EVALUATION OF IRRIGATION WATER FULFILLMENT IN SUMBER BATANG SECONDARY CHANNEL MADIUN REGENCY

Abstract

The Sumber Batang Irrigation Area in Metesih Village, Madiun, has an irrigation canal spanning 15.11 km, supplying water to 2,358.6 hectares of rice fields. The Sumber Batang Secondary Canal (SSSB) relies on water supplementation from the Jati Weir, which was rehabilitated in 2022 due to damaged canals. Before the rehabilitation, water supplementation reached 40%, but it decreased to 25% afterward. This study evaluates the performance of SSSB using rainfall data from 2013-2022, assuming a 100% rice planting pattern. Evapotranspiration is calculated using the FAO Modified Penman method, while water discharge is determined using the F.J. Mock method. The results are presented in a water balance and analyzed hydraulically to assess SSSB's capacity after rehabilitation.

The results of water demand and water availability are presented in the form of a water balance, after which a hydraulics analysis is carried out to determine whether (SSSB) is able to accommodate the discharge flowing after rehabilitation using a 100% rice planting pattern. From the results of the analysis that has been carried out, it can be concluded that the availability of water in the Madiun SIM DI (SSSB) condition before rehabilitation is the highest at 1.7 m³/s and the lowest at 1.48 m³/s, while in the condition after rehabilitation the highest is 4.7 m³ / s and the lowest is 4.4 m³/s with a ratio of the fulfillment of irrigation water for the Batang Source Secondary Channel as follows: Water requirement 2.83 m³/s - before rehabilitation 1.7 m³/s (Less) - After rehabilitation 4.7 m³/s (Sufficient). After hydraulic analysis, it can be concluded that the channel is unable to accommodate the discharge of water flowing at the Teak Weir. With a maximum Q3,664 m³/s, the channel can only accommodate 3,251 m³/s for BM 4 to BSB 1 sections. However, after recalculation, the maximum discharge can be accommodated with a maximum Q of 3,675 m³/s.