Brahmani River near Akalipur in Birbhum. Image Source: Pinakpani via Wikimedia Commons.
The Brahmani and Baitarani river basin is a landscape of rivers, forests, farms, mines, industries and growing towns. But the way people use this landscape is changing its thermal balance and, with it, the movement and availability of water.
Mining strips land of vegetation and leaves exposed surfaces that absorb and retain heat. Industrial and urban clusters release heat and pollutants, while agriculture and deforestation alter land cover and surface temperatures. Growing settlements bring more energy use, vehicles and construction, adding further heat to an already changing landscape. Together, these pressures are raising local temperatures and altering conditions that influence the basin’s rivers, soil moisture and ecosystems.
The Brahmani and Baitarani River Basin covers around 55,000 square kilometres and is bordered by the Chhotanagpur Plateau, the Mahanadi River basin and the Bay of Bengal. It includes the Brahmani and Baitarani sub-basins, with most of the area located in Odisha and Jharkhand. In 2020, around 1.3 crore people lived across its 21 districts and 17 parliamentary constituencies. The basin receives around 1,400 mm of mean annual rainfall, while annual average temperatures range between 32°C and 20°C.
It is also an important economic region. Coal mining is concentrated in the Talcher and Angul region, while the Banaigarh, Joda and Jagannathpur belt is known for iron ore and manganese. Gumla and Lohardaga are important bauxite-producing areas. Agriculture is prominent across Jajpur and Bhadrak, the Keonjhar Plateau and Simdega, while major industrial and manufacturing centres are located around Angul and Dhenkanal, Bhuban and Byasanagar, and Rourkela and Rajgangapur. As these activities have expanded, land cover, surface temperatures and population patterns have changed.
A recent open access study by Dibya Jyoti Mohanty & Jajnaseni Rout published in Geocarto International uses satellite data to investigate temperature trends within the BBRB river basin from 2000 to 2022, focusing on its significant industrial, mining, and agricultural centres and the contribution of anthropogenic pressures to temperature changes. The findings offer a picture of a basin that is becoming warmer, while its water cycle is also changing.
The study found that the average maximum temperature across the basin increased by 0.35°C since 2000. The authors associate the warming with areas where urban and industrial expansion has been rapid. Built-up areas increased by 74 per cent between 2000 and 2020, and the study found a strong relationship between this expansion and rising temperatures.
The warming is visible across different seasons. In January, the average maximum temperature increased from 25.68°C to 25.76°C, with an anomaly of 0.075°C. The increase became more pronounced in February and March, with anomalies of 0.42°C and 0.39°C, respectively.
August, September, November and December recorded higher anomalies, ranging from 0.47°C to 0.56°C. Across the seasons, the average maximum temperature anomaly was 0.36°C during the monsoon, 0.37°C during the post-monsoon period and 0.40°C during winter. The hot season recorded the smallest increase, at 0.20°C.
Across the full period studied, the basin had a mean annual temperature of 31.15°C, with an upward trend of 0.012°C per year. The study connects this warming with the expansion of human activity, particularly in areas where mining, industry, agriculture and urbanisation have transformed the land surface.
Mining and industrial activity have helped drive the growth of settlements across several parts of the basin. Population density has increased around mining areas such as Talcher and Angul, Gumla and Lohardaga, and Banaigarh, Joda and Jagannathpur.
Industrial belts including Angul and Dhenkanal, Byasanagar and Anandapur, and Rourkela and Rajgangapur have also experienced population growth. Agricultural areas such as Simdega, Torpa, Keonjhar and Jajpur and Bhadrak have undergone similar changes.
Growing populations and settlements increase demand for infrastructure and services while adding pressure on land and water resources. The expansion of human activity also contributes to habitat fragmentation and biodiversity loss.
The land cover changes documented by the study show the scale of this transformation. Around 2.93 per cent of forestland has been converted to cropland and 1.14 per cent to built-up areas. Another 0.91 per cent of cropland has been converted to built-up land.
The greatest land use and land cover changes are concentrated around mining and industrial belts, particularly Talcher and Angul and Bhuban and Byasanagar. These areas also have higher population densities.
The Koira, Joda, Barbil and Jagannathpur belt presents a different pattern. The study records fewer land use changes here, which it associates with policies restricting land modification and the continued presence of tree cover from the Saranda and Baitarani forest ranges around the mining region. State policy promotes mining in the area while seeking to protect surrounding biodiversity.
The differences in land cover are reflected in the distribution and intensity of heat across the basin.
The study identifies significant clusters of high temperatures around urban and industrial centres, where human activity and land use changes are more intense. Talcher and Angul and Bhuban and Byasanagar emerge as major urban and industrial hotspots. Gumla and Lohardaga and Banaigarh show intense heating associated with bauxite and coal mining.
The Koira, Joda, Barbil and Jagannathpur belt also contains dispersed hotspots, although the study indicates that surrounding forest cover appears to suppress some of the heat. Rourkela and Rajgangapur show moderate to high heating associated with industrial expansion. Agricultural areas are also warming. Keonjhar, Simdega and Torpa recorded clear temperature increases. The study links this warming to concerns around cropping patterns, soil moisture and water stress.
In some areas, temperatures were up to 4°C higher than the baseline. Bhuban and Byasanagar recorded the strongest anomaly at 4.71°C, along with a 17.5 per cent rise in temperature. The region includes the Sukinda and Kalinganagar industrial clusters, where mining and steel production are prominent.
Gumla and Lohardaga recorded a 4.35°C increase, equivalent to a 20 per cent rise. Sparse vegetation and barren land can intensify heat absorption in the area. Keonjhar recorded a 4.25°C anomaly. As an important agricultural region, the finding has implications for cropping patterns, soil moisture and water availability.
The study therefore shows that the effects of human activity are not confined to built-up areas. Changes in forests, croplands and exposed land are also associated with changing thermal conditions.
The warming of the basin has implications beyond temperature. As temperatures rise, more water can be lost to the atmosphere through evapotranspiration. This process transfers water from soil and vegetation to the atmosphere and can influence how much remains available to rivers, ecosystems and communities.
The study found an upward trend in evapotranspiration across the basin between 2000 and 2022, increasing by around 5.5 kg per square metre each year. The authors link the increase in evapotranspiration to rising temperatures and changes in land use and land cover. As vegetation, cropland, built-up areas and exposed surfaces change, so too can the way water is stored, used and returned to the atmosphere.
At the same time, river discharge has been declining. Data from the Jenapur station on the Brahmani River shows a downward trend in river flows. The combination of rising temperatures, increasing evapotranspiration and declining river discharge points towards growing water stress in parts of the basin.
Lower river discharge means less water is available for agriculture, ecosystems and human use. Changes in river flows can also alter sediment transport and nutrient movement, with consequences for riverine and riparian habitats.
This makes the connection between land use, temperature and water particularly important. Human activities that alter the land surface can influence local temperatures, while rising temperatures can increase water loss through evapotranspiration. Together, these changes can affect the amount of water that remains within the basin.
For industrial and mining areas, rising temperatures can increase heat exposure around asphalt, concrete, metal surfaces and heat-generating activities. Higher temperatures can increase the need for cooling, add to emissions and increase heat-related health risks for workers. For workers exposed to intense heat, this can mean greater risk of heat stress and illness, with potential consequences for productivity and medical costs.
Agriculture faces a different set of pressures. Higher temperatures can alter local microclimates and affect crop growth and yields. Increased evapotranspiration can raise crop water requirements, adding pressure to already stressed water resources and potentially increasing competition for water.
Changes in temperature and moisture conditions can also affect soil health, fertility and the resilience of agricultural systems. These impacts connect the basin's thermal changes directly with livelihoods that depend on reliable water and productive land.
The study points towards measures that address temperature, land use and water together.
Reforesting and restoring wetlands: Expanding riparian forest buffers along riverbanks, protecting and restoring wetlands and encouraging community afforestation in mining areas could help cool the landscape and regulate evapotranspiration.
Regulating mining and industry: Since mining and industrial areas contain some of the strongest heat hotspots, maintaining green cover around mines, monitoring thermal discharges from steel plants and limiting expansion in already stressed hotspots could help address local heating.
Promoting sustainable agriculture: Agroforestry and mixed cropping, reducing stubble burning and soil exposure, and encouraging water-efficient irrigation could help reduce some of the pressures associated with agricultural intensification.
Introducing urban cooling measures: In urban centres such as Talcher and Angul and Bhuban and Byasanagar, green roofs, shaded streets, improved public transport and cooling corridors could help reduce heat exposure.
Involving communities: Local communities could participate in water conservation campaigns, tree planting and maintenance, temperature monitoring in hotspots and heat safety training.
The Brahmani and Baitarani basins are undergoing several interconnected changes. Population is growing in many areas, built-up land is expanding, mining and industrial activity remain important economic drivers, forests and agricultural land are changing, and temperatures are rising.
The study shows that these changes are not occurring independently. Human activity has altered land cover and contributed to warming across parts of the basin, while rising temperatures are associated with increasing evapotranspiration. At the same time, river discharge is showing a declining trend.
The basin's future water availability will therefore depend not only on how much rain it receives but also on what happens to that water after it falls. How much is retained in the soil, taken up by vegetation, returned to the atmosphere, reaches rivers or remains available to ecosystems and communities is increasingly important.
The satellite-based evidence from 2000 to 2022 provides a picture of how temperature, land use and water dynamics are changing together. Understanding these connections can help inform planning across mining areas, industrial centres, agricultural landscapes and urban settlements. For a basin where economic activity and water resources are closely connected, the changing thermal landscape is also a warning about the wider consequences of altering the land on which its rivers depend.