Keywords

Meteorological drought, Rainfall, Deviation index, Solapur.

INTRODUCTION

Agriculture is one of the most important activities, engaging more than 70 percent populations in India. Indian economy is inextricably linked with the agriculture and its prosperity is entirely dependent on the amount of rainfall received. The rainfall is one of the most important and governing factor in the planning and operation strategies of any agricultural activity for any area. The rainfall patterns have high intra seasonal variability. Also, there is high spatial variability of rainfall over districts of Maharashtra [1,2]. It is very important to study the changing trend of annual precipitation to analyze the cycle of rainfall and drought [3]. The changing pattern of rainfall is also investigated by computing seasonality Index of rainfall. The relative seasonality of rainfall represents the degree of variability in monthly rainfall throughout the year [4-7]. Factors effecting runoff is evapotranspiration and infiltration [8-12].

Drought is a threat to the food security and human mortality all around the world. On an average 18% of the geographical area of India is vulnerable to droughts. Meteorologically ± 19% deviation of rainfall from the long term mean is considered as normal in India. Deficiency in the range of 20 to 59 % represents moderate and more than 60 % severe drought [13].

Solapur is an administrative district of Maharashtra in India. It lies in between 17° 10' to 18° 32' north latitudes and 74° 42' to 76° 15' east longitudes and covers an area of 14,895 sq. km. It is divided into 11 tehsils and total population of 43, 15, 527 as per 2011 census. The climate of Solapur district is dry as daily mean maximum temperature range between 30°c to 37°c and minimum temperature range between 18°c to 21°c with the highest temperature about 45°c in the month of May.

The annual average rainfall is 561.78 mm (last one decade) in Solapur district. Rainfall is uncertain and scanty. The monsoon period is from the second week of June to end of September bringing rains from the south-west monsoon. The major river in the district is Bhima and Sina, Nira, Mann and Bhogawati are its tributaries. The Bhima and Sina run towards the southeast from north-west. The Nira and Mann flow towards nearly east. During the dry season all the rivers are nearly dry. The district is situated on the south east fringe of Maharashtra state and lies entirely in the Bhima and Seena basins. The whole of the district is drained either by Bhima river or its tributaries.

MATERIALS AND METHOD

The present study is based on the rainfall data collected for sixty years from Agricultural Statistical Information State, Socioeconomic Review Solapur District. Yearly intensity of drought is determined using the criteria suggested by IMD (1971) which is based on percentage deviation of rainfall from its long term mean and it is given by (Eq.)

Where Di is the percentage deviation from the long term mean,

Pi is the annual rainfall, mm and μ is the long term mean of annual rainfall, mm.

RESULTS

Solapur, district of Maharashtra falls in semiarid region and average rainfall is 553.01 mm (previous 6 decades). Interpretation of rainfall data of 6 decades is carried out for analysis of drought intensity in the area. According to deficiency index, every years is categorized into three category e i. No drought (M0), moderate drought (M1) and severe drought (M2) (Table 1). Rainfall trend (Fig 1) and table 2 shows that maximum years (48 years) have no drought (±19 % deficiency from long term average rainfall). Ten years have moderate drought (-20 to -59 % deficiency from long term average rainfall) and severe drought has occurred only during three years. This shows that Solapur has a normal rainfall.

Table 1: Drought codification based on percentage departure of rainfall from normal value

Table 2: Yearly intensity of drought for Solapur

Figure 1: Yearly rainfall trend for Solapur, Maharashtra

During 60 years of rainfall trend of Solapur district, one heavy rainfall and one high drought years has occurred in every decade (Fig. 2). Difference between adjacent heavy rainfall and high drought is around eight to twelve years. Frequency of M0, M1 & M2 is shown in Fig. 3 which clearly shows M0 to be very high and M1 & M2 are comparatively very low.

Figure 2: Drought analysis for Solapur, Maharashtra

Figure 2: Frequency of drought intensity for Solapur, Maharashtra

In spite of having normal rainfall (M0), Solapur is facing water scarcity problem in maximum part of year due to the maximum runoff of rainwater and over exploitation of ground water. The current situation, demands to prepare a management plan for water resources development.

CONCLUSION

By the interpretation of rainfall data and drought frequency, Solapur has a normal rainfall which fluctuates in between 442.41 to 663.61 mm annually and no drought in maximum years. Moderate and severe droughts have found in few countable years, which is a natural trend. The results suggest for preparation and execution of proper plan of rainwater harvesting and artificial recharging structures.

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