Bulletin of Arunachal Forest Research 22 (1&2) : 33-39, 2006.
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT
AIZAWL , MIZORAM ( INDIA )
Ramesh Chandra Tiwari
Department of Physics , Mizoram University, P.B.-190
Aizawl – 796 009, Mizoram (India)
ABSTRACT
The climatic conditions play an important role in every sphere of human
activities such as water supply, agriculture, forestry, tourism. Among the various climatic parameters viz. pressure, humidity, temperature, wind-speed,
rainfall etc. the rainfall assumes special significance as it affects not only
agricultural activities directly, but also the water supply in the hilly states like
Mizoram. The development of forest cover is very much dependent on the
amount of rain received by the area concerned, which in turn affects the environment as a whole. In the present paper an attempt has been made to
study the variation in the rainfall with temperature and also to correlate this
variation with the forest cover at Tuirini area in Aizawl district of Mizoram.
weather conditions of a particular area. The important climatic parameters are temperature,
humidity, sunshine hours, cloudiness, pressure,
rainfall, number of rainy days, wind velocity etc.
and any change in one parameter affects the
other either directly or indirectly. The climatic
conditions of a particular area are of great importance as they control a variety of human activities like tourism, agriculture, water-supply etc.
Any change in the climatic conditions also affects the living organisms by imbalancing the
ecology of the physical environment.
INTRODUCTION
Mizoram, one of the eight north east
Indian states is located between 200 15’ and 230
30’ N and 92 0 16’ and 93 0 26’ E. (
Pachuau,1994).The tropic of cancer i.e. 23030’
N latitude divides the state in almost two equal
parts. The Aizawl District in Mizoram also lies
on the tropic of cancer. Mizoram assumes strategic importance as it has international boundaries with Myanmar (Burma) in the east and
Bangladesh in the west. The state is also bordered by Manipur and Assam on north and
Tripura on west. The weather of the state is highly
affected due to any cyclonic development in the
Bay of Bengal because of its short aerial distance from the ocean system. The state receives
quite a sizable amount of rainfall not only during
the monsoon season, but also as and when any
cyclonic system hits the area.
The climate of Mizoram is neither very
hot nor very cold, but moderate throughout the
year. The whole state falls under the directinfluence of south-west monsoon and receives
an adequate amount of rainfall. The climate of
the state is humid-tropical, characterized by
short winter, long summer with heavy rainfall.
The fluctuation in temperature is not much and
the highest temperature is observed during
The term climate refers to the regular
33
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT AIZAWL
DISCUSSION
May to July and starts decreasing with the
onset of monsoon. This fall of temperature
continues with the span of monsoon and becomes more evident with the retreating monsoon. The temperature becomes minimum in
December and January. In autumn the temperature ranges between 180 C to 250 C. During winter season, the minimum and maximum
temperature ranges between 110 C to 310 C.
During the last two decades, a substantial increase in average temperature has been observed, which may be due to global-warming.
The global warming is mainly due to non-sustainable model of development and mismanagement of environment ( Lalunmawia,2006).
The plot 1.1 describes the variation of
total amount of rainfall annually with mean maximum temperature for the period (1991-2000) at
Aizawl (Tuirini river). The plot shows the rainfall variation from 1984 to 2000 but the mean
temperature variation is shown for the period
1991-2000 due to non availability of data for
the period 1984-1990. The variations in the curve
gives interesting information. The curve shows
a continuous increase in annual rainfall from
1986 to 1990 except for the year 1989 where a
sharp decline is observed. From the period 1985
to 1996, there has been a periodic decrease in
the amount of rainfall for the years 1996, 1989,
1992 and 1995 although this trend does not
sustain further. The highest amount of rainfall
has been recorded in the year 1993 followed
by the year 1990 with its second highest
amount. The sharp increase and decrease in
rainfall is recorded in the year 1993 followed by
the year 1990 with its second highest amount.
The sharp increase and decrease in rainfall is
recorded during the year from 1992-‘93 and
1993-‘94 respectively. The rainfall has an approximately stable trend during the years 1996
to 1999. A substantial increase in the rainfall is
observed during the year 2000.
THE CLIMATE OF STUDY AREA
The present study has been carried out
at Tuirini river in Aizawl district of Mizoram.
The climatic conditions (Sinha,2001) of the study
area may be divided in to 4 seasons viz. winter
season (December to February), summer season (March to May), monsoon season (June to
September) and retreating monsoon season (October to November). The winter season is characterized by cold weather, occasional thunderstorms and frequent fog in the morning. During
the summer season, temperature is high with
occasional thunder-showers and clear sky in
morning times. In monsoon season, the weather
is cloudy and humid with low speed wind which
blows from different directions. Rainfall is heavy
in this season and the temperature starts falling
with the onset of south-west monsoon during
the beginning of June. In post-monsoon season,
the rainfall gets reduced drastically followed by
clear sky and decrease in temperature and
morning fog.
There is hardly any major variation in
mean maximum temperature; except for the
year 1999 the variation is between 1-20 C. But
the variation looks significant (about 30 C) if we
compare the mean maximum temperature for
the year 1991 with the year 2000. But the overall change in mean temperature certainly affects the amount of rainfall and its pattern.
The decline in the rainfall during 1996-2000 as
compared to 1990 and 1993 may be due to
rise in the mean maximum temperature as one
of the factors. Table .1 describes the mean temperature and annual rainfall data of Tuirini river
during 1991-2000, but the rainfall data is from
1984-2000.
In the present paper, the author has
attempted to study the variation in rainfall with
mean maximum and mean minimum temperatures and its impact on the forest cover.
34
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT AIZAWL
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT AIZAWL
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT AIZAWL
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT AIZAWL
Table. 1 : Mean temperature and annual rainfall data of Tuirini river ( from meteorological
register of Pushpak Project, Zemabawk (Aizawl) Mizoram)
Sl. No.
Year
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
Mean Maximum
Temperature (in 0 C)
N.A
N.A
N.A
N.A
N.A
N.A
N.A
25.37
24.30
25.12
26.37
25.62
26.25
25.15
26.30
28.30
26.05
Mean Minimum
Temperature (in 0 C)
N.A
N.A
N.A
N.A
N.A
N.A
N.A
16.47
16.12
15.40
16.87
19.35
19.37
16.85
17.75
17.85
16.22
The plot 1.2 describes the variation of
annual rainfall with temperature except that the
temperature along X-axis is the annual mean
minimum temperature. The variations in the
mean minimum temperature curve are more significant than that in the case of mean maximum
temperature. This curve interestingly shows that
the amount of rainfall was maximum for the year
1993, with lowest mean minimum temperature.
The temperature data gives few more important
informations which may have significance in the
explanation of the net decrease in the amount
of annual rainfall.
Annual Rainfall
(in cm.)
216.61
206.34
173.06
178.95
219.75
186.50
266.89
248.03
248.03
330.45
217.29
192.36
220.06
229.62
226.00
229.05
238.75
ture but the mean minimum temperature has
been deduced to increase by 2.180 C during the
period of 1996-2000 as compared to the period
of 1991-1995.
The plot 1.3 describes the bi-yearly
variation in the area of forest cover in Mizoram.
The curve indicates that the highest forest area
was recorded during the reporting year 1987 followed by the reporting year 1991, while the reporting year 1989 indicates the minimum forest
cover during the period 1987-2004. As per the
availability of data ( Lalnundanga, 2006), there
has been a sharp decline in the forest cover
during the period for 1997-2004 (Table.2). The
decline in the mean forest cover may be responsible for the increase in the mean temperature
values which in turn may be affecting the amount
of rainfall also ( De & De, 2001 ).
The analysis of the temperature data
shows that there has been a rise in mean maximum temperature by 1.80 C during the period of
1996-2000 as cam pared to the period of 19911995. Not only the mean maximum tempera-
38
ANALYTICAL STUDY ON VARIATION OF CLIMATIC PARAMETERS AT AIZAWL
ACKNOWLEDGEMENTS
Table 2 : Bi-yearly forest cover of Mizoram (
from State of Forest Report 1997, Survey of
India.*Directorate of Environment and forest,
Government of Mizoram).
Year
1987
1989
1991
1993
1995
1997
2004
The author is grateful to Dr.
Lalnundanga and Dr. F. Lalnunmawia, Department of Forestry, Mizoram University Aizawl for
fruitful discussions; to Shri Kalidas Upadhyay,
Department of Forestry, Mizoram University for
the data of forest cover and to Dr. R.K. Thapa,
Department of Physics, Mizoram University for
computer facilities .
Forest Cover (in Sq. Km.)
19084
18170
18853
18697
18576
18775
18338*
REFERENCES
Pachuau, Rintluanga (1994). Geography of
Mizoram. R.T. Enterprise Publication
Aizawl , Mizoram.
CONCLUSION
Anonymous ( 1997 ) . State of Forest Report ,
Survery of India-Ministry of Environment
and Forest, Govt. of India, New Delhi :
2-10.
From the above data analysis it may
be concluded as (1). There has been erratic
behaviour of rainfall during the period of study.
However, for certain years a periodic decrease
in rainfall is recorded but it does not continue for
the whole period. There has been an increase in
the mean maximum temperature by 1.80 C just
in 5 years which seems to be one of the reasons for erratic and non periodic nature of the
rainfall. This increase in mean max. temperature may be linked with overall decrease in mean
forest cover by 20.33 sq. km during the period
of 5 years. (2). The mean minimum temperature
shows an alarming rise of 2.180 C during the
period of 5 years. The analysis also interestingly shows that the highest mean annual rainfall coincides with minimum mean temperature.
However, mean rise in annual rainfall by a 27.83
cm is reduced for the period 1993-2000 as compared to that for the period 1985-1992. ( 3 ).
Irregular behaviour of rainfall and the rise in mean
maximum and mean minimum temperatures
may be due to a sharp decline in the forest cover
due to various activities like road construction,
lack of proper implementation of the forest acts
and absence of the monitoring body.
Lalnunmawia, F. (2006). Environmental and
Socio-economic Impacts of Gregarious
Bamboo Flowering in Mizoram. Proceedings of the U.G.C. sponsored State
level Seminar on Environmental Issues
in Mizoram : 2-06.
Lalnundanga (2006), Impact of Road Construction in Mizoram. Proceedings of the
state level seminar on Environmental
Issues in Mizoram : 7-13.
Sinha, N.K. (2001). Micro-watershed Management Study of Tuirini River. (Ph. D.
Thesis )North-Eastern Hill University,
Shillong.
De, Anil Kumar and Arnab Kumar De (2001).
Environmental Studies . New Age International Publications.
39