Experimental Study of Open Channel Model of Glass Fiber Reinforced Polymer and Its Flowing Characteristics

One of the efforts to reduce water losses in irrigation channels is to provide lined materials in the earth’’s irrigation channels. Construction of these lined materials in Indonesia requires raw materials (such as sand, gravel, and split stone) mined from nature, and in Indonesia, known as class C excavated materials. Excessive exploitation of class C excavated materials will impact environmental damage. To overcome these problems, therefore, research is needed to find alternative lined materials, and in this research, the alternative lined material is Glass Fiber Reinforced Polymer (GFRP). The study’’s primary objective was to determine the value of the Manning roughness coefficient for lined channels made of GFRP material. The research involved experimental testing using an open channel model (flume) lined with GFRP material. The flow tests were conducted with three variations of the pump flow discharge and nine variations of the channel bottom slope. The test results from the physical model were compared with the results of the mathematical model simulation using the HEC-RAS software. The model’’s performance was evaluated using the graphical technique and quantitative statistics specifically the Nash-Sutcliffe Efficiency (NSE) method. Model evaluation with the NSE method shows that the performance of the physical model is “very good”. The Manning roughness coefficient value for rigid-lined GFRP material range from 0.0071 to 0.0102. The recommended Manning roughness coefficient value for practical application in the design of irrigation channels in Indonesia is 0.0081.