The study area discussed in this article is the Upper and Middle Modder River basin situated in a semi-arid area of central South Africa. According to the article, this is an important catchment because of the relatively large nearby towns of Bloemfontein, Botshabelo and Thaba Nchu. The area of land suitable for in-field rainwater harvesting (IRWH) in the basin is estimated to be 80 667 ha, of which 15 000 ha are located in the communal land. The two catchment management option`s compared in this paper are to allow the 80 667 ha to remain under grassland and utilizing the runoff downstream for irrigating maize and to utilize the 80 667 ha for maize production in the basin using the IRWH technique.