Sizing of a small irrigation weir

This paper presents the determination of weir dimensions and its applications based on the equations derived specifically for an irrigation weir and introduced in the standard design manual entitled “KKU-2527 Weir”. The manual was used nationwide as a guideline for the construction of weirs. However, due to technical constraints that probably have a significant impact on weir design such as on-site conditions and budget constraints, among others, the main objective of this study is to determine the weir dimensions that best captures the hydraulic characteristics of flow over a weir and remedy the aforementioned technical constraints. According to the numerical solution of related equations in this study, it was found that weir dimensions are interchangeable. For example, with the significant limitations in deepening a river channel, a higher stilling basin floor elevation can be compensated by increasing the weir width. In brief, such design flexibility can be very useful for on-site weir design modifications in dealing with construction problems and dealing with the financial constraints of local administrative organizations.