The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report 4.6.5 Water Source (1) Hydrological and morphological data of Padma River The Ganges River drains the southern slope of the Himalayas. After breaking through the Indian shield, the Ganges swings to the east along recent multiple faults between the Rajmahal Hills and the Dinajpur Shield. The river enters Bangladesh at Godagari and is called Padma. Before meeting with the Jamuna, the river travels about 2,600km, draining about 990,400km2 of which about 38,880km2 lies within Bangladesh. The average longitudinal slope of water surface of the Ganges（Padma） River is about 5/100,000. Size of bed materials decreases in the downstream. At the Harding Bridge, the average diameter is about 0.15mm. The river planform is in between meandering and braiding, and varies temporally and spatially. Sweeping of the meandering bends and formation of a braided belt is limited within the active corridor of the river. This corridor is bounded by cohesive materials or man-made constructions that are resistant to erosion. Materials within these boundaries of the active corridor consist of loosely packed sand and silt, and are highly susceptible to erosion. Hydrological and morphological data of Padma River has been corrected by BWDB at Harding Bridge and crossing line of RMG-13 shown in the Figure I-4-6-4. Harding Bridge Origin (x=0) RMG-13 Padma River 3.66km Figure I-4-6-4 Bheramara site and Padma River Figure I-4-6-5 shows the water level at Harding Bridge between 1976 and 2006. In generally, the Padma River starts rising at the-end of June and attains its peak level in August or September, with a corresponding increase in its sediment load in the period. After mid November, water level in the Padma River becomes lower, and naturally very little sediment is borne by the river during the season. I-4-45 The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report Water levels of Padma River at Hardinge Bridge are following; LLWL = EL+4.22 m LWL = EL+5.47 m* MWL = EL+8.74 m* HWL = EL+13.63 m* HHWL = EL+15.19 m (*: average between 1976 and 2006) 1976 Water Level at Harding Bridge (1976-2006) 1977 1978 1979 16.0 1980 Average 1981 1982 14.0 1983 1984 1985 12.0 1986 1987 10.0 1988 1989 1990 8.0 1991 1992 Level (m) Level 1993 6.0 1994 1995 1996 4.0 1997 1998 1999 2.0 2000 2001 2002 0.0 2003 2004 2 1 2 2 1 01 0 0 0 /0 / / / l/ p v un/01 u 2005 Jan/01 Jan/31 Mar Apr May/0 J J Aug/01 Se Oct/01 No Dec/01 Jan/01 2006 Month/Date average_y Figure I-4-6-5 Water level at Hardinge Bridge Figure I-4-6-6 and Figure I-4-6-7 show the monthly variation of minimum discharge at Hardinge Bridge. Minimum discharge of Padma River at Hardinge Bridge as follows: Minimum discharge : Qmin=183m3/sec (Mar. 1997) Averaged minimum discharge : Qmin=709m3/sec (Apr.) I-4-46 The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report Monthly Variation of Discharge at Harding Bridge (min.) 1980 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1996 1997 1998 70,000 1999 2001 2002 2003 2005 2006 average 60,000 50,000 40,000 30,000 Q (m3/sec) 20,000 10,000 0 b r y ul ug p Jan Fe Ma Apr Ma Jun J A Se Oct Nov Dec Month Figure I-4-6-6 Monthly variation of minimum discharge at Hardinge Bridge Monthly Variation of Discharge at Harding Bridge_in dry season (min.) 1980 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1996 1997 1998 4,000 1999 2001 2002 2003 2005 2006 average 3,500 3,000 2,500 2,000 Q (m3/sec) Q 1,500 1,000 500 0 Jan Feb Mar Apr May Jun Month Figure I-4-6-7 Monthly variation of minimum discharge at Hardinge Bridge in dry season I-4-47 The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report Figure I-4-6-8 shows the velocity at Hardinge Bridge. Velocity of Padma River at Hardinge Bridge in 2007 is following; Maximum velocity : Vmax=3.62m/sec Minimum velocity : Vmin=0.32m/sec Velocity at Harding Bridge 4.0 2006 3.5 2007 3.0 2.5 2.0 V (m/sec) 1.5 1.0 0.5 0.0 1 1 r/2 /2 /1 a ay/2 p/ Jan/1 an/31 M Apr/2 M Jun Jul/2 Aug/ Se Oct Nov/1 J Dec/1 month/date Figure I-4-6-8 Velocity at Hardinge Bridge Figure I-4-6-9 shows the bed elevation of Padma River at cross section of RMG-13. The bed elevation has been measured almost once a year during dry season. I-4-48 The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report Cross Section of RMG13 (1992/2-2006/4) 1992/2/1 1992/12/5 1993/12/30 1995/3/25 1995/11/29 20.0 1996/12/4 1997/12/4 1998/11/30 1999/12/20 2001/9/1 2002/2/2 2003/2/15 2005/1/29 2006/4/11 15.0 10.0 5.0 Level (m) Level 0.0 1:20 -5.0 -10.0 1,500 1,700 1,900 2,100 2,300 2,500 2,700 2,900 3,100 3,300 3,500 3,700 3,900 4,100 4,300 4,500 Distance from the Origin on the Left bank of Padma Rver (m) Figure I-4-6-9 Bed elevation of Padma River at cross section RMG-13 I-4-49 The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report (2) Ground water Investigation Ground water may be pumped up to secure the makeup water for the cooling tower, therefore, in order to obtain information on the baseline situation of aquifer condition present in the site area and assess any impact on the existing wells by long-term constant pumping, ground water investigation/study was conducted. 1) ground water investigation Groundwater investigation with a set of one 100m pump well and twelve 100m observation wells was conducted. Groundwater investigation includes the following physical works: - Test drilling and analysis - Drilling, installation and development of pumping well and observation wells - Geo-electrical logging of borehole - Recording of pumping test (continuous pumping test of 72 hours duration and recovery) - Evaluating results Pump/Observation wells layout is shown in the Figure I-4-6-10. OW-12 OW-08 Padma River OW-04 PW-01 OW-11 OW-09 OW-07 OW-01 OW-03 OW-05 OW-02 OW-06 OW-10 0 50 100 150 200m Figure I-4-6-10 Pump/Observation wells layout I-4-50 The Study on Bheramara Combined Cycle Power Station in Bangladesh Final Report Aquifer of the site area was determined by sieve analysis of drilled samples from pumping well and observation wells and also electrical logging. Test pump capacity is max. 2.0 ft3/sec (=3.40m3/min=204m3/hr) and actual discharge of pumping well was 159.0 – 163.3 m3/hr. Information of hydrostratigraphic units are shown in Table I-4-6-2. Table I-4-6-2 Information of hydrostratigraphic units Depth of Depth of Depth of Total Height Total Depth of upper upper part main part depth of of well depth of screen below Well aquitard of aquifer of aquifer boring casing well GL Discharge ID below below GL below GL below above below GL (m) (m) (m) GL(m) GL (m) GL(m) (m) not 159.00-163.30 PW-01 6.09 36.58 92.68 0.46 86.91 42.71–85.39 defined (m 3 /h) TTW/ not 12.19 36.58 100.00 0.305 83.84 79.27–82.32 36 l/s OW-01 defined not OW-02 9.14 42.68 100.00 0.305 84.15 79.58–82.63 36 l/s defined not OW-03 6.09 30.48 100.61 0.305 50.00 45.43–48.48 32 l/s defined not OW-04 6.09 48.78 101.22 0.305 77.75 73.18–76.23 37 l/s defined not OW-05 3.04 27.43 100.61 0.305 83.84 79.27–82.32 36 l/s defined not OW-06 12.19 36.58 100.00 0.305 76.22 71.65–74.70 36 l/s defined not OW-07 6.09 42.68 100.61 0.305 76.83 71.65–74.70 31 l/s defined not OW-08 6.09 36.58 100.61 0.305 77.75 73.18–76.23 32 l/s defined not OW-09 6.09 24.39 100.00 0.305 76.22 71.65–74.70 36 l/s defined not OW-10 6.09 42.68 100.61 0.305 74.70 70.13–73.18 37 l/s defined not OW-11 6.09 36.58 100.00 0.305 79.27 74.70–77.75 35 l/s defined not OW-12 6.09 42.68 100.00 0.305 79.88 75.31–78.36 38 l/s defined Longitudinal cross sections of aquifer both S-N and W-E direction are shown in the Figure I-4-6-11, 12.