Agroclimatic assessment of watersheds for crop planning and water harvesting

Agroclimatic analysis of two watersheds, viz. Malleboinpally (Alfisols) in Jadcherla mandai of Mahabubnagar district and Nandavaram (Vertisols) in Banaganapalle mandal of Kurnool district, Andhra Pradesh (India), was carried out using agromet data for the period 1971-2006. Water balance analysis indicated moderate water surplus at Malleboinpally (179 mm), and at Nandavaram it was low at 40 mm. Both watersheds had similar water deficits of 1050-1100 mm/year. Runoff analyses indicated that ~0.3 to 0.5 million m3 water are available for storage during normal years at the watershed area of 500 ha. In the wet years, Malleboinpally has a potential of ~1.25 million m3. Nandavaram has the lowest potential even in wet years. Though both the locations have a semi-arid type of climate, there is a tendency for the climate to temporarily shift towards drier side. Malleboinpally has the most stable climate (semi-arid) climate. In contrast, Nandavaram showed higher tendency towards arid type of climate. Nandavaram provides greater opportunity for double cropping as the LGP here ranges from 120 to 195 days. Malleboinpally has LGP ranging from 100 to 160 days and provides greater potential for sole cropping during rainy season and intercropping with short to medium-duration crops. Early and mid-season droughts occur at Nandavaram and this watershed would require crop/varieties tolerant to early or mid-season droughts depending upon the location. Malleboinpally has greater potential for water harvesting and offers opportunity for supplemental irrigation. These results help in arriving at efficient and sustainable management of natural resources and thereby sustaining rural livelihoods at watershed level