Hydropower in the context of Air pollution

The Danube (/ˈdæn.juːb/ DAN-yoob; see also other names) is a river in Europe, the second-longest after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest of Germany south through the Danube Delta in Romania into the Black Sea. A large and historically important river, it was once a frontier of the Roman Empire. In the 21st century, it connects ten European countries, running through their territories or marking a border. Originating in Germany, the Danube flows southeast for 2,850 km (1,770 mi), passing through or bordering Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova, and Ukraine. Among the many cities on the river are four national capitals: Vienna, Bratislava, Budapest, and Belgrade. Its drainage basin amounts to 817,000 km (315,000 sq mi) and extends into nine more countries.

The Danube's longest headstream, the Breg, rises in Furtwangen im Schwarzwald, while the river carries its name from its source confluence in the palace park in Donaueschingen onwards. Since ancient times, the Danube has been a traditional trade route in Europe. Today, 2,415 km (1,501 mi) of its total length are navigable. The Danube is linked to the North Sea via the Rhine–Main–Danube Canal, connecting the Danube at Kelheim with the Main at Bamberg. The river is also an important source of hydropower and drinking water.

The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succeeding the Second Agricultural Revolution. Beginning in Great Britain around 1760, the Industrial Revolution had spread to continental Europe and the United States by about 1840. This transition included going from hand production methods to machines; new chemical manufacturing and iron production processes; the increasing use of water power and steam power; the development of machine tools; and rise of the mechanised factory system. Output greatly increased, and the result was an unprecedented rise in population and population growth. The textile industry was the first to use modern production methods, and textiles became the dominant industry in terms of employment, value of output, and capital invested.

Many technological and architectural innovations were British. By the mid-18th century, Britain was the leading commercial nation, controlled a global trading empire with colonies in North America and the Caribbean, and had military and political hegemony on the Indian subcontinent. The development of trade and rise of business were among the major causes of the Industrial Revolution. Developments in law facilitated the revolution, such as courts ruling in favour of property rights. An entrepreneurial spirit and consumer revolution helped drive industrialisation.

The Rhodopes (/ˈrɒdəpiːz/; Bulgarian: Родопи, Rodopi; Greek: Ροδόπη, Rodopi; Turkish: Rodoplar) are a mountain range in Southeastern Europe, and the largest by area in Bulgaria, with over 83% of its area in the southern part of the country and the remainder in Greece. Golyam Perelik is its highest peak at 2,191 meters (7,188 ft). The mountain range gives its name to the terrestrial ecoregion Rodope montane mixed forests that belongs in the temperate broadleaf and mixed forests biome and the Palearctic realm. The region is particularly notable for its karst areas with their deep river gorges, large caves and specific sculptured forms, such as the Trigrad Gorge.

A significant part of Bulgaria's hydropower resources are located in the western areas of the range. There are a number of hydro-cascades and dams used for electricity production, irrigation, and as tourist destinations.

Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other renewable sources combined and also more than nuclear power. Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel-powered energy plants. However, when constructed in lowland rainforest areas, where part of the forest is inundated, substantial amounts of greenhouse gases may be emitted.

Construction of a hydroelectric complex can have significant environmental impact, principally in loss of arable land and population displacement. They also disrupt the natural ecology of the river involved, affecting habitats and ecosystems, and siltation and erosion patterns. While dams can ameliorate the risks of flooding, dam failure can be catastrophic.

Surface water is water located on top of land, forming terrestrial (surrounding by land on all sides) waterbodies, and may also be referred to as blue water, opposed to the seawater and waterbodies like the ocean.

The vast majority of surface water is produced by precipitation. As the climate warms in the spring, snowmelt runs off towards nearby streams and rivers contributing towards a large portion of human drinking water. Levels of surface water lessen as a result of evaporation as well as water moving into the ground becoming ground-water. Alongside being used for drinking water, surface water is also used for irrigation, wastewater treatment, livestock, industrial uses, hydropower, and recreation. For USGS water-use reports, surface water is considered freshwater when it contains less than 1,000 milligrams per liter (mg/L) of dissolved solids.

A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production of many material goods, including flour, lumber, paper, textiles, and many metal products. These watermills may comprise gristmills, sawmills, paper mills, textile mills, hammermills, trip hammering mills, rolling mills, and wire drawing mills.

One major way to classify watermills is by wheel orientation (vertical or horizontal), one powered by a vertical waterwheel through a gear mechanism, and the other equipped with a horizontal waterwheel without such a mechanism. The former type can be further subdivided, depending on where the water hits the wheel paddles, into undershot, overshot, breastshot and pitchback (backshot or reverse shot) waterwheel mills. Another way to classify water mills is by an essential trait about their location: tide mills use the movement of the tide; ship mills are water mills onboard (and constituting) a ship.

Renewable energy (also called green energy) is energy made from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also significant in some countries. Some also consider nuclear power a renewable power source, although this is controversial, as nuclear energy requires mining uranium, a nonrenewable resource. Renewable energy installations can be large or small and are suited for both urban and rural areas. Renewable energy is often deployed together with further electrification. This has several benefits: electricity can move heat and vehicles efficiently and is clean at the point of consumption. Variable renewable energy sources are those that have a fluctuating nature, such as wind power and solar power. In contrast, controllable renewable energy sources include dammed hydroelectricity, bioenergy, or geothermal power.

Renewable energy systems have rapidly become more efficient and cheaper over the past 30 years. A large majority of worldwide newly installed worldwide electricity capacity is now renewable. Renewable energy sources, such as solar and wind power, have seen significant cost reductions over the past decade, making them more competitive with traditional fossil fuels. In some geographic localities, photovoltaic solar or onshore wind is the cheapest new-build electricity. From 2011 to 2021, renewable energy grew from 20% to 28% of the global electricity supply. Power from the sun and wind accounted for most of this increase, growing from a combined 2% to 10%. Use of fossil energy shrank from 68% to 62%. In 2024, renewables accounted for over 30% of global electricity generation and are projected to reach over 45% by 2030. Many countries already have renewables contributing more than 20% of their total energy supply, with some generating over half or even all their electricity from renewable sources.

A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions.

The word dam can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities, such as Amsterdam and Rotterdam.

Uttarakhand (Hindi: Uttarākhaṇḍ, pronounced [ˈʊt̪ːəɾaːkʰəɳɖ], lit. 'Northern Land'), also known as Uttaranchal (English: /ˌʊtəˈræntʃəl/; the official name until 2007), is a state in northern India. The state is bordered by Himachal Pradesh to the northwest, China to the north, Nepal to the east and Uttar Pradesh to the south. Uttarakhand has a total area of 53,483 km (20,650 sq mi), equal to 1.6% of the total area of India. Dehradun serves as the state capital, with Nainital being the judicial capital. The state is divided into two divisions, Garhwal and Kumaon, with a total of 13 districts. The forest cover in the state is 45.4% of the state's geographical area. The cultivable area is 16% of the total geographical area. The two major rivers of the state, the Ganges and its tributary Yamuna, originate from the Gangotri and Yamunotri glaciers respectively. Ranked 6th among the Top 10 Greenest States in India with Best AQI.

Uttarakhand's history dates back to prehistoric times, with archaeological evidence showcasing human habitation. It was part of the ancient Kuru and the Panchal kingdoms during the Vedic age, and later saw the rise of dynasties like the Kunindas and influence of Buddhism as evidenced by Ashokan edicts. Though primarily driven by agriculture and hydropower, the state's economy is now dominated by the service industry. The service sector comprises primarily travel, tourism, and hotel industry. The Gross State Domestic Product (GSDP) of Uttarakhand is ₹3.78 lakh crore (US$45 billion). The state contributes five seats to the lower house Lok Sabha and three seats to the upper house Rajya Sabha.

Sir Richard Arkwright (23 December 1732 – 3 August 1792) was an English inventor and a leading entrepreneur during the early Industrial Revolution. He is credited as the driving force behind the development of the spinning frame, known as the water frame after it was adapted to use water power; and he patented a rotary carding engine to convert raw cotton to 'cotton lap' prior to spinning. He was the first to develop factories housing both mechanised carding and spinning operations.

Arkwright's achievement was to combine power, machinery, semi-skilled labour and the new raw material of cotton to create mass-produced yarn. His organisational skills earned him the accolade "father of the modern industrial factory system," notably through the methods developed in his mill at Cromford, Derbyshire (now preserved as part of the Derwent Valley Mills World Heritage Site).

River engineering is a discipline of civil engineering which studies human intervention in the course, characteristics, or flow of a river with the intention of producing some defined benefit. People have intervened in the natural course and behaviour of rivers since before recorded history—to manage the water resources, to protect against flooding, or to make passage along or across rivers easier. Since the Yuan Dynasty and Ancient Roman times, rivers have been used as a source of hydropower.

From the late 20th century onward, the practice of river engineering has responded to environmental concerns broader than immediate human benefit. Some river engineering projects have focused exclusively on the restoration or protection of natural characteristics and habitats.

Statkraft AS is a hydropower company, fully owned by the Norwegian state. The Statkraft Group is Europe's largest generator of renewable energy, as well as Norway’s largest and the Nordic region's third largest energy producer. Statkraft develops and generates hydropower, wind power, gas power, district heating and solar power. It is also a player in the international energy markets. The company has 7,000 employees in over 20 countries with their headquarters located in Oslo, Norway.

The Ogosta (Bulgarian: Огоста [oˈɡɔstɐ], Latin: Augusta), is the largest river in Northwestern Bulgaria, a right tributary of the Danube. It originates at Chiprovska Mountain, a 2,168 meters high section of the Western Balkan Mountains, at an altitude of about 1,760 meters, on the border with Serbia. The towns of Chiprovtsi, Montana, and Miziya are situated on the river's banks.

The Ogosta river is 147.4 km in length and is fed by 40 tributaries (including the Skat River) in a watershed of 3,157 square kilometers. The average water discharge in the lower course of the river is 18 cubic meters per second. Along the river's length there are 14 irrigation systems, 8 hydropower plants, and 13 dams.