The increasing urbanisation, ongoing density and paving of ground surfaces affect not only the water mission, but more and more are causing higher temperatures and heat stress in towns and cities. This effect is reinforced by climate change and the resulting increases in temperature. Recent studies show that in the Haaglanden and Rotterdam regions the difference in surface temperatures between rural areas and highly urbanised areas can be as much as 10°C on hot days. [Duyzer et al., 2011]
Higher temperatures cause a higher mortality rate and affect the health, wellbeing and productivity of people, but also of flora and fauna. Higher temperatures are a direct cause of greater energy consumption for cooling and greater water consumption for cooling and for irrigating green areas. Higher temperatures have a direct impact on the quality of water. Urban planning solutions that incorporate more vegetation, green roofs, fewer impervious surfaces and the use of materials with high albedos (a material’s albedo is its reflection factor) can cause temperatures to drop significantly in towns and cities. Other factors such as the sky view factor (the portion of the firmament that is visible from a particular location) and the emissivity of surfaces (the amount of heat radiating from a surface) also play important roles in causing heat stress. [Duyzer et al., 2011]