Understanding north Java coastal aquifer system : evidence from Kendal, Mid Java

This slide was presented in the ICES ITB July 2016. The official website of this event is http://portal.fi.itb.ac.id/ices2016/. I also invite you to visit my blogs: dasaptaerwin.wordpress.com and dasaptaerwin.net/wp.

The first author is Ali Lukman, an ITB graduate, now pursuing master program in geology. He is now working as a engineering consultant for PT. Supra Indodrill (http://supraindodrill.com/).

@dasaptaerwin
ORCID: 0000-0002-1526-0863

Transcript

1. [RNW-­‐104]   Understanding  north  Java  coastal  aquifer  system  :   evidence  from  Kendal,  Mid  Java   Lukman,  A.  (1),  Aryanto,  M.  D.  (2),  Pramudito,  A.  (2),  Andhika,  A.  (2),  and   Irawan,  D.  E.  (1*)   (1)  Faculty  of  Earth  Sciences  and  Technology,  InsFtutu  Teknologi  Bandung   (2)  PT.  Supra  Indodrill  Indonesia     *  dasaptaerwin@outlook.co.id       26th  July  2016,  East  Hall,  ITB  
2. Background  and  LocaGon   •  Northern  part  of  java  is  a   favorable  place  for   economical  acFvity  due  to  its   strategic  locaFon   •  RelaFvely  flat  topography   and  the  existant  of  abundant   transportaFon  access  makes   it  easier  to  be  built   •  The  probable  increasing   development  acFvity  needs   to  be  anFcipated    with   learning  the  groundwater   resource  study  and  research  
3. regional     physiography   •  Alluvial  plain  with   flat  topography  and   influence  of  Fdes   •  Land  used  for   “empang”  (brackish   fishpond)  
4. LocaGon     DescripGon   swamp  area  and  wetland  
5. geoelectric   method   Where : K = Geometrical factor AB = Distance between current electrodes (m) MN = Distance between potential electrodes (m) V = Potential (mV) I = Electrical Current (mA) = Apparent Resistivity (m.Ohm) ρ Telford and Sheriff, 1990  
6. acGvity  
7. •  Aluvial  Deposite  (Qa)  à  coastal   environment,  consist  of  clay  and   sand  deposit  with  average   thickness  around  >  50  m.   •  Damar  FormaFon  (Qtd)  à  tuff,   volcanic  breccia,  sandy  tuff  à  main   aquifer   regional   geology   Thaden et al., 1975  
8. soil  test  result   •  Dominant  clay  layer   Fll  70  m  of  depth   •  The  clay  layers  are   from  aluvial  deposit   •  Loose  /  not   consolidated   •  Shallow  groundwater   table  around  0,3-­‐2  m   contain  brackish   water  
9. verGcal  secGon     from  previous  well  
10. geoelectric     measurement     locaGon  
11. data     processing  
12. interpretaGon  and  correlaGon  
13. interpretaGon  and  correlaGon  
14. interpretaGon  and  correlaGon  
15. interpretaGon  and  correlaGon  
16. Discharge  EsGmaGon   Dominico and Schwartz, 1990   Sichardt formula, 1990   Qmaks = maximum discharge of water extracted (m3/s) re = effective radius (m) b = aquifer thickness (m) k = hydraulic conductivity Assumption : -  Aquifer Thickness is 70 meter -  Effective radius is 10 meter -  Hydraulic conductivity value 3.10-10m/sec and 6.10-6 m/sec Hydraulic   ConducGvity Q  (m3/s) Q  (l/s) 3.10-­‐10  m/sec 0.005076 5.076 6.10-­‐6  m/sec 0.071786 71.786 The different value of discharge depends on the following conditions: -  Porosity and permeability rate of aquifer. -  Fragment size of sandstone -  Matrix precentage of the sandstone.
17. conclusion   •  From the correlation between literature, previous borehole and field measurement data, it is known that there are four layers identified, the first layer is silty clay with resistivity values vary ​​ between 0 - 10 ohm.m, then the second layer is tuffaceous claystone with resistivity value between 10 - 60 ohm.m, both of this layer is interpreted as an impermeable layer. The third layer is sandy tuff with resistivity value ranged between 60 - 100 ohm.m and the last layer is compact breccia with resistivity value more than 100 ohm.m. •  There is two system of aquifer in research location : shallow aquifer (0-70 m), deep aquifer (70-150 m) •  Shallow aquifer contain brackish water as result of seawater intrusion •  Recommended depth for screen : 70-150 meter •  Interval 0-70 m must be sealed with casing and cement to preventing brackish water entering the well. •  Discharge estimation recharge result : Hydraulic  ConducGvity Q  (m3/s) Q  (l/s) 3.10-­‐10  m/sec 0.005076 5.076 6.10-­‐6  m/sec 0.071786 71.786
18. Some  result  of  measurement