Required Hydro-Oceanography Survey for Marine Work in CFSPP Project

Survey works for Coal Fired Steam Power Plant (CFSPP) project is one of mandatory things need to be done prior of detail design of marine work. There are some surveys needed to obtain primary data at and around the planned location consist of topographical and bathymetrycal survey, hydro-oceanography survey (tidal observation, current speed measurement, sub-bottom profilling, wave recording, sediment sampling and temperature measurement).

The topographical survey includes planned location of the power plant and its surround in order to obtained detailed map of the location, including planned location map as well as chimney location and coal fly ash influencing area. Detailed map shall be consist of land surface including land situation and height also appearance position on the planned location of the Power Plant and its surround. Bathymetric surveys are carried out in order to get the water depth map of the project area. Bathymetric and topographic map shall be integrated in one coordinate reference.

The objective of the other hydro-oceanography surveys are to obtain knowledge of general hydro-oceanography condition at the project location which will be used as parameters for further simulation and analysis.

Following are the surveys which commonly performed in Indonesia:

Topography Survey

  • Measurement of reference points
  • Control Survey
  • Distance measurement
  • Horizontal angle measurement
  • Elevation measurement
  • Situation mapping and installation of BMs
  • Field data processing and topography map as the final result

Bathymetry Survey

  • Position and water depth measurement
  • Field data processing and bathymetry map as the final result

Sub-Bottom Profiling

  • the purpose of this survey is to obtain the sub-bottom layers profile and sea/river bottom relief. This survey also can indicate whether any subsea structure such as pipeline or cable line at the site.
  • Commonly, the sub bottom profilling is execute at the plan location of navigation line, turning basin area and intake channel.

Observation of Water surface elevation

  • For measurement by using convensional tidal gauge, hourly tidal data is recorded for at least 30 days
  • Coordinate observation eith refer to the BM which has been made during tophography suryey.
  • Data processing to obtain tidal component and important elevation.

Water Sampling (the amount of sampling point is depend on general layout arrangement, and whether any sediment source nearby such as river)

  • Water sampling is taken at least 2 times each during neap and ebb tide.
  • For each sampling point, the water sample is taken at three different depths (0.2d; 0.6d; 0.8d, where d is water depth)
  • Chemical and physical content of the water sampling
  • Suspended solid concentration
  • Dissolved solid concentration

Current speed, density and salinity (the amount of sampling point is depend on general layout arrangement, and whether any discharge flow nearby such as river estuary)

  • For measurement by using convensional currentmeter, current speed and direction along with density and salinity measurement are taken hourly for at least 24 hrs within 2 times, each during neap and ebb tide.
  • For each measurement point, the measurement is taken at three different depths (0.2d; 0.6d; 0.8d, where d is water depth)

Water Temperature

  • For measurement by using convensional equipment, the measurement of water temperature is taken hourly for at least 24 hrs within 2 times, each during neap and ebb tide. Water temperature measurement should be executed at the same time with current measurement.
  • For each measurement point, the measurement is taken at three different depths (0.2d; 0.6d; 0.8d, where d is water depth)

Bottom Sediment Sampling

  • Bottom sediment sampling
  • Grain size analysis

Wave Survey

  • The ideal period for wave recording is at least 1 year. However, since the allocated time to do the survey is very short and the schedule is very tight, the recording only executed for 1 month. In common practice, wave data is predicted from long period (at least 10 years) of wind speed data at the nearest meteorology station.
  • Wave data shall include wave height, wave period and direction
  • Wave measurement point shall be located offshore and outside the breaking zone 

All obtained data from the survey will be combined with secondary data which may be obtained from another Indonesia agency such as BMG (the Indonesian agency in charge of administering meteorological data) to obtain long period of meteorological data and Dinas Hidro-oseanografi TNI-AL (Dishidros, Hydro-oceanography Office of the Indonesian Navy) to obtain the regional nautical chart, tidal and current data.

As addition, for average significant wave height and period for Hindia Ocean can be obtained from KNMI (Koninklijk Nederlands Meteorologisch Instituut) and can be obtained from the KNMI website.

Example of Average of significant wave height and period in February (from KNMI website)

The global wave forecasting for someday during the wave measurement perioda can be obtained from FNMOC (Fleet Numerical Meteorology and Oceanography Center)

Example of wave forecasting made by FNMOC

In these recent years, conventional equipments are commonly replaced by automatic recorder which is capable to measure and record wave, tide and current at once in a single equipment.

Leave a Reply

Your email address will not be published. Required fields are marked *