Prioritizing maintenance work in agricultural drainage ditches: A procedure

Abstract

<b><sc>Abstract.</sc></b> Productive agricultural lands are vital for food production. Intermittently maintain drainage ditches helps secure soil fertility. Tools are needed to prioritize agricultural ditch segments for maintenance work. Here, we present a procedure to identify drainage ditches segments that are likely to need maintenance works. Focus is placed on the susceptibility to soil erosion by water flowing in the ditch. Susceptibility to soil erosion was evaluated using a Cohesive Strength Meter (CSM) to derive estimates of critical shear stress for soil erosion. An important part of the CSM method is to relate the pressures of the CSM with the pressures acting at the soil surface. Here, we present a relationship between CSM jet pressures and pressures at the soil surface, obtained from measurements done with a pressure sensor plate. This relationship suggests that the pressures acting on the soil surface are in the range 0 – 275 Pa, which are, in some cases, one order of magnitude lower than the estimates obtained using the relationship proposed by Vardy et al. (2007). At the same time, lower values of the pressures at the surface will cause lower estimates of the critical shear stress for erosion. We consider our estimates reliable since they are based on direct measurements of the pressures at the surface for each CSM jet pressure. Finally, we argue that the CSM is useful to compare soils regarding its resistance to soil erosion. This information is useful when deciding which drainage ditch segments should be prioritized for maintenance works).