About the Region

The Damodar River Basin (DRB) is a sub-basin and part of the Ganges River spreading over an area of about 23,370.98 sq. km in the states of Jharkhand and West Bengal. The geographical boundary of the basin lies between 22"15' to 24"30' N latitude and 84°30' to 88°15' E longitude (Figure 1). The basin is bounded by Giridih and Santhal Pargana districts in the north; Hazaribagh and Palamau districts in the west; Ranchi, Purulia and Bankura districts in the south; and Hooghly and Howrah districts in the east and southeast.

 The basin extends over six districts of Jharkhand viz., Palamau, Hazaribagh, Giridih, Dhanbad, Santhal Pargana and Ranchi and five districts of West Bengal, viz., Purulia, Bankura, Burdwan, Hooghly and Howrah. The coverage of each constituent district is shown in Table 1. The basin represents about 8.1% and 10.4% of the total population of Undivided Bihar and West Bengal, respectively. The distinctive feature of the basin is that around three-fourth of its area representing the upper catchment falls in Jharkhand, while the low-Iying flood plains entirely lies in West Bengal. The region is richly endowed with varied mineral resources. Consequently, the region supports several eco-Nomic activities related to mining and mine-based industries (311 coalmines, 182 non-coal mines, 78 urban centers and 82 industrial centers).

Table 1 : Constituents of Damodar River Basin

Physiography

The Damodar River Basin has varying landforms such as plateaus, hills, uplands and plains. Physiographically, four prominent divisions constitute entire basin with different litho logy, slope, soil and vegetation. The first division comprises of extensive plateaus and hills, which cover most of the basin area with characteristics high elevation. The rolling uplands developed over Archaean rock form the second division which descends due east. The third division is characterized by rolling plains with sharply raised terraces. This broad undulating terrain has significant soil and vegetation cover in comparison to other areas. The fourth division comprises of low-Lying alluvial plains with riverine aggregates and marches. They occupy the lower basin areas and are prominent as a rich paddy land.

Geology

The geology of the  basin is spelt out by different types of rocks ranging from Archaean to recent age with economic deposits like coal and mica. About 2/3rd of the deposits are in upper and middle basin, covered by Archaean rocks. The lower basin is characterized by alluvium soil. The Gondwana and Vindhyan deposits, covering considerable areas are in the middle part of the basin. At most places, the crystalline and Gondwana areas are criss-crossed by  post-Gondwana intrusions and are punctuated by multi-directional faults and lineaments.

Drainage System

Damodar and its principal tributary, the river Barakar forms the core drainage system of the basin. This riverine system drains about 23,370.98 sq. km. area of Jharkhand and West Bengal states. The Damodar in its upper reaches is known as the Deonad, and originates in Khamarpet hill range (1,062 m) near Chandwa in Palamau district. The Waters of the Deonad traverse through the steep slope of the pat region to descend on the gneissic flat plain of  Chandwa basin. The flow of the river is sluggish over the flat top surface, which later on got dissected into tabular blocks by fluvial action. After the confluence of the Dharamauti near Mahuamilan, Damodar enters the Gondwana Basin and the landscape around the river changes. The gradient of the stream becomes steeper and waterfalls abound the course, which traverses through the hilly and woody country carved out of hard sandstone and grit of Gondwana age. The Damodar receives a number of tributaries in this section both from the southern and the northern slopes.The southern tributaries (Chati, Dainkata, Saphi, Batuka, Nalkari and Dhobdhab) flow over the granite-gneissic surface of Ranchi plateau, while the northern tributaries are Haharo (W), Bakri-Garhi, Haharo (E) and Marmarhar.These tributaries originate from the Hazaribagh plateau and flow for considerable distance over the Archaean gneiss before entering the Gondwana basin. The streams of Konar and Bokaro originate in the Hazaribagh plateau near Hazaribagh town. The Konar flows over the Archaean gneiss country while Bokaro traverses through the Archaean gneiss country for some distance and finally enters the Gondwana basin near Bokaro coalfields. The combined courses of the Konar and Bokaro rivers meet the Damodar near Tenughat. 

The Damodar flows further east from Tenughat and before reaching Panchet, it receives a few other tributaries from the north and south. The Jamunia and the Khudia join the Damodar from the north after flowing over the Jharia coalfields, while from the south Ijri and the Gowai meander eastward to meet the Damodar near the western end of Panchet hill reservoir. 

The Barakar river basin has an area of 7026 sq. km. It rises from the Koderma plateau and runs for a long distance to meet the Damodar near Dishergarh and traverses through a steep sided valley. It has two important tributaries the Barsoti and the Usri. A low divide separates the Barakar basin from the Damodar. Damodar enters flat alluvial plains after Dishergarh, and runs eastward upto Barsut in Burdwan and the flow of the river becomes very sluggish at this stage. Here, Damodar receives its last tributary, the Sali from the south. After-wards the Damodar takes a sharp turn towards south near the village Chachai, 24 km south-east of Burdwan. Within its elbow several spill channels, locally known as hanas, are found. These hanas carry surplus water of the Damodar during monsoon months. Turning south, it has a distributary named the Kana Damodar, which ultimately drains out water in the Hooghly. Traversing further south Damodar splits into two important channels, the Mundeswari and the Damodar. The Damodar channel flows over the Arambagh sub-division of Hooghly district and Uluberia sub-division of Howrah district to meet the Hooghly opposite Falta. At present 75% of the run off from the Damodar is carried by the Mundeswari channel through the Begor and the Mushir hanas and drains out water in the Rupnaran-yan. This channel can not carry the total flood discharge of the Damodar and as a result the elbow area of the Damodar gets inundated occasionally notwithstanding the construction of barrage and dams over the Damodar in its upper reaches. Flood protection embankments have been constructed along the banks in the lower reaches of the Damodar, but are not sufficient to cope up with the steadily rising river bed due to silting.

Climate

Damodar river basin experiences tropical climate with the hottest summer and the coldest winter. The month of May is the peak of summer season with an average maximum temperature of 43°C and minimum of 30°C, while December and January are the coldest months. Temperatures during winter fall below 4°C at some locations in the DRB.

Rainfall: Annual rainfall over the basin varies between 765 and 1607 mm with an average of 1200 mm of which 80% occurs during the monsoon season. The average annual rainfall in the three sub-catchments namely Barakar, Damodar and lower basin are approximately 1200 mm, 1250 mm and 1400 mm, respectively. The rainfall is the highest in the southern part and decreases gradually towards the northern part of the Barakar catchment.Rainfall due to squalls in upper basin is not uncommon during summer. The evaporation is maximum during summer (21 mm) and minimum in monsoon season (2.5 mm).

Wind Parameters:Wind direction varies in each season. During the first quarter of the year, the predominant direction is E-W while in second quarter, it is NE-SW and E-W. During third and fourth quarters of the year, the wind direction is southeasterly and northwesterly respectively. Wind speed over the basin differs from place to place with season, being about 10.5 km/h (maximum) during summer season and 1.8 km/h (minimum) during winter season.

Soil

In upper and middle basin of Jharkhand region, the soil has been grouped into major red and yellow loam sedimentary types. They have a tendency of laterisation; are highly leached; neutral to acidic in reaction; deficient in organic matter, nitrogen and available phosphorus acid but the potash content is high. 

Vegetation

Damodar basin has varying types of terrestrial ecosystems with diverse vegetation allover the basin. The floral biodiversity of the basin is rich and is represented by 137 flowering plant families and 853 species belonging to 535 genera. Poaceae is the. Dominant family of the region with 148 species followed by leguminoseae, the second largest family with 92 species. These floral species are found in various forest types, open grasslands, agricultural fields, fallow lands, wastelands, mined out areas and their overburden dumps. A large number of these plants have socio-economic importance, besides their role in natural ecosystem functions. Since a majority of human population resides around the forests, their daily requirements of food, fodder, shelter and medicine are met by these natural plant resources. Some of these plant species have great potential for exploitation by pharmaceutical and cosmetic industry and these species can become an important resource for economic development of the local population.

Fauna

A rich and luxuriant vegetation cover in the upper basin provides good habitat for animals and birds. There are 24 species of large and small mammals, 17 species of reptiles and about 300 species of birds in the basin. Damodar River has shown tremendous decrease in its fish fauna since 1950s. The numbers of species have declined from 64 in 1950s to about 25 during 1994-95. 

The resident population of large mammals like tiger and elephants is rather low, but the forest provide important migration corridors for these animals. However, their habitat continuity in the protected areas like Palamau Tiger  Reserve in the west, Koderma wildlife sanctuary in the east and Dalma wildlife sanctuary in the south of the basin makes the area critical for these animals. 

Despite the fact that the upper basin has a good forest cover the aggregate of wild animals is too small in diversity. The main factors responsible for the decrease of wild animals are: the fragmentation and destruction of habitat, poaching and too much of other human interference. The basin and surrounding areas have a number of large and small-protected areas and some of them like Palamau Tiger Reserve and Dalma Wildlife Sanctuary harbour a good population of mammals. However, increased mining activity in the upper basin will seriously jeopardize the survival of these species. The limited migration routes will be subjected to destruction and the future of animals, which may be living outside Damodar Basin, seems rather bleak. The proposed mining activity, particularly in the North Karanpura valley, will deal a severe blow to the animal species and their survival chances will reduce to a great ex-tent. In the face of already diminishing population of animals like Tiger, these animals may be faced with ultimate Extinction in and around the basin.