Tumakuru district is located in the eastern belt in the southern half of the Slate. Spanning an area of 10598 sq.km. this district lies between the latitudinal parallels of 12 degree 45 minutes North and 14 degree 22 minutes North and the longitudinal parallels of 76 degree 24 minutes East and 77 degree 30 minutes East. The shape of the district is somewhat irregular and has a peculiar feature in that the north-eastern portion is totally detached from the remaining areas of the district. This portion constituting Pavagada taluk is almost surrounded on all sides by territories belonging to AndhraPradcsh, But for the fact that on its; western border for a very short stretch it touches Chitradurga district, Pavagada would have been an enclave territory. Tumakuru district is bounded on the north by Anantpur district of Andhra Pradesh; on the east by the districts of Kolar and Bangalore; on the south by Mandya district and on the west and north-west by the districts of Hassan and Chitradurga. In the mid-west, Chikmagalur district too touches this district and shares a common border though only for a very short distance.
Tumakuru district is surrounded on all sides by lands belonging to the neighbouring districts and has no natural boundary such as sea, river or mountain ranges on any side. The landscape consists mainly of, undulating plains interspersed with a sprinkling of hills. To the east of Tumakuru and north of Devarayanadurga there is a short stretch of hilly country intersected by cultivated valleys. Besides – these, there are several hill ranges and isolated hills as well. While the. western parts a:e occupied by long ranges of hills running in a south by south easterly direction the eastern parts are occupied by a narrow range of granitic hills running north and south. There are two parallel ranges running north to south and the first one of these in the eastern . portion passes through Pavagada, Madhugiri, Koratagere and northern part of Tumakuru tal uk. The second range, mainly composed of schistose rocks; passes through the western parts of the district in the taluks of Chiknayakanhalli, Sira and Gubbi. There is another cluster of hills covering the middle and the southern parts of Kunigal taluk. In this zone the tree-growth is comparatively dense and trees tend to grow taller and stouter. The prominent hill peaks of the district arc Devarayanadurga (1169 metres), Ramadevarabella (1164 metres), Nijagal (1069 metres) and Seetakal (1004 metres) in Tumakuru taluk; Madhugiri-durga (1179 metres), Midigeshi-durga (1023 metres), Doddanaramangala (930 metres) and Byalya (874 metres) in Madhugiri taluk; Hutridurga (1112 metres), Hcmagiri (925 metres), Rangaswami-betta (899 metres) and.' Huliyurdurga (831 metres) In Kunigal tal uk; Kamana-durga (lOGO metres), Nidugal (1131 metres) and Pavagada hill (904 metres) in Pavagada tal uk; Channarayana-durga (1120 metres) and Koratagiri hill (867 metres) In Koratagere taluk; and Bommanahalli (938 metres) and Choudanahalli (800 metres) in Tiptur tal uk. The watershed separating the river systems of the Krishna and the Cauvery may be defined by a line drawn from cast to west touching Koratagere and Tiptur.
Shimsha, Jayamangali and Suvarnamukhi are the important rivers of the district. Shimsha has its origins in the southern portion of the Dcvarayana-durga hill range and flows in a general south by south-westerly direction cutting through the taluks of Tumakuru, Turuvekere, Gubbi and Kunigal. After traversing a total distance of about 100 krn this river enters Mandya district and finally joins the Cauvery. Enroute, this river feeds the large Kadaba tank and is itself enriched by the numerous streams that flow into it from several directions. Naga stream which joins it near. Kallur and the Nagini stream that emerges from the Kunigal tank and merges with the river near –Hanumapura are the streams that deserve a special-mention. The waters of this river have been harnessed for purposes of irrigation by constructing a dam near Marconahalli in Kunigal taluk. This reservoir has an atchkat area of 4500 hectares. The Jayamangali river too originates in the Devarayanadurga hill range, but unlike Shimsha it. emerges on the northern side of the hill at a gorge called Jaladagondi and consists of two distinct streams. It flows in a north by north-easterly direction, enters Madhugiri taluk where it is augmented by the incoming waters of Garudachala near Holavanahalli from the east and by the inflow of Suvarnamukhi near Kyasavara from the west. The total length of this river is 65 km and this is a tributory of the North Pinakini river.
Strange as it may appear, it is a fact that Tumakuru district contains two rivers bearing the same name. These may be called the Suvarnamukhi of the eastern belt and the Suvarnamukhi of the western belt respectively. The eastern Suvarnamukhi is a smaller stream with a course of about 25 km running through the taluks of Tumakuru, Koratagere and Madhugiri. The river is formed 'by the confluence of . streams, one of which has its origins near Devarayanadurga of Tumakuru taluk and another has its origins ncar Kolikal State Forest of Koratagere taluk, The former stream flows in a northern direction while the latter, known as DoddahaIla, flows in an easterly direction for a' distance of about 15 km before uniting with the other' stream near Rampura village. This Suvarnamukhi flows into the Jayarnangali river ncar Kyasavara village and loses its identity thereafter. The western Suvarnamukhi is an important tributary of the Vedavati river. This too is composed of several streams, the chief stream having its origins near Badamuddanahalli village which is located south-west of Channarayanadurga in Koratagere tal uk. This stream flows north through the taluks of Koratagere and Madhugiri, traverses a distance of about 5 km in Anantpur district of Andhra Pradesh, turns west and enters Sira taluk ncar Madalur village. Thereafter it takes a west by north-westerly course across Sira taluk and ncar . Adalur it is enriched by the incoming waters of Doddahalla from the south. This Doddahalla originates in the southern portion of Sira tal uk. Another main stream which constitutes this river) has its origin near Settikere in Chiknayakanhalli. This stream, Chikk Tore, takes a northerly course and cuts through Chiknayakanhalli. A dam has been built across this stream at Boranakanive to form a large reservoir which provides irrigation facilities to about 600. hectares of land: A few kilometres to the north-east this is joined by Kare Tore flowing in a north westerly direction near the Suvarnamukhi State Forest. It is from this place onwards that the combined stream gets the name Suvarnamukhi. Thereafter it continues to flow in the general north-easterly direction and is joined by the other branch of the Survarnamukhi, which flows in from the east, near Hunaschalli in Sira tal uk. Finally this river joins the Vedavati ncar Kudalur in Hiriyur taluk of Chitradurga .district. The total distance traversed by this river in the- district adds up to about 100 km.
North Pinakini flows through Pavagada taluk for a short distance. Likewise Kumudwati cuts through the eastern borders of Madhugiri tal uk. Among the other streams, Nagini deserves mention. The Sankanpura Lake formed by the construction of an anicut across this stream as early as in 1901 irrigates about 250 hectares. Recently one more anicut has been built across this stream ncar the village Mangala.
The northern and the north-eastern portion of the district covering the taluks of Madhugiri, parts of Koratagcre and Pavagada taluks, is known for its tala pariges (springs) which provide water for irrigation also. Water obtained from these spring-heads is. either conducted directly by narrow channels to the fields or else, large wells have been constructed so that water can be stored, lifted and channclised. The district is also known for its large number of tanks, ~most of which are important from the point of view of irrigation potential. It may be mentioned in passing that the atchkat area is more than 400 hectares in the case of 8 tanks and between 200 to 400 hectares in the case of another 36 tanks. Sira taluk has the distinction of having the largest number of tanks.
Geologically, Tumakuru district is situated right on the archaen complex. The rock formations are represented by the crystalline schists, the granitic gneisses and the newer granites. The crystalline schists of this district, which form the southern extension of the well defined Chitradurga schist belt of the Dharwar system, are the oldest members of the archaean complex. The schist belt which passes to the east of Chiknayakanhalli send out, near Banasandra, a branch that extends over 40 km. This narrow belt is composed of chloritic schists, micaceous schists, quartzites, limestones and ferruginous quartzites. In this belt, lens-shaped masses of grey trap occur between the villages of BeUara and Bukkapatna. These are basic and intermediate types of'volcanic rocks. Portions of the schist belt near Doddaguri exhibit dear evidences . of sedimentation. The thin patches of schists scattered about in gneissic complex show evidences of repealed metamorphism. These schists are intensely altered and new minerals like diopside, hypcrthcnc, garnet, cordicrite, sillimanite and corundum have developed giving rise to several interesting rock types. A major' portion of the district is covered by gneissic complex which is said to be composed of four major components; banded gneisses, granitic gneisses, gneissic granites and granites, and grano-diorites, diorites, inter-action diorites and other varieties. The younger granites; which are coarse-grained and porphyritic, constitute a well-defined narrow range of hills, which run north and south in the eastern portion of the district. Gold, manganese, sillimanite, asbestos, corundum, feldspar, garnet, quartz, ochres, clay, silver sand, soapstone and building as well as ornamental stones constitute the chief items of mineral wealth. The soils of the district arc hard and poor in general. Red, gravelly, sandy, clay, loam, black soil, sandy' loam and sandy clay arc the main types of soil met with in various parts of the district.
About 4 per cent of the total area of the district stands classified as forests. The forest regions are found to a large extent on the lower slopes of hill ranges. The forests are mostly open and consist of mixed species varying from dry deciduous to throny bushes. Because of the scanty rainfall the trees are short, twisted, knotty and full of branches. The forests contain very few timber species and the wood that is generally available is fit for use only as fuel. These forests have also been over-exploited since decades and the free grazing facility permitted therein has had an inimical effect on the natural and artificial regeneration. In the southern portion however there arc forest tracts containing tall and well grown trees. By and large it may be observed that the soil, rainfall and climatic conditions are not quite favourable for the growth of rich and variegated vegetation. In the absence of adequate forest cover the district has very few species of wild animals. Tiger, panther and cheeta have now totally outrnigrated from these forests. Bear, wild boar, hyena, fox, spotted deer and rabbit are the important species of wild animals encountered in the district.
The climate of the district is quite aggreable /and free from. extremes, However, amongst the taluks, Pavagada which is located in the north-cast is noted for its relatively hot climate. The year is usually divided into four seasons: summer from March to May; rainy season or south-west monsoon season from June to September; post-monsoon,seasorl covering the months of October and November and dry or winter Season from December 10 February. Generally the period from March to May is one of continuous and steady rise in temperatures. The day temperature reaches a maximum of 41 degree cclcius at times. April is the hottest month, During April as well as May there would be thunderstorms followed by heavy pre-monsoon showers, in almost all parts of the district. With the onset of the monsoon, the temperature drops' appreciably and throughout the monsoon period the weather remains pleasant. After October the night temperature dips further. December is usually the coldest month, during which the minimum temperature would be as low as9 degree celcius on certain days. Relative humidities are high during the monsoon period, moderate during the other months and comparatively low during the summer afternoons, Winds arc generally moderate with some increase in strength during the monsoon months, especially June and July.
The average annual rainfall in the district IS 687.9 mm. This amount of rainfall is subject to considerable fluctuations from year to year. Within the district itself the northern and the eastern regions receive comparatively lesser amounts of rainfall than their southern and south-western counterparts. The average number of rainy days being 45, the number of rainy days varies between 35 in Pavagada located in the north-east and 54 in Tumakuru which enjoys a central location. The precipitation during the south-west monsoon period usually accounts for 50 per cent of the annual rainfall and remaining 50. per cent of rainfall is spread over the pre-monsoon months of April and Mayan the one hand and the northeast monsoon months of October and November on the other. The remaining months of the year are comparatively free from rains. September and October arc the months which are noted for heavy rainfall. It is during this period that the innumerable tanks of the district receive large quantities of water and gel filled to the brim. Delays in the onset of these rains, as also inadequate downpour during this . period, quite often cause great anxiety and hardship to the farmers of the district. Certain parts of the district are known to be often afflicted by drought and scarcity conditions.