Beach and Estuary Management Concept

Coastal Reform

To start the discussion on coastal reform, consider the condition of Indonesia’s beaches. Currently, there is physical development being carried out in estuaries, such as moving river mouths, building jetties (current-directing buildings) in estuaries, straightening and narrowing river channels in estuaries, strengthening river banks in estuaries with stone masonry (talut) or seat piles. , as well as the construction of embankments along the river estuary and other physical efforts.

Physical infrastructure development in this estuary has started since the 1970s until now. The impact of this constructive approach to estuaries will be changes in the dynamics of coastal currents, both locally (at the construction site and its surroundings) and regionally (in other areas hydrologically affected by the construction). Another impact is a change in the ecosystem in the estuary and associated coastal areas, which results in a decrease in the fish population caught by fishermen due to a decrease in environmental quality. This causes high maintenance costs for these buildings, thus continuing to burden regional and state finances.

In 2001-2002, there was a plan for a reduction project on the Citandui River. This drainage plan aims to drain the water from the Citandui River directly into the sea, without going into the Immediately Anakan. However, this effort was halted due to resistance from the public who were worried that there would be mudflow on Nusawiru Beach and the eastern Pangandaran Beach area, as well as major changes that would occur at the mouth of the Citandui River.

The main problem in this dewatering plan is related to rubbish and river sediment. The Citandui River carries around 75% of the sediment that enters the Segara Anakan, so that gradually the Segara Anakan will become land because of the large supply of sediment and cannot fully exit to the sea. In order to avoid this possibility, it is planned to make a shortcut that can throw sediment and garbage directly into the sea, so that it will then be carried away by ocean currents. However, the analysis carried out showed that there was an impact on East Pangandaran Beach due to the cut. In addition, there will also be changes in water salinity in Segara Anakan which can cause changes in the population of aquatic fauna and damage to the habitat there.

Solving the problem of sedimentation in Segara Anakan must focus on the root of the problem, namely handling the upper and middle parts of the Citandui River Basin and other rivers, not just at its estuary. Therefore, it is more appropriate to make efforts to reduce the intensity of erosion, sediment and waste originating from the middle and upstream areas. Funds planned for constructing the sewer can be diverted to reforestation of the Citandui River watershed and other vegetative methods, as well as involving the community in waste management to reduce and control sediment and waste in the middle and upper reaches of the river towards the estuary in Segara Anakan.

The dredging approach to deal with sediment is not effective because the volume of incoming sediment is very large, so that within a few months the sediment will be filled again. Therefore, the most appropriate decision is to improve the quality and quantity of watersheds so that the volume of sediment entering from rivers can be reduced significantly. Funds planned for constructing a sewer can be used for reforestation and other watershed improvements.

Reforms needed in the management of coastal areas are efforts to consider systemically matters related to the hinterland area. Coastal and estuary development cannot be carried out separately, but must be integrated with related watershed development.

To realize systemic and integralistic coastal development, strong cooperation between departments is needed. This cooperation is not enough just to be limited to coordination, but must start from joint planning, implementation, monitoring and evaluation. Activities, resources and funding sources must also be coordinated so that there is no competition or resistance between activities. For example, if there are funds for building a sewer from a department but the activity is considered unsustainable, then the funds can be diverted to reforestation activities carried out by another department as the leading sector.

Indonesia as an archipelago has the longest beaches in the world, so knowledge about holistic and integral beaches is very important in the regulation, preservation and utilization of related coastal areas. Many cities are located on the coast (around 70% of cities in Indonesia), so damage in coastal areas will be more intensive compared to other areas due to the penetration of urban communities into coastal areas.

The reform that needs to be done is to change the mindset of urban communities in viewing the beach. Currently, urban communities such as Jakarta, Medan, Surabaya, Semarang, and others tend to use the beach exploitatively. Beaches are built with large construction as a place for recreation, holidays and rest, without paying attention to the preservation of the coastal environment, even eliminating coastal areas. To prevent increasingly intensive degradation of estuary areas, it is necessary to apply beach management concepts in peri-urban areas of cities or in front city areas that maintain the function and characteristics of estuaries and beaches so that beaches can continue to function according to their role.

In the context of coastal reclamation, reform is needed that beach reclamation is only carried out under conditions of extreme necessity and with the concept of exchange. This means that reclamation is only carried out if there are no other options and the area of reclaimed coastal and border areas must be replaced outside the reclaimed area with a similar area and ecological-morphology, so that it is still possible to create a new coastal environment that maintains hydro-oceanographic dynamics. ecology, and socio-economics of coastal communities.

However, as an alternative to reclamation, it is advisable to build new islands in the middle of the sea so that the country can obtain additional land area on these islands. Making islands and reclamation will provide positive benefits if using sediment that settles along the downstream river channel. It can also solve the problem of flooding due to silting of rivers by sediments. Therefore, sediment management in the future is very important, especially to overcome floods, meet material needs, and maintain the sustainability of rivers as transportation routes. It is important to ensure that development in the coastal area does not use piled up soil from the upstream area, but adheres to the principle of zero input of piled up soil from the upstream area. Thus, erosion from upstream can be minimized. Reform thinking like this needs to be implemented immediately considering that the beach problem in Indonesia has become an urgent problem to be resolved.

Definition of Estuary

Estuaries are coastal areas that are semi-enclosed and have a free connection with the open sea and receive fresh water from the mainland. In simple terms, an estuary can be interpreted as a meeting place for fresh and salt water (Nybakken, 1988). Most estuaries are dominated by muddy substrates formed from sediments carried by fresh water and seawater.

Estuaries are waters that are partially enclosed and have a free connection with the sea, so that sea water with high salinity can mix with fresh water (Bengen, 2002; Pritchard, 1976). The combination of the influence of sea water and fresh water creates a unique community with diverse environmental characteristics (Supriharyono, 2000), including:

The meeting of opposing water currents and tidal currents, which has a strong influence on sedimentation, water mixing, other physical characteristics, and has a major impact on biota life.
Mixing these two types of water produces a physical environment that is different from river water or sea water.
Changes that occur due to tides require communities of organisms to undergo physiological adjustments to the surrounding environment.
The level of salinity in an estuary depends on the tides, fresh water flows, other currents, and the topography of the estuary area.
Estuaries can be classified based on their characteristics, such as:

1) Geomorphology: flooded river valleys, fjord-type estuaries, estuaries formed by levees, and estuaries formed by tectonic activity.

Coastal inland estuaries are the most common, formed by rising sea levels flooding the gently sloping shores of rivers.
Semi-enclosed lagoons or bays are formed by the existence of a sandbank parallel to the shoreline, which blocks direct and open interaction with the sea.
Fjords are deep estuaries that are formed due to glacial activity which causes ice valleys to be submerged by sea water.
Tectonic estuaries are formed due to tectonic activity such as earthquakes or volcanic eruptions, which cause the land surface to subside and then become inundated by sea water at high tide.

Variations in salinity in estuaries determine the life of marine/brackish organisms. Animals that live in brackish waters (salinity 0.5 – 30‰), hypersaline waters (salinity 40 – 80‰), or saline waters (salinity > 80‰) usually have a tolerance to a wider range of salinities than organisms that live in sea water or fresh water (Supriharyono, 2000). Organisms capable of surviving salt concentrations ranging from almost pure water to a salinity of nearly 300‰ under active living conditions (Ruinen, in Supriharyono, 2000 a).

Some species can survive at salinities above 200‰, such as brine shrimp (Artemia salina) and dipteran larvae, Ephydra (Remane and Schlieper in Kinne, 1964). In the Laguna Madre estuary, there are at least 25 species of animals that can survive at a salinity of around 75 – 80‰. Several species such as Nemopsis bacheri, Acartia tonsa, Balanus eburneus, and several types of fish are also found at salinities as low as 15 ‰ (Hedgpeth, 1967).

Animals that are tolerant of a wide range of salinities are called euryhalines, while those that are tolerant only of a narrow range of salinities are called stenohalines (Kinne, 1964). The effect of salinity on organisms can occur through changes in total osmo concentration, relative proportions of salt content, absorption coefficient and dissolved gas saturation, density and viscosity, and perhaps also through radiation absorption, sound transmission, and electrical conductivity (Kinne, 1967).

The number of species of organisms that live in estuaries is much smaller than those in fresh and marine waters. This limitation in the number of species is mainly caused by fluctuations in environmental conditions, so that only species with physiological adaptations are able to survive in the estuary. Apart from the low diversity of fauna species, the estuary also has limited flora diversity.

The turbidity of the water in the estuary means that only plants that stick out can grow and dominate. The low primary productivity in the water column, few herbivores, and the presence of lots of detritus indicate that the food chain in the estuarine ecosystem is dominated by detritus. Detritus acts as a substrate for the growth of bacteria and algae, which then become an important food source for suspension and detritus consuming organisms.

The accumulation of food resources utilized by estuarine organisms is the net production of this detritus. Fauna in estuaries, such as fish, crabs, shellfish, and various types of worms, interact and are interconnected through complex food chains (Bengen, 2002).

2) Water circulation and stratification:

High stratification or salt wedge estuaries, are characterized by a clear boundary between fresh and salt water
Partially mixed is the most common type. In this estuary, the flow of fresh water from the river is balanced by seawater entering through the tidal currents. This mixing can occur due to turbulence that takes place periodically by tidal action.
Perfectly mixed. This type of estuary occurs in locations where tidal currents are dominant and strong. Based on salinity (salt content), estuaries are divided into three types, namely: