Drought studies for Kalahandi district in Orissa - A research report by National Institute of Hydrology

The study attempts to advance the understanding of regional drought phenomenon in the Kalahandi district of Orissa and present mitigation strategies. The dry spells during the monsoon crop growing season and wide variations in the quantum of rainfall from year to year result in frequent failure of crops in Kalahandi and as a result the district is categorised as drought prone. 

The hydrological and agricultural aspects of drought have been studied for all the thirteen blocks in the district. The 31 years rainfall data for all the blocks have been analyzed in order to predict the drought frequency, duration, date of onset & withdrawal of monsoon and critical dry spells.

According to the rainfall departure analysis, the different parts of the district have experienced drought with an average frequency of 4-8 years. It was observed that the Koksara and Kalampur blocks were least affected. The probability distribution of annual rainfall revealed that the probability of occurrence of 75 % of normal rainfall varies from 0.72 to 0.88. Also, the range of annual rainfall at 75 % probability level varies from 800-900 mm at Lanjigarh to 2000-2100 mm at Th. Rampur.

The period between 13th June and 19th September is ascertained to be the usual period of monsoon in Kalahandi. On an average, the monsoon period incorporates two to three intervening critical dry spells, which lead to crop losses. The crop evapotranspiration (ETc) has been computed using reference crop evapotranspiration (ETo) and crop coefficient (Kc) values.

The water requirement for different crops namely paddy, maize, greengram (kharif), greengram (pre-rabi), blackgram, sesamum and minor millet have been estimated as 587 mm, 551 mm, 297 mm, 268 mm, 358 mm, 413 mm and 283 mm respectively. The irrigation requirements for the critical dry spells have been worked out to plan for alternate supplemental irrigation. 

The district needs alternative provisions for supplementary irrigation for kharif crop and at least one assured irrigation for rabi crop. This leads to the need for extending irrigation facilities by conserving the monsoon runoff in tanks, ponds and reservoirs, to cater to the requirements of deficit rainfall months. The area has a vast scope for exploitation and development of groundwater, which can provide supplemental irrigation and tackle drought.

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