Spatial and temporal changes in drought since 1961 in Haihe River basin

Drought is considered one of the weather disasters that restrict the socioeconomic development in China. The Haihe River basin is a typical region suffering from droughts. Daily meteorological observations from 58 stations are selected for the current drought study. The data covers the period 1961-2010 and the stations are located in the basin and its surrounding areas. The accumulated relative moisture index and FSPAAM (Fuzzy and set pair analysis evaluation method) are used in the study, as they can take into account the accumulated effect of drought as well as the fuzziness boundary conditions and the distribution of objects being evaluated. The characteristics of spatial and temporal drought variations in the Haihe River basin are analyzed. Results show that ① the Haihe River basin is dominated by moderate drought and severe drought, respectively affecting 73 000 km and 77 800 km. The severe drought-affected area increases significantly over the past 50 years; ② during the period 1986-2010, there is a tendency for the expansion of severe drought-prone areas. The latter has gone up to 149 000 km², which is 1.6 times higher than that of 1961-1985.