AREA UNDER STUDY
The tract : Location, Area, Boun11es
'l'he area comprises of four districts of Konkan/ namely, Thana, R.eigad, Rstnagiri llnd Sindhudurga; the hilly terrsin, i.e., parts of Nasik, Pune, Sat~rs ~nd Kolhllpur districts and the gentle e.estern slopes covering eastern parts of
Nasik, Pune, Ahm~dnagar, Satara and Sangli Districts. It is loc~ted between 15° 75' and 21° 00' North Latitudes and 72° 75' and 75° 00' East Longitudes and comprises of &bout 20,000 sq. km, about one fifth of gross total area of the
Maharashtra State. It is bounded by the Arebian ~ea towards west along its entire length while the eastern boundary comprised of the crest of Ghats end the gentle spurs extend ing towards east. Towards north are semiarid parts of Gujaret and towards soL,th ere luxurient forests of Goa and North KaMra in KarMtaka (Map 2.1).
Physiography
Physiographically the area is much veried. The
Western Ghats dominate the topo~rephy of the region. They ere formed of continuous chain of mountains from north to south more or less running parallel to the sea coast, with an average height of 1300 m above mean sea level. Leteral spurs of lo~1 hills run from the hill range towerds east end west. The Konken region is a nt"~rrow coastr~l strip of 11bout Map 2 ·1
73'
NASIK
•1
i~~-· ·...... ······ ··· . • NASIK
.. ···· .· .. .:······:...... ·· THANA AHMADNAGAR
···:.··· ·::: " ...... : .. . . ·. AHMADNA,AR ,· ·.. ) ·.. ~. .. \. ...: ...... ·.. •,.·.. :0 ' .· )::...... • PUNE .. - · .... ··.: "'t '•'\.··· l.u ···;_:.·... : .. ·
Cf) 1!'.
.. . <: ·····. .• KUDAL GOA AREA UNDER ST.UDY 12 25-40 km breadth between base of the ghats end the sea. The fall in elevation is rather abrupt towards Konkan exposing a vertical profile as seen at Arthur seat, Mahabaleshwar. Towards east the hills slope rather gently ·and merge into the Deccan plateau, with an average altitude of 400-600 m above mean sea level. The Konkan plains and the Deccan plateau are linked with few gaps in the hill range called ghats, such as Thal ghat, Bor ghat, Kumbharli ghat, Amba ghat, Phonda ghat and Amboli ghat. The crest of the ghats carry at their top, huge plateaus, the table lands. Important among them are Mahabaleshwar (1438 m) and Herishchandraged (1424 m). The hig~est peak is at Kalsubai (1646 m). The area can be broadly divided into five zones each showing homogenicity in physiographical as well as climato logical conditions. They are (1) The coastal region and alluvial plains, (2) Low lying hills, (3) Crest of ghats, (4) Eastern gentle spurs mostly comprising rainshadow areas, and (5) Eastern plains. Geology Major part of the ares forms a part of Deccan Trap. Rock formation is basaltic trap cepped with laterite, giving rise to red loamy, porous, acidic soils at higher elevations. It is interesting to note that the southernmost portion of Sindhudurga district is outside the "Traps" a~ incorporates 13 detritel leterites most probably trensported from the parent Deccan Trap elsewhere. The difference in the geology of south Konkan plays an important role in deciding the local veget~tion pattern. (Map 2.2). I Local soils are broac:Hv classifieo into two tYpes - (a) ~oils developed in situ by netural metamorphosis and the degeneration of underlying rocks, and (b) soils trans ported from elsewhere and deposited in successive layers of varying depths. The weathered rocks form the soils of various depths, texture and colour. The$e can be further classified into black, red and grey (berad) according to their local elevation and composition. These soils blend with each other in varying proportionsand in turn are modi fied by sand, gravel, lime and other ingredients. Black soils belong to the flat eastern plains, commonly occurring in many layers, each few meters deep. This type of soil covers a wide area, but often gets mixed with send and clay. Red soil is generally shallow,slightly acidic, porous and with l~w water holding capacity. This type of soil is chiefly found at higher elevations (above 1200 m) and in Konkan. Along hill slopes and pl~teaus sustaining good vegetal cover, soils rich in humus may be encountered. Many a time, this red soil is mixed with gravel. Grey soil is very loose, coarse and gravelly and is subjected to erosion. This type is mostly found along hel!vily eroded barren hill slopes and uplands. (Map 2.)). Map. 2·2 eEl """' ·.. . ,/ . z ·., (i " \. ~- g~ ...... ,. .. ) ·~·- f!J . ~) ,•' r- .-· . ·············· " .... .. ·...... · ·.. \{ ..... '•, ...... ·. .. .. '· ...... ·: ... GEOLOGY mf1l Coastal Tertiary a Pleistocene ~ Deccan Trap . • Cud dapah J:·:-:-·.j Uncia ss1f ied cry st a II in e Map. 2 · 3 71" • I 2 a· .,· . ••• SOILS ~ Costal saline Laterite and lateritic soils ~ Yellow1sh brown soils 0 Medium black soils 11~ Hydrography Because of peculi~r physical features of the area under study, the river system fells into two main groups: ( 1) Dec·~an rivers and their tribut~ries, and ( 2) short but swift Konkan rivers (Map 2.4). The main Deccan rivers ere GodavAri, Bhima and Krishna which flow through the pl~tesu eastward. These flow in broad open valleys with fairly steep banks r~nging in height between 10-15 m. They have distinct monsoon high waters during July September. Low water mark is reached just prior to onset of monsoon in April - May. Godavari is the largest river system rising at Trimbak near Nasik P.nd flowing east and southeast. The basin lies between Sahyadries in the west and eastern limits of state and covers an area of 100,000 km within Maharashtra State. Varna and Pravara are the main right tributaries while Purna Dudna, Pranshita and Indravati are the left tributaries. Bhima, the large tributary of Krishna, rises near Bhirueshankar in Pune district, flow south-eastwards for ebout 500 km. The basin lies between Mahedeo renge and Balaghat renge. Mula, Mutha, Nira 2nd 1-'lp~1 are the mclin right tribu taries while Ghod and Sina are the left tributaries. . ' Krishna basin is formed along the sides of Krishna river which rises in the northern slop.e of Mehabeleshwer. This besin is seperc:-ted from Bhima bBsin by M~h;:~deo rBnee. Map 2 · 4 20'. ·'-' 18'. Shima R. -..~- KrishnaR. RIVER BASINS rn Tapl baSin EB Godavari basin g Shima basin E7'".J Krishna basin 1 5 Koyna, Varna,' Panchganga ~re the right tributaries and Yerla is the only left tributary. Hiranyakeshi, a stre~m of Ghataprabha drains the extrem~ southern part of the Kolhapur district. Konkan rivers are small and have a swift current. Rising in steep western scarp of the Ghats at an height of about 1000 m., they drain into the Arabian sea. These have high w~ters in monsoon ~nd are completely dry in summer. Import~nt amongst these are Surya, Vaiterna, Ulhas, Kund~lica, Kal, s~vitri, Vashishthi and Terekol. Sea water enters these rivers during high tide forming creeks. Vasai, Dharamtar, Mahad, Ghiplun, Dabhol, Jaigad, Rajapur, Vijeydurga and Terekhol are the main creeks. The area has a peculiar network of water reservoirs constructed through dams for hydroelectricity and irrigation facilities. Major amongst them are Koyna, Varna, Mulshi, Vir, Panshet, Bhs.t.ghar, Kukdi, Mula, Gengapur etc. Climate The factor of significance in determining the climate of the area is North-South tendir,g Sahye.dri. Close proxi mity of Sahyadries to the Arabian Sea restricts the equable coast climate to narrow strip as against the continental climate on the lee side of the Ghats. This contr~st is further sharpened by the fact that rain-be~ring monsoon winds derived from the sea are limited to the co~stal low- 16 lands by orographic berrier. 1'he only pleces of penetr~- tion of these rain clouds into the deeper ~reP.s are the gaps i.e. ghats in Sehyadries. As e whole the climate is typically monsoonic in character for the area under study. I ) Rainfall 1'o the west of the Western Gh~ts on the account of orographic rise, the rainfall is higher than 1500-2000 mm and increases from coastal plains to the summit of the ghats where it rains more than 4000 mm. There i~ a rapid and considerable decre~se in rainfall along eestern slopes and it becomes less than 1000 mm tow~rds e~stern plains {Map 2.5). The transition towC~rds immediate eastern plains from Western Ghats is marked by the "Rainshadow" CJreas, where there is an abrupt decrease in the precipitation. Two examples of this rainshadow phenomenon may be cited as follows : 1 • Rain~had£w_a~e~ ~etw~en ~h~~a1a_-_K~d&a£n_ (Graph). KhAndala Crest of the ghat REJinfall 5000 mm Lonavala 5 km towards east Rtlinfall 4000 mm Talegeon 40 km towards east REJinfall 1 ~00 mm Pune 70 km towards east Rainfsll 600 mm Kedgaon 110 km tow8rds eest RainfBll 300 mm GRAPH OF RAINSHAOOW ARE;..S MAHA BALESHWAR I I 5000 ~ MAHABALESHWAR- NtRA RAINSHAOOW AREA I :< HANOALA .•- KEOGAON RAINSHADOW AREA I I I I I 1.000 LbNAVALA I \ I \ \ E 'tl t: \I <:..... 3000 _,...... , \ ~ . ~\ -..<: <( 4·~ANCHGANI . Q: I ' \ \ \ ' \ 2000 1000 20 1.0 60 80 TOO 120 DIS TANC£ FROM CREST OF GHATS IN Km, 17 Thus there is ~ significent dccreBse in rainfell from 5000 mm to 300 mm within 110 km distance. Crest of the Ghats Reinfall 6635 mm Penchgani 19 km towards east R~infall 2500 mm Wai 35 km towRrds east Rainfall 1000 r.!m Nira 95 km towards east RainfPll 300 rnm A decrease of 633~ mm rainfall within a short distancP of 95 - 100 km is remarkable. These rapid changes in the rsinfoll influence the vegetation considerably which ranges from semi-everorf~en tc semi-arid or thorny type. Temperature There are three m~rked seasons viz., the wet season from July to October, the cold season from November to February and hot sepson from March to June. In the coastal districts, the temperature is controlled by sea breezes and ranges from 17° C to 2g° C in winter and from 19° C to 30° C in summer. Along the crest of the Ghats, the climate is ( much more cooler than on the plains even in the middle of 0 0 summer. In winter the temperature ranges from 17 C to 21 C and in summer 18° C to 27° C. Alon~ the eastern plains, the temperature goes extremes during winter and summer. At pla~es like Jejuri, Yewat and Pune the temperature often exceeds 40°C during the summer. 18 Humidity P nd Winds In wet season the relPtive humidity is of the order of 60% to 80% in the coastfll division while in the interior it is inbetween 60% to 75% in morning and about 25% - 50!~ in the evening. Hot season is a period of low relPtive humidity in interior, mean values pre as low c!IS 1 5% - 20~1. 1'hese t:re quite higher in the coastPl areas. Cold se~son is the period of cool and bracing climate with clear blue skies. Dew and mist early morninp, 1 dis appears soon after the sun rises. Winds are generally light and from South to North- East. Clim.!tologic~l f .e.!tures of Vl'!rious loc.!'!lities in the .!reo! under study ere presented in the t~ble 2.1. Table 2.1 : Climatological data ------Sr. Locality Altitude Averflge Average Bioclimate 1~0. in m rainfall temperature type * in mm Min. Mex. ------1 • Bombsy Sea 2100 21 .1 30.1 Humid bio- level climPte support littorE~l swampy 2. Ali bag -"- 2074 22.2 31.8 vegetation ). Vengurla -"- 22.0 2cL 5 19 Table 2.1 contd./ ------Sr. Locality Altitude AverE=~ge Average Bioclim~te No. in m r~inf~ll temperpture type * in mm Min. Max. ------4. Ksnekeshwar 388 1500 20.3 32.9 Sub-humid bioclim.=te 5. Pen, 4J.,OO 2866 25.2 32.2 support mix- Mire dongar ture of semi- evergreen ~ nd 6. Panvel 2741 moist decidu- ous forest. 7. K8rnala 475 2500 24.5 34.6 Forest of trpnsition 8. Metheran 803.4 5242 16.0 30.8 type. 9. Amboli 664 7446 20.9 30.7 10. Harishchendra- gad 1425 6370 16.6 30.0 Pre-humid bioclimete 11. Khandala 670 4899 19.6 29.7 support semi-~v~roreen 1 2. Sakharpather- 900- 4570 20.2 30.2 and evergreen forest type. 13.MahabaleshwBr 1370 6635 13.0 27.2 14. Raigad 860 5500 1 5. RBdhanegari 549- 6350 20.8 32.8 915 16. SaptE!shringi 1553 6500 16.9 31 • 1 Dry bioclimE~te Nasik support dry deciduous 17. Surgana- teak beering H~rsul, Nasik 600 2352 19.0 36.8 forest. 1 g. Kelsubai 1654 2600 16.8 31.5 19. Pune 460 650 21 .o 32.2 20. Sinhsgad 690 2500 21. Kat raj 750 22. Patlond, 1010 6200 Sengli 20 Table 2.1 contd./ ------Sr. Locality- Altitude Average Average Bioclimate No. in m rainfall teoper~ture type * in mm Min. M.ctx. 23~ Purandh~r 1387 1564 14.6 27.8 Very dry bioclimste 24. Tornl! 3960 support dry deciduous 25. Prevsrssangsm 650 550 16.0 35.0 forest and thorny 26. Bswdhsn 500 600 22.3 34.2 forest ------~ - - * Bioclim~te types described following Legris and Meher Homji ( 1973).