Assessments of Irrigation Water Requirement from Deduru Oya Left Bank Canal to Supplement Deduru Oya Left Bank Irrigation Demand
By Sampath D.S., Weerakoon S. B., Mishra B., Herath S.
- Rainfall in Deduru Oya basin shows significant temporal variation, resulting in flash floods during the rainy season and low flows during the dry season.
- The construction of the Deduru Oya reservoir upstream of the existing Ridi Bedi Ela anicut aims to regulate the discharge of Deduru Oya for better utilization of water resources, particularly for irrigation.
- The multi-purpose Deduru Oya reservoir project has a capacity of 75 MCM and enhances water resources for 136 existing tank-based irrigation systems in the Deduru Oya Left Bank through a Left Bank (LB) canal.
- The project also diverts water to Iginimitiya tank in the Mee oya basin through a right bank transbasin canal.
- A model is developed for water management in the LB canal development area and to assess the diversion requirement from the Deduru Oya reservoir through the LB Canal to supplement LB irrigation demand.
- The Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) is used for runoff estimations, while the CROPWAT model estimates crop water requirements.
- The Water Evaluation And Planning (WEAP) model is utilized for water balance simulations in Deduru Oya LB canal development area and to calculate water requirements from the LB canal over the past 10 years.
- The study reveals that the annual water requirement from the LB canal for 100% cropping intensity in the proposed 3000 ha irrigable area in the LB canal development area ranges from 26 MCM to 41 MCM.
