CHAPTER
AGROCLIMATIC FEATURES OF THE STUDY REGION
2.1 Introduction
Agroclimatic potential of any region depends upon its natural and human resources as well as level of technology and investment of capital. However, the present study is concerned with the analysis of the natural resources and that too with regard to climate. The natural resources mainly include, Climatic factors - temperature, moisture, wind, sunlight etc.; Physiographic factors - rock type, topography, altitude, and Edaphic factors - soil texture, structure and chemical composition.
The most crucial among these is climate interacting with soil which is manifested through water availability to a crop. The present chapter, therefore, discusses the agroclimatic features such as topography, climate, soil, landuse etc. of the study region.
18 2.2 Background of the study region
2.2 Background of the study region
2.2.1 Physiography
Dry Farming Tract, as mentioned earlier, includes the area where the annual rainfall ranges from 40 to 100 cm (Swaminathan, 1970). Of the total geographical area (307609 sq.km) of Maharashtra state, the DFT covers approximately 12300 sq.km area. Lying on the east of Sahyadris it coincides almost with the Maharashtra Plateau excluding the Vidarbha (Fig.2.1). The entire region can be resolved into a number of smaller plateaus and river valley plains. The altitude declines towards the eastern and northern periphery of the DFT. The Tapi-Purna valley an east-west furrow in the Deccan tableland lies in the northern part of the region. The study region is mainly drained by Godavari. Bhima and Krishna rivers and their tributaries. The broad valleys of these rivers bounded by 600 meter contour are separated by flat-topped divides which project eastward from the Sahyadri range. From north to south the plateau exhibits an alternate arrangements of hills and plateaus which form the divides and river valleys. The most prominent among these are the Satmala-Ajanta Range between the Tapi and Godavari; the Harischandragarh-Balaghat Range between the Godavari and Bhima; and the Mahadeo Range between the Bhima and Krishna, all rising above 600 meter height.
2.2.2 Climate
Forming a part of the tropical monsoonal lands, the DFT displays significant regional variations in thermal conditions and in the amount and intensity of rainfall. April and May are the hottest months when the mean maximum temperature rises above 40°C over much of the central and eastern parts of the DFT whereas in the western upland part of the DFT, the temperature maxima in summer are more moderate; at Nasik and Pune it does not exceed 40°C. December is "Z 2.2 Background of the study region
the coldest month in the DFT. The mean minimum temperature of December varies between 11°C and 15°C. An exceptional feature of winter is very low temperature at Jalgaon and Nanded both located in the valleys where drainage of cold air from valley sides is significant at nights.
Within the DFT, far greater contrasts are observed in the distribution of rainfall (Fig.2.2). The decline in the amount of annual rainfall in the western part is quicker than its rise in the east. The Sahyadris really cast their shadow to create a rainshadow area. More than 85% of the rain falls during the five monsoon months, June-October. The minimum annual rainfall (<500 mm) within the study region is observed in the south-central parts covering the areas of eastern Pune and Satara, northwestern Solapur and southern Ahmednagar districts. On the other hand, the maximum annual rainfall (1000 mm) forms the eastern and western margins of the DFT. Unimodal distribution of rainfall with July maximum is noted at Nasik, Dhule, Jalgaon, Buldhana, Akola, Amraoti and Satara and September maximum at Solapur and Beed while rainfall at Pune, Aurangabad and Parbhani, Nanded, Sangli and Ahmednagar is characterised by bimodal distribution with July and September maxima.
2.2.3 Soils
The DFT is almost entirely covered by vertisols of varying depth. The coarse shallow (upto 25 cm depth), medium black (25 to 50 cm) and deep black (upto 100 cm depth) soils roughly correspond with high plateaus, low divides and river valleys respectively. Thus these soil types are the topographic variants of black, dark and grey soils(Fig. 2.3).
Shallow soils are observed on the Ajanta and Balaghat plateau and
2.2 Background of the study region
Mahadeo range where the thickness of the soil is restricted by the depth of weathering. These soils occupy a zone having 600 to 750 mm of rains and are neutral or alkaline in reaction. The moisture storage is limited because of their shallow profile and coarse texture which does not permit capillary water. The free water is easily drained or evaporated.
The medium black soils occupy the eastern margins of the plateau divides which are either lowered or replaced by erosional plains. These, covering largest area, grade into deep black soils which are popularly known as black cotton soils. These occur in areas of moderate rainfall usually occupying the valleys, terraces, flood plains and lower parts of almost all basins. They are darker and deeper with a larger fraction of clay. They are poor in organic content and nitrogen but do not show any deficiency in potash and phosphates (Dixit, 1986).
2.2.4 Landuse
The topography, the rainfall and the distribution of soils do not ideally coincide to provide the best possible conditions for agriculture in the DFT. In spite of the relatively higher rainfall in the west the soils on the plateaus and slopes being thin can be used only for growing rainfed crops. The deep soils unfortunately occur in drier central tracts of the DFT which seriously limits their usefulness. With more rainfall their utility would have increased several fold which is being achieved by extending irrigation. These soils are sustaining sugarcane, wheat and other cash crops replacing hardy jowar and bajra wherever irrigation is possible. In terms of acerage, in the west jowar, bajra, groundnut and pulses are the principal crops while towards central and eastern parts of DFT jowar, cotton, pulses and groundnut are predominant. The agriculture, as a whole, of this
24 2.2 Background of the study region region is mostly dependent on rainfall and it suffers from the twin problems of low production and instability.
The information on crop landuse at taluka level is presented in the table 2.1 given below.
Table 2.1 Area under various crops (%) for 1986-87
Talukas Kharif Rabi Bajra Cereals Pulses Ground Saff Oil cropped jowar jowar nut lower seed area (%)
Kalvan 6.0 13.5 23.3 60.8 16.8 8.3 0.2 5.3 45.5 Haveli 3.7 24.0 16.1 52.5 5.8 3.0 0.5 4.2 60.5
Dhule 23.6 0.1 38.3 64.8 12.7 12.9 14.4 65.2 Niphad 10.2 2.2 35.6 61.9 9.5 2.4 02.9 79.6 Parner 0.3 46.7 26.3 75.8 10.1 0.6 11.3 12.2 74.5 Phaltan 1.7 63.4 8.1 79.9 3.1 0.7 1.7 02.5 76.7 Jath 0.3 44.8 28.0 75.9 15.6 1.1 03.5 62.8
Jalgaon 23.5 9.7 3.7 40.9 28.3 4.5 3.3 11.2 72.6 Buldhana 8.1 8.2 8.4 2.5 1.2 3.9 85.7 Akola 28.1 0.2 36.0 12.8 0.8 0.1 3.0 90.0 Amraoti 23.3 0.3 27.0 11.5 1.8 0.3 3.8 75.6 Aurangabad 4.4 33.6 23.7 65.6 17.0 0.4 7.0 8.8 84.6 Mominabad 37.0 13.0 9.8 66.2 16.0 1.8 4.7 13.4 64.1 Solapur 0.3 75.2 0.7 78.3 7.2 0.8 1.2 10.8 73.9
Nanded 32.6 1.6 44.7 12.7 0.3 1.4 3.9 88.9 Pusad 30.6 1.2 34.9 13.7 3.6 0.5 4.7 59.3
Source: "Socio-economic Review and District Statistical Abstract", Govt, of Maharashtra, 1991-92.
The proportion of cropped area within the study region, as the table denotes, ranges from 45.5 (Kalvan) to 90% (Akola) which indicates highly diversified environmental conditions in the DFT. The area under cereals too varies in a wide range from 8 (Buldhana) to 80% (Phaltan). The former situated in a good rainfall area has predominance of cash cropping whereas the later being from the drought-prone area has sole cropping of rabi jowar. Kharif jowar is the major crop of the eastern half while rabi jowar is of the rainshadow part of the
25 2..i Methodology
DFT. Bajra is an important crop of Dhule. Kalvan. Niphad. Aurangabad, Parner and Mominabad area. Area under pulses is very less throughout the region except for Jalgaon. Similarly, the oilseeds also occupy smaller area. Among the oilseeds groundnut and safflower are significant at Dhule and Parner respectively.
So far, the discussion pertained to the characteristics of the study region, in general, while the following sections deal with the spatial variations in agroclimatic features at micro level.
2.3 Methodology
Indian Council of Agricultural Research (1991) has identified 9 agroclimatic zones of Maharashtra of which the study region represents 4 zones viz.. Western Maharashtra Plain Zone, Western Maharashtra Scarcity Zone, Central Maharashtra Plateau Zone and Central Vidarbha Zone (Fig.2.4). The first and the last zones occupy relatively smaller area and, therefore, 2 stations for each zone are taken as representative for them. Zones II and III together covering more than two-third area of the DFT are represented by 5 and 7 stations respectively. Thus the agroclimatic study of the entire region is based on 16 stations (Table 2.2).
Table 2.2 Agroclimatic zones and representative stations
Zone Name of the Zone Raingauge Stations Stations with ail No. Climatic Elements I. Western Maharashtra Pune. kalvan Pune Plain Zone II. Western Maharashtra Dhule. Niphad, Dhule. Scarcity Zone Parner, Phaltan Jath Nipliad III. Central Maharashtra Solapur, Jalgaon, Solapur. Plateau Zone Buldhana, Amraoti Akola Aurangabad, Akola, Mominabad IV. Central Vidarbha Nanded, Pusad Nanded Zone
2.4 Discussion
For the first zone, as an example, general climatic conditions are analysed from the meteorological data of Pune whereas the rainfall features are derived from the rainfall data for both, Pune as well as Kalvan. For this, the daily weather data for these stations available for the period from 1956-85 is used. Since this study is primarily of non-irrigated kharif crops, the weather parameters during the monsoon season ( Meteorological Week i.e. MW 21-45) are analysed. Therefore, the categorisation of the study period on the basis of seasonal rainfall (MW 21-45) has been done as per the standard statistical procedures using mean and standard deviation (SD), (Appendix II). This analysis is further used to identify dry and wet rainfall years from the study period for respective stations.
2.4 Discussion
2.4.1 Western Maharashtra Plain Zone
Western Maharashtra Plain Zone which is also referred to as Transition Zone II is a narrow strip running parallel to the Eastern side of Sub-montane Zone of Maharashtra and extends eastward upto the boundary of the Scarcity Zone. This zone occupying about 5.82 % of the State's area includes areas in western tehsils of Dhule, Ahmednagar, Sangli and central tehsils of Nashik, Pune, Satara and Kolhapur districts.
The topography, in general, is plain in the zone. The soils are predominantly greyish, black with varying texture and depth ranging from 0.25 to 1.0 meter. The soils are clay-loam in texture and moderately alkaline. The predominant soil type in the middle part of this zone is reddish and yellowish brown soils of hill slope while in the north, patches of coarse shallow soils are observed. These soils are well drained and considered to be fairly good for irrigated
28 2.4 Discussion
cultivation. The deep black soils of the south, however, pose problem of waterlogging when excessively irrigated.
The gross cropped area of the zone is 9.9 lakh hectares, out of which nearly 10.64 % area is irrigated (ICAR,1991). The principal kharif crops grown in this zone are jowar, groundnut and bajra.
2.4.1.1 Climate in general
Weekly distribution of various climatic parameters is depicted by the figure 2.5. For convenience, the period is divided into three parts namely, pre-monsoon (MW 21 and 22), monsoon (MW 23 - 41/42) and post-monsoon (MW 42/43 - 45). The pre-monsoon period at Pune is characterised by high temperature and low relative humidity while the monsoon season is marked by high weekly rainfall and low temperatures. During post-mousoon period, the rainfall decreases sharply below 5 mm. The general climatic conditions during the post- monsoon period may be described as fall in both maximum and minimum temperatures, low wind velocities and cloudless skies indicating the onset of cold weather season.
2.4.1.2 Rainfall characteristics
As per National Commission on Agriculture (1976) Pune and Kalvan are located in the rainfall zone nos. V and VII of which rainfall characteristics are E4 C4 D1E3 and E4 B1C3 D1E3 respectively (Fig. 2.6).
This zone has, in general, well-distributed rainfall ranging from 700 to 1250 mm annually which is mostly received from southwest monsoon during June to October. The monthly rainfall pattern of the zone is having unimodel distribution except for Pune. The zone is, therefore, predominantly a kharif tract suitable for a single rainfed crop. The detailed rainfall statistics for this zone is presented in the Normal Climatic Conditions During Kharif Season 40- At Pune
JS.
30-
O 2S- 100
90 i ^i5'!I?.y!??Jemperature 520- 80 u "TO ua*!™!™ ??-~-- ~~-.^ _ .- -:--r.^ 70 L_ 01 60 E >— SO- 10- 40-
30
5- 20
1CH
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SO- 6 HOURS 45-
1 40-
35 73 CX. ~ 30- 15 CO e w — 20- TO- a. (0 1S E " 3 ^ 10- 3-
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0- ~?1 22 23 24 2 5 26 27 2B 29 3D 31 32 33 34 35 36 37 39 39 i40 41 42 43 44 45 L Weeks
FIG. 2-5.
2.4 Discussion
table given below.
Table 2.3 Rainfall Features of Western Maharashtra Plain Zone . mMm'A. ;Pun e Kalvan" 7 Mean Seasonal 643.5 746.6 Rainfall
SD of Seasonal 163.5 241.48 Rainfall
Dry Year 1972 1957 (301/12) (234.6/10)
Wet Year 1956 1976 (987/34) (1406/34)
Good Year 1975 1964 (706/29) (707/26)
The first figure in the parenthesis denotes the seasonal rainfall (mm) while the second, rainy days (RD). A rainy day is an agricultural rainy day which receives rainfall > 6.3 mm. The table reveals that the rainfall in this zone decreases from north to south in contrast to its variability. Though the wet years at both the places are marked by same number of RDs due to higher amount of rainfall, intensity of rainfall at Kalvan is very high. The similar pattern is noted for the good year also.
2.4.2 Western Maharashtra Scarcity Zone
This region includes entire Ahmednagar and parts of Satara, Sangli, Pune, Kolhapur, Nashik, Dhule, Jalgaon, Aurangabad, Beed, Osmanabad and Solapur districts with total geographical area (TGA) of 73.23 lakh hectares (about 23.8 % of the State's area).
The general topography of this zone is rolling with slopes between 1 and 2 percent. The soils are vertisol with montmorillonite clay. They
32 2.4 Discussion
swell when wet and shrink on drying producing deep cracks. About 40% of the TGA is covered by very shallow and shallow soils. Very shallow soils are 5 to 7 cm thick, gravelly loam in texture and reddish- brown in colour. They are moderately to steeply sloping and severely eroded in hilly areas. Shallow soils are upto 25 cm in thickness and gravelly clay-loam in texture. They are gently sloping with high permeability and are subject to moderate erosion. Shallow soils are classified as Entisols and Inceptisols and generally suited for kharif cropping. The rest of the region is covered by moderately deep, deep and very deep soils (Anonymous, 1983), classified as Vertisols. With high moisture retention capacity, they are suited for rabi crops.
The net cultivated area is 72% of the TGA of the zone, out of which only 6.8% is irrigated. Based on the bimodal distribution of rainfall, two cropping seasons are practised; shallow soils for kharif while medium deep and deep soils are diverted for rabi cropping. The proportion of kharif cropping is about 30% with the crops such as bajra, jowar, pulses and groundnut. The productivity of kharif as well as rabi crops is very low.
2.4.2.1 Climate in general
The figures 2.7 and 2.8 depict the weekly normal of various meteorological parameters recorded at Dhule and Niphad respectively. The pie-monsoon period experiences hot, sunny and dry climate. The period from MW 23 to 40 and MW 23 to 39 make a monsoon phase with high relative humidity and a fairly high weekly rainfall of 25 to 50 mm and 20 to 40 mm for Dhule and Niphad respectively. Normal Climatic Conditions During Kharif Season fcS-j At Dhule
fcO-
35r
, Maximum
u 30- Temperature
33 ?s- 100- o 0) o 90- O) —: —^ -.... Minimum Temperature * l_ 2 0- 80- 3 Maximum "v^ •••. -•—« Relative *"\ c 70- a. Humidity >' -. \ 3 60- e 15- ex 50-
T0- 1.0- Minimum 30 Relative Humidity?0
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FIG.2-7 us - Normal Climatic Conditions During kharif Season
40- At Niphad
35-
30-
25 100- 1 1 90- X)
...Minimum Temperature 70- ~*-
31 BRIGHT 9(4^3 SUN •••OO3OO03O©33O93OOOOfc^« SHINE HOURS 2.4 Discussion
2.4.2.2 Rainfall characteristics
The scarcity zone suffers from very low rainfall ( < 7 50 mm) with uncertainty and ill-distribution. The occurrence of drought is noted once in three years. This zone suffers from twin problems of low productivity and high instability in agriculture, as a result of inadequate and undependable rainfall. Dry spells of varying durations extending from 2 to 10 weeks at a stretch are experienced in July and August (Anonymous, 1983). Besides, the weather aberrations like delayed onset or early cessation of monsoon are frequently observed resulting in shortening the water availability period. Thus, it becomes difficult to mature even a single crop in a year (ICAR,1991).
According to National Commission on Agriculture (1976) Parnor, Rarner Phaltan and Jath are situated in rainfall zone I, Niphad^in II and Dhule in IV of which the rainfall characteristics are E4 C1D3 D1E3, E4 C1D3 D1E3 and E4 C4 E4 respectively (Fig. 2.5).
Table 2.4
Rainfall Features of Western Maharashtra Scarcity Zone
Dhule Niphad Parner Phaltan Jath
Mean Seasonal 582.5 519.0 501.2 447.3 558.4 Rainfall SD of Seasonal 147.05 145.3 125.6 156.39 219.1 Rainfall Dry Year 1972 1972 1972 1972 1983 (353/11) (208/10) (203/10) (202/9) (221/11) Wet Year 1969 1956 1956 1973 1975 (847/28) (903/36) (720/29) (746/29) (1081/33) Good Year 1984 1980 1975 1978 1973 (581/19) (452/19) (526/22) (382/17) (491/24)
The above table denotes that mean seasonal rainfall for all the 2.4 Discussion
stations in this zone is very low; <600 mm. The rainfall in the northern and the southern part is higher which is decreasing toward the middle part of the zone. The dry and the good year at Phaltan records the lowest rainfall with lowest RDs. Standard deviation of seasonal rainfall at Jath is highest which is the result of the largest range in the rainfall amounts from dry and wet years.
2.4.3 Central Maharashtra Plateau Zone
The zone, also recognised as Assured Rainfall Zone, consists of entire Jalgaon,- Buldhana, Jalna and Latur districts and major parts of Parbhani, Osmanabad, Beed, Aurangabad, Akola, Amraoti and Nanded. It is the largest agroclimatic zone occupying 24.4% of the TGA of the state.
The topography is rolling in few districts viz, Aurangabad, Buldhana, Beed, Osmanabad, Jalna and mostly plain in remaining districts. Soils are derived from Deccan trap and range from black to red colours. The types of soils are vertisols, entisols and inceptisols.
The net sown area accounts for 71% of the total area of the zone; out of which 11.9% area is irrigated. Kharif cropping is predominant in the districts of Osmanabad, Latur, Beed, Aurangabad, Buldhana, Akola, Amraoti and Jalgaon. The major crop grown in kharif season is jowar followed by cotton and bajra. The pulses like tur, mung and udid while the oilseeds like groundnut and sunflower are cultivated in kharif season (ICARJ991). Normal Climatic Conditions During Kharif Season IS At Akola
CO
35- Maximum Tempera*^ 30
O 25. 100 X) Minimum Temperature 90 20 I ^ayimum_ Relative Humility '-., eo- 70- X Q. c e « S'' ^i^imum ReUtiVp 60- 3 CD .- -""""' "NS^*, 50' 10 x UQ- • xv V._ 30- ^' 20- 10-
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35
30
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20 80- 3 ^aXimu^ii •*•* k_ ">1 X 0) c GO 3. £ >...Jin>um Relative /, 50,-
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5- ^ 15-1
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 li42 l43 44 45 0 , Weeks : FIG.2-10. 2.4 Discussion
2.4.3.1 Climate in general
The Figure 2.9 indicates that at Akola from MW 21 to 41 both the temperatures, bright sunshine hours and wind velocity decrease with increase in mean RH denoting the monsoon phase. The climate of Solapur, however, is slightly different which is illustrated by the Figure 2.10. During the pre-monsoon period maximum and minimum temperatures are very high about 39°C and 24°C respectively while the mean RH is low. Thus, the weather is very hot and dry with long sunshine durations and from the MW 23 to 41, monsoon phase is observed. The post-monsoon season after 41st week, however, is marked by lowering minimum temperatures and relative humidity and long sunshine hours at both the places.
2.4.3.2. Rainfall characteristics
Average rainfall (Fig. 2.2) varies from 700 to 900 mm. Aurangabad Mominabad and Solapur of this zone are located in rainfall zone IV, while Jalgaon, Buldhana, Akola and Amraoti in zone VI (Fig. 2.4) of which rainfall characteristics are E4 C4 E4 and E4 B1C3 E4 respectively. Rainfall features of these places based on the daily rainfall data of 1956-85 are given in the table 2.5.
The table reveals that the seasonal rainfall within this zone decreases from north to south. Mominabad, Aurangabad and Solapur from the rainfall zone IV record high SD and thereby high annual variability in the seasonal rainfall. The range of rainfall variation from dry to wet year is also higher for these stations as compared with the remaining stations belonging to rainfall zone VI. It is interesting to note that at Aurangabad the largest amount with the lowest RDs for the wet year indicates the high intensity of rainfall.
40 2.4 Discussion
Table 2.5 Rainfall features of the Central Maharashtra Plateau Zone
• ••.. Jalgaon Buldhana Akola Amraqti A*bad M'bad Solapur
Mean seasonal 716.2 797.1 754.0 760.8 713.8 695.8 691.1 rainfall
SD of seasonal 146.7 216.4 164.6 181.8 253.9 205.8 203.7 rainfall
Dry year 19S4 1984 1966 1971 1972 1971 1972 (468/14) (414/17) (520/20) (370/22) (275/12) (356/15) (234/11)
Wet year 1959 1959 1959 1970 1978 1956 1975 (1060/43) (1355/35) (1236/35) (1093/40) (1685/27) (1167/43) (1048/41)
Good year 1978 1974 1963 1956 1963 1974 1962 (704/31) (738/33) (675/26) (781/35) (717/36) (613/29) (717/36)
2.4.4 Central Vidarbha Zone
This zone also referred to as the Moderate Rainfall Zone occupies 16.62% of the total geographical area of the State and includes parts of Wardha, Nagpur, Yavatmal, Chandrapur, Parbhani, Akola and Nanded districts. However, the present study area is delimited by the boundary of Dry Farming Tract of Maharashtra, only the parts of Yavatmal, Akola, Parbhani and Nanded districts are considered under this zone.
Soils of the zone derived from basalt rocks are black in colour and have varying depths depending upon the local topography. Vertisols predominate in this zone.
The cropping pattern mainly involves cotton and kharif sorghum with predominance of the former followed by tur and other pulses.
41 2.4 Discussion
2.4.4.1 Climate in general
Weekly march of meteorological parameters at Nanded (Fig.2.11) denotes hot, dry and sunny climate in the pre-monsoon period whereas the period from MW 23-41 is marked by rapid fall in temperatures and rise in mean RH, cloudiness and rainfall. Thereafter, minimum temperatures drop considerably; the sky becomes clear indicating the onset of winter season.
2.4.4.2 Rainfall characteristics
The average annual rainfall is 1130 mm; out of which 90% is received during southwest monsoon season. July is the wettest month receiving around 300 mm of rain.
Pusad and Nanded are located in the rainfall zone no. VI and VIII of which rainfall characteristics (National Commission on Agriculture, 1976) are E4 B1C3 D1E4 and E4 B2C2 E4. Their detailed rainfall features are given in the Table 2.6.
The table highlights that Nanded receives higher rainfall but is marked by high variability than that of Pusad. The range of seasonal rainfall as well as RDs from dry to wet year is larger for Nanded. Normal Climatic Conditions During kharif Season At Nanded 60-
35-
30-
_ 25. 10O O Minimum Temper,^ o 90 a> 20 - i~ eo- D *-» 70 Maximum Rc/af/Vo ,, 60
E 50 / "~ 10. * •—•- 40- N//> 30
20-
10- 0 1s2 BRIGHT ^^^^^^^^^G(3^^oo^e)(3^(!)(!)(!)(5Oo^s 0^s
FIG.2-11. If) < cc UJ t— z X in o < cc M < 2 ZO N li_ 5 Z > cr i— < cr WEST E SCARC I UJ UJ - J o (WW) N] "HVdNIVM (WW ) Nl IIVdNIVM < cr "? < cr > o u. ^: o < (X t— X to < cr < x < 2 (X LU h- LO UJ ~5 5 3 5 3T ~S 5 5 3 S" •« un J m c*. n LT> .J- M r* — (ww) NI nvdNivd — (ww) NI nvdN|va — 2.5 Normal Weekly Rainfall Pattern Table 2.6 Rainfall characteristics of Central Vidarbha Zone "&l-53TFfX: Nanded Pusad Mean Seasonal 910.9 822.3 Rainfall SD of Seasonal 287.8 221.2 Rainfall Dry year 1972 1967 (306/14) (537/21) Wet year 1983 1983 (1983/44) (1425/47) Good year 1964 1964 (786/36) (723/31) 2.5 Normal Weekly Rainfall Pattern The normal weekly rainfall for various zones is computed by averaging the weekly rainfall for the study period as well as for all the stations representing the respective agroclimatic zones. As an example, the average of weekly rainfall for the period of 1956-85 for Pune and Kalvan represents the rainfall pattern for the Western Maharashtra Plane Zone (Fig. 2.12). In the early phase of monsoon season, the zone I experiences a moderate peak (40 mm), while the highest peak (60 mm) is noted in the mid-season and the third peak of the magnitude of the first one is seen in the late-season. In the zone II early and the mid-season monsoon phases receive low rainfall (<30 mm) and the only peak of moderate rainfall (45 mm) is observed in late season. The zone III has peaks in early and mid-season. Later rains are also significantly high. The zone IV is marked by one minor peak (55 mm) in the early season and the major one (>70 mm) in the mid-season. The later 2.6 Summary rains are intermittently significant. The normal weekly rainfall thus for the zone I shows high fluctuations while that of the zone III indicates slight variation. The peak rainfall of the zone IV is highest among all the zones. 2.6 Summary The agroclimatic potential of a region is determined by its physical as well as socio-economic characteristics. The present chapter deals with the physical and landuse features of the DFT. From north to south the region exhibits alternate arrangements of hills and plateaus which form the divides and river valleys. The amount of rainfall decreases from the margins towards the central part of the study region. However, the decline in the western part is quicker than its rise in the east. In the study region seasonal mean rainfall of Parner is lowest with the lowest SD while that of Nanded is highest with the highest SD. However, the variability of the seasonal rainfall is lowest at Jalgaon and highest at Jath. The lowest rainfall associated with the lowest RDs is noted in the dry year at Phaltan while the highest rainfall of the wet year with lowest RDs is a feature of Aurangabad. The region is predominantly covered by vertisols of varying depth. The coarse shallow, medium deep and deep black soils roughly correspond with high plateaus, low divides and river valleys respectively. The proportion of cropped area ranges from 45 to 90% indicating highly diversified agroclimatic conditions in the DFT. Kharif jowar is the major crop of the eastern half while rabi jowar is of the rain shadow part of the DFT.