On the rapid process of urbanization in developing countries it is not surprising that many spots in urban areas could be found informal settlements particularly squatters on riverbank in most Indonesian cities, such as Jakarta, Surabaya, Palembang, Semarang, Yogyakarta, etc. The informal settlement is any residential activities in any areas that are conducted without formality aspect relating to the government, such as tax, regulation, location permit, license, etc. This paper will analyze the landscape of the informal settlement on the Code Riverbank in Yogyakarta to respond the urban heat island issue. Landscape is characterized by a broad area of common unique visual character based on physically landform, vegetation, waterfront, and land use pattern. Urban landscapes with a high content of vegetation elements in particular, have thus potentials to perform a variety of social functions and as such to establish or regain a role of healthy, desirable and restorative urban landscapes. However, on the Code Riverbank in the city of Yogyakarta, there are many informal settlements that dominate the land use pattern of the urban riverfront. The physical component of the high density of the informal housing represents a variety of social functions of urban land uses. The high density of the informal settlement on the Code riverfront has avoided the ecological function of the Code watershed. The high density of the informal housing is able to influence the urban temperature in Yogyakarta that support the issue of urban heat island issue as a part of global warming phenomena. “Urban Heat Island” (UHI) refers to the tendency for a city to remain hotter than its surroundings. The casual factors of the UHI are mainly building density, more paving, and less vegetation. The research suggests that the informal housing density in urban riverfront has visually represented a low content of natural landscape, particularly landform, vegetation and water and this visual has reduced the uniqueness of the natural potential of the Code Riverfront. This phenomenon has a contribution to the higher level of urban temperature as an aspect of the UHI effect. Another finding is that the proposed balance landscape development between natural and man-made construction on the river watershed of the Code Riverfront will support the cooler urban landscape.
Key Words: Urban informal settlement, Code Riverfront
Landscape study has been practiced in the earliest time, when human pointed out where is the best location for agricultural field, trading center, or even residential uses. Historically, it was found that urban settlements or other development centers located close water resources, such as lakes, beaches or rivers. Ecologically, the river should be treated as a main water resource and played as a natural drainage system on continuous water cycle. Due to the population growth, urbanization, and technology inventions in many sectors including constructions, urban population need more housing, paved streets, and other built area. This growth has reduced vegetation and increased building density in urban areas. One of the basic urbanization problems in developing countries is illegal settlement. A slum is a house especially built on public or private land illegally. Due to the economic and social conditions, taking down of these slums owned by low income persons is very difficult.  In Indonesia, this phenomenon has been the way how people try to occupy more land that people can found in urban areas, including riverbanks that referred to be watershed and not permitted for construction.
The development created by current urbanism in Indonesian cities caused serious changes to the quality of the riverfront landscape. River Code, one of three main rivers in the city of Yogyakarta has been degraded with loosing its function as a water resource and watershed. This river has many houses occupy land on the riverbank and most buildings are informal settlements. Therefore, the quality of the Code riverfront landscape has formed a slum area that has more illegal housing constructions and not much vegetation. Any urban areas with many building construction and with little vegetation will be hotter compared with its surrounding areas.
2. ISSUE AND OBJECTIVE
The current development on the Code riverside in the city of Yogyakarta does not concern with ecological development. The Ecological development is respecting to the value of river as natural drainage system and as protected area on riverside. Intensive development on the riverside has created very high density of people and building houses, mostly informal settlements. This development pattern has reduced green areas of vegetation increased pavement along the Code riverfront in the city of Yogyakarta. This development phenomenon will support the issue of Urban Heat Island where the city of Yogyakarta is hotter compare with surrounding areas, particularly rural areas. Therefore, Yogyakarta needs some alternative of development model constructing any human settlements along the river, particularly on the Code River in Yogyakarta.
The objective of this paper is to (1) analysis the current development along the Code riverside by using a river as natural drainage system, (2) analysis the current development of informal settlements (on the Code riverfront in the Yogyakarta municipalities) relating to the casual factors of the urban heat island issue, (3) suggests a development model of informal settlements on the Code riverside that is likely able to reduce the problems of Urban Heat Island in urban areas. The method of analysis is using the qualitative approach. The analysis model consists of three concurrent flows of activities including data reduction, data display and conclusion drawing or verification. 
3. Riverfront Landscape
Natural conditions of river landscape providing a proper drainage system and well-continuous water cycle. When rainfall occurs, the water is absorbed by vegetation that covering the soil surface (for itself and groundwater) and the others gently returned to surface water such as river or lake. By the river stream, the water journey continued to the sea, which a great evaporation take place, form a clouds, and thus become a rainfall again.
Figure 1. Natural Water Cycle
By the change of human development, the contours are smoothed and the landscape is comprised of hardened surfaces (rooftops, paved streets, etc.). These changes resulting in higher run off velocity that increased erosive potential. Hence, at a high concentration of rainfall, it can be resulting as floods or landslide 
Figure 2. River as natural drainage system
Figure 3. Areas must be protected along the riverside
The riverfront natural landscape gives the basic concept for analyzing the current Code riverside development, particularly the existence of informal settlements, based on the value of river as water cycle as natural drainage system, and to protected river watershed.
4. Urban Heat Islands Effect
Urban Heat Island (UHI) effects are created when natural vegetation is replaced by heat-absorbing surfaces such as building roofs and walls, parking lots, and streets. Through the implementation of measures designed to mitigate the UHI, urban people can decrease their demand for energy and effectively “cooler” the urban landscape.   The analysis of the UHI issues will focus on the natural aspect of environment particularly vegetation, that is crucial component of the cooler urban landscape and it is able to reduce the demand of cooling energy when it is placed on the proper area in the urban landscape. Urbanization that followed by rapid development that make less vegetation in order to be replaced by concrete materials was determined as significant factors that causing urban heat island.
Figure 4. Urban Heat Island Profile
Heat islands develop when a large fraction of the natural land cover in an area is replaced by built surfaces (building and paving) that trap incoming
solar radiation during the day and then re-radiate it at night  . This means that building and paving on urban areas replace land vegetated land cover will increase heat on the area.
The mitigation measures to reduce the heat island effect provide a link to local as well as global issues. The economic cost of implementation strategies is not only by the cooling energy savings, but also by the reduction in greenhouse gas emissions, esthetic value of urban forestry, and the increased quality of human health . Therefore, the UHI issue recommends that urban areas are (1) to decrease building density and provide more open space for public, (2) to decrease paved land surface, and (3) to increase vegetation. This suggestion is relevant to the case study of the Code riverside that has been a very dens residential building with little vegetation.
5. INFORMAL SETTLEMENTS and URBANIZATION
The main reason of the urbanization movement, where rural people move to urban areas, is the insured job, high salary, and the other facilities such as education, health, culture etc. Primary objectives of the rural people migrating to urban areas is having a guaranteed and permanent job and then having a shelter. Nevertheless, if the financial inefficiencies of the local authorities, the level and quality of the services have been low, especially the lack of convenient residential areas has led to construction of informal settlements .
Informal settlements are usually a phenomenon which mostly occurs in developing and newly industrializing countries . The UN  defines informal settlementsas:
„Areas where groups of housing units have been constructed on land that the occupants have no legal claim to, or occupy illegally; 2. unplanned settlements and areas where housing is not in compliance with current planning and building regulations (unauthorized housing).“
Based on its conceptual categorization, informal settlements were classified into three types, (1) Unauthorized land development or informal subdivision, (2) squatter settlements, and (3) informal rental housing . Those concept reflected most of informal settlements concept that marked it as visual pollution and social economic problem. The other concepts of informal settlements rely on the paradigms that informal settlements is a kind of solution for poor and marginal urban people to live in urban areas.
Table 1. Population Density and Flat Housing Need 
Population Density and Flat Housing Need
150 – 200 jiwa/ha
200 – 400 jiwa/ha
As ALTERNA TIVE for special area
As RECOMMEN DATION for urban central activities and special are
As REQUIRE MENT for urban revitalization
As REQUIREMENT for urban revitalization
Source: Badan Stadarisasi Nasional, 2004
Informal settlements could be viewed as great intelligence in the use of resources, in shifting single use to mixed use, from low density to high density, and from absence of infrastructure to full infrastructure . Therefore, the informal settlement on the Code riverfront is crucial to be analyzed by measuring the landscape based on the main causal factors of the UHI issue which are (1) building density, (2) vegetation, and (3) paving.
Table 1 will be used to analyzing the population density on the Code Informal Settlement and the need for flat housing development.
6. Informal Settlement on the Code Riverfront as a case study area
Based upon regional administration, Code river is located in three local administrations which are the Sleman Districts, the Bantul District, and the Yogyakarta Municipality. The upper stream is drawn from north side of the mount Merapi until its lower downstream in the south that relate to a cross section with Opak River in the Bantul Ditrict. The middle downstreen of the Code River is situated in the Yogyakarta district where the riverside of Code is fully occupied by informal settlements . Based on the Yogyakarta Statistic Office in 2005, from 151,420 households living in Yogyakarta Municipality, 2.14% of them lived next to riverside including in Code riverside called Code community. Code community consisted of 71% native people and 29% migrants. Most of them (53%) have been living there for more than 25 years. .
The expansion of Code riverside by squatters was determined by two reasons. The first one was the independent status of land, encouraging people to squatter. While the second reason for Code riverside expansion was represented cultural, economic, and social demands . Based on the survey, it was found that the reason in choosing Code riverbanks as their settlements were compiled and classified into three main reasons, as an economic motivation (33%), for comfort living (40%), and as a forced movement option because they didn’t have any alternative place for living (27%).
With high density and high population indeed, waste become an ecological problem. Littering it away to the river was an easy and cheap way for Code community. By recent years, it became a more serious problem causing degradation of river quality and higher risk of flood. From the other Code’s study, it was founded that an area with high density would also raise the risk for groundwater pollution . It was reported by Harian Jogja, 26 December 2007 that Code is the most polluted river among three main rivers in the Yogyakarta Province.
The two previous paragraphs proofs:
(1) The Code riverside is not treated a natural drainage as suggested by the North Carolina Department of Environment and Natural Resources Division of Water Quality
(2) The Code riverside is not protected to avoid any intensive development and make the Code River as the most polluted river in Yogyakarta.
According to government riverside policy that laid down by Indonesian Ministry of Civil Works in 1993, minimum space required between a river and built up area is 15 meters. However, by considering that the existing development growth on the Code watershed has been a high density informal settlement, the official government of the Yogyakarta Municipality has determined 3 meters space between river and built area on the Code riverside. This government policy does not concern with the value that rivers to be protected as a natural drainage system as suggested by the North Carolina Department of Environment and Natural Resources Division of Water Quality. This also suggests that the Yogyakarta municipality is not aware with the long term issue if the river conservation.
The term of informal could be determined as anything conducted without formality or ceremony . Using this as analogy, informal settlements then referred as settlements without any supported formality aspects relating to the government. Informal settlement were often remarked with its illegal status of land ownership. Reported on this definition, most of dwellings settled on Code riverbanks were marked as an illegal or informal settlements. From data survey collected by the direct observation, it was founded that less than 50% of settlements have legal documents. Only 38% of settlements in Code riverbank already have the SHM (Certificate of Land Ownership) and 9% only have HGB (Right to Use the Property). Most of them (40%) have to pay for living in those areas by renting lands or rooms. The remaining precentage of Code community (11%) still lived in “Magersari” landstatus. In term of rights for build property, 61% of them don’t have IMB (Rights to Construct Building) that means, 61% of building settlements on Code riverbanks are illegal. Hence, the survey reported that 47% of people lived in Code riverbanks get their land as an inheritance land.
RT 69/RW 19 Dusun Karang Anyar Kelurahan Bronto Kusuman was recorded density value for 481 people/hectares, made it classified as very high density area. Within this area, more than 60% of settlements were too small to be noted as dwellings. Most houses on the Code riverbank have a mixed-use, commonly for economic and residential functions. Visually, the main characteristics of informal settlements in Code riverside were high density, small size houses, lack of ventilation, and narrow streets . In the recent observation on April 2009, the population density in the kampung Jogoyudan was 480 persons/hectare. The research found that:
(1) Based on the Indonesian Standard of Urban Settlement (SNI 03-1733-2004) the population density in the Kampung Jogokaryan can be categorized as very high density and this will be required for revitalizing the Code settlement to flat housing.
(2) With the high density of population, the Code riverside also has a high density of building houses mostly one story building. This construction building density is contributing to the urban heat island. This fact also suggest that lowering building density and increasing more space for public activities more vegetation could reduce urban heat island problem in Yogyakarta city.
(3) The Code informal settlement is very high density of people and building creates the area lack of vegetation. This fact also supports to increase the urban heat of Yogyakarta (See Figure 5).
A crucial concept to transform horizontal housing to be vertical one can be adopted from  (See Figure 6). The concept suggests that the government should develop a new law put into practice to formalize illegal or informal settlements.
Figure 5. Code River in Yogyakarta
Figure 6. Transforming Horizontal to Vertical Housing
The urgent recommendations are as follows:
a. Slums or informal settlements are constructed in a low-qualified manner , not meet with river conservation, and support urban heat island effect. Therefore, the transformation of the informal settlement to horizontal building should be provided to support river conservation and reduce the UHI problems.
b. Instead of leaving settlement right to slum owner completely, this right should be shared with public authorities. In other words, slum or informal settlement owners should not be given all development right on building plot; instead, they should only be given a single flat.
- Building contractors, called as land developer, which works according to the general rule of ‘giving flats to land owners for their landownership’, the remaining flat dwelling can be rented of sale with a long scheme of payments to other migrants who have no land or building certificate on the Code riverside area.
The scheme of transforming horizontal to vertical housing is appropriate with the government policy plan of “one million towers” for revitalizing urban slums and fulfilling the current and future urban housing need, especially for urban community with the low income segment.
Urbanization in Yogyakarta creates informal settlements on the riverside. The growth of informal settlement in Yogyakarta is due to lack of balance development between urban and rural improvement.
The informal settlements on the riverside perform a high density of population and buildings, and reduce open space with rich of vegetation in Yogyakarta urban riverfront, such as the Code river. The Code River with informal settlement proofs that imbalance landscape (between natural and man made construction) has occurred in Yogyakarta. This phenomenon has supported the problem of urban heat island in Yogyakarta urban area. The government policy on the Code riverside so far does not improve significantly the ecological landscape quality.
To mitigate the Urban Heat Island Effect in Yogyakarta, the local community, investor, and the government are to work together in transforming horizontal to vertical housing construction from now end then. This transformation suggests: (1) The Code riverside is to be protected from the intensive development, (2) vertical housing on the Code Riverside will give more open space and more vegetation to be planted., (3) paving can be used if necessary and porous paving is better construction.
By increasing the transformation of horizontal informal settlement to formal vertical housing, open space, public, and vegetation in urban areas will increase in urban areas, including the landscape on the riverside. This action will make the urban environment cooler and be able to mitigate the UHI problem.
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 Yogyakarta Province has a special policy referred to its special status that acknowledge Sultan’s land for people to live in. People that lived in Sultan’s Land called “magersari”. They don’t have any payment for live or settled on the Sultan land, form as Sultan’s pity for his people in the previous time. The status of “magersari” is still debated by local government and national government.