Drip irrigation design to aid grass establishment on railway formation steep slopes

Embankments and cuttings are integral parts of rail and road networks that support the economy of every country including Australia. Water induced soil erosion from the steep slopes (batters) of these civil engineered structures costs tax-payers in terms of ongoing operation and maintenance of the land transport networks. Also the environment is degraded and sediments transported from sites have the potential to pollute the nearby water bodies downstream. Development of a cost-effective drip irrigation system that sources water from either an existing pressurized water main or a temporary excavated pond/ dam (with solar or petrol pump) to supplement the unpredictable natural rainfall for quick grass establishment is an integral part of the HEFRAIL Project strategies developed. This paper presents the hydraulic modeling effort for the drip irrigation lateral network. Estimated hydraulic model parameters of commercially available pressure compensating laterals are given. A few examples of irrigation network bays based on the basic subunit of 3 laterals placed at the top section of the batters are presented. Simulation results have shown that for the fire-fighter petrol pump used on the HEFRAIL Project, a bay consisting of a maximum of 4 subunits can be run at the same time to ensure that the emitter pressures are within the pressure compensating range. For sites where more than 4 subunits are required, multiple bays are set up with controllers to schedule irrigation.