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Understanding Water Debit: Cause – Calculation

by Widiya

One factor in the existence of life on this Earth is the presence of water. Water is a very important factor, it’s no wonder that until now  astronomers are competing to find Earth-like planets and the main requirement of the planet is to have water. So it is not surprising if the water is very important in the survival of living things in the world.

Planet Earth has become the most suitable planet for living things in this universe. In addition to its orbital position that is not too far from the sun, which is the center of the solar system, planet Earth has a sufficient composition of water to fulfill all kinds of activities and needs of living things in it. Those are some examples of the advantages of planet Earth compared to other planets found in this universe.

Speaking of water, the forms or forms of water found on the Earth are of various kinds. Broadly speaking, the types of water on Earth are divided into surface water, space water and groundwater. Understanding of surface water is water that comes from rainwater that falls until it finally flows on the surface of the Earth because the water cannot be absorbed by the soil. Surface water is divided into 2 types, namely river water and lake water.

Talking about river water, we certainly know that the river has many benefits, one of which is transportation. In the past, many trade activities were carried out around the downstream of the river close to the sea. So it is not surprising that regions or countries near the coast or waters are usually more advanced than areas that are far from the territorial waters or better known as regions or inland countries.

Speaking of rivers, it is very closely related to water discharge. The term water discharge itself is not only found in rivers, but also in other places that have water flows such as dams or reservoirs. Maybe some of us still don’t understand what water discharge is. In this explanation, we will discuss the definition of water discharge to what factors affect the size of the water debit. Let us see the discussion!

Definition of Water Discharge

In general, discharge is closely related to hydrology and is a large number of volumes of flowing water including solid (sand) sediments, dissolved minerals (magnesium chloride), and other biological materials such as algae which flow through certain cross-sectional areas. While the water discharge can be interpreted as a measure of the volume of water that is able to pass through a place or that can be accommodated in a place per unit time. It turns out that the term discharge is not only related to water but can also be found in other fields such as gas flow.

For river water discharge itself is the height of the river water which is measured using a special measuring instrument of river water level. Measurements can be done every day, especially when the rainy season arrives, because at that time usually, the river water discharge will increase when compared to normal days. River water discharge can also be referred to as the water flow rate that passes through a cross section of the river per unit time. Water discharge has a special unit, namely volume per unit time which is m3/s (read cubic meters per second) in international units.

Further reading:

Factors That Affect Water Discharge

There are many factors that affect the large and small water debit, especially water discharge in the river. These factors include:

  1. Rainfall

No doubt if rainfall is the main factor of the amount of water discharge. If the rainfall is not high, there is a possibility that the river water discharge will not be high and of course, the flow in the river is not so heavy. Whereas when rainfall is in a high condition, especially in the upstream area, it is likely that the water discharge will also increase along with the high volume of river water. River flow around the downstream will also be very heavy if it continues to occur there is a possibility that the area around the downstream will experience flooding if the volume of river water gets higher and exceeds the river’s ability to hold water.

  1. Topographic Form

The topography also affects the water discharge especially those found on the slope in the form of the degree of slope of the land, length of slope and so on. It can be said that if the land surface or land is tilted, the water debit will also increase. So it is not surprising if the upstream water discharge is greater than the water discharge in the downstream area. According to the Directorate of Land Use at the Ministry of Home Affairs, the slope of the land is divided into:

  • Slopes with a slope of 0 – 2%
  • Slopes with a slope of 2 – 15%
  • Slopes with a slope of 15 – 40%
  • Slopes with a slope of more than 40%
  1. The Amount of Vegetation

If the area around the river is overgrown with vegetation, it is probable that rainwater will be blocked by parts of plants such as leaves and branches so that the soil does not receive too much water from rain. In addition, the growing vegetation will absorb water that falls to the ground; otherwise, the water will continue to flow towards the river. The growing vegetation also increases the soil properties and the capacity to absorb water by plant roots so that the soil structure becomes better and helps the soil reduce the water content in it by transpiration.

  1. Area of ​​Flow

The area or river that does not have a large size or in other words including a small river, usually the water discharge will be small during the dry season. But the water discharge will increase and increase when the rainy season arrives. The biggest water discharge will be applied to small rivers and usually, the volume of water will exceed the capacity of the river itself so it is not surprising that the area around the river will be affected by flooding.

How to Calculate Water Discharge?

To find out the amount of water discharge, we need to use the formula:

Debit = A (area of the pipe or channel (m2)) × v (velocity of the liquid (m/sec))

From the calculation above, it can be seen that units from the water discharge are m3/sec, m3/hour, liter/hour, liter/second, etc., depending on the unit used.

That is the explanation of the water discharge along with the factors that affect it. Hopefully, the information above can be useful.

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