Hydrologic Cycle (Water Cycle)
Understanding the Hydrological Cycle
The hydrological cycle is the never-ending circulation of water from the atmosphere to the earth and back to the atmosphere through condensation, precipitation, evaporation and transpiration. Heating sea water by sunlight is the key to the hydrological cycle process being able to continue continuously. Air flow evaporates, then falls as precipitation in the form of rain, snow, sleet and sleet, drizzle or fog.
Understanding the Hydrological Cycle According to Experts
The following are several definitions of the hydrological cycle according to experts, including:
1. According to Suyono (2006)
According to Suyono (2006), the hydrological cycle is water that evaporates into the air from the surface of the land and sea, changing become clouds after going through several processes and then fall as rain or snow to the surface of the sea or mainland.
2. According to Soemarto (1987)
According to Soemarto (1987), the hydrological cycle is the movement of sea water into the air, which then falls into the air land surface again as rain or other forms of precipitation, and ultimately flows into the sea return. Heating ocean water by sunlight is the key to the hydrological cycle process being able to run continuously.
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Stages of the Water Cycle (Hydrological Cycle)
On the way to the earth, some precipitation can evaporate back up or fall directly and then be intercepted by plants before it reaches the ground. After reaching the ground, the hydrological cycle continues to move naturally, continuously in three different techniques:
1. Evaporation / Transpiration
Water found in the sea, on land, in rivers, in plants, etc. then it evaporates into space (atmosphere) and then it will become clouds. In a saturated state, the water vapor (clouds) will become water spots which will then fall (precipitation) in the form of rain, snow, hail.
2. Infiltration / Percolation Into Soil
Water moves into the soil beyond the cracks and pores of the soil and rocks towards the groundwater table. Water can move due to capillary action or water can move vertically or side to side below the ground surface so that the water enters the surface water system.
3. Surface water
The water moves from the surface of the land close to the main stream and then the lake; The sloping the land and the fewer soil pores, the greater the surface flow. Land surface flow can be seen generally in urban areas. Rivers join each other and form primary rivers which carry all surface water around the river's bow area towards the sea.
Surface water, both flowing and stagnant (lakes, reservoirs, swamps), and all subsurface water collects and flows to form rivers and ends up in the sea. The process of water traveling on land arises in the components of the hydrological cycle that form the City of Rivers (DAS) system. The total water on earth as a whole is relatively constant, what changes is its form and location. The largest place arises in the sea.
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The Process of the Water Cycle
The hydrological cycle is the circulation of water by changing various forms and returning to its initial form. This shows that the volume of water on the earth's surface is constant. Even though climate and weather change, the location causes the volume in certain forms to change, but overall the water remains the same.
The water cycle naturally lasts quite a long time. It is difficult to calculate exactly how long water goes through its cycle, because it really depends on geographical conditions, human use and a number of other factors.
The water cycle or hydrological cycle is the never-ending circulation of water from the atmosphere to the earth and back to the atmosphere through condensation, precipitation, evaporation and transpiration.
Just like the photosynthesis process in the carbon cycle, the sun also plays an important role in the hydrological cycle. The sun is an energy source that drives the water cycle, heating the water in the oceans and seas. As a result of this heating, water evaporates as water vapor into the air. 90% of the water that evaporates comes from the ocean. Ice and snow can also sublimate and directly become water vapor. Apart from all that, water evapotranspiration also occurs from plants and evaporates from the soil which increases the amount of water entering the atmosphere.
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After the water becomes water vapor, rising air currents pick up the water vapor so that it moves up into the atmosphere. The higher a place, the lower the air temperature. Later, cold temperatures in the atmosphere cause water vapor to condense into clouds. In certain cases, water vapor condenses on the earth's surface and forms fog.
Air currents (wind) carry water vapor moving around the world. Many meteorological processes occur in this section. Cloud particles collide, grow, and water falls from the sky as precipitation. Some precipitation falls as snow or hail, sleet, and can accumulate as ice and glaciers, which can store frozen water for thousands of years.
Snowpack (solid snow) can melt and melt, and the melt water flows over the ground as snowmelt (melted snow). Most of the water falls to the surface and returns to the sea or land as rain, where the water flows over the land as surface runoff.
Some of the runoff enters rivers, sewers, streams, valleys, etc. All these flows move towards the ocean. some of the runoff becomes groundwater and is stored as fresh water in lakes. Not all runoff flows into rivers, much of it seeps into the ground as infiltration.
Water infiltrates deep into the ground and recharges aquifers, which are freshwater stores for long periods of time. Some infiltration remains close to the ground surface and can seep back to the surface of water bodies (and the sea) as groundwater discharge. Some of the soil finds openings in the ground surface and comes out as freshwater springs. Over time, the water returns to the ocean, where our hydrological cycle begins.
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Types of Hydrological Cycle (Water Cycle)
The hydrological cycle is divided into three types, namely:
1. Short Cycle
Sea water evaporates then through a condensation process it turns into fine water droplets or clouds and then the rain falls directly into the sea and will repeat itself.
2. Medium Cycle
Sea water evaporates and is carried by the wind towards land and through a condensation process it turns into clouds and then falls as rain on land and then seeps into the ground and then returns to the sea through rivers or water channels.
3. Long Cycle
Sea water evaporates, after becoming clouds through a condensation process, then carried by the wind to places higher on land and snow or ice falls on the mountains tall. Blocks of ice settle on mountain peaks and because of their gravity slide to lower places, melt to form glaciers and then flow through rivers back to the sea.
Elements in the Hydrological Cycle
The following are several elements in the hydrological cycle, including:
- Precipitation
Water vapor that falls to the earth's surface. Most precipitation occurs as rain, but in addition, precipitation also occurs as snow, hail, fog drip, graupel, and sleet.
- Interception canopy
Precipitation is intercepted by plant leaves and ultimately evaporates back into the atmosphere rather than falling to the ground.
- Snow melting
Runoff produced by melting snow.
- Runoff
The various ways in which water moves across the country. This includes both surface runoff and channel runoff. As it flows, water can seep into the ground, evaporate into the air, be stored in lakes or reservoirs, or be extracted for agricultural or other human uses.
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- Infiltration
The flow of water from the ground surface into the soil. Once infiltrated, the water becomes soil moisture or groundwater.
- Subsurface Currents
Underground water flow, in Vadose zones and aquifers. Subsurface water can return to the surface (e.g. as a spring or pump) or eventually seep into the ocean. Water returns to the ground surface at a lower elevation than where it was infiltrated, under the pressure of gravity or induced gravity. Soil tends to move slowly, and is replenished slowly, so it can remain in aquifers for thousands of years.
- Evaporation
The transformation of water from the liquid to the gas phase as it moves from the ground or body of water into the upper atmosphere. The energy source for evaporation is mainly solar radiation. Evaporation implicitly includes transpiration from plants, although together they are typically referred to as evapotranspiration.
- Sublimation
Direct change of state from solid water (snow or ice) to water vapor.
- Advection
The movement of water – in solid, liquid, or vapor form – through the atmosphere. Without advection, water evaporating from the oceans cannot fall as precipitation on land.
- Condensation
The transformation of water vapor to liquid water droplets in air, clouds and fog is its form.
- Transpiration
Release of water vapor from plants and soil into the air. Water vapor is an invisible gas.
Benefits of the Hydrological Cycle
This hydrological cycle is a natural cycle that contains many benefits. The benefits of the hydrological cycle include:
Biosphere Wash
The biosphere is a place where living things, plants and animals, including humans, live. The biosphere consists of the lithosphere (rock/land), hydrosphere (water), and atmosphere (air). In its journey, the hydrological cycle passes through three places, namely the lithosphere, hydrosphere and atmosphere. Water is an excellent universal solvent, whatever it passes through will be dissolved by water, except for liquids such as oil.
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When water first experiences the hydrological cycle, river, sea, lake, etc. water experiences evaporation. The result of evaporation is relatively clean water. This clean water is the basic ingredient for washing the biosphere. When it travels into the atmosphere, water will dissolve dust particles, gases (NOx, SOx), aerosols, fume, fog, etc., likewise when water becomes cloud water droplets or precipitation. Everything in the atmosphere is dissolved and bound by water to be brought to the earth's surface, so that the atmosphere becomes naturally clean.
Clouds in the atmosphere are water that is electrically charged so that clouds meeting one another cause lightning or lightning. Lightning is very useful for fixation so that N is formed2 which is useful on Nitrogen cycle.
Before reaching the ground surface, some of the rainwater hits the leaves which have been covered with dust or Pb particles on plants on the highway, lime dust in the area the lime, cement, etc. industries will be cleaned, so that the leaves can carry out photosynthesis perfectly, the leaf stomata will open, leaf evaporation will be impossible disturbed. Likewise, treat the roof of the house. The shape and position of the leaves vary, greatly influencing the fall of rainwater to the ground.
Rainwater that falls to the earth with a certain gravitational force will open a thin layer topsoil. Some of the water that falls on land undergoes percolation into the ground as ground water and partly as surface water (run off). When it flows, water will dissolve the mineral elements found in ground rocks.
Water on the surface will dissolve nutrients on the surface of the soil, including residue or excess from agricultural, residential and industrial activities. When river water enters residential areas, the water will dissolve domestic waste, for example detergent, oil, excreta, rubbish, etc. When entering agricultural areas, the remains of fertilizers, pesticides, etc. are dissolved.
Entering industrial areas will dissolve industrial waste, for example oil, dyes, ammonia, etc. Meanwhile, groundwater, whether free groundwater or compressed groundwater, flows towards the ocean by dissolving rock minerals in the soil.
All water flow eventually stops in the lake or sea. Excessive mineral deposits cause sea water to be full of mineral elements, one of which is salt which causes sea water to become salty. Other waterborne materials will be deposited slowly on the seabed.
The nutrient elements of soil rock will be pushed by sea waves towards the coast so that a fertile land delta is formed. Pollutant elements carried by water will naturally degrade themselves over time do not exceed the threshold of water capacity or the water will carry out its own washing mechanism Alone.
Water Move Position
The amount of water on earth is relatively stable, it does not increase or decrease, only the position/place and quality change. The total amount of water in the world is 1,362,000,000 km3, which consists of oceans (97.2%), ice/glaciers (2.15%), ground water (0.61%), surface water (0.05%), fresh water lakes (0.009%), sea/salt lake (0.008%), rivers, atmosphere, etc. (0.073%) (Lamb James C in July Soemirat, 1996, 79).
So the water that can be used directly is around 2.8% of the world's water. Theoretically, all water on earth is static, due to the heat of the sun, geothermal heat, the height and low of the earth's surface, so that water moves according to the laws of the hydrological cycle. The hydrological cycle directly rotates or moves water from various places. Originally on land, in the ocean, transferred to the air, to the ground, etc.
In each place/position water has different benefits, depending on humans' ability to use it. According to Lamb James C (July Soemirat, 1996, 79), water that participates in the circulation of the hydrological cycle is only 521,000 km3/yr (0.038% of total water).
Water circulation in the hydrological cycle process of evaporation is 521,000 km3 / year which comes from 84% ocean evaporation and 14% land evaporation, but when precipitation falls into the ocean 80% and 20% falls onto land. Compared to the proportion of evaporation and precipitation on land, there is a difference of 6% or around 31,260 km3/th.
This situation is because on land there are mountains and highland hills which can prevent clouds from forming condensation and precipitation in mountainous areas, so that water will flow into rivers and underground water towards lowlands and up to sea.
In flat lowlands and oceans there is a random balance between evaporation and precipitation. The condition of excess precipitation from evaporation is balanced by river water or bottom water that flows towards or enters the sea (July Soemirat, 1996, 79).
Water Supply
Only 521,000 km of water participates in the circulation of the hydrological cycle3/th, which means 1,427.1015 liters/day. If the earth's population is 6 billion and the water requirement is 200 liters/day, it will require 1.2.10 water12 liters/day, while the water circulating is 1,427.1015 liters/day.
So there is still excess water that is utilized by plants and other animals which will not disturb the condition of water flowing in rivers, underground water, lakes and the existence of the sea. In hydrological circulation, water passes through various places. Especially on land, whether through the surface or underground.
Based on the calculations above, the amount of water is very sufficient to meet the needs of humans, animals or plants. However, each region has different quality and quantity, there are deficiencies, sufficiency and advantages, but in total it is still very sufficient.
Mountain residents do not need to go to the sea to meet their water needs, they just have to wait for rain or surface flow or take it from a shower or lake. Flat urban areas, simply take water from underground water or purify it from surface water. All water needs are met both in terms of quantity and location.
Resource Life
Water is an absolute necessity for every living creature. Without water it is impossible for life to exist. After the earth was formed, then it cooled and shrank, water began to form which filled the wrinkles of the earth. New water droplets are formed as volcanic activity occurs. The water at that time was still fresh and there was no life. Then, due to the heat of the sun, geothermal heat and the nature of water, evaporation, clouds, rain, groundwater, rivers, lakes and seas begin to form, so that the hydrological cycle is perfect.
Life was first formed from lightning from the meeting of two clouds, which hit the surface of fresh water, ultra violet rays, heat and radiation rays (Hendro Darmodjo, 1984/1985, 4). At that time, the elements of life began to form and finally simple creatures formed at the bottom of fresh water. Then, evolutionarily, creatures like today emerged. Until now, water is an inseparable part of a living creature or life.
A microorganism, grain is less able to develop or is inactive in dry conditions without water, when there is water the grain begins to grow, the microorganism begins to be active. Even in the dry lithosphere, it is almost certain that life there is slow, lacking active, slow to develop, but once there is water all life shows its identity as a creature life.
Resource Energy
The hydrological cycle allows rainwater to fall on mountains or highlands. Due to gravity, water flows towards low places. Differences in the height of the land through which the water passes will result in the force of the water flowing stronger, the higher to lower the stronger the force of the water.
The power of water can be utilized as an energy source. If sufficient power is used by the population to turn the mill, pound, while the power The large ones can be used to spin turbines to produce electricity that can be enjoyed in our homes at the moment This.
Tourism site
Fog in the mountains, waterfalls, thick clouds, drizzling rain, lakes, streams, underground rivers, stalactites, stalagmites, springs, artesian wells, ocean waves, are all part of the cycle hydrology. This situation was formed by thousands of years of hydrological cycles, and now its beauty can be used as an attractive tourist attraction. You can imagine that if water did not flow according to the hydrological cycle, all of the conditions mentioned above would not exist.
Impact of Human Activities on the Hydrological Cycle
Negative impact of human activities on the water cycle
Deforestation
Excessive deforestation which has an impact on water infiltration into the soil. Denuded forests will not be able to absorb water so that when it rains the water will flow directly into the sea. Because no infiltration occurs because the forest is denuded, as a result the top layer of soil and humus is eroded by flowing water. The opening of the ground surface causes the rain interception capacity to decrease drastically, causing the rain to fall directly hits the soil surface and breaks the soil matrix into soil particles small.
Some of the soil particles close soil pores and compact the soil surface, thereby reducing infiltration capacity. With decreasing infiltration capacity, the amount of surface flow increases and the amount of water flowing to the subsurface to replenish groundwater decreases. Surface flow becomes energy that can erode soil particles on the surface and transport them to other places as part of the erosion process.
Residential development
Residential development does not pay attention to aspects of water absorption land, resulting in land that should be used as a place water absorption becomes covered by residential areas, where it is certain that most residential yards are closed by roads, cement/concrete.
Large-scale human manipulation
Large-scale human manipulation of water is significantly changing global patterns of river discharge. The resulting changes in sea level, ocean salinity, and in the biophysical properties of the land surface may ultimately result in climate feedbacks. Human regulation of river flow and dry vegetation has reduced river runoff by approximately 324 km/year.
The annual decrease in runoff corresponds to lowering sea levels by 0.8 mm/year. This figure represents a significant fraction of the observed sea level rise of 1–2 mm/year, but in the opposite direction. So, if it weren't for human diversion of runoff, sea levels would be rising faster than they actually are.
The majority of humans influence the water cycle processes on land
Water storage in reservoirs, groundwater mining, irrigation, urbanization, burning, deforestation, use of wetlands. The annual decline in runoff corresponds to lowering sea levels; were it not for human diversion of runoff, sea levels would rise faster than they actually do.
Land clearing
For profits in terms of business, economy and socialization of the community, many forests are being cut down and New land that has been opened up is converted into industrial land, housing or land agriculture. As a result, the water catchment area is reduced.
Use of Various Chemical Substances
Various chemical substances released into the air and the environment as a result of human activities also affect the content of rainwater that falls to the earth. These various chemical substances will accumulate in rainwater which is currently dangerous for humans.
BIBLIOGRAPHY:
Chow, VT., Maidment, DR., and Mays, LW. 1988. Applied Hydrology. McGraw-Hills. New York.
Kodoatie, RJ and Sjarief, R. 2008. Integrated Water Resources Management. Andi Publisher. Yogyakarta.
Linsley RK., Kohler, MA., and Paulhus, JLH. 1982. Hydrology for Engineers. McGraw Hills. New York.
Viessman, W., Lewis, G.L., and Knapp, J.W. 1989. Introduction to Hydrology. Harper Collins Pub. New York.
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