Investigations of Rainwater harvesting system from Rooftop catchment (Case study: babolrood catchment)

Abstract

Unfortunately, in Iran and other countries in the Middle East region, water becomes scarcer than ever before, and over the last decades, the demand for domestic water has increased due to population and economic growth. Although rainwater harvesting is considered to be a safe and reliable alternative source for domestic water, the inconvenience or impracticalities related to the cost and space needed for the construction of ground or underground storage tanks makes this practice not widely common in rural areas and rarely implemented in urban cities. This paper introduces a new technique to rainwater harvesting which can be easily used in both rural and urban areas; it collects and stores rainwater directly from rooftop catchments and not necessarily in the special ground or underground ones. This system was examined in one of villa garden of Mazandaran province (Babolrood catchment) to provide the irrigation water for one-hectare citruses garden, this villa garden has one two-story building that the second floor is to settlement and the first floor is a water storage with 100 m3 capacity that each time 26 m3 and during the year 52 m3 water is stored and transfers from storage to pool of gathering water and then it is transferred by Hydration pipes through gravity as drip irrigation to the foot of the trees and consuming water has been estimated for each hectare to irrigate 19 m3, and in a normal water year 3-5 years old trees need 2-3 irrigation that mostly is 50-57 m3 water. Therefore harvesting water is a suitable method to meet water of one-hectare citrus grove by floor insulation levels, and also it needs 4-5 irrigation courses in the drought times. We usually encounter to drought period every ten years, we need to advance the floor insulation levels and if the area of the garden is increased we must increase our floor insulation levels. If widely adopted in Iran Particularly in Mazandaran province, this technique could help in: (1) collecting around 70 % of the current deficit in the domestic water supply) of rainwater (2) saving around 7 % of the amount of electric energy usually needed to pump water from an aquifer well and ground or underground tank, and (3) considerably reducing the rate of surface runoff of rainwater at the hill area where rainwater is not captured at all and ultimately goes to the sea.