Spatio-temporal analysis of rainfall patterns and their climatic implications in Mahanadi basin of Chhattisgarh, India

Introduction

Rainfall is a natural phenomenon that provides us with water that sustains life on the earth. According to one estimate, the amount of total water in the world is approximately 1.386 billion km3.Precipitation is the primary source of water for all living organisms, resulting in the maximum contribution of water. The world's average annual rainfall is around 1000mm, but it is dispersed across the globe. Southeast Asia's monsoon region is where the equatorial zone and the rainy season areas have the highest rainfall. To understand the spatial and temporal variations of rainfall, it is crucial to study the distribution of rainfall over time and space. It aids in comprehending the hydrological balance at a regional level and water management in agriculture. Activities profoundly depend on micro-level rainfall, variability analyses of rainfall in Indian context require urgent and systematic attention due to important promising suggestions on fresh agriculture, water availability etc. Planning and managing water resources are crucial. Modifications in rainfall trend, amount variability and its spatial and seasonal distribution critically modify the river runoff pattern and regimes (Gosain et al. 2006) [1] soil moisture, (Jain and Kumar, 2012) [2] , frequency of rainfall extremes, ground water reservoirs, including droughts, floods and and agricultural productivity vegetation activity and cropping pattern Dore, 2005 [3] and Kumar et al. 2010 [4] . The most important and variable climatic parameter in the semi-arid tropics, according to interpretation, is rainfall. Trend and variability study of rainfall in Indian context require urgent and systematic attention due to important possible suggestions on agriculture, fresh water availability, food security and primary economic activities, etc. Jain and Kumar 2012 [2] . According to reports, India's most pressing issues are climate change and rainfall patterns. Due to number of factors that influenced directly or indirectly the rainfall pattern of any regions may change. It also becomes very important to know the distribution of rainfall over an area. This one factor not only helps in knowing the climatic condition but also helps in understanding natural vegetation, soil and also helps in selecting the crop. The quantity of rainfall an average, annual and seasonal or monthly scales is key elements affecting the water availability. The concentration of precipitation in time is also play a decisive role in agriculture production system. The analysis of changing rainfall distributions from the long term data helps to know the cycle of rainfall pattern across the particular area that also helps in knowing the future planning in agriculture and allied sectors.

Materials and Methods

Study Area Chhattisgarh is located in the east-central part of India, between the latitude of 17º 46´N -24º 5´ N and the longitudes of 80º

Results and Discussion

The rainfall variability, in terms of trend analysis, rainfall seasonality index and Precipitation concentration index was worked out for 10 parental districts they are Bilaspur, Korba, Mahasamund, Kabirdham, Dhamtari, Raigarh, Janjgir-Champa, Rajnandgaon, Raipur, Durg viz., monthly, seasonal and annual across the Chhattisgarh.

Trend analysis of annual rain fall for Bilaspur district

The outcome of trend analysis of rainfall workout for Bilaspur district is presented in (Table 3.1 and depicted in Fig. 3

Trend analysis of annual rainfall or Korba district

The outcome of trend analysis of long term data of rainfall recorded for Korba district is presented in (Table 3.1 and depicted in the Fig. 3.1). It is quite clear from the table the 1920.2mm was maximum rainfall with the minimum rainfall of 751.5mm in the year 2000. The average annual rainfall of Korba district was 1281mm during last 38 years. A significant decreasing trend of rainfall was recorded in the district with decrease rate of 8.389mm per year.

Trend analysis of annual rainfall for Mahasamund district

The outcome of trend analysis of rainfall workout for Mahasamund district is presented in (Table 3.1and depicted in Fig. 3.1) indicates that district received a maximum rainfall of 1582.1mm in the year 1985 and the lowest rainfall of 640.1mm in the year 1996, with the average annual rainfall of 1105.2 mm during the last 38 years. The district rainfall data is subjected to trend analysis and outcome indicates increasing significant trend at 5% level for annual rainfall in linear trend.

Trend analysis of annual rainfall for Kabirdham district

The results of trend analysis of rainfall of Kabirdham district carried out with the help of last 38 years data is presented in (Table3.1 and drawn in Fig. 3.1). It is quite clear from the table that the highest rainfall was 1589.1mm in the year 1985, while in the year 2000 realized lowest amount of rainfall i.e. 687.4.mm with anaverage rainfall of 970.5mm. The result showed significant decreasing at 5% trend of rainfall on annual basis at the rate of 1.9mm per year. Contrast to the different findings Devendra showed that rainfall trend show large variability and reported nonsignificant stable trend and significant increasing trend at 10% significant level.

Trend analysis of annual rainfall for Dhamtari district

The rainfall data of Dhamtari district was shown in (Table 3.1 revealed that district received a maximum rainfall of 1320.4 mm in the year 2006 and the lowest rainfall of 770.5 mm in the year 1987, with the average annual rainfall of 1129.1 mm during last 38 years. The district rainfall data was subjected to trend analysis and outcome indicates nonsignificant increasing trend of annual rainfall in linear trend graph (Fig. 3.1).

Trend analysis of annual rainfall or Raigarh district

The outcome of trend analysis of long term data of rainfall recorded for Raigarh district is presented in Table 3 [7] that Raigarh district showing significant decreasing trend of rainfall.

Trend analysis of annual rainfall for Janjgir-champa district

The effect of trend analysis of long term rainfall data of Janjgir-Champa district is presented in Table 3.2 and depicted in Fig. 3.2). The maximum amount of rainfall was obtained in the year 1983 i.e. 1773.1mm and the lowest rainfall was 782.4 mm in the year 2000, with the average annual rainfall of 1193.5 mm during the 38 years. The district rainfall data is subjected to trend analysis and outcome indicates non-significant stable trend of annual rainfall in linear trend graph.

Trend analysis of annual rainfall for Rajnandhgaon district

The rainfall data of Rajnandhgaon district was shown in Table 3.2 revealed that district received a maximum rainfall of 2506.6mm in the year 1993 and the lowest rainfall of 769.8mm in the year 2009, with the average annual rainfall of 1179.2 mm during the 38 years. The district rainfall data was subjected to trend analysis and outcome indicates nonsignificant decreasing trend of annual rainfall in linear trend graph (Fig. 3.2).

Trend analysis of annual rainfall for Raipur district

The effect of trend analysis of long term rainfall data of Raipur district is presented in Table 4.1(c) and depicted in Fig. 4.15. The maximum amount of rainfall was obtained in the year 1994 i.e. 1654.9mm and the lowest rainfall was 707.8mm in the year 2009, with the average 1136.7mm annual rainfall during the last38 years. The district rainfall data was subjected to trend analysis and outcome indicates non-significant stable trend of annual rainfall in linear trend graph (Fig. 4.15). Contrast to one finding Swain et al. 2015 reported that there is a decreasing significant trend in Raipur.

Trend analysis of annual rainfall for Durg district

The outcome of trend analysis of long term data of rainfall recorded for Durg district is presented in (

Conclusion

On the basis of our study the following important outcome can be drawn: There was significant increasing trend of rainfall in Dantewada and Mahasamund districts at the 8.918mm per year respectively. While the districts Korba and Jashpur-Nagar reported significant decreasing trend of rainfall at the rate 8.3mm, 16.3mm and 1.9mm per year. The Seasonality Index for mean annual rainfall indicates that Mahasamund, and Raipur showed extreme seasonality which indicates that the rainfall in a year is in between 1-2 months and the values for these districts ranges from 1.2 to 1.3. The Seasonality Index for south-west monsoon showed that Korba, Janjgir-champa having the maximum value with more than 0.40 which indicates that there was short-drier period in the season. The Precipitation Concentration Index for the annual rainfall value indicates that the Chhattisgarh state comes under high precipitation concentration area with a strong irregular distribution of rainfall whereas, Drug district observed the maximum value of Precipitation Concentration Index i.e in between 28-30. The Precipitation Concentration Index for the south-west monsoon indicates that Korba, Mahasamund, Janjgir-Champa, and Rajnandhgaon show the maximum values of Precipitation Concentration Index that was between 10.2-10.8 which means that the precipitation concentration was of moderate over this period. Whereas, the rest of the districts having uniform rainfall distribution with low precipitation concentration throughout the southwest monsoon.

Suggestions for future research work

Based on the present study the following suggestion can be taken up for future research. This study can be drawn sized up to block and village level for better output.

References

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2. 1: Annual precipitation concentration index from (1981-2018) of Bilaspur, Korba, Mahasamund, Kabirdham, Dhamtari of Chhattisgarh state
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