THE FARTHER MODIFICATION OF PALMER DROUGHT SEVERITY MODEL

To evaluate the ravages of a drought, a farther modified Meteorological Drought Severity Model for China was developed based on the Palmer Drought Severity Model and the modified Palmer Drought Severity Model corrected by An Shunqing etc. The monthly temperature and precipitation data at Jinan, Zhengzhou and Taiyuan (1961—2000) were used as basic data and relevant data gained at other 21 stations (Harbin, Jiamusi, Hohhot, Shenyang, Beijing, Guyuan, Xian, Hanzhong, Qingdao, Dezhou, Yuncheng, Changsha, Wuhan, Nanchang, Hangzhou, Fuzhou, Guangzhou, Kunming, Nanning, Chengdu and Guiyang) to obtain the weighing coefficient. The potential evapotranspiration for an individual month was computed by the Penman-Monteith equation commended by FAO. The available soil moisture in both layers (0—20 cm, 20—100 cm) was determined by the soil moisture data and the soil characters. The monthly Palmer Drought Index was computed at 139 stations of North China from 1961 to 2000. Comparing the computed Palmer Drought Index with the situation of drought and waterlog recorded in some documents, it is found that the farther modified Palmer Drought Severity Model can reflect the severity of meteorological drought or waterlogging comparatively and is applicable for China.