Multivariate Drought Index, Case Study: Najafabad Plain, Iran

Abstract

Drought is an extended period of deficient rainfall that causes damage to crops and reducing their performance, causes temporary scarcity of water for human/livestock consumption and influences the economic renewable resources. Because of the spatial and temporal variability and multiple impacts of drought, it is necessary to develop an integrated index for assessment of vulnerability of this phenomenon. Vulnerability includes physiographic, social, environmental and other factors like coping ability, awareness and regional economic activities. Over the years, various indices have been developed to identify onset, characterize and quantify the attributes of meteorological, hydrological and agricultural drought by various researchers. Anyway, an integrated index for assessment of vulnerability to drought is important especially for developing countries. The aim of this paper is presenting an integrated hydro-meteorological index for assessment of vulnerability to drought using multiple factors which includes hydrological, meteorological, land use and social factors. Spatial information of various factors was categorized in to various sub classes and maps were prepared in spatial domain using Geographic Information System (GIS). Different layers of above independent indicators and rainfall deficiency have been integrated using a weighing scheme. The study area is Najafabad plain a part of the Zayandehrood River Basin located in west-central Iran with semi-arid region. The long-term climate data (1991-2011) used for assessment. The results have been validated with intensive field surveys.