Assessment of Drought impact on Irrigated Agriculture in Lorestan Province

Agriculture in Lorestan Province is based on irrigated and rainfed agriculture, which uses two sources of surface water and groundwater. One of the most important natural hazards affecting the Lorestan Province agriculture is the occurrence of drought and its consequences. The main purpose of this study is to investigate the effects of drought on irrigated agriculture in this province. The data used included characteristics of irrigated agriculture, characteristics of water resources used in irrigated agriculture, land use map, and drought indices. The results showed that the increasing trend of drought and repetition of long-term drought and wet cycles in Lorestan Province is evident. In addition, drought events with different intensities have occurred during the study period and the time distribution of these periods can be seen overall 36-year period. Also, the results of the correlation analysis between the yield of irrigated crops, especially wheat and barley, with the different drought indices during the period 1991-2017 indicate a positive and direct relationship between the yield of irrigated plants and the values of drought indices. In terms of time, the highest correlation index is observed between yield and drought indices on a time scale of one to six months, and on longer time scales, the correlation value decreases. One of the main reasons for this condition is that short-term drought events affect rainfed agriculture and pasture vegetation and longer-term drought events have a greater impact on irrigated agriculture due to the greater dependence of irrigated agriculture on surface and groundwater resources. Finally, it can be said that the increase in drought and heat stress in Lorestan Province has reduced yields and increased the water needs of various irrigated crops.