Evaluasi Neraca Air Irigasi sebagai Dasar Peningkatan Indeks Pertanaman (IP) dan Pengembangan Infrastruktur Irigasi di Desa Gedung Karya Jitu

Abstract

Increasing the Cropping Index (CI) is a strategy to improve agricultural productivity by optimizing available water resources without expanding cultivated areas. However, increasing CI depends not only on water availability but also on the capacity of irrigation networks to convey and distribute water effectively. This study aims to evaluate the irrigation water balance as a basis for increasing the Cropping Index and developing irrigation infrastructure in Gedung Karya Jitu Village, Tulang Bawang Regency, Lampung Province. The research method involved comparing irrigation water availability and requirements for each planting period, evaluating the existing cropping pattern, and analyzing the hydraulic capacity of irrigation channels to determine infrastructure development needs. The results show that water availability is sufficient to serve 499 ha of agricultural land, with an average discharge of 41.89 m³/s compared with an average irrigation water requirement of 0.45 m³/s. The water balance remains in surplus throughout the year, with an average surplus of 41.44 m³/s. The existing Rice–Rice–Fallow cropping pattern with a CI of 150% remains feasible and has the potential to increase to 250%. However, unnormalized channels and tidal-induced backwater may reduce conveyance capacity. Channel normalization provides a conveyance capacity of 1.36–2.20 m³/s with an average velocity of 0.52 m/s. Therefore, irrigation infrastructure development through channel normalization and improvement of hydraulic structures is required to support a sustainable increase in the Cropping Index.