Sei Teras fishpond area was developed by the Banjar community in 2006. The conditions of the ponds in Sei Teras are still very simple, where the availability of seeds and feed is completely dependent on nature. The evaluation is based on the level of control and the production rate, while efforts for improvement are planned through controlling water quality. In the rainy season, the shrimp productivity ranges from 180 Kg/ha, while it can reach 450 kg/ha in the dry season. From the measurements results in November 2020-Mei 2021, it was noted that the salinity of the water in fishponds and canals ranged from 2 to 24.3 ppt while the water pH ranged from 6.11. to 7.87. Water quality parameters such as DO and pH have met the criteria for applying higher aquaculture technology, while other parameters such as Nitrate, Nitrite, Ammonia, TDS and Salinity require improvement and/or control. An alternative design is in the form of rearranging the fishpond system such as individual fishpond size. In addition, it is necessary to manage the fishpond irrigation network, namely by planning the main control structures separating fresh water and saline water, and rehabilitation of channels that experience sedimentation.

Sei Teras Village has been developing aquaculture since 2006 and has fresh and saltwater sources. Recently, there has been a plan for upgrading the traditional extensive ponds to intensive ones. It is expected to cultivate vannamei shrimp, which delivers a better return. An average of 5-15% of the total water volume in the ponds is recommended to be replaced every day to keep the water quality within the range of the requirements. This study aims to find an alternative design and operation of pond gates for better use of tides for fishpond water leaching. Measurements were carried out for topography, tides, and current boundary conditions for calibration. The flow simulations on the fishpond irrigation network are modeled with two scenarios of pond water gate size and variations in the number of fishpond gates operated simultaneously using HEC-RAS software. Flow simulation is carried out to determine the process of entering and leaving water into ponds. The results of the simulations are evaluated based on their water replacement capacity and changes of discharge and water level at the control point. The initial results show that wider gate opening increases the capacity of water replacement and simultaneous opening operation gives the maximum result.