Page 233 - Çevre Şehir ve İklim Dergisi İngilizce - Özel Sayı

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system that follows a first flush device before connecting to the storage tank.
Additionally, it is recommended that each storage tank be equipped with an
overflow system to discharge excess water.
For this system to function efficiently, it is essential to know the average
precipitation amount in the region where the system is located, annual
rainwater To make efficient use of this system, the annual rainwater yield, the
average daily water consumption per user in the building, the roof coefficient
(a factor calculated considering that not all rain falling on the roof can be
collected, rainfall intensity, storage capacity limitations, and losses due to
wind and evaporation), and the area where the water will be collected.

Figure 4: An example to roof surface water harvesting
(Selimoğlu and Yamaçlı, 2022)

2. Studies Conducted Across the World on Rainwater Harvesting

2.1 Africa

It is known that there are 1.87 billion hectares of cultivated land worldwide
(USGS, 2024). Three fourth of the global cultivated land is made up of fields
with sprinkler irrigation. These areas meet 60% of the global food demand. In
Sub-Saharan Africa, particularly in Ethiopia, 95% of agricultural land consists
of rain-fed farming areas, serving as a significant food source and a means of
livelihood for households (Wakjira, 2024). In this sense, water storage and use
in food production when needed is of great importance in terms of meeting

220 Journal of Environment, Urban and Climate