><span style="font-family:Verdana;">2021, provides the prospect of congestion pricing. A price and optimum approach were established for this article. The congestion price is only payable for the </span><span style="font-family:Verdana;">segments and is accessible for private cars under this system. Two urban </span><span style="font-family:Verdana;">street segments along the MRT route were selected for the study and congestion toll for a private car is estimated for each segment separately. The sum of the toll in monetary terms is determined using certain associated parameters from the discrepancy from the actual Level of Service (LOS) travel time and traffic flow to the desired LOS. The outcome has shown that the price per </span><span style="font-family:Verdana;">passenger car is $0.3 - $0.44. The price is flexible, which means it will vary</span><span style="font-family:Verdana;"> b</span><span style="font-family:Verdana;">ased on traffic volume. The findings for politicians to enforce congestion</span><span style="font-family:Verdana;"> pricing are viewed as recommendations.展开更多
文摘The study was undertaken for understanding the potential of deep aquifers as a source of safe drinking water and for assessing the status of groundwater aquifer near Madunaghat area, Chattogram. The specific issues are salinity, interconnectivity of the shallow and deep aquifers, mixing of groundwater with the adjacent Halda river water, recharge condition and groundwater age. The isotopic data suggest that most of the groundwater results from a mixture between recent recharge and an older component recharge under climatic conditions cooler than at present. The interconnectivity between shallow aquifers and river waters are mostly found in the line wells installed particularly in shallow depth (16 m) close to Halda river as evidenced from the similar tritium values of sampled line well water with that of the Halda river water. The groundwater in Madunaghat well field area is not affected by salinity, as it is evidenced by higher values of Na/Cl ratio of the groundwater samples compared to the sea water fresh water mixing line. The geochemistry of intermediate and deep groundwater is dominated by Na-Mg-HCO<sub>3</sub> and Na-HCO<sub>3</sub> type waters. Even the relationship between chloride and oxygen-18 (Cl-<em>δ</em><sup>18</sup>O) depicts that the waters from the deep, intermediate and shallow wells do not fall on the seawater mixing line. The Carbon-14 contents of intermediate to deep groundwater samples vary from 16.2 to 59.3 pMC indicating the residence time in the range of 4300 to 15,000 years BP, <em>i.e.</em>, the sourced water recharged the aquifers a long time ago. The intermediate and deep wells have water with arsenic concentrations less than the detection limit of 3.0 μg/L. Only a few shallow wells have arsenic concentrations greater than the detection limit varying from 13.7 - 47.4 μg/L, which is less than the DoE permissible limit (50 μg/L) implying that the groundwater at Madunaghat area is not affected by Arsenic contamination.
文摘Dhaka, Bangladesh’s capital, already has a congestion problem to handle the ever-growing demand for traffic. The usage of private cars cannot be stopped by charging and the town is not encouraged by quality public transport. It is impossible to enforce congestion prices here in line with traditional cordon pricing systems since the region uses unusual land patterns. However, the </span><span style="font-family:Verdana;">current project Mass Rapid Transit (MRT) Line 6, which will be built by </span><span style="font-family:Verdana;">2021, provides the prospect of congestion pricing. A price and optimum approach were established for this article. The congestion price is only payable for the </span><span style="font-family:Verdana;">segments and is accessible for private cars under this system. Two urban </span><span style="font-family:Verdana;">street segments along the MRT route were selected for the study and congestion toll for a private car is estimated for each segment separately. The sum of the toll in monetary terms is determined using certain associated parameters from the discrepancy from the actual Level of Service (LOS) travel time and traffic flow to the desired LOS. The outcome has shown that the price per </span><span style="font-family:Verdana;">passenger car is $0.3 - $0.44. The price is flexible, which means it will vary</span><span style="font-family:Verdana;"> b</span><span style="font-family:Verdana;">ased on traffic volume. The findings for politicians to enforce congestion</span><span style="font-family:Verdana;"> pricing are viewed as recommendations.
