Rainwater Harvesting for Urmia Island (I.R.Iran) Wildlife

The Urmia Lake (N-E Iran) is about to be completely dried so that many precious animals species could be scattered around looking for water and food. Occasional counter measures have been undertaken by local authorities including water transformation by ship and helicopter which could not be considered to be a sustainable solution in the long term scale. One should note that apart from water scarcity, animal forage has been also affected by recent drought. Therefore, any solution proposed for providing animal drinking water, should consider a sustainable planting practices at the same time. Rainwater harvesting (RWH) is a modern solution for collecting, conducting and storing rainfall induced runoff from natural and artificial impermeable surfaces. This method is particularly useful for remote area where usual water supply systems may not be applicable. Rainwater harvesting systems is composed of a catchment, conveying devices and storage facilities. Catchment should be almost impermeable and large enough to provide required amount of water during individual or several consequent rainfall events. Catchment surface may be naturally impervious or can be artificially isolated for maximum runoff production using different material types such as cement, bitumen or PVC membranes. Runoff generated by impervious catchment can be conveyed into a downstream reservoir using a pipeline or low height ditches. Reservoir capacity should be tailored with respect to the long term average or minimum monthly rainfall using frequency analysis. The results of the study presented here shows that in three out of four important Urmia islands (i.e. Espir, Kaboodan and Ashk) there exist long slopping rock surfaces with a good distribution along the area which can be used as impervious catchment for runoff collection. It is only in the Arezoo Island that contains more gentle topography and is covered with a weathered surface layer so that artificially constructed impervious catchment may be needed. Other possibilities such as groundwater dam to be constructed along some of the main stream channels are also considered as a good alternative and more durable solution.