PHYSICAL QUALITY OF RIVER WATER AND ITS VARIOUS UTILIZATION

River is one of the natural resources which is a gift from God to fulfill the life needs of humans and living things on Earth. But today, the benefits of the river are decreasing because many rivers have been polluted due to human activities, for example due to industrial waste, household waste, agriculture, and oil waste. According to the story of parents/old man that in ancient times, when river water had not been polluted, people around the river used to use the river for their daily needs, such as the need for clean water for drinking, bathing and washing. Besides that the river is also a source of freshwater fisheries. Therefore, there are many traditional residents villages along the river. At present it is rare to find people who use river water directly, except in certain areas such as the islands of Borneo (Kalimantan) and Sumatra.

The quality of water for living needs must meet health standards, especially for drinking water. The requirements of good drinking water are to be clear, colorless, odorless, and there is no content of organic substances that cause disease. Today, taking river water for drinking is dangerous for the body. In modern settlements, river water for drinking water needs to be processed first through cleaning and screening conducted by Drinking Water Company (PAM in Indonesia).

One country that has many rivers is Indonesia. There have been many mass media that discuss the quality of rivers in Indonesia. River water quality in the most densely populated island in Indonesia, Java, especially in large cities such as Jakarta, Bandung, Tangerang and Surabaya tends to decline. Decrease in river water quality can be seen by changes in the levels of certain parameters such as pH levels, Dissolved Oxygen (DO) levels, Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). BOD and COD parameters of riversin all provinces in Java that have exceeded the specified quality standards, including the Ciliwung, Sunter, Citarum, Kaligarang, Bengawan Solo, and Surabaya Rivers. Basically there have been efforts to normalize a number of these rivers, but they cannot be said to be successful. This must also be supported by the community to help preserve it.

The degree of acidity or pH is a chemical quality criterion. Good water must be neutral (pH around 7), so there are no pollutants that change the nature of water to acid or base. According to the Decree of the Minister of Environment (Indonesia) No. Kep-03 / MNKLH / II / 1991, February 1, 1991 stipulates that factory wastewater can be disposed of into the river if the pH of wastewater ranges from 6 to 9. BOD is the amount of oxygen needed to degrade (break down) organic waste, while COD is the amount of oxygen which is needed to break inorganic waste.

If a lot of water contains organic waste, the amount of oxygen needed by microorganisms to degrade the waste will be large, and means that the BOD number is high so that the DO rate is low. With the amount of oxygen to degrade waste, the dissolved oxygen level in water will decrease. The same thing happens if the COD number is high. Waters with high BOD usually cause unpleasant odors. If the BOD number is high and the DO rate is low, the degradation of organic waste will be anaerobic (without oxygen). Anaerobic processes are oxidations that do not use oxygen to produce NH₃, H₂S, CH₄ compounds that smell bad. The high number of BOD and COD and the low DO numbers make it difficult for animals and aquatic plants to develop, even die.

Turbidity of the Bengawan Solo River from Above

Object Source: https://www.youtube.com/watch?v=O6OUh8NQ7Y0

Bengawan Solo Upstream, Kali Wiroko in Wonogiri regency, has experienced excessive sedimentation. This river water flows to Gajah Mungkur Reservoir and towards Bengawan Solo

Object Source: Personal Documentation

Water turbidity in rivers on the island of Java generally shows a fairly high level. Estimates of the amount of mud carried by rivers on the island of Java can reach 25 million tons per year. This indicates that soil erosion has occurred in the upstream section.

The regulation of river use is important because it is related to the pollution threshold value. The basis for determining river benefits is the dominance of utilization in the region, based on the quality of river water at that time. Water users and those who potentially pollute water must play an active role in maintaining and utilizing river water well and are expected to overcome water quantity and quality problems. Prokasih's effort (program kali bersih/clean river program) in Indonesia is one of the efforts made to overcome river pollution. This program is a centralized activity and aims to reduce the amount of pollutants entering the river, so that rivers can be used properly and safe for life.

Rivers have benefits that are very important for human life, for example as follows.

a.       The river contains many building materials such as sand, river stone, and gravel.

Merapi Volcano Sand collection activities in Klaten regency, Indonesia

Object Source: https://www.youtube.com/watch?v=5JYOpeX3s7o

b.      Rivers can provide livelihoods for residents such as sand collection, rocks, looking for gold ore, diamonds, alluvial tin, and fisheries.

c.       Waterfalls on rivers can be used as power plants.

d.      Rivers can be used for irrigation needs, for example by making dams or reservoirs. With the existence of a dam, a hydroelectric power plant can also be built. Examples of reservoirs are Gajah Mungkur Reservoir in Wonogiri, Central Java, and Jatiluhur Reservoir in West Java.

Gajah Mungkur Reservoir in Wonogiri which functions as a hydroelectric power plant

Object Source: https://www.youtube.com/watch?v=7mKodBqJkl4

e.       Can increase soil fertility because the river contains many minerals that are needed for plants.

f.       The result of sedimentation of the river can be a fertile alluvial plain.

g.      Rivers have an important role for the survival of an industry that requires a lot of water, for example the brick industry, tiles, and others.

h.      Rivers as a means for traffic by water transportation. This is common in areas that have large rivers, such as in Kalimantan (Borneo), Sumatra, and Papua. Examples of these rivers are the Kapuas, Barito, and Musi rivers.

i.        Freshwater fisheries.

j.        Water recreation and sports.

Reference:

·         Wardiyatmoko, K. 2004. Geografi SMA Jilid 1 untuk Kelas X Kurikulum 2004 Berbasis Kompetensi. Jakarta: Erlangga.

·         Utoyo, Bambang. 2009. Geografi 1 Membuka Cakrawala Dunia untuk Kelas X Sekolah Menengah Atas/Madrasah Aliyah. Jakarta: Pusat Perbukuan Departemen Pendidikan Nasional.

·         Soegimo, Dibyo and Ruswanto. 2009. Geografi: untuk SMA/MA Kelas X. Jakarta: Pusat Perbukuan Departemen Pendidikan Nasional.

·         http://www.bintangmedia.id/indikator-kualitas-air-ph-bod-do-cod/