State of Water Resources in Iran

Abstract

1 Introduction Riparian forests and their associated floodplains provide an important buffer for freshwater ecosystems against human impacts stemming from land use practices and land cover change. The removal of riparian forests decreases bank stability and the retention of both nutrients and sediments, alters the quality and quantity of organic matter in freshwater systems, increases light penetration and water temperature, and alters the hydrologic balance between runoff and evapotranspiration in the watershed (Allan 2004). The impact of riparian forest clearing on rivers can have varying effects depending on the specifics of human activities within a given river reach. Human impact mapping and the Expected Local Stress Intensity (ELSI) index seek to quantify the locations and frequencies of different riparian zone land uses and translate them into scores that estimate the intensity of stresses originating from a particular river segment (Esselman 2001). The technique represents a rapid and inexpensive alternative for natural resource managers and communicates spatially accurate information on human impacts to freshwater ecosystems.