Matching degree of precipitation and rice water consumption and analysis of drought and waterlogging vulnerable characteristics of rice in Sihu Basin, Hubei of China

Rice is one of the main food crops in the paddy field. The regional water resources can be allocated to manage the irrigation and drainage. This study aims to determine the matching relationship between precipitation and rice water consumption, the crop water surplus and deficit Index (CWSDI) and the vulnerability of rice in drought and waterlogging in climate change environment. Taking the Sihu basin of Jianghan Plain in Hubei Province as the research area, the daily meteorological data was collected from five meteorological stations from 1961 to 2020. The spatiotemporal distribution of precipitation, water consumption, CWSDI and the rice vulnerability in the drought and waterlogging were analyzed by Penman-Monteith formula, Mann-Kendall trend test, climate tendency rate and spatial interpolation analysis. Results showed that the multi-year average precipitation was 1 209.2 mm. There was a significant increase at an average rate of 35.1mm/10a. Both the precipitation and increase rate in the southeast were higher than that in the northwest. The multi-year average precipitation was 492.0, 509.9, and 269.1 mm, respectively, in the growth periods of early, middle and late rice. There was an insignificant increase in the precipitation at an average rate of 17.9 and 18.4 mm/10a, respectively, in the early and middle rice growth periods. By contrast, an insignificant downward trend of precipitation was found at an average rate of -10.7 mm/10a in the late rice growth periods. The multi-year average water consumption was 411.4, 595.5, and 401.4 mm, respectively, for the early, middle and late rice. The water consumption of the middle rice was much greater than that of the early and late rice. The water consumption of early and middle rice decreased significantly at an average rate of -5.54 and -11.43 mm/10a, respectively. While the water consumption of late rice showed an insignificant downward trend at an average rate of -1.52 mm/10a. The multi-year average CWSDI values were 0.22, -0.12 and -0.31, respectively, for the early, middle and late rice. The CWSDI values of early and middle rice showed an insignificant upward trend at an average rate of 0.06/10a and 0.04/10a, respectively, whereas, there was an insignificant downward trend of late rice at an average rate of -0.03/10a. Therefore, the water surplus degree of early and middle rice increased, while the water deficit of late rice was intensified. The drought frequencies of early, middle and late rice ranged from 10.0% to 16.7%, 28.3% to 40.0%, and 51.8% to 60.0%, respectively, where the late rice was the most vulnerable to drought. The frequencies of flood in the early, middle and late rice ranged from 1.7% to 15.0%, 1.7% to 3.3%, and 0 to 1.7%, respectively, where the early rice was more vulnerable to waterlogging. In general, the frequencies of drought and flood disasters for early rice were less (20.7%), followed by the middle rice (37.0%), and the late rice was the most vulnerable to drought and flood threats (56.0%). The matching degree of water consumption of rice and precipitation was ranked in the descending order of early rice > middle rice > late rice. Much attention should be paid to the drought and water shortages in the late rice.