2. Dry Spell and Wet Spell Characterisation of Nandani River Basin, Western Maharashtra, India

Soil and water conservation measures are necessary to know the sequence of dry and wet periods along with the onset and withdrawal of rainy season for successful agricultural management and planning. Daily observed rainfall (1998–2017) are analysed to compare and contrast the large-scale duration characteristics of rainfall over semi-arid region. This paper analyses the trend of rain spell frequency in terms of duration by using standard statistical methods. The analysis has been carried out at four locations, namely Kadegaon, Karad, Vaduj and Vita, in and nearby the Nandani river basin. In the Nandani river basin, the duration of dry spell varies from 69 to 119 days, and wet spell varies from 34 to 87 days. In this study, the rain spells were classified into low, medium, high, very high and extreme rain spells. The important results have been found through analysis of this study. These results are: the spells were examined only for the monsoon season (June–October) because all the above categories of rain spells occur only in this monsoon season. The rain spells help to coordinate various activities, like water effect on crop growth, supplementary irrigation, water release schedule and so on. The maximum dry spell (DS) was 119 days at Vaduj in 2003 and minimum 69 days at Kadegaon in 2006. The maximum wet spell (WS) was 87 days at Karad in 2005 and minimum 34 days at Vaduj in 2003.