CHAPTER 4 PEDOGEOMORPHIC RELATIONS WITHIN THE BASIN 4.1. liitrodactioii Although Robinson (1949) had tried to establish a relationship between soil and landfbmn when he said 'the domain of pectology may come to engross a considerable amount of dynamic geolog/" the two have been frequently treated separately with only a token of awareness of one on the other and vice versa. The increasing awareness due to modem research has led to the understanding that soil and landfbrms are closely dependent upon one other as one influences the other. This has led to the evolution of a new discipline of 'pedo-geomorphology" or soil geomorphology (Conachar & Dalrymple, 1978). The drainage basin provides a convenient and ideal natural unit for the study of pedo-geomorphic parameters and their intenelationships. Within this unit the constituent parameters of landform, soil and drainage frequently show an organized relationship and without the knowledge of the basin in which they occur many of these evente become Incomprehensible (Sarkar, 1987,1994). A realistic correlation can only be drawn if the processes of soil formation are in equilibrium with the surface and sub-surface processes, acting on the slope (Norton & Smith, 1930; Furley, 1968 & 1969; Young, 1968; Jordan, 1974; Gen-ad, 1980;). It is often assumed that the meaningful relationship t}etween slope and soil properties becomes the result of any well-organised study. In the present work pedo-geomorphic study has been carried out to determine and assess the intricate inter-relationship among some of the parameters that include the slope, infiltration and soil properties, in the Balason basin of Darjeeling Himalaya. Collection of the soil samples were made from 50 different sites, randomly selected, within the study area during 1998-2000 (figure 4.1). Slope angle, soil colour, thickness of A horizon were measured at the sample sites. The rate of infiltration was measured with the help of galvanized steel tube (diameter of 20 cm) which was inserted into the soil with a head of water of about 6 mm. 59 Table 4.1 Pedo-geomorphic parameters obtained from 50 sample site SI. Locality Altitude Slope in Sand Silt Clay Organic Hygroscopic PH No. In metre Degree % % % matter % moisture % 1 Matlgara 121 1 32.51 42.76 24.73 0.89 1.13 6.5 2 Fulbari Pump house 190 1 56.25 21.11 22.34 2.05 2.63 6.5 3 Khaprail 164 1 27.45 46.03 26.52 1.87 2.18 6.4 4 SImulbarle P.O. 213 1.2 53.02 21.93 25.05 1.43 2.01 6.3 5 Panighatta Dispensary 255 1.5 40.03 25.13 34.81 3.3 2.83 5.8 6 Panlghatta Bridge 267 11.3 46.1 27 279 2.91 2.01 6.1 7 Rohlnl 220 1.6 43.64 20.14 36.22 3.71 3.29 5.3 8 Marlonbarle T.G. 229 1.3 55.37 25.26 18.37 1.22 1.77 6.4 9 Garldhura 246 1.7 50.31 31.76 21.75 2.07 2.03 6.5 10 Dudhia Khola 308 1.8 40.9 23.41 35.69 3.36 2.9 5.9 11 Pankhabarl 540 15.3 65.52 18.31 16.17 2.07 1.73 5.4 12 Kochlgoan 560 13.4 70.91 16.91 12.18 1.93 1.91 5.5 13 Bungkulung R.H. 640 6 70.31 12.15 17.54 3.62 1.29 5.3 14 Gayabari 768 19.2 46.75 15.09 38.16 3.93 2.93 5.4 15 Ambootia 948 18.7 69.09 13.75 1716 2.41 1.93 5.2 16 Kaphebarl 918 13 56.51 8.73 34.76 3.7 2.31 5.3 17 LongvlewT.G. 570 2.6 65.52 18.31 16.17 2.09 1.73 5.4 18 Cedars T.G. 1100 11.1 69.09 13.75 17.16 2.41 1.03 5.1 19 Oooteriah 1260 214 60.65 9.56 30.39 4.01 2.92 6.2 20 MandakotI 1100 17.4 65.73 15.09 19.18 3.83 2.79 5.3 21 Gopaldhara 1340 13.1 58.73 16.93 24.34 2.69 3.29 5.3 22 Nagri 1348 14.2 68.4 16.09 15.51 2.92 2.71 5.6 23 Mane P.O. 1349 7.4 58.4 16.09 25.51 3.41 2.95 5.1 24 Sungma Terminus 1340 22 81.73 5.91 12.34 1.81 1.49 5.6 25 Seeyok 1520 19.5 66.32 17.31 17,37 2.01 1.81 5.5 SI. Locality Altitude Slope In Sand Silt Clay Organic Hygroscopic No. In mrtre^ Degree % % % matter % moisture % 26 Kale] Valley 1693 J 22 66.93 14.86 18.22 2.45 3.21 27 Rungbull 1900 18 64.32 17.31 18.37 2.03 1.86 26 Mirik P.S. 1600 14 67.2 17.09 25.71 2.4 2.5 29 Pokrfabong Market 1727 14.4 66.2 16.09 27.71 1.98 1.93 30 Pubong 1744 17 53.93 1045 35.62 2.31 2.54 31 Tumsohg 1833 J 20 66.95 11,03 2002 2.41 3.15 32 Talkot 1640 14 66.2 18.09 25.71 2.35 2.43 33 Gorabari 1900 15,4 63.71 12.26 23.99 2.71 1.98 34 Diiaram 1700 14.4 60.71 15.28 23.97 2.81 2.15 35 Nayagoan 1547 9.5 60.81 15.2 2399 3.81 2.51 36 Margaret's Hope 1360 6 50.91 26.1 2399 3.93 3.12 37 Rington 1302 12.4 59.32 11,78 29.9 2.69 1.92 38 Tung P.O. 1620 19.4 73.91 6,1 20.99 3.74 2.62 39 Bhotey BustI 1540 15 66.81 101 24.09 2.41 2.13 40 Go^hal's School 1540 12 58.35 11.76 29.9 2.41 1.96 41 Kurseong Jail 1380 11 65.3 10.2 24.5 2.91 2.01 42 St. Mary's Seminary 1540 12.4 58.32 11.78 30.9 2.31 1.79 43 Mane P.O. 1007 21 8381 5.28 10.91 2.05 2.1 44 Makalbari 1252 28 66.71 9.09 24 2.31 1.79 45 2 km from Gayabari 1270 16.2 86.91 4.92 8.75 1.91 1.43 46 Simana Busty 2355 13.5 55.75 14.2 29.92 3.4t 2.9 47 Chamong 2100 20 8291 16.18 10.91 2.1 2.61 48 PaQOda Forest Dhauki 2106 17.4 64.91 14.12 20.97 2.43 1.98 49 Sonada P.O. 2000 14.4 60.81 15.18 2398 2.91 2.43 50 Lepchajagat 2502 18.9 63.91 15.1 20.99 3.74 3.18 INDEX MAP FOR SAMPLE SITES FOR PEDOGEOMORPHIC STUDIES SSoiO'E 88° 16' 88° 20' 27° :27 IV N •31 ^ 46 • 30 •26 -\ 19 1 •47 45 1 -29 32- '- A •49, ( «24 •33 N .25 26° 23\''^ •34 26° 55'1 •21 •22 J 20- 35- 38. / '55' 37- 36 .39/ -. -28 16-\^ 40- ; 427 ^ •15 / V. -iQ. / ( 41 \ •44 26° 26' 50'' s.. •50' 17- •14 •12 ( •10 J r j / • V 4^.. \.'5 \ 26° 45'] 26° 45' \ SC^E \ 10 12 3 I Kms 88° 10' E 88° 15' 88° 20' Figure 4.1 The collected soil samples were thus furtiier analysed in the laboratory, for the determination of pH, organic cartx}n (%), base exchange capacity (m.e.), nitrogen (%), hygroscopic moisture (%) along with the percentage of sand, silt and clay (table 4.1} The data thus obtained were processed and analyzed statistically to find out the exact nature of relationships among them. In order to apprehend the pedogeomorphic relations under different environmental setup, a number of statistical analysis have also been done. 4.2. Pair wise relations The numerical assessment of tiie relationships among the different pedo­ geomorphic parameters have b^in conducted based on correlation and regression metiiods. The data for tiiese study have been otJtained from 50 sample sites (figure 4.1) which has been represented In table 4.1. 4.2.1. CoiTelatitni among pedogecanoiidiic parameters : The resulte of the correlation anal^is have been presented in a matrix form in table 4.2. The correlation coefficients have also been checked against significance table and an account of these have also been indicated in the correlation coefRdent matrix (table 4.2). The correlation coeffidents among the various soil properties and slope are consistentiy significant at tiie level of 99% in most cases. Significant positive correlations have been found between slope (x) and sand content (y) and between infiltration (y) and sand content (x), while significant n^ative correlations have been found between slope (x) and silt content (y), pH (y) and slope (x), Infiltration (y) and day (x). However, most of the remaining pedogeomorphic parameters are found statistically insignificant .This is due to tiie fact that these parameters are not dependent on any one parameter but are inter-related and thereby, multiple correlation analysis becomes necessary to apprehend tiieir exact nature of relationships. The correlation matrix table 4.2) also proves tiie esdstence of high correlation 60 Table 4.2 Correlatioii* matrix for Pedogeomorpliic variables in the Balascm basin.