Climatic fluctuations in Durg district of Chhattisgarh

N.K. Baghmar¹*, S.K. Yadav², C.R. Ratre³

¹Reader, SOS in Geography, Pt. Ravishankar Shukla University, Raipur (C.G.)

²Ex. Research Scholar, SOS in Geography, Pt. Ravishankar Shukla University, Raipur (C.G.)

³Technical Officer, SOS in Geography, Pt. Ravishankar Shukla University, Raipur (C.G.)

ABSTRECT:

The present study aims to identify the climatic fluctuations and changes and evaluate the water balance and calculate the moisture index for climatic types of the Durg district of Chhattisgarh. The study is based on secondary data. The analysis of monthly rainfall data of 12 stations for a period of thirty three years i.e. 1972-2005 and average monthly potential evapotranspiration data of Durg station. These data are used to calculate water balance of the region to know the actual climatic condition, aridity and moisture indices occurs (Thornthwaite and Mather 1954).

A trend of decline and high fluctuation of rainfall amounts during the last few decades have affected the agricultural production adversely. Such situation necessitates a detail study of the different aspects of agro climatology of the region,. The climatic fluctuation shows the alarming situations for the cultivators in the region . Every year the climatic situations are forced changed. There for the predictability about agricultural production and climatic conditions are not possible.

INTRODUCTION:

Climate can be thought of as an average of the weather over a period of years or decades. The climate of a region is never identical from on year to the next, the frequency of certain types of weather events varies from year to year and decade to decade. A climate change can be defined as a change in the average climate from one averaging period to the next. Some of these fluctuations in climate are due to process that is internal to the climatic system.

Objectives:

The present paper aims to Identify the climatic fluctuations and changes, Evaluate the water balance in Durg district of Chhattisgarh during 1972 to 2005 and calculate the moisture index for climatic types of the study area.

Study Area:

Durg district extends over an area of 87⁰1.80 Km2 between 20⁰23’ N 22⁰2’N and 80⁰46’E to 81⁰58’E on the middle part of Chhattisgarh. The area known as rice bowl of the state.

Data and Method:

The study is based on secondary data. The analysis of monthly rainfall data of 12 stations for a period of thirty three years i.e. 1972-2005 and average monthly potential evapotranspiration data of Durg station. The data were also obtained from the regional metrology office Nagpur.

These data are used to calculate water balance Bookkeeping procedure, actual evapotranspiration and climatic condition of every month, moisture indices and aridity index. For the calculation of above parameter (Thornthwaite and Mather 1954). Methods are adopted. Further it is redesigned by the Prof.V.P.Subrahmaniam for Indian conditions. A soil type’s map obtained from NATMO district planning map of the Durg district (Fig.1). The types of the soil are used to calculate the field capacity i.e. soil moisture retention capacity of these four types of the soils has been assumed to be 150,200,250 and 300 mm respectively ( Thornthwaite and Mather 1957).

Analysis and Result:

Such a situation needs a detail study of the different aspect of climatic conditions of the region. The present study is on attempt in this direction.

A. Rainfall:

Average annual rainfall in the district varies 780.16 mm. at Saja in the north western part to 1257.40 mm at Gurur in southern part of the district. The area received average annual rainfall 1052.00 mm. About 90.1 of the annual rainfall is received in the period of June to September. The withdrawing monsoon provides some rain in October also (nearly 4% of the annual total). The rest of the months go almost dry. The rainfall varies from year to year, coefficient of variation ranging from nearly20.49% to more then 39.41%.The highest variability is found in Dondi block (fig.2).

B. Trend of Rainfall:

Regression line for the rainfall shows the negative trend in the study area. Out of twelve station all of have negative trend it varies 2.48 cm. in saja to 0.57 annual at Dhamdha development block (Fig.3)

C. Water Balance:

The elements of water balance obtained from the book keeping procedure when plotted graphically against the month of the year present a clear picture of the marches of not only the water surplus and water deficiency through the year but also reveal the accumulations and depletions of soil moisture for the purpose of illustration. The water balance diagram is presented in (Fig.4 ) for twelve stations of Durg district.

Water Surplus:

Climatically this district has an annual water surplus at 161 mm accumulated essentially during August and September. But it is varies lowest from Berla 68mm. to highest 460 mm at Grurur block.

Water Deficit:

The condition of water deficit prevail form October to June. It is slightly amounting to about 10mm in October but goes on increasing and exceeds 200mm at May. In June again it is only slight at some station even zero. The annual water deficit ranges from 724 mm at Gurur to 812.5 mm at Saja.

D. Moisture Index and Climatic Fluctuations:

Moisture Index ( Im ) represents the percentage ratio of the difference between water surplus and water deficit to the potential evapotranspiration. It may be expressed as below.

Im = S-D X 100/PE

Thornthwait has assigned primary emphasis to the moisture index in climatic classification. A moisture index value of zero separates the dry and moist climates. Positive value are found in moist climates and negative values in dry climates. According to Thornthwait’s 1955 climatic classification, the moisture indices from the different climatic types or moisture regions are as under (Mather and carter 1966)

Climatic type	Moisture index -%
Peri humid	100 and above
Humid (Four sub types)	20-100
Moist sub humid	0-20
Dry sub humid	-33.3-0
semi arid	-66.6- 33.4
arid	-66.7 above

E. Climatic Fluctuations (Shifts):

In most of years of the study period water deficit exceeded water surplus due to which moisture indices indicate negative values. The total area divided in to dry sub humid climate to semi arid climate (Fig.5). The area falls and semi arid climate comes under the rain shadows area around one third area of the district comes under this category. Rest of the area comes under dry sub humid climatic conditions.

The station wise yearly climatic fluctuations of the district discuss below (Fig.6)

I. Dry sub humid climatic Region :–

1. Durg – situated on the Middle Western border of the district Durg receives an average annual rainfall of 109.55cm. The field capacity of this place is assumed to be 300 mm Ims rang form – 61.93% (1989 to 3.67% in 19999. The average 1m is 31.14 which indicate dry sub humid. Durg experienced dry moist humid climate in one year. Humid climate in one year, and around 200 year it have dry sub humid climate. Around 13 year the station experience semi and climate.

2. Patan – It lies in the south eastern part of the district and receives an annual rainfall at 122.46 cm. The field capacity of this place is assumed 300mm in 1994 the Patan experience in 0.24 which is humid. It is further increase -43 .11 in 2001-2002. The ….negative limit of 1m is -4.54 % (1992). The area comes under dry sub humid climate (1m-23.93%) out of thirty two year of calculation. one year facing (2 moist sub humid climatic, nine year (C) dry sub humid climate and five year of these are facing (D) semi and type of the climate.

3. Balod – Situated on the southern part of the district. Balod receives on average annual rainfall 104.15cm with the field capacity of the soil is 200 mm , The average in indicates ranges from -2.05% (1990) to -4.79 % (1973) The average 1m indicate of Balod is 33.34% which comes under C Dry Sub Humid climate. The fluctuation of climate ranges 7 year for dry sub humid and 11 year for semi arid.

4. Dondi– Laying in the southern part of the district. This area receives average annual rainfall 108.00cm. With the field capacity of soil is 200 mm an average 1m indices -32.24% which comes under dry sub humid climate. The fluctuation recorded 7 year for Dry Sub Humid climate 11 year for Semi arid and rest of the lime it varies between Dry Sub Humid to most Sub Humid type of climate.

5. Dondi Lohars – Located south-western part of the district. The Dondi Lohara station receives an average annual rain fall 111.61 mm with the soil field capacity assumed 150 mm. The average 1m indices of this station are 27.95% which comes under Dry Sub Humid climate. The 1m indicates ranges from lower -24% in 1998 to -50.46% in 1988) The area experiences one year Sub Humid climate, 11 year Dry Sub Humid and 8 year for Semi arid climate.

6. Gurur – It lies south eastern part of the district with an average annual rainfall of 125.24mm. Field capacity of Soil is assumed 250mm in this area. The average 1m indices come – 22.11 this comes under the Dry Sub Humid climate. The 1m indices vary -2.11 in 2003 to 53.83 in 2002. The climate of this station fluctuation 3 year for moist Humid, 9 year for Dry Humid, 6 year for Semi arid climate.

7. Bemetara – Located northern part of the district. This area receives 112.75 cm. annual rainfall with 250 mm field capacity of the Soil. Out of 32 Years of observation the 1m ranges -3.17 in 2003 to -55.20 in 1974. This station comes under Dry Sub Humid climate (-30.27% 1m) The station experiences 3 year for moist sub humid climate, 15 year for Dry Sub Humid climate and 16 year for Semi arid type of the climate, The govt. of Chhattisgarh declared this area in to drought prime area.

8. Nawagarh – The upper northern part of the Bematara, located Nawagarh station. The station receives an average annual rainfall of 107.31 cm with the field capacity of Soil is 250mm . The area comes under the Dry Sub Humid climate. The lowest 1m receives -3.55% in 1999 and the highest 1m recoded -50.28% in 1987, Nawagarh station experiences fluctuation of climate Nine year for Dry Sub Humid climate, 11 year for Semi arid and last of the year is bounded from moist sub humid to Dry Sub Humid climate.

II. Semi Arid Region :–

1. Dhamdha – The Dhamdha station located middle part of the study area. The area receives average annual rainfall with the 1m indices -40.29% it comes under of they are around 12 year it is facing semi arid climate, 4 year Dry Sub Humid climate and rest of the year it is border of Dry Sub Humid to most Sub Humid climate climate.

2. Gunderdehi – The Gunderdehi located south eastern part of the district. The average annual rainfall receives 103.9 cm and water holding capacity of soil is 300 mm. The station experiences 6 year for Dry Sub Humid climate, 10 year for Semi arid and rest of the year the 1m indices touched Dry Sub Humid climate.

3. Berla – The Eastern part location of the station receives 78.16 cm average annual rainfall with 300 mm for field capacity. The average 1m indices show the Semi arid climate for the Berla station.

4. Saja – Located north western part of the district. It comes under the semi arid type of the climate. Hence average annual rainfall 87.85 cm with 250 mm field capacity of the soil out of thirty two year of 1m indices the station experience 4 year for Dry Sub Humid climate 12 year for semi arid.

RESULT:

The following conclusion were made after calculation of water deference and moisture indices –

1. The area holding moist sub humid to Dry Sub Humid climate before 1950. (District Gazetteer Durg 1945 p.p. 7-8)

2. The present study showed the fluctuation of climate toward Dry Sub Humid to Semi arid.

REFERENCES:

1. Marther J.R., “Climatology Fundamentals”. NewYork, MC Graw hills Book Co. 1974

2. Marther J.R. and D B Carter “Climatic Classification for Environmental Biology”, Puabli. Climeto l lab of climatology 19(4) 305-395,1966

3. Penman H C Procee. Royal. Soc. Series A 193. P. 120-145, 1948

4. Subrahmaniyam V.P. “ Water Balance and its applications” (Ardhra univ.-Press Waltair), 1982

5. Thornthwaite CW and JR Mather “ The Water Balance” Pub. Climatol. Lab. of Climatology” 8 (1)104, 1955

6. Thornthwalte CW and JR Mather “Instructions and tables for Computing Potential evapotranspiration and Watar Balance Publ. Lab of Climatol. 10, 244.s, 1957

7. Wilm HG and “Trans. Am. Geophys 25, 686-693 Thornthwaite Cw 1944

Received on 25.08.2011

Accepted on 12.09.2011