Evaluating the Improved Ability of Irrigation Water Conservancy Engineering Projects Since 2011 in Mitigating Flood and Drought in China

Abstract

【Background and objective】 The No.1 central document in 2011 proposed to improve farmland water conservancy construction. Since then, constructing well-facilitated farmland water projects has developed rapidly with an average of annual investment more than 80 billion Yuan. The objective of this paper is to evaluate the efficacy of these projects in mitigating floods and droughts across the country. 【Method】 We divided precipitation, standard ratio of areas affected by flood and drought to total sowing areas in each province into 1994—2010 group and 2011—2018 group. A linear model was used to fit the changes in flood and drought ratio in response to precipitations in the two periods. The one-way ANOVA analysis was used to test significant difference in precipitation, difference in standard ratio of areas affected by flood and drought to the total sowing areas, between the two groups. 【Result】 The standard ratio of flood-affected areas to the total sowing areas increased significantly with precipitation from 1994 to 2010, indicating a positive impact of precipitation on floods. Since 2011, however, the floods did not show a significant relationship with precipitation, implying the efficacy of the projects newly constructed or revamped. The standard ratio of the drought-affected areas to the total sowing areas decreased significantly with the increase in precipitation from 1994 to 2018, but the slope of the linear increase for 2011 to 2018 was smaller than that for 1994 to 2010, implying the effectiveness of the newly constructed projects in mitigating the occurrence of drought. Compared to those in 1994—2010, the ratios of drought-areas and drought-damaged areas to the total sowing areas decreased by 5.14~22.52 percentage points and 2.21~16.79 percentage points, respectively, in 2011—2018, while the ratio of flood-areas and flood-damaged areas to the total sowing areas decreased by 3.26~8.00 percentage points and 1.95~4.54 percentage points, respectively, in the same period. The newly constructed or revamped projects were most effective in mitigating drought in the arid, semi-arid and semi-humid regions in provinces including Hebei, Shanxi, Inner Mongolia, Liaoning, Jilin, Heilongjiang, Tibet, Gansu, Qinghai and Xinjiang. For provinces in humid regions, including Fujian, Jiangxi, Hubei and Hunan, they were more effective in alleviating floods. For those in semi-humid regions, such as Shandong and Henan, and in humid regions such as Jiangsu, Guangdong, and Chongqing, they were effective in ameliorating both drought and flood. 【Conclusion】 The effectiveness of the newly constructed and revamped water engineering projects since 2011 varied with regions. On average, they are more effective in relieving droughts than floods. Our analysis provides valuable information for guiding future farmland water conservancy engineering construction.

Keywords

• farmland water conservancy engineering
• well-facilitated farmland
• flood and drought
• mitigation
• evaluation