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Demographic dependencies on drainage condition: an assessment for some parameters.

Introduction

All over the world maximum portion of people lives surrounding the rivers. It influences our life in different ways. Therefore, Clarke (1965), Zelensky (1971), Chandana (1986) etc. rightly remarked that surface drainage and subsurface water condition determine the distribution and density pattern of population. As drainage has strong linkage with economic pattern, indirect influence on demographic pattern like literacy is very strong. Drainage is not only important for supplying water for irrigation and related economic activities but it also regulates morphological landscape, soil fertility, fishing etc. All these are directly linked with lives and livelihood of the people.

Objective

* To find out the pattern of drainage density, drainage frequency and drainage texture of the study area

* To assess the pattern of allometric growth and trend of growth of some selected demographic parameters namely total population, population density, literacy rate, cultivator, rural population etc.

* To articulate correlation demographic dependencies on drainage conditions.

Database and Methodology

Population data have collected from Census of India for different years and drainage information has collected from Toposheets of Survey of India, Satellite imageries.

For analysis of drainage the following equation have used.
Parameter Formula Reference

Drainage Density (Dd) Dd = [summation]L/A L Horton, 1932
 = Length of the rivers; A
 = Area

Stream Frequency (Df) Df = [summation]N/A N Horton, 1932
 = Number of river
 segments A

Drainage Texture (Dt) Dt = N[mu]/P N[mu] = Total Horton, 1945
 number of stream in all
 segments; P = Basin
 perimeter


Allometric Growth of population parameters since 1961 to 2001 has measured by power regression. Trend of population growth has measured using straight line equation: y = a + bx. Product Moment Correlation Coefficient has done to show the control of drainage on demographic parameters.

Study Area

Birbhum district is one of the physically diversified, rivere districts of West Bengal. This district is located in between 23[degrees]32'30"N to 24[degrees]35"N latitude and 87[degrees]05'25"E to 88[degrees]01'40"E longitude. Total area of this district is 4545 sq. km. Total population is 3015422 persons and density is 663 persons/sq.km. More than 70% people lives in rural area and more than 60% people is directly or indirectly engaged with agricultural activities.

[FIGURE 1 OMITTED]

Drainage Condition

A part of dendritic drainage pattern is existing in this district. Most of the rivers are flowing toward east and south east maintaining the natural topographical slope to meet with mighty Bhagirathi (Fig. 2). The main rivers of the district are Mayurakshi, Dwarka, Brahmni, Bansloi, Kopai, Brakeswar etc. Seasonal climatic regime controls the seasonal behaviour of most of the rivers. In the western portion of the district this seasonal characters are more prominent than eastern portion. Elevated topographical conditions in the west initiated numerous small stream segments and it encourages greater concentration of stream frequency, drainage density and drainage texture. All the drainage components have become sparse toward east. But wider channel, low slope etc. in the eastern portion of the district have increased the chance of permanency, water supply potentiality etc. The quantitative pattern of the drainage parameters has described in table 1 and figures 3, 4 and 5.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

Demographic Parameters and Spatial Trend of Growth

Demographic parameters include a lot of population related components but as per the availability of data and purpose of the paper 1.Total Population, 2. Density Pattern, 3. Literacy Status, 4. Agricultural Population, 5. Rural population have incorporated. Power regression and least square regression equations have employed to assimilate the components individually since 1961 to 2001. Dasgupta, A and Chokroborty, K, 2010, successfully employed power regression to assimilate temporal pattern of population data in different blocks.

The spatial status of allometric growth of different demographic parameters, trend values of those same parameters have described in table 2. Figure 6 to 9 describe the spatial scenario of allometric growth pattern of demographic parameters.

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

[FIGURE 9 OMITTED]

Result and Discussion

Drainage has control on different economic parameters which strongly influence on population density, distribution, literacy, pattern of rural population etc. The natures of the control of drainage on different demographic parameters are different. As so many other demographic determinants are concerned, it is quite different to describe absolute and significant relations. But the analysis of correlations has provided some distinct spatial and temporal trend.

In the westerns blocks like Rajnagar, Khoirasole, Dubrajpur etc. drainage frequency, density and texture are very high and in consequence with that temporal growth of total population, density, rural population etc. are losing (table 2 and figure 6, 7, 8 and 9). On the contrary, the blocks toward east show either balancing or gaining growth of the said demographic parameters. Wider river channel, greater rate of permanencies, spreading of canals from the main rivers like Mayurakshi, Dwarka etc. help to irrigate the agricultural land and multiplicate agricultural crops and productivity.

Drainage density, frequency and texture have negative correlation with selected demographic parameters. But all the relations are not significant in 95% level (vide table 3). High drainage frequency, density etc. dissect the land, make the landscape erosive, frequent loss of top soil force to decline the fertility level and thereby reduces agricultural productivity of the agriculturally dependent settlements. Seasonal character of the rivers does not supplement the long lean rain fall period and it again does not encourage crop multiplications.

Interestingly rural population growth since 1961 to 2001 is losing in character in the western blocks. Unfavorable characters of the drainage and associated consequences on soil, agriculture etc. have discouraged people to live and maintain their livelihood on those blocks. Even some of the blocks having low drainage frequency and density also register losing cultivator population. It is due to apathy on marginal agricultural return, steady rise of the cost of agricultural inputs but less growth of output cost, more interest on white collar jobs etc.

Conclusion

In the rural Bengal hydrological potentiality of the rivers supports good agriculture and therefore always allures people to concentrates there. Intensification of relation between drainage and crop chart is required in agriculturally dependent regions. In most of the blocks of this district high water consuming paddy culture is practiced by the peasants. But the western blocks are not capable to supply water during non monsoon periods. So boro cultivation is not practicing properly due water scarcity in these blocks. Crop chart moderation in concomitant with hydrological potentiality, surface water availability in the river segments may yield greater resources for better survival. Moreover, soil conservation practices through crop chart moderation may encourage productivity level. Earlier it is mentioned that potent rivers assure greater population concentration, increase the level of cultivability, better livelihood pattern etc. But qualities of river regime manipulate all the demographic parameters. Spatial pattern of demographic parameters in relation with drainage spatiality in this district manifests all kinds of diversity.

References

[1] Dasgupta, A and Chokroborty, K (2010): Spatial Growth Dynamics of Literate Population and its Relationship with Socio-economic Parameters: A study of Birbhum district, West Bengal, Indian journal of Landscape Systems and Ecological Studies,vol.32, no. 2, pp 309-318.

[2] Chandana, R.C. (1986): Geography of Population, Concepts, Dynamics and Patterns, Kalyani Publishers, Ludhiana, New Delhi, Noida (U.P.), Hyderabad, Chennai, Kolkata, Cauttack. P. 529.

[3] Clarke, John I. (1965): Population Geogrphy, Pergamon Press, Oxford.

[4] Cole, J.P. and King, C.A.M. (1968): Quantitative Geography, John Wiley and Sons Ltd., London.

[5] Government of India (1961, 1971, 1981, 1991, 2001): Census of India

[6] Horton, R.E. (1932): Drainage Basin Characteristics. Trans. Am. Geophys. Union, 13: 350-361.

[7] Horton, R.E. (1945): Erosional Development of Stream and their Drainage Basins: Hydrological approach to quantitative morphology. Geol. Soc. Am. Bull, 56: 275-370.

[8] Zelinksy, W. (1971): The Hypothesis of Mobility Transition, Geographical review, 61(2).

Dr. Swades Pal and Krishna Gopal Ghosh

Assistant Prof., Research Scholar, Deptt. of Geography, Rampurhat College, Rampurhat, Birbhum, West Bengal, India

E-mail: swadeshpal82@yahoo.in, krishsansegeo@gmail.com
Table 1: Block wise status of drainage parameters.

Name of the Drainage Drainage Drainage
Block Density Frequency Texture

Nalhati 15-35 6-26 0.2-0.5
Murarai 5-25 6-10 0.1-0.3
Mayureswar 15-55 2-22 .1-.8
Rampurhat 15-65 2-38 .2-.8
Md. Bazar 35-75 10-38 .4-.9
Sainthia 35-45 6-10 .2-.3
Dubrajpur 15-115 2-54 .2-1.3
Rajnagar 5-115 6-54 .2-1.3
Suri 35-115 6-38 .2-1.3
Khoyrasole 5-85 2-42 .2-1.1
Bolpur 15-35 6-14 .2-.4
Labpur 5-45 2-10 .1-.3
Nanoor 5-45 2-14 .1-.4
Illambazar 5-45 2-14 .2-.8

Table 2: Demographic allometry and trend.

C.D Blocks Total Rural Literate
 Population Population Population

 AG LS AG LS AG LS

Nalhati 1.068 0.997 1.106 0.988 1.351 0.998
Murarai 1.086 0.997 1.152 0.996 1.344 0.998
Mayureswar 0.877 0.997 0.992 0.994 1.139 0.998
Rampurhat 1.034 0.997 1.002 0.999 0.554 0.946
Md. Bazar 1.142 0.931 0.955 0.991 1.142 0.998
Sainthia 1.157 0.974 0.980 0.980 0.958 0.971
Dubrajpur 0.847 0.997 0.885 0.995 0.864 0.990
Rajnagar 0.712 0.995 0.715 0.995 0.981 0.996
Suri 1.032 0.998 0.994 0.998 0.765 0.895
Khoyrasole 0.860 0.977 0.787 0.997 0.977 0.994
Bolpur 1.186 0.957 1.025 0.997 0.726 0.910
Labpur 0.867 0.989 1.124 0.996 1.034 0.996
Nanoor 0.789 0.909 1.04 0.993 1.034 0.999
Illambazar 1.046 0.993 1.072 0.997 1.267 0.999

C.D Blocks Density of Cultivator
 Population

 AG LS AG LS

Nalhati 1.076 0.996 0.754 0.783
Murarai 1.094 0.995 0.619 0.554
Mayureswar 0.884 0.977 1.241 0.888
Rampurhat 1.041 0.994 0.802 0.92
Md. Bazar 1.146 0.923 0.36 0.315
Sainthia 1.169 0.978 1.245 0.97
Dubrajpur 0.853 0.995 1.601 0.925
Rajnagar 0.682 0.964 0.635 0.99
Suri 1.040 0.996 1.418 0.69
Khoyrasole 0.879 0.921 0.641 0.849
Bolpur 1.201 0.961 0.918 0.97
Labpur 0.947 0.873 1.156 0.954
Nanoor 0.876 0.906 1.035 0.977
Illambazar 1.051 0.992 1.12 0.94

Table 3: Correlation matrix between drainage parameters and
demographic parameters.

 Total Rural Literate Density of
 Population Population Population Population

Drainage r -.378 -.516 -.348 -.477
Density t .183 .059 .223 .085
Drainage r -.283 -.386 -.302 -.531
Frequency t .326 .173 .294 .051
Drainage r -.439 -.500 -.424 -.612
Texture t .116 .069 .131 .020

 Cultivator

Drainage r -.372
Density t .190
Drainage r -.415
Frequency t .140
Drainage r -.430
Texture t .125
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Author:Pal, Swades; Ghosh, Krishna Gopal
Publication:International Journal of Applied Environmental Sciences
Date:Feb 1, 2012
Words:1845
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