Definition and Characteristics of Rivers

Surface water includes rivers, where rivers are defined as a system that is complex but not disorderly (complex but not complicated). A complex system is a system that consists of many components, where these components are interconnected and influence each other in a synergistic system, capable of producing efficient work systems and products. Meanwhile, a complicated system is a system whose components do not work synergistically, so that the system produces an inefficient product or output (Maryono, 2008). Complex river components, according to Government Regulation Number 37 of 2012 concerning River Watershed Management (DAS), a river is a natural and/or artificial water channel or container in the form of a water drainage network and the water in it, starting from the upstream to the estuary, with a right-hand boundary. and left by the boundary line. The river basin is a unified ecosystem composed of natural resources and humans as their users (Asdak, 2010). River watersheds are seen as natural resources with a variety of ownership (private, common, state property) and function as producers of goods and services for society, thereby causing interdependence between parties, individuals and groups (Wulandari, 2007).

Complex river components, for example the shape of river channels and branches, river bed formations, river morphology, and river ecosystems. Each of these components is complicated to explain because it is influenced by various factors that carry the nature of the river. Factors carrying the characteristics of the river into a unit called the character of the river (Maryono, 2008).

Mawardi (2010) states that indicators of watershed damage can be marked by changes in hydrological behavior, such as the high frequency of flood events (peak flows) and increased erosion and sedimentation processes and decreased water quality. Watershed management efforts must be carried out optimally through the utilization of natural resources in a sustainable manner (Sucipto, 2008). Efforts to handle watershed management include implementing policies in environmental management, preventing land conversion, forest and land rehabilitation and institutional arrangements in watershed management (Mawardi, 2010). According to Canter (1996) in Dhany (2015) the dominant parameters of land use activities are presented in table 2.1 below:

Table 2.1. Types of pollutants originating from land use activities

Meanwhile, Law No. 7 of 2004 concerning water resources defines a watershed as a land area which is one unit with a river and its tributaries, which functions to accommodate, store and channel water originating from rainfall into lakes or the sea naturally, which The boundary on land is a topographical divider and the boundary at sea is up to water areas that are still affected by land activities. In addition, watersheds have hydrological functions as (Noordwijk et al., 2004):

(1) water transmission;

(2) buffer at the peak of rain events;

(3) slow release of water;

(4) maintaining water quality, and

(5) reducing the movement of land mass, for example flooding.

The function of rivers for life, especially human life, includes providing water and water containers to meet household needs, environmental sanitation, agriculture, industry, tourism, sports, defense, fisheries, power generation, transportation and other needs. Other functions of the river are related to the natural environment, namely as a water quality restorer, flood channel, and as a habitat for flora and fauna ecosystems (PP No. 37 of 2012 concerning Watershed Management)

According to Mulyanto (2007), the character of the river based on the nature of the flow can be divided into 3 types, namely:

Permanent/Perennial Rivers, namely rivers that flow water throughout the year with a relatively constant discharge. Thus between the rainy season and the dry season there is no significant difference in flow.
Seasonal/ Periodic/ Intermitten Rivers, namely rivers whose water flow depends on the season. In the rainy season there is a stream and in the dry season the river is dry. Based on the water source, intermittent rivers are distinguished: 1) Spring fed intermittent rivers, namely intermittent rivers whose water sources come from groundwater; 2) Surface fed intermittent river, which is an intermittent river whose water source comes from rainfall or melting ice.
Non-permanent/ephemeral rivers, namely rain-fed rivers that flow their water shortly after it rains because the water source comes from rainfall, so when it doesn’t rain the river doesn’t flow water.

According to Noordwijk et al. (2004), river slope plays a very important role in the balance of aggradation (river bed elevation) and degradation (river bed lowering). By increasing the slope of a river, it will result in an increase in degradation tendencies. On the other hand, reducing the slope will increase aggradation. Apart from that, the balance also describes the regular characteristics between the longitudinal slope of the river and the type of material that makes up the river bed. The higher the slope, the coarser the size of the material making up the river bed and vice versa. This means that any change in slope that is not in accordance with the natural conditions of the river will cause instability in sediment transport along the river.

In general, watershed ecosystems are divided into upstream, middle and downstream areas which have biophysical connections through the hydrological cycle and the upstream part functions to protect all parts of the watershed (Asdak, 2010). According to Noordwijk et al. (2004) this protective function can be provided by cover of various types of vegetation as long as the system is capable of:

Maintaining a layer of litter on the soil surface;
Prevent the formation of grooves and ditches due to erosion; 12
Absorbs water for evapotranspiration. Both state forests and community forests, which are often called gardens, such as rubber forests, mixed coffee plantations, and mixed fruit and wood-producing plantations, are systems that can still fulfill a protective function in the upstream watershed area.

River Water Quality Standard Criteria

River water quality standards according to Government Regulation no. 82 of 2001 concerning Water Quality Management and Water Pollution Control are the limits or levels of living creatures, substances, energy or components that exist or must be present and/or pollutant elements that are allowed to exist in river water. . Water quality standards are used as a benchmark for water pollution. Apart from that, it can be used as an instrument to control activities that dispose of waste water into rivers so that it meets the required quality standards so that water quality is maintained in its natural condition.

As an ecosystem that is very strategic for human survival, rivers require a holistic and sustainable management system, of course adapted to the purpose or function of the river. If the river functions as a flood controller, then a river flow model must be made as a flood controller. However, if the river functions as a water source for the surrounding community, then the quality of the river water must be maintained from pollution, including through efforts to divide water classes, reduce the burden of waste entering the river by tightening regulations on waste quality standards, and especially enforcement through monitoring. appropriate, consistent, as well as increased community participation.

Table 2.2 Classification of water quality

The quality of surface water on the earth’s surface is expected to be able to support aquatic animal life, support livelihoods, and have aesthetic value, although it will depend on the surrounding environment. Criteria for water quality standards, criteria in which this class division is based on the good level of water quality and the possibility of its use for a designation (designated beneficial water uses) (see table 2.2). Most surface water is usually classified according to usage requirements where the watershed is a complex megasystem which includes physical systems, biological systems, and human systems that interact and relate to each other to form a single ecosystem unit (see table 2.3) (Wulandari 2007).

Table 2.3. Water Utilization Category

Toxicity

It is estimated that thousands of chemicals have been produced commercially in both industrialized and developing countries. Through various ways these chemicals come in contact with the population, from human involvement in the production process, distribution to consumers, and finally at the user level. The increasing world population demands, one of which is an increase in the amount of food production. In this case, chemicals are needed, such as fertilizers, pesticides, and herbicides. Not infrequently the use of pesticides that are not in accordance with the rules, or in excess, actually creates a burden of pollution on the environment, changes in the ecosystem, because eradication of one of the insecticides will have an effect on the food chain of the organism, so that it can also result in a reduction or even extinction of these insect predators. It is suspected that the use of pesticides has resulted in genetic mutations of these insecticides, which in turn gave birth to mutant insects that are actually resistant to certain types of pesticides. Improper use of pesticides is also one of the inducers of chronic (long-lasting) toxicity. Farmers wish to get high profits from their agricultural products, it is not uncommon to spray excess pesticides on agricultural products one or two days before harvest, with the aim that the fruit or vegetable leaves are not eaten by insects before harvest, in this way ranun fruit or vegetables will be obtained. not eaten by insects. However, all of these actions can actually be dangerous, because residues of toxic chemical pesticides may accumulate in water bodies, through consumption of water from these waters, eating fishery products originating from these waters, then slowly causing poisoning (Wirasuta and Niruri, 2007).

Among the water pollutants there are those that have a direct or indirect effect. Some have indirect effects such as suspended material, rubbish, and so on. Based on toxic properties, pollutants are divided into two, namely non-toxic pollutants and toxic pollutants (Effendi, 2002 in Ardhani, 2014). Non-toxic pollutants usually occur in ecosystems naturally. The destructive nature of this pollutant appears when it is in excessive amounts so that it can disrupt the balance of the ecosystem through physicochemical processes in waters. These pollutants consist of suspended materials and nutrients. Suspended materials can affect the properties of waters, including increasing turbidity, thereby inhibiting the penetration of sunlight. In this way, the intensity of sunlight in the water column becomes smaller, thereby inhibiting the photosynthesis process. The presence of excessive nutrients/elements can trigger the enrichment (eutrophication) of waters and can encourage rapid growth of microalgae and aquatic plants (blooming), which in turn disrupts the balance of the ecosystem.

Effendi (2002) in Dhani (2015) suggests several types of pollutants and their sources, namely in the following table:

Table 2.4 Types and Sources of Pollutants

Toxic pollutants are usually in the form of chemicals that are stable and not easily degraded so that they are persistent in nature for a long time. These toxic pollutants include:

Meanwhile, according to Syafrudin, basically river pollution itself is divided into two based on the nature of the pollutant, namely the level or ability of the pollutant to change chemically in a body of water or river.

1. Conservative polluter

Conservative pollutant is a pollutant in river water that is chemically relatively stable in water bodies, and does not change or decrease in concentration due to sedimentation in the riverbed or purification of river water. The elements included in this conservative pollutant group are, for example, heavy metals such as Hg, Cr, Cd, Cu, Zn, and other metals which are dissolved and precipitated in river flows. Heavy metals tend to be difficult to decompose through river hydrological processes, as well as by microorganisms.

2. Non-conservative polluters

Non-conservative pollutants are pollutants that can be broken down by microorganisms, for example BOD and COD. These pollutants can change shape into new forms with significant reaction rates.

Self Purification

Self purification is the ability of the river to repair itself from pollutant elements. The decrease in pollutant content proves that river self-purification actually occurs in rivers. The thing that needs to be considered is that according to natural rules there are limitations to self-purification in the river so that if a large amount of pollutant enters it, this ability becomes not very meaningful to return the river to a better condition (Tian et al., 2011). It is this natural ability of the river that limits the capacity of the river to pollutant. Biological processes can occur in a bacterial manner where bacteria help convert toxic compounds into non-toxic compounds. The existence of aquatic plants, plant roots around water bodies, and aquatic animals contribute to improving river water quality. The ability to clean yourself naturally depends on several factors, namely:

1) River water condition:

Water discharge
Types of contaminants present
Concentration of existing pollutant
Water temperature
Rapid flow (turbulence)

2) The state of the pollutant source

Waste discharge
Type of contaminant
Concentration of contaminants

River Management

According to Republic of Indonesia Government Regulation no. 37 of 2012, watershed management is a human effort to manage the reciprocal relationship between natural resources, with human resources in the watershed and all its activities in order to realize sustainability and harmony of the ecosystem and increase the benefits of natural resources for humans in a sustainable manner. Asdak (2010) defines watershed management as a process of formulating and implementing activities or programs that involve the manipulation of natural and human resources in the watershed to obtain production and service benefits without causing damage to water and land resources.

Watershed management is a management that is better known as ‘One watershed, one plan, one management’ (Asdak, 2010). The objectives of managing watershed natural resources are formulated together and sectoral programs are synchronized to achieve sustainability of the watershed ecosystem. Because of its nature as a complete ecosystem from upstream to downstream, watershed management must be integrated as a single ecosystem and not limited by administrative boundaries. The management of watersheds across administrative borders involves multiple parties and is not partial on the basis of regional government interests. Watershed management must be carried out based on sustainability principles that combine a balance between productivity and conservation to achieve the following watershed management objectives: (1) increasing water system stability, (2) increasing soil stability, including controlling land degradation processes, (3) increasing income farmers, and (4) increasing community behavior towards conservation activities that control surface runoff and flooding (Wulandari, 2007). So, watershed management must fulfill environmental, social, and economic aspects. Watershed management is intended to provide maximum economic benefits for humans, especially for local communities and the poor, without ignoring environmental sustainability and creating an independent, participatory society.

Water Pollution Control

Determination and application of water quality standards is one of the effective efforts in controlling water pollution. Water quality standards established for the purpose of protecting water quality will provide direction/guidance for parties involved in water pollution control programs. Good spatial planning regulates space utilization by considering the potential burden or pressure on the environment originating from space utilization activities. In addition to spatial planning, an approach is needed in the legal aspect in the form of guidance and law enforcement, setting quality standards, protecting water sources, monitoring and evaluation, and developing industries engaged in waste processing (Agustiningsih, 2012).

Minister of Environment Regulation number 1 of 2010 concerning Procedures for Controlling Water Pollution states that implementing efforts to control water pollution includes several activities as follows: