Managing the Irrigation Water Requirements of Command Area of 4(L) Distributory of Pollachi Main Canal under Variable Rainfall Conditions.

Abstract

The 4 (L) distributory of Pollachi main canal, Parambikulam-Aliyar-Palar (PAP) basin has been selected for an in-depth water management study. The project area has been divided into two zones namely, A zone and B zone. Each zone would get water from the canal system once in every two years. From the analysis of rainfall data of the rain gauge stations located in Parambikulam-Aliyar-Palar basin, it was observed that there was a wide temporal and spatial variability in annual rainfall over the years. The lowest annual rainfall recorded was 210.6 mm (over the plain) in 2003 and the highest of 5346.4 mm (in the hills) in 2007. The average annual rainfall for the period 1988-2010 was 1372.1 mm. The irrigation water requirement for the crops grown in the 4 (L) distributory was estimated using AquaCrop3.1 model for the years 2000-2010. The total irrigation water requirement during deficit rainfall year (2002) was 58.4 percent which is higher compared to normal year (2008). During the excess rainfall year (2007), the demand was 5.32 percent lower than the normal year demand. Therefore, the conjunctive use management of surface and groundwater resources in a command area can play a significant role in managing water by distributing the water throughout the season, while also maintaining the long-term sustainability of groundwater resources.