Optimasi Pemanfaatan Air Di Daerah Irigasi Senggowar Kabupaten Nganjuk

The Senggowar Irrigation Area is one of the irrigation areas in Nganjuk Regency that utilizes water from the Bening Reservoir as its main source to meet irrigation water demand. During certain cropping periods, water availability has been insufficient to meet irrigation needs according to the applied cropping pattern, causing a portion of the existing land area to not be optimally irrigated. This condition highlights the need for a study on more efficient water allocation arrangements so that the available water can provide maximum benefit to farmers in the area. This study aims to analyze the balance between irrigation water availability and demand, and to determine the optimal land area that can be irrigated using the Deterministic Dynamic Programming approach. The data used include dependable discharge, climatological data, cropping patterns, crop coefficients, and service land area. Irrigation water demand was calculated based on crop water requirements minus effective rainfall, while water availability was determined based on the dependable discharge. The optimization process referred to the cropping pattern established in the Global Cropping Pattern Plan (RTTG) of the Senggowar Irrigation Area. The optimization results show that in the Senggowar Right Secondary Canal, the irrigable land area from Cropping Season I to Cropping Season III increased to 1335,24 ha, compared to 1284,89 ha before optimization, an increase of 3,92%. In the Senggowar Left Secondary Canal, the irrigable land area from Cropping Season I to Cropping Season III increased to 806,62 ha, compared to 731,63 ha before optimization, an increase of 10,25%. In the Senggowar Right Secondary Canal, profits increased from Rp40.817.754.602,43 to Rp41.871.929.453,66, while in the Senggowar Left Secondary Canal, profits increased from Rp22.657.251.712,18 to Rp24.985.553.901,83. After the addition of the pump, profits in the Senggowar Right Secondary Canal increased to Rp74.232.085.497,44, and in the Senggowar Left Secondary Canal increased to Rp35.193.570.082,46. The results of this study indicate that the application of Deterministic Dynamic Programming, supported by an additional pump, can optimize irrigation water allocation and significantly increase farming profits across the entire existing land area in accordance with the cropping pattern applied in the Senggowar Irrigation Area.