A daily water balance modelling approach for simulating performance of tank-based irrigation systems

Tanks are small reservoirs, which are widely distributed in South India and Sri Lanka, where they present an important water resource for people, crops, livestock and fish. Considerable efforts have been made to rehabilitate tank irrigation systems in recent decades, but there have been few studies carried out to improve understanding of their hydrology. This paper presents a daily water balance approach, which aims to simulate the dynamic behaviour of tank storage. The model was validated over four seasons for two representative tanks within Mahaweli System H, a major irrigation system in the dry zone of Sri Lanka. Use of the model to evaluate current performance and scope for improvement is demonstrated.