Hydrological Reservoir and Channel Routing

The word ‘reservoir’ is defined as a tank or a storage space where water or gas is stored. A reservoir is a man-made lake or dam or freshwater body. A reservoir can be made out of natural lakes whose outlet has been dammed to control water levels. There are around three types of the reservoir such as bank-side reservoirs, valley-dammed reservoirs, and service reservoirs.

Hydrologic cycle reservoirs

Hydrologic cycle reservoirs are those types of reservoirs where the water is stored naturally by the process of the water cycle. The Hydrologic Cycle is also known as the water cycle i.e. the normal or general form of the water cycle that occurs on this planet through the process of evaporation, transpiration, condensation, and precipitation. Due to the heat of the sun water evaporates from lakes, seas, rivers, and other water bodies; this process is known as evaporation, water also evaporates from the plant’s leaves, which is known as transpiration. As the water rises from lakes, seas, rivers, and other water bodies in the atmosphere, it gets cool and condenses to form clouds as a continuous process of evaporation and condensation, gradually the clouds get heavy, and as a result, precipitation occurs in the form of rain. And this rainwater is stored in any of the following reservoirs such as the ocean, soils, glaciers, under the Earth’s surface as groundwater, lakes, snowfields, etc. 

Some human activities interfere with the natural process of the hydrochloric cycle. These are:-

1. When water is diverted from one region to another, runoff patterns are altered.
2. Infiltration gets decreased due to the high demand of the fascinated tall building, highways, parking lots, pollution, etc. Also cutting of natural vegetation and forests decreases infiltration and can affect transpiration.
3. A high level of global warming that is rising in temperature causes the melting of glacial ice and increases the water balance in other reservoirs and water bodies.
4. Large use of irrigation waters in dry areas increases evaporation.

Classification of the reservoir in hydrology and channel tunnel route

• Storage/Conservation Reservoir
• Flood control Reservoir 
• Multipurpose Reservoir
• Distribution Reservoir

Hydrological Characteristics of Markonahalli Reservoir

Markonahalli Reservoir is situated across the river Shimsha in the Kunigal Taluk of Tumkur district. The minimum air temperature of the reservoir area varied from 11.0 to 20.0°C and the maximum temperature varied from 29.0 to 37.0°C. The average range of wind velocity counts from 2.7 to 6.0 km/hr. The time between May and October is generally recorded with higher velocity winds. Two troughs and two peaks were recorded, the former during April – May, and September – October, and the latter during December – January and July – August. In the rain-shadow region of Western Ghats, the catchment of Markonahalli reservoir is situated and is subjected to periodic droughts. The southwest monsoon is generally active in this part during its receding phase that is between September and October and much of the precipitation occurs during this period. The impact of the northwest monsoon is also significant in some years. The average annual rainfall in the reservoir area is 677 mm. However, the data collected since 1940 showed no correlation between the rainfall at the reservoir area and the inflow of water into the reservoir (r = 0.142, P<0.05). Peak inflows generally occurred during October. The quantum of annulling inflow about the capacity of the reservoir has shown a marked fall over the decades from the inception of the reservoir. It was 4 times the capacity during the 50s, 3 times during the 60s and 70s, 2 times during the 70s, and 0.8 times during the period of investigation. Only during 1991-92 and 1992-93, the inflows were higher than the capacity and the reservoir attained to full level. During 1994-95 water from the Hemavathy project was diverted into Markonahalli reservoir in November and December to augment inflows. During August-September and again during November-December the outflows reach maximum to meet the agricultural needs. Due to higher outflows and low inflows during August-September, reservoir levels were minimum in this period.

Conclusion

It is to conclude that the word ‘reservoir’ is defined as a tank or a storage space where water or gas is stored. A reservoir is a man-made lake or dam or freshwater body. A reservoir can be made out of natural lakes whose outlet has been dammed to control water levels. There are around three types of the reservoir such as bank-side reservoirs, valley-dammed reservoirs, and service reservoirs.