Integration of Green and Blue Space, and Their Potential to Support The Mental Health of Tropical Urban Residents

Problems in metropolis cities such as rising air temperature, traffic density often cause discomfort. It will result in heat stress and impact on mental health. Integration of blue space and green space is needed to reduce these risks. Urban parks, natural or artificial lakes are examples of integration. This paper describes opportunities for integrating blue spaces and green nature urban parks that have the potential to support mental health of tropical urban residents. Method used in this research is observation. Pondok Jagung lake-Tangerang used as a case study. The study was conducted in context of biophilic design. Results of study indicate that the integration of blue space and green space in urban parks has potential to support mental health for residents. Aspects that are considered are design aspects and environmental aspects. Design aspects include proportion of blue and green space, arrangement of colored vegetation, natural or non-natural shading, lighting, activity with water, accessibility, safety, security. Environmental aspects are cleanliness, order of hawkers. All aspect affects multi-sensory such as thermal comfort, visual, audio, olfactory, tactile.


Introduction
Population growth in urban areas has an impact on problems.The increase in population causes green space to decrease.Important issues at metropolitan cities related to the urban environment are increasing temperatures, traffic density and stress.This paper identifies blue space opportunities to reduce the risk of stress and as relaxation area in urban park.Blue space is outdoor space that is formed naturally or artificially.The blue spaces must be accessible, visible or felt [1].Blue spaces in urban areas such as natural lakes, artificial lakes, ponds or rivers.Several previous studies have shown that blue spaces provide a cooling effect or reduce city temperatures.[2] stated that green and blue areas provide a cooling effect.Addition of 10% green area can reduce the temperature around the 0.39 C and the blue area by 0.42 C. The water surface has a higher evaporation process than green plants.According to [3] stated that the cooling effect of water bodies can reach 1 km, but there are several influencing factors, namely the average building height, SVF, building density and wind speed.For information that environmental temperature around water bodies is higher at night.This shows that the integration of blue and green space will reduce air temperature.Reducing air temperature will indirectly reduce the risk of heat stress.
According to [1] mental health is the basis for being able to think, express, interact with others, and live happily.The built environment, natural, urban neighbourhoods can affect mental health.Research on integration of these two things has been carried out but not in a humid tropical climate.Mental health is one of the sustainable development goals.[4] [5] [6] stated that blue space can relieve stress by doing IOP Publishing doi:10.1088/1755-1315/1351/1/012015 2 physical activity and social interaction.The existence of repeated activities in the same place can support place attachment.Comfortable outdoor air temperatures can encourage visitors to come to the lake often.To feel optimal comfort, it is recommended to visit after 12.00 pm.During this period the water bodies provide a cooling sensation [7].Physical activity such as walking around blue space and aesthetic arrangement of vegetation needs to be considered.[8] explained the potential of blue space, such as active or passive activities in beach areas and lakes, to have a positive impact on mental health.
This paper proposes the concept of integration between blue and green spaces in tropical urban park.The integration concept aims to be a relaxation area.This relaxation function can be useful for reducing stress for residents in tropical urban areas.This research in the context of biophilic design.Biophilic design states that interaction with nature directly, indirectly and the experience of space and place have a positive impact on mental health [9].Several parks in big cities in Indonesia do not fully have integration between blue and green space.Pondok Jagung Lake at Tangerang is used as a case study.

Design method
Pondok Jagung Lake, Tangerang, is used as a case study.This lake has a particularity, which is located in the area of a large public road and semi-public residential roads.This lake can be categorized as a public space.Currently the lake functions as a catchment area for the surrounding settlements.Right now, this research is a preliminary study.At this stage it is descriptive qualitative research.The observation method is used to obtain an overview of the existing conditions and the naturalness of the lake environment.
Observations were carried out on weekdays and weekends, at 07-09.00 am, 12-02.00pm, 04-05 pm.This period is assumed to have visitors coming and doing activities at the lake.The Tangerang city government plans that this lake can be used as a rowing competition area.

Finding and discussion
Pondok Jagung Lake is located in North Serpong District, South Tangerang, and has an area of 8,943.15m2.The environment around the lake is a grid-patterned real estate settlement.The lake is surrounded by middle socio-economic class settlements.The position of the lake surrounded by residential areas gives residents the opportunity to interact with nature.This is because the distance to nature is closer than the distance to the city center park [10].The activity of walking from home to the lake can maintain physical health, thus indirectly providing opportunities to support residents' mental health.
When viewed from above, the blue space is more dominant than the green space.The proportion of blue space to green space will affect the type of activity.Right now, Pondok Jagung lake have function as catchment lake.Even though it functions as a catchment lake, the quality of the lake water also needs attention.It was stated by [11] that in order as a place of relaxation, it need quality of water, freshness of air and sensation of cooling.These factors are related to the proportion between blue space and green space.Wide canopy vegetation is required around the lake.Wide canopy vegetation arrangements around lakes and settlements contribute to reducing depression and prolonging life [12].Figure 1 below is the position of the Pondok Jagung lake and the surrounding settlements.The main access to Pondok Jagung lake has a red color signed.Striking color makes this sign easily recognized by users (see Figure 2).Pondok Jagung Lake is located in a tropical urban area, as tropical urban park require shade to reduce exposure to solar radiation during the day.Shading design is recommended with vegetation or artificial shade.Vegetation design should consist of plants with a wide canopy and colorful plants.This aims to support visual perception [14 [15].Composition between shade plants, the colored shrubs and flowers depends on the local or micro climatic condition.High trees with wide canopies and also with wide leaves can be planted around lakes and paths leading to lakes.Trees with these characteristics can provide shade and thus encourage residents to frequently visit Pondok Jagung lake.
There is a pavement line around the lake as shown in Figure 3.This pavement line or road is an access for river inspection lines.Pavement design or use of pavement can use perforated pavement.Using this type of paving can support the water ecosystem.Because when it rains, water will be absorbed by the soil.Pavement should be used in light colors.Generally light colors have low albedo.Low levels of albedo accelerate the reflection of solar radiation.
At this time, the path was used as a jogging track.In general, residents or users walks around or jogging on weekdays and weekends at 07-00-09.00am or 03.00-05.00pm.They carry out activities in groups, families or individually.They are 12-45 years old (see Figure .3).People have active during this period because solar radiation is in the comfortable level.
Between the lake and the jogging track there is a natural embankment.It is proposed that the embankment and the jogging track be provided with an operable safety fence.The aim is to provide safety for users, as well as a safeguard in the event of a rise in lake surface water during the rainy season.
According to [16] regarding blue space, several aspects need to be considered, namely visibility, accessibility, along the blue area.[17] added that the blue space provides a physical and psychological cooling effect up to a height of 1-2 meters, the multisensory experience of which is sonic appeal.This sonic appeal supports the thoughts of [6] through experiencing safe water.The relaxation activities above (see Figure 5) support [10] that contact with direct nature provides physical benefits and reduces stress.Trees and other natural elements support healthy mental health, including reducing stress.Tangerang as a humid tropical area has high solar radiation and temperatures throughout year.High plants with wide canopies are able to absorb solar radiation [18].
A park environment that has a comfortable thermal environment can attract users to visit frequently, including visits for a long duration.Hight canopy trees are needed in tropical urban parks as shade to rest for the elderly or other users.Interaction with vegetation and feeling the freshness of air in contact with water as part of an experience of place and space.Experience of place and space is a strategy for biophilic design [9].[19] stated that green open spaces can provide serenity.This requires a design of plants that provides fresh fragrant, bright colors, and absorbs pollution.Therefore, existing green spaces should be able to reduce noise.Some of the following types of plants are possible to apply on Pondok Jagung lake.Fragrant aromatic plants such as roses, jasmine, murraya paniculata, lavender.Brightly colored plants such as pentas lanceolata, lantana, hibiscus, canna, marygold.Plants with wide canopies such as terminalia mantaly and samanea saman can be used around lakes, or types of edible plants such as mango and longan which can live in the lowlands.Plants absorb pollution, for example sansevieria, spider plants, english ivy, dracaena.If possible, provide an area as an edible landscape, particularly organic vegetable or fruits.Gardening is also a form of relaxation that supports mental health.Activities at Pondok Jagung Lake also can do in the afternoon, as shown in Figure 6 below.At nighttime, this location almost dark, then artificial lighting is needed.The existence of activities in the evening or nighttime would require artificial lighting.This artificial lighting should be spread out, so that at night it remains bright.The need for artificial lighting will be better if the energy source is solar panels.Artificial lighting and shading must be arranged to support each other.
There are approximately 8 hawkers around the lake.It is relative due to the changing location of sales.Based on the survey, there were 3 fresh drink sellers, 1 meatball and chicken noodle seller, 1 ketoprak seller, 1 chicken porridge seller, 1 fried rice seller, and 1 egg roll seller.The existence of hawkers is a peculiarity in this place (see Figure 7).Hawker needs to be given a special place, including the circulation arrangement.The design must be integrated with its environment, integrated arrangement between blue space, green space and hawker so that the lake's ecological system continues to run well.The existing condition on the lake has a floating market.If desired, the floating market can be used to accommodate hawkers.The existence of mutually necessary activities between residents and sellers can increase social interaction.Good social interaction is a form of mental health.

Conclusion
Character of a humid tropical climate has high temperatures and humidity throughout the year and relatively low wind velocity in urban areas gives uniqueness to activities in urban parks.It requires  shading for users to take a rest temporarily.The interaction between water bodies, nature and its users can provide an experience and then feel relax.Aspect of social interaction is also a consideration in supporting the surrounding economy, namely providing an area for hawkers.
Another potential for maintaining water bodies is an effort to cool outdoor urban spaces and to achieve environmental sustainability.Aspects of design include the proportion of blue space and green space, arrangement of coloured vegetation, natural or non-natural shading, lighting.This aspect affects multi-sensory such as thermal comfort, visual, audio, olfactory, interaction with the body.Environmental aspects that need attention are accessibility, safety, security, cleanliness, order of hawkers.All assessment based on the availability of area facilities.
For further research, in-depth observations involving residents around the lake are needed.Assessment for quality of area facilities also as part of further research.Initial observations show that the residents around the lake are from middle economic communities, ages ranging from children to the elderly.Distance from settlement to nature plays an important role in mental health.This research is in line with that carried out by [10] but with different climatic conditions.

Figure 2 .
Figure 2. Sign in the lake

Figure 3 .
Figure 3. Pavement line around lake

Figure 6 .
Figure 6.Activities of residents in the afternoon and artificial lighting on path.