By Aditya Sidik Waskito – (Thesis M.Si Sriwijaya University, 2012), Supervised by Prof. Bart Schultz, PhD, MSc; Prof. Ir. Robiyanto H. Susanto, PhD, M.Agr.Sc; F.X. Suryadi, PhD, MSc.

Population and economic growth in Indonesia has led to an enormous land conversion from agricultural areas to other usages. Due to the limited farmland, lowlands, which had not been used optimally, are one alternative for agriculture. To optimise the potential of these tidal lowlands, an integrated approach is needed. In order to develop, analyse and promote the required integrated approach, the programme Land and Water Management Tidal Lowlands (LWMTL) was implemented in the period 2004 – 2006 in three pilot areas in the Musi Delta, South Sumatra. In 2007 – 2008, Strengthening Tidal Lowland Development (STLD) programme was held in the Telang I Scheme as a continuation of the LWMTL programme. Generally, the STLD programme aimed to improve the crop production in tidal lowland schemes, particularly paddy and secondary crops.

The STLD programme was completed in 2008 and over time, some changes may have occurred in the field. These changes may include changes in the water management system, physical changes of the canals, land subsidence and changes in land use. Due to these changes, crop production may eventually have been affected. Therefore, a study is needed to evaluate the current condition, compared to the objectives of the STLD programme, in terms of crop production.

The first objective of this research is to analyze the existing hydraulic structures and water management practice and to identify options for improvement. Secondly, this research evaluates the existing operation and maintenance rules of water delivery and drainage in the scheme at secondary and tertiary canal level. The third objective is to formulate some possible approaches at secondary and tertiary levels to improve the performance in order to obtain an optimum crop production. Lastly, it is expected to formulate recommendations for improvements.

The rainfall data analysis taken from SMB II station shows that the effective rainfall on the study area is relatively high and able to support rice cultivation with rainfed practice. However, CROPWAT 8.0 simulation result shows that to achieve the maximum yield, irrigation is needed on particular growing stages. On the other hand, excess water from rainfall should be removed from the farm if it exceeds the crop requirement.

DUFLOW simulation results show that in the secondary block P6-3N, the recent design gives the best result among other scenarios. On the other hand, in secondary block P8-12S, installation of moveable flap gates on both ends of each tertiary canal is needed to improve canal performance. In addition, water management on tertiary canal is more important to improve yield production.