Identifying potential rainfed fields for supplementary irrigation in Qazvin province

With the increasing population, increasing production in rainfed fields is necessary for food security. With regard poor distribution of rainfall in recent years, Water management for rainfed fields in critical conditions has priority. The results showed that for one or two irrigation in sensitive times, the yield of rainfed fields increased. Although supplementary irrigation in order to improve yield and water use efficiency in rainfed fields is the attention the study of special characteristic rainfed fields such as topography, slope, and the access to water resources is essential. The main purpose of this study is to evaluate the ability of supplemental irrigation in rainfed fields is based on the topography and slope. According to the land use map of Qazvin province, about 284 thousand hectares are irrigated lands and 132 thousand hectares are rainfed fields in the province that most of these lands in the Qazvin plain. Then with regard to the slope map from the region, rainfed fields for doing supplementary irrigation are classified into 4 classes: 0-5%, 5-8%, 8-12%, and more than 12%. The two land use and slope maps of Qazvin province were unified. In rainfed fields, 83, 10.7, 3.8, and 2.5% of fields have slope 0-5, 5-8, 8-12, and more than 12%, respectively. So 97.5% of rainfed fields have the ability to do supplementary irrigation. Most of these lands are in the Qazvin plain and in the vicinity of irrigated lands.