The principal tasks included in the terms of reference for the supplementary study are summarised below: ol; liUndertake a topographical survey of the whole project area and beyond its boundary, by up to 500 m where necessary. /li; liCarry out a semi-detailed soil survey of the project area including comprehensive in situ and laboratory analyses of soil and water samples./li; li Review the hydrology of the Juba river with particular regard to' the low flow periods and project flooding and the influence of Bardheere dam on the project. /li; liCarry out a preliminary design of the irrigation and drainage system including layout drawings, canal and drain longitudinal and cross-sections, flood protection details, pump station design, typical structure drawings and preliminary details of project infrastructure./li; /ol