The purpose of this study is to find the value of the discharge coefficient (Cd) on a sieve with a circular perforated plate so that it can be used for application in the field. The method used is to make a physical model test of the screen weir in the laboratory with a width of 40 cm and a length of 797 cm, then the screen is made variations in the diameter of the hole 6, 8, 10 and 12 mm, flowrate Q = 453–4 481 cm3∙s–1 and the slope of the screen θ = 20–45°. The result was quite ef-fective, the sediment did not enter above the screen and did not clog the screen even the catch was quite good about 80% of the screen rods. The discharge coefficient (Cd) is directly proportional to the square value of the number Froude (Fr), the slope of the screen (θ) and the ratio of distance, diameter of the screen (a:d) and inversely proportional to the value of the specific energy square (E). From modelling the average value of the discharge coefficient (Cd) between 0.1–2.75 with NSE = 0.71, MAE = 0 and RMSE = 0.12.

The head loss is a decrease in compressive height caused by friction and direction changes of flow at the sliced bend. This method expected to provide is easy, fast, and economical. The elements of influence are the velocity of flow, the num-ber of slices, average length of sliced walls, angle changes of the sliced, coefficient of friction, acceleration of gravity, and slope of the pipe. Equation for coefficient of head loss (Kb) is an analysis method for the head loss (hL) calculation. The analysis results that have obtained are the larger diameter of the pipe, and the more slices with a fixed discharge, the coefficient of hL becomes small. Conversely, if the diameter of the pipe is getting smaller, and the slice is getting less, then the coefficient of hL becomes bigger. This method, expected to give new knowledge in pipeline network applications, especially for the large diameter of pipelines.

In 2021, pak choi production in Indonesia was 727.47 Mg, marking an increase of 8.2% compared to the 2020 production, which was 667.47 Mg. Therefore, there is a clear need for cultivation improvement, particularly through the implementation of organic fertilisers. This study aimed to investigate the impact of liquid organic fertiliser (LOF) derived from fish waste and duck manure on the growth and yield of the pak choi plant ( Brassica rapa. L. var. Nauli F1). A randomised block design factorial was used with two factors and three replications. The first factor considered was LOF from fish waste, comprising three levels (LOF ₀ = control, LOF ₁ = 25 cm ³∙dm ^–3 of water, and LOF2 = 50 cm ³∙dm ^–3 of water). The second factor focused on duck manure fertiliser (DMF) and involved four levels (DMF ₀ = control, DMF ₁ = 3.7 kg∙plot ^–1, DMF ₂ = 5.55 kg∙plot ^–1, and DMF ₃ = 7.4 kg∙plot ^–1). The results showed that the application of LOF from fish waste positively influenced the growth and yield of pak choi, with the most effective treatment observed in LOF1 (25 cm ³∙dm ^–3 of water). However, the application of DMF did not yield a significant difference in its effect on the growth and yield of the pak choi plant. The control treatment (DMF ₀) reported comparable results and the combination of LOF from fish waste and DMF did not show a significant effect, with the most favourable findings observed in the LOF ₂DMF ₀ treatment (50 cm ³∙dm ^–3 and control).