Balance of Green Open Space to Support Green Settlement in YOGYAKARTA Urban Area

The greatest problem relating to settlement growth in Yogyakarta urban area is the declining number of green open spaces. This study aimed to analyze the balance between the availability of and need for green open space development to promote the existence of green settlement in Yogyakarta urban area. The methods employed in this study were field research and studio analysis by referring to the related research methods previously conducted by the researcher as well as by the others. The results showed that the extent of green open space in Yogyakarta urban area reached 1,469.45 Ha or 16.2% of the total area. Therefore, the need for green open space lacked 13.8% of the total area. The general condition of the green open space was categorized as average in either housing clusters or settlements (non-housing clusters). Good condition was found only in low-density settlement, while poor condition of green open space was located in high-density settlement. The development of green open space should focus on public green open space while maintaining the private one. Some of the potential areas for this included rice fields, village treasury lands, riverbanks, roadsides, railway boundaries, public areas, and others.


INTRODUCTION
The availability of green open space (GOS) is one of the important factors for urban microclimate.
The average temperature of urban area is 40C higher than that of the suburban (Widodo B. et al, 2011). This indicates the decreasing quality of open space in urban area due to imbalanced condition between built-up area and non-built-up area.
According to the UN projection, three out of five world inhabitants will live in urban area by 2030 (Baiquni, 2002). Yogyakarta urban area (YUA) has experienced a significant level of urbanization.
The available area is limited, forcing urbanization in Yogyakarta to spread across Sleman Regency and Bantul Regency. Consequently, settlement area becomes broader and denser. Widodo B. (2005) and Widodo B. et al (2009b) predicted that rice fields in Sleman, Yogyakarta, and Bantul would be completely used for settlement by 2030s if no control was taken.
The more complex urban dynamics have become a tough challenge to sustainable development. The urban physical area keeps being filled with buildings, surface of both building roofs and yards is hardened, and green open space continues to narrow or even almost to disappear. The urban environment tends to develop economically but to decline ecologically (Harjito, D.A., 2007). One of the impacts is an ambient temperature raise that will trigger urban heat island -though on a small scale (Li et al., 2005). On the other hand, global warming issue continues to frighten the world.
The most effective strategy to mitigate the threat of global warming is improving the condition of local environment (Widodo B. et al, 2009a). Widodo B et al (2011) andDinas Kimpraswil DIY (2006) suggested two main principles to overcome urban heat island, which are to shade hardened surface in public spaces and to sustain the flow of winds. Law No. 26 Year 2007 on Spatial Planning has also mandated urban area to provide GOS with a minimum of 30% of the total extent, consisting of 20% public GOS and 10% private GOS. Micro climate change is an environmental hazard and has the potential to bring disasters (Coburn, 1994;Reed, 1995

Data Collection Techniques
The socio-economic data were collected primarily and secondarily. The secondary data were gathered from the reports or other official sources of related institutions. Meanwhile, the primary data were collected through semi-structured interview with questionnaire. In addition, the physical data of GOS were obtained from field survey, semi-structured interview with questionnaire, as well as in-depth interview. The survey results were in the form of documentation photos, sketches, numerical figures, and others.
The research population involved households living in Yogyakarta urban area. The respondents were the patriarchs selected through proportional cluster random sampling. The settlement clusters were divided into the settlement area in large housing complex (elite), medium housing complex, small housing complex, and urban kampong. The total samples used in this study were 100 patriarchs.

Analysis of the existing GOS condition
The analysis of existing condition of GOS in each settlement cluster was conducted for the following aspects: 1. Tree density or canopy volume The analysis was performed by interpreting the satellite imagery from GIS-based Landsat 2016.

Evaluation of GOS quality
An evaluative analysis was conducted through a field survey of GOS availability. The observation result was then compared to the standard of infrastructure for environmental conservation. The analysis results consisted of three (3) criteria, including environmentally friendly (good), less environmentally friendly (average), and not environmentally friendly (poor). The criteria and data gathering techniques are presented in the following table.

Existing Condition of GOS
The identification of GOS existing condition used GIS technique and field survey. Figure 4.1 illustrates the distribution of existing GOS in Yogyakarta urban area according to the Landsat8 Satellite Imagery year 2016. The detail of distribution area is presented in

Large Housing Complex (Elite)
The result of field survey analysis for the quality of GOS in large housing complex (elite) is presented in Table 3. The table shows that, in general, the conservation effort through GOS has been made with average quality.

Medium Housing Complex
The evaluation of GOS quality is illustrated in Table 4. This table indicates the condition of environmental conservation facility with average quality. Good condition was located in only one housing complex.

Small Housing Complex
The result of quality evaluation can be seen in the following Table 5.  Table 5 indicates that in general the GOS was of average quality. Good condition existed in six housing complexes (45.55%).

High-Density Settlement
The result of GOS quality evaluation is described in Table 6. It shows that the GOS availability was in poor condition.

Medium-Density Settlement
The evaluation result of GOS quality is illustrated in Table 7 indicating that the GOS was of average quality.   (2016) All the above results of evaluative analysis are summarized in Table 9. On a macro scale, both the housing clusters and non-housing settlements have the average GOS quality. This evaluation becomes the basis for the selection of GOS management and supply model. 2. The need for GOS was therefore lacking 23.8% of the total area.
3. The GOS condition was generally average in both housing clusters and non-housing or settlement. Good condition was located in low-density settlement, while poor GOS condition was found in high-density settlement.