At Manikaran in Himachal Pradesh, hot springs are famous for their high water temperature. What is the primary natural source of energy that heats these hot springs?

Introduction / Context:
Manikaran in Himachal Pradesh is well known for its hot springs, which attract pilgrims and tourists. Understanding why water in such springs is naturally hot is part of general science and geography. This question asks you to identify the primary natural source of energy that heats the hot spring water at locations like Manikaran, linking local examples with global concepts such as geothermal energy.

Given Data / Assumptions:

• The location is Manikaran, which has naturally hot springs.
• The options include geothermal energy, biomass energy, thermal energy from burning fuels, and hydro energy.
• The question focuses on natural energy, not on man made heating systems.

Concept / Approach:
Hot springs occur where groundwater is heated naturally beneath the Earth surface and then rises to emerge at the surface. The heat generally comes from geothermal sources, such as hot rocks or magma closer to the surface, or from deep circulation of water in regions with higher geothermal gradients. Biomass energy refers to energy from plant and animal material, thermal energy from burning fuels would be artificial heating, and hydro energy refers to electricity from flowing water. The approach is to match the natural heating mechanism with the correct energy source name.

Step-by-Step Solution:
Step 1: Recognise that Manikaran hot springs are natural. There is no continuous burning of fuel to heat the water; instead, heat comes from below the ground. Step 2: Understand that geothermal energy is defined as heat energy from within the Earth crust and deeper layers, which can warm rocks and underground water. Step 3: Biomass energy involves burning wood, crop residues, or other organic matter, which does not match the mechanism of a natural hot spring. Step 4: Hydro energy refers to energy obtained from moving water in rivers or dams, typically used to generate electricity, and is not directly responsible for heating spring water. Step 5: Therefore, the natural heating of the springs at Manikaran is due to geothermal energy rising from hot rocks or magma beneath the Earth surface.

Verification / Alternative check:
Geography and earth science descriptions of hot springs worldwide, whether in Iceland, New Zealand, or India, consistently link them with geothermal activity. In some areas, hot springs appear near volcanic zones or tectonic plate boundaries where magma is relatively close to the surface. Manikaran is situated in a geologically active Himalayan region, where deep circulation of groundwater can bring it into contact with hotter rocks. This explanation fits the definition of geothermal energy and eliminates biomass, artificial thermal, or hydro energy as causes.

Why Other Options Are Wrong:

• Biomass energy: Requires the burning of organic matter, which is not involved in natural hot spring heating.
• Thermal energy from burning fuels: Implies artificial heating systems rather than a natural underground source.
• Hydro energy: Refers to mechanical or electrical energy drawn from moving water, not to heat that warms the water itself in a spring.

Common Pitfalls:
Some learners may be tempted by the term thermal energy, because hot water obviously involves heat. However, the question clearly points to natural energy, and natural underground heat is properly called geothermal energy. Another pitfall is to confuse hydro energy with any process involving water. Remember that hydro energy in everyday usage refers to water used to generate electricity, not to warm water in springs. Keeping these distinctions clear will help avoid such errors.

Final Answer:
The hot springs at Manikaran are heated mainly by geothermal energy from within the Earth.