CoBAGNPS: A toolbox for simulating water and sediment control basin, WASCoB through AGNPS model

Abstract

A WASCoB constituting a modest detention pond (berm), surface inlets and tile drains; designed to capture the flow and release it gradually into the drainage system is an efficient watershed BMP. Henceforth; a toolbox, CoBAGNPS for the AGNPS model, is developed to simulate WASCoBs through the AGNPS model. The toolbox utilizes the inputs from AGNPS, through the launching of an application for execution of the WASCoB module. Finally, the output files are generated after routing flow through WASCoBs. The toolbox was applied with a case study in the Gully creek watershed and one of its sub-basins (DFTILE sub-basin) located in Ontario, Canada. The toolbox reproduced the required outputs successfully. Henceforth, significantly enhancing the capability of the AGNPS model to simulate flow through a WASCoB and a network of WASCoBs. Furthermore; the efficiency of the drainage system is also analyzed under different scenarios of pipe risers and tile drains. Also, few scenario analyses were considered in which different diameter drainage pipes were considered to route flow for extreme events for WASCoB3 in the DFTILE sub-basin. A 375-mm diameter drainage pipe is efficient in routing flow for a 10-year 24-h design storm without it overtopping the berm. Finally, another component of the toolbox was tested, where the flow from the DFTILE sub-basin was directly routed to the outlet of the Gully creek watershed (GULGUL 5) through a drainage pipe of 200 mm with 1% slope, assuming a lag time. The hydrograph at the watershed outlet increased marginally due to the small size of the DFTILE sub-basin.