Lowering the heat, feeding citizens: scaling up a circular model for urban agriculture in Depok City, Indonesia

By 2045, over 70% of Indonesia's population, around 220 million people, will live in cities. Jakarta is surrounded by four satellite cities forming the Jabodetabek megacity region. Depok City, one of Jakarta's satellites, has a high Human Development Index (HDI) of 80.29, the highest in West Java Province, with a population growth rate of 1.92 and a density of 10,415 people per km2 in 2021. 

Urbanization in Depok and its surroundings has led to challenges such as the urban heat island (UHI) effect, where cities experience higher temperatures due to replacing natural land cover with heat-absorbing surfaces. Indonesia generates 24-48 million tons of food waste annually, equivalent to 115-184 kgs per capita, leading to an economic loss of about 4-5% of GDP annually. Rapid urbanization has also reduced agricultural land in Depok, increasing its dependence on food from other regions. This has increased food insecurity, which is highlighted in the latest regional plan. Promoting urban and peri-urban agriculture and optimizing available land types could support food security in Depok. 

The Urban Heat Island initiative in Depok City aims to reduce the Urban Heat Island effect and improve climate adaptation by addressing the challenges of rapid urbanization. It plans to develop a sustainable urban agriculture model that recycles food waste into fertilizer, creates a viable business model for urban produce distribution, and pushes for policy integration. The approach involves multi-stakeholder collaboration and strategic investments to promote sustainable practices and enhance the city's resilience. 

The initiative involves a wide range of stakeholders, including urban farmers, local entrepreneurs, municipalities, and collaborations with Perkumpulan Indonesia Berseru and IPB University. These stakeholders play crucial roles in capacity building, developing a scalable urban agriculture model, promoting urban agribusiness, and advocating for policy changes to integrate the circular urban agriculture model into Depok's food, climate, and development policies. 

The key challenges faced in Depok City include the Urban Heat Island (UHI) effect, driven by urbanisation that replaces natural land cover with heat-absorbing surfaces. This effect is causing cities to heat up at a rate twice the global average, potentially leading to a four °C temperature increase by the end of the century. Additionally, Indonesia produces 24-48 million tonnes of food waste annually, resulting in significant economic losses. Rapid urbanisation is also pressuring the urban food supply in Depok, as agricultural land decreases and the city becomes more dependent on food from other regions. To address these challenges, promoting urban and peri-urban agriculture, especially circular urban agriculture models, is a solution to enhance food security and reduce the UHI effect.

Rikolto's approach in Depok includes developing a circular urban agriculture model to reduce the Urban Heat Island effect through:

1. Capacity building for urban agriculture is achieved through training in regenerative farming practices. This training includes instruction on soil preparation, planting, healthy nursery practices, seedlings, composting, maintenance, and harvesting. Additionally, farmers receive regular technical assistance on-site in collaboration with IPB University and Perkumpulan Indonesia Berseru.

2. The development of six ecological demonstration plots in six locations with six farmer groups. A total of 156 urban farmers are participating in the programme, which covers an intervention area of 16,850 square meters. Most farmers are over 35 years old (70%) and female (72%).

3. We document evidence as the outcomes of farming activities and their influence on the microclimate. The measurements were taken through two techniques: automatic and manual. The automatic method employed an automatic weather station (AWS) instrument, allowing real-time results monitoring through the website. The weather elements observed were solar radiation intensity (watts.m-2), air temperature (°C), air relative humidity (%), air pressure (mbar), wind speed and direction (deg), and rain intensity (mm/h). The manual method was implemented by farmers who recorded the elements of daily rainfall (mm/day), air temperature (°C) and air relative humidity (%). Each demo plots have one AWS instrument.

4. The implementation was also supported by multistakeholder meetings, which further introduced the integration of a circular urban agriculture model into the city's food, climate, and development policies and developed an urban agriculture map to support sales and distribution.

Evidence shows that urban farming activities in Depok have impacted the DTR (diurnal temperature range). This value was analysed by comparing the urban farming area with the area of the IPB University Teaching and Research Meteorological Station (SMPR). In the urban farming area, there was a change from open land to vegetated land, while in the SMPR, it remains open land. Comparison with observations in the areas with no land cover change was used to determine changes in DTR due to land cover change. The results of observations of five urban agricultural sites with crops such as chillies, tomatoes, aubergines, water spinach, long beans, lettuce, and other vegetables during the observation period showed an average decrease in DTR of about 0.16 ± 0.07°C. Vegetated surfaces increase the heat storage capacity on the surface so that the rate of heat release to the air can also be reduced, resulting in an increase in minimum temperature and a decrease in maximum temperature.

In 2024, Rikolto and partners will continue capacity building on urban agriculture, emissions calculation, and business development to ensure the sustainability of urban agriculture.