Influence of varied drought types on soil conservation service within the framework of climate change:insights from the Jinghe River Basin,China

Severe soil erosion and drought are the two main factors affecting the ecological security of the Loess Plateau,China.Investigating the influence of drought on soil conservation service is of great importance to regional environmental protection and sustainable development.However,there is little research on the coupling relationship between them.In this study,focusing on the Jinghe River Basin,China as a case study,we conducted a quantitative evaluation on meteorological,hydrological,and agricultural droughts(represented by the Standardized Precipitation Index(SPI),Standardized Runoff Index(SRI),and Standardized Soil Moisture Index(SSMI),respectively)using the Variable Infiltration Capacity(VIC)model,and quantified the soil conservation service using the Revised Universal Soil Loss Equation(RUSLE)in the historical period(2000-2019)and future period(2026-2060)under two Representative Concentration Pathways(RCPs)(RCP4.5 and RCP8.5).We further examined the influence of the three types of drought on soil conservation service at annual and seasonal scales.The NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP)dataset was used to predict and model the hydrometeorological elements in the future period under the RCP4.5 and RCP8.5 scenarios.The results showed that in the historical period,annual-scale meteorological drought exhibited the highest intensity,while seasonal-scale drought was generally weakest in autumn and most severe in summer.Drought intensity of all three types of drought will increase over the next 40 years,with a greater increase under the RCP4.5 scenario than under the RCP8.5 scenario.Furthermore,the intra-annual variation in the drought intensity of the three types of drought becomes smaller under the two future scenarios relative to the historical period(2000-2019).Soil conservation service exhibits a distribution pattern characterized by high levels in the southwest and southeast and lower levels in the north,and this pattern has remained consistent both in the historical and future periods.Over the past 20 years,the intra-annual variation indicated peak soil conservation service in summer and lowest level in winter;the total soil conservation of the Jinghe River Basin displayed an upward trend,with the total soil conservation in 2019 being 1.14 times higher than that in 2000.The most substantial impact on soil conservation service arises from annual-scale meteorological drought,which remains consistent both in the historical and future periods.Additionally,at the seasonal scale,meteorological drought exerts the highest influence on soil conservation service in winter and autumn,particularly under the RCP4.5 and RCP8.5 scenarios.Compared to the historical period,the soil conservation service in the Jinghe River Basin will be significantly more affected by drought in the future period in terms of both the affected area and the magnitude of impact.This study conducted beneficial attempts to evaluate and predict the dynamic characteristics of watershed drought and soil conservation service,as well as the response of soil conservation service to different types of drought.Clarifying the interrelationship between the two is the foundation for achieving sustainable development in a relatively arid and severely eroded area such as the Jinghe River Basin.

不同环流背景下极端高温天气特征和预报服务要点

基于2013年和2017年湖北省2次极端高温过程中气象要素、NCEP再分析数据、灾情资料和服务材料等数据,对比分析2次高温重灾害年的环流背景、高温特征、主要影响和服务要点等方面的异同。结果表明,2017年环流指数明显偏强,高温来势猛、强度大,高温日平均有效积温值高,但前期降水正常,抗旱水源充足,造成损失小; 2013年副高控制湖北省中东部时间长,52站连续高温日数达到极端高温事件标准,同时,2011—2013年降水均低于历史平均值,且梅雨期降水偏少,持续高温和少雨导致重旱和特旱明显,经济损失为近10 a来最重。不同的天气背景导致高温的影响不同,重点服务方向有差别,2013年与抗旱增雨有关的决策材料占64%,而2017年更突出新媒体的应用,提供高温体验式预报服务,获得了较好的服务效果。通过对前期天气背景的分析和未来天气形势的预测,可以为气象服务的重点方向提供指导,有效加强灾害性天气服务针对性。

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本文采取改进的“ＢＭ”方法，分旬、分县（市）客观、定量诊断气候旱涝灾害，进而模拟未来旬由旱（涝）转为正常所需的降水量（或无雨旬数）及其出现的气候概率。并在此基础上设计应用服务的实施方案．有效地提高防抗灾害的决策能力。

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