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Lack of surface water is a key factor leading to agricultural drought in karst regions and exacerbates the karst rocky desertification, which is characterized by high rate of exposed bedrock. With the characteristics of impermeability, runoff collection, and wide distribution, stone bud and karren (SBK), a unique karst landscape type composed of exposed bedrock and gullies, has a great potential to solve water shortage in agricultural irrigation, especially in the rain-rich karst regions of Guizhou Province, China. Using unmanned aerial vehicle images to identify SBK and measured rainfall–runoff data for validation, we applied SBK as a basic unit to harvest rainfall water on rocky desertification slopes and analyzed the benefits of rainfall water collection and irrigation via SBK. The results showed the following: (1) Karrens on rocky desertification slopes could be identified using a method coupling terrain opening difference and depression filling, and the simulated runoff on SBK could achieved the average NSE and R 2 of 0.82 and 0.86, with RMSE and RSR less than 0.03 m3 and 0.51, respectively. (2) The exposed bedrock utilization rate and rainfall water collection coefficient of SBK were 0.62 and 0.55, respectively, such that the area ratio of exposed bedrock to the cultivated land meeting irrigation water demand reached 1:3.1, 1:3.7 and 1:7.0 under 90 %, 80 % and 50 % possibilities of irrigation. (3) Implementing SBK for rainfall water harvesting and irrigation could efficiently avoid crop failure in the karst regions where crops faced drought within only one week after rainfall, and was at an affordable cost to local farmers with limited environmental damage. The use of SBK to harvest rainfall water could also alleviate surface water shortages in karst regions caused by problems such as uneven temporal distribution of rainfall and engineering water shortages. Consequently, SBK demonstrate a strong application potential to alleviate agricultural drought in karst rocky desertification regions. • Stone bud and karren (SBK) on rocky desertification slope were effectively identified. • The simulated runoff on SBK achieved the average NSE and R 2 of 0.82 and 0.86, respectively. • The rainfall water collection coefficient of SBK was 0.55 resulting in a high irrigation capacity. • SBK demonstrated low costly but beneficial to alleviate agricultural drought in karst regions. [ABSTRACT FROM AUTHOR]

• The increase in carbon sinks is limited compared to the increase in carbon emissions. • The carbon sequestration ratio remains deficient and generally maintained around 10%. • The Hu Line spatial pattern of carbon emission and sink showed an unbalanced state. • The Hu Line's southeast side contributed the most GDP and terrestrial carbon sink. China's commitment to achieving the goal of carbon peak and carbon neutrality (CPCN) has attracted worldwide attention, and the efforts made by China are critical to realization of the 1.5 °C temperature control objective of the 2015 Paris Agreement. However, it is unclear whether long-term spatiotemporal changes in China's carbon emissions and carbon sinks exhibit specific spatial patterns, such as the Hu Line, which might affect China's future policymaking. Based on the emission factor, inventory, and eddy covariance methods, this study calculated China's carbon emissions (2003–2018) and terrestrial carbon sinks (2003–2020). Results showed that the increase in carbon sinks is limited in comparison with the increase in carbon emissions, and that the carbon sequestration ratio remains deficient and generally maintained at around 10 %. The spatial pattern of carbon emissions and carbon sinks showed an unbalanced state across the Hu Line, mainly reflected in accelerated increase in both the carbon emission rankings and the proportion of emissions to China's total carbon emissions of provinces on the northwestern side of the Hu Line. Despite this, the gross domestic product (GDP) rankings of those provinces have not improved substantially, whereas provinces on the southeastern side of the Hu Line have contributed most to China's GDP and terrestrial carbon sinks. The findings of this study improve understanding of the spatiotemporal relationship between carbon emissions and terrestrial carbon sinks in China, and represent alternative insights that could support adjustment of carbon-related policies and promote realization of CPCN in China. [ABSTRACT FROM AUTHOR]