Abstract
Drought monitoring at large scale is essential for fighting against drought. Aiming at the limitation of acquiring long-time serial soil moisture and actual evapotranspiration for Palmer drought severity index (PDSI), the paper modified the PDSI based on distributed hydrological model on subbasin level in Luanhe river basin, North China. The water balance was simulated using the Soil and Water Assessment Tool (SWAT). Calibration and validation results showed good agreement between simulated and measured discharges, and the SWAT model can be used to predict hydrological processes in the study area. Then the simulation results of main hydrologic components were used to establish PDSI. The verification of the drought indices showed that the modified PDSI based on SWAT model and Palmer drought severity index could better describe the characteristics of regional drought evolution in the Luanhe river basin. High drought frequency areas were mainly distributed in the grassland regions of upstream located in the eastern part of Inner Mongolia plateau, and the drought area had a significant upward trend form 1973 to 2010. Compared with the traditional Palmer drought severity index, the modified PDSI could reflect the spatial heterogeneity of regional drought and improve the physical mechanism of PDSI. The drought monitoring method can provide technical support for comprehensive understanding of drought and effective preventing and relieving of drought disasters.
Highlights
Drought is a major natural hazard that can have devastating impacts on regional agriculture, water resources, and the environment, with farreaching impacts in an increasingly globalized world [1]
The spatial heterogeneity of precipitation cannot be well reflected in some years, which led to the monthly discharges being underestimated at each hydrological station, and the value of R2 and ENS had decreased for validation period
The indicators basically can meet the requirements of accuracy. These results showed that the calibrated model can describe the hydrological processes, implying that Soil and Water Assessment Tool (SWAT) model was applicable to the Luanhe river basin
Summary
Drought is a major natural hazard that can have devastating impacts on regional agriculture, water resources, and the environment, with farreaching impacts in an increasingly globalized world [1]. It is important to assess and monitor drought due to the consequences and pervasiveness of drought, and various drought indices had been derived to encapsulate drought severity on a regional basis and provide information for decision maker in recent decades [3]. The commonly used drought indices include standardized precipitation index (SPI) [5], Palmer drought severity index (PDSI) [6], and surface water supply index (SWSI), vegetation condition index [7, 8]. Heim [9] gave a comprehensive review of 20th century drought indices used in the United States
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