EVALUASI DIMENSI SALURAN IRIGASI UNTUK EFISIENSI JARINGAN TERHADAP KEBUTUHAN AIR TANAMAN (Studi Kasus: D.I Ciasih-Kalibunder)

Water is a key factor in supporting life and the success of the agricultural sector, particularly in rice cultivation, which requires a consistent and evenly distributed water supply. The Ciasih Kalibunder Irrigation Area in Sukabumi Regency serves 408 hectares of agricultural land through a network of primary and secondary canals. However, several problems such as drought, silt deposition, aquatic plant growth, and direct water withdrawal by the community. This causes uneven water distribution and decreases the efficiency of the irrigation network. This study aims to channel the existing canal capacity and plan optimal dimensions to be able to meet plant water needs efficiently. The methods used include field surveys, primary and secondary data collection, and discharge analysis using a technical calculation approach and trial and error methods. The results show that the highest water demand occurs during the land preparation stage, namely 510 l/s/h in the rainy season and 296 l/s/h in the dry season. Evaluation of the existing canal dimensions shows that most secondary and main canals from sections 2 to 8 are unable to flow the discharge according to the planned requirements. Only the main channel section 1, which has been repaired with a trapezoidal cross-section (2 m wide, 0.45 m water level), is able to meet the planned discharge requirement of 0.71 m³/s, with the existing discharge reaching 0.81 m³/s. Therefore, improvements to the channel dimensions and more efficient water management are needed. Keywords: discharge, dimension, water distribution, irrigation channel evaluation