Water conservation functionality of rangeland ecosystems in Taham watershed of Zanjan, Iran

Water, as the most valuable component of natural resources, is badly needed by humanbeing for various perposes. Understanding of water conservation role of different types of rangeland ecosystems, increases the accuracy of monetary value estimation and  prevents underestimation its value by consumers. This study focuses on  the role of vegetation to increase water storage. For that, the runoff height was estimated in each homogeneous map unit by Justin method, then the economic value of water was calculated using the replacement cost method. Results showed that vegetation reduces runoff to 895,335 cubic meters per year/ha and increases the absorption and penetration of surface water into underground aquifers. According to the cost per cubic meter of water in the region, the economic value of runoff absorption and infiltration into the groundwater aquifer is estimated at 1.22551 million Rials per year/ha. Based on this, the economic value of each hectare of rangeland ecosystem is equal to 1.64 million Rials per year. Based on the results, the value of water conservation performance varies in different units of a watershed. This is due to structural differences in the ecosystem. Therefore, rangelands should be classified by homogeneous units and then the relevant estimates should be made.