Spatio-temporal Variability of Water Deficit in Huang-Huai-Hai Plain During 1961-2013

Water shortage is recognized as the most serious problem for agriculture production in Huang-Huai-Hai plain (3H plain) and the changing characteristics for water resources in context of climate change remains unknown yet. Based on measured meteorological data obtained from 41 stations located in 3H plain, potential evapotranspiration was calculated by applying Penman-Monteith equation, and water deficit was described as the difference of precipitation and potential evapotranspiration at the same period. Finally, the spatial and temporal variation characteristics of water deficit in four seasons over 3H plain were analyzed by using Kendall-Theil robust line method, Mann-Kendall trend test and Morlet wavelet function. Results showed that multi-year average water deficit was negative in most part of 3H plain and varied between -650mm and 100mm with the spatial variation pattern of decreasing gradually from south to north,. Among four seasons, spring is presented as the most serious water situation with the shortage of 210.61mm in multi-year average, which is higher than any other seasons. Trend analysis of seasonal multi-year average water deficit among 41 stations generally shown an upward trend except in autumn where only stations surrounding Jing-Jin-Ji district increased. Annual water deficit variation among 6 sub-regions was -391.45,-510.11, -560.42,-427.21, -284.19 and -21.63mm in respectively and this variation was mainly induced by precipitation. For seasonal difference in 6 sub-regions, spring amounts for the highest water shortage period which occupies annual water shortage at 56.4%, 51.7%, 40.6%, 59.7%, 59.3% and 66.1%, respectively. Spring water deficit showed higher period, lower period alternately with the main period of 28 years for these six regions, 10 years for region V and VI. The seasonal and spatial difference of water deficit in 3H plain indicated a high drought risks with spatio-temporal variability, especially in spring season. Thus, effective climate changing adoption needs water resources be operated rationally and agriculture irrigation arrangements with seasonal.