The applicability of A Modified Palmer Drought Severity Index on Agricultural Drought Evaluation in the North China

State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China

^a Corresponding author: xiaoweihua@iwhr.com

Abstract

Agricultural irrigation is an important factor affecting the development of agricultural drought, which is not showed in the Palmer Drought Severity Index (PDSI). In this work, the water balance model in PDSI has been modified by adding irrigation items, which improves the accuracy of the calculation results of the model and shortens the calculation time step. The modified Palmer Drought Severity Index (M_PDSI) is constructed by using daily weather data and irrigation data from 1985-2012 in the study area. Weekly indices cumulated in each growth stage are used for the implementation of crop models by a linear multiple regression model. The crop yield models are evaluated to determine a more appropriate agricultural drought index between M_PDSI and PDSI by comparing the predicted yields to the observed yields. By comparing the development of agricultural drought, it can be seen that the M_PDSI can improve the sensitivity to the dynamic change of soil wet and dry in short-term, and the development process of drought is more in line with the actual situation; by comparing the fitting test results of the predicted yields, it can be seen that, the M_PDSI ranks better than the PDSI in all four goodness-of-fit measures, M_PDSI is proved to be more suitable than PDSI for evaluating agricultural drought.