The concept of green space as espoused by the Harare Gardens is becoming increasingly important in town planning
SLOWLY, they are chopping it off, decimating over 110 years of history. First, was the National Art Gallery that bit off large parts of the iconic Harare Gardens several decades ago — and continued to do so in later years. Now, divided Harare city authorities have agreed to give up almost two hectares of the century old recreational park to a hotel group keen to boost its profits, never ecosystems.
Squeezed for cash, the Harare city council has agreed a $1,8 million deal with listed hotelier African Sun Ltd for that piece of land — the equivalent of two football fields — south of the 21-hectare Harare Gardens.
The African Sun Ltd says it wants to expand northwards its Crowne Plaza Monomotapa Hotel, built on the southern fringes of the park, by constructing a conference centre, a restaurant and a place for drinkers.
But little concern has gone towards the ecological benefits of maintaining, and improving, the Harare Gardens’ current status quo — built over several decades — as a haven for plants and trees in the heart of an expanding metropolis that is steadily losing sight of what it means to grow sustainably at a time of rapidly changing climates.
The Harare Gardens has a rich history. Thomas Ross, who designed Harare’s original layout of over 2,400 stands just after the settlers moved in, late in the 19th century, used the park as the centre from which the town spread in grid pattern, according to historians.
Some of the trees in that park are between 50 and 100 years old — irreplaceable wealth now at risk of being obliterated simply by a show of hands at Town House. It is a tough job getting trees to such a level of maturity.
The concept of green space — as espoused by the Harare Gardens — is becoming increasingly important in town planning, particularly at a time cities are keen to reduce their infrastructure-related carbon footprint.
Trees and other plants in parks or sidewalks do not only add beauty to a city, but can also “help mitigate the urban heat island effect, filtering air and reducing runoff,” say experts.
With demand for prime land in Harare’s central business district on the increase, we wonder whether 50 or 100 years from now the Harare Gardens as we know it today — already home to a restaurant, bowling club, children play centre, drama and music platforms — will still be in existence.
The African Sun Ltd deal appears to be perpetuating the continuous attack on this historic park.
In the interview below, I discuss with Terrence Mushore, a climate change expert and lecturer at the Bindura University of Science Education, the value of green spaces in cities in the context of climate change and global warming, hoping city authorities will see reason and return to their senses. I am represented JG and Terrence Mushore, TM.
JG: Across the world, major cities build recreational garden parks. How important are such parks? Can city gardens make a difference in climate change and global warming? If so, how many gardens do we actually need, say of the same size as Harare Gardens?
TM: Green is the most visible colour to the human eye. Any place with a lot of greenery/vegetation attracts human attention and is deemed as beautiful. Parks offer beautiful scenery for outdoor activities and big events such as weddings. Vegetation is a carbon sink which makes the air in parks clean and refreshing. They also play a significant role in the energy and water balance of an area.
Each time an areas receives heat, that heat is used either to evaporate water from the surface (latent heat), to heat the surface (ground heat) or to warm the air above the surface (sensible heat). An area with abundant and healthy greenery experiences a lot of evaporation (latent heat flux). This results in a decrease in ground and sensible heat flux resulting in low surface and air temperatures in parks. The heat mitigation value of a park depends on its size, vegetation abundance and vegetation water content.
Areas such as city centres and high density residential areas are very hot during a clear summer day compared to areas where vegetation proportion is higher. This implies that parks with low fraction of vegetation (or a lot of bare and impervious surfaces), that are not well maintained/irrigated and with dry vegetation have very low heat mitigation value. Furthermore, buildings and impervious areas absorb a large proportion of long wave radiation received by the lower atmosphere resulting in high temperatures.
The impact of greenhouse concentration induced global warming is exaggerated more in built-up areas than where vegetation fraction is high such as in well-maintained parks. As a result, parks serve as hideouts for ‘heat refugees’ during the hot season. Temperatures are projected to continue increasing especially in urban areas. Therefore, this translates to projection of demand for daytime cool places such as parks and lakes in major cities of the country.
JG: Is there a correlation between temperatures in cities where there are more recreational gardens compared to those with less, or completely without?
TM: Temperature of a city is not directly affected by the number of parks inside it as size and spatial configuration of the parks relative to the built-up areas also matters. Therefore, besides parks, vegetation within built-up areas is also important. For example, temperatures are generally lower in the low and medium density residential areas of Harare compared to the CBD and the high density residential areas.
Low and medium density residential areas are cooler because there is a lot of greenery around buildings which increases latent heat transfer In a nutshell, increasing the number of urban parks will result in many points where there is localised cooling effect. In order to achieve a broader cooling effect vegetation within built-up areas such as loan, green roofs and street trees need to be promoted. This will increase vegetation fraction and latent heat transfer while reducing surface and air temperatures.
JG: Some experts say green spaces in cities have boosted the value of properties in surrounding areas. Does this hold true for Harare and Zimbabwe as a whole? Are there any studies that support this view?
TM: I do not have records of greenery related demands for housing areas. However, I project that due to elevated temperatures in densely built-up areas, urban residents will favour areas with abundant vegetation and which are close to parks. This reduces energy costs associated with air conditioning during the hot season.
JG: Others postulate there are health benefits associated with green spaces. How far true is this?
TM: The health benefits include reduction in thermal discomfort as heat related diseases and mortality. Urban greenery improves air quality and thus help to reduce air quality related infections such as tuberculosis.
JG: Generally, do you believe Harare (Zimbabwe) has been managing its recreational gardens sustainably?
TM: Harare has a lot of grassland wetlands which in my view have largely been well managed. We have seen most parks such as Harare Garden being well maintained by the municipality. We have also witnessed grassland wetlands such as at Cleveland dam being protected by the Environmental Management Agents (EMA). What are needed are urban climate management policies and strategies which continue to promote establishment and maintenance of urban green space. This will help to sustain existing parks as well as to increase vegetation fraction in built up areas.
God is faithful.