Thornthwaite moisture index and depth of suction change under current and future climate‒An Australian study

Climate change is one of the major global challenges and it can have a significant influence on the behaviour and resilience of geotechnical structures.The changes in moisture content in soil lead to effective stress changes and can be accompanied by significant volume changes in reactive/expansive soils.The volume change leads to ground movement and can exert additional stresses on structures founded on or within a shallow depth of such soils.Climate change is likely to amplify the ground movement potential and the associated problems are likely to worsen.The effect of atmospheric boundary interaction on soil behaviour has often been correlated to Thornthwaite moisture index(TMI).In this study,the long-term weather data and anticipated future projections for various emission scenarios were used to generate a series of TMI maps for Australia.The changes in TMI were then correlated to the depth of suction change(H s),an important input in ground movement calculation.Under all climate scenarios considered,reductions in TMI and increases in H s values were observed.A hypothetical design scenario of a footing on expansive soil under current and future climate is discussed.It is observed that a design that might be considered adequate under the current climate scenario,may fail under future scenarios and accommodations should be made in the design for such events.

Characteristics of Dry and Wet Climate in Shandong Province Based on Standardized Precipitation Index

Based on the monthly precipitation data of 116 meteorological stations in Shandong Province during 1970-2021,standardized precipitation index(SPI)was calculated,and the methods of linear fitting,mutation test and Morlet wavelet analysis were used to analyze the change trend and temporal and spatial distribution characteristics of SPI index in the past 52 years.The results show that there were more normal years in Shandong Province,and the frequency reached 38.46%.There was severe drought in the 1980s and more wet years after 2003.SPI index showed an upward trend in spring,summer and winter but a weak arid trend in autumn.In addition,intense dry weather was more frequent in summer.Spatially,the climate was normal or humid in most areas of Shandong Province.The regions with more wet years were located in the central and northeast Shandong and the peninsula,while the climate was normal in the southwest and north of Shandong.The areas with more dry years were mainly located in the northwest of Shandong Province.There was mainly local and global drought in Shandong Province,and the arid area showed a decreasing trend.In the past 52 years,Shandong Province experienced quasi-4 times of alternation between dry and wet climate.The long period of 21 a was the first main period,and the climate would be still wet in Shandong Province in the future.In terms of mutation,the climate in Shandong Province became humid after 2003,and 2003 was the mutation point.After the abrupt change,the climate changed from gradually drying to wetting.

Changing Characteristics of Comfort Index of Human Body in Bengbu City in the Past 40 Years under the Background of Climate Change

Based on the daily meteorological data of Bengbu City during 1981-2020,the changing characteristics of three elements needed for the calculation of the comfort index of human body(CIHB)were discussed,and daily CIHB was classified and discussed.The results show that from 1981 to 2020,annual average temperature tended to increase significantly.Annual average wind speed and relative humidity showed a decreasing trend before 2011 but an increasing trend after 2011.The duration of the four seasons in Bengbu City mainly rose in spring,reduced in winter,declined first and then increased in summer,and rose first and then decreased in autumn.As CIHB was at grades 1 and 9(the most uncomfortable),the three factors had different effects on them.For cold weather,the influence of relative humidity and wind speed on CIHB can not be ignored besides temperature.In hot weather,the influence of temperature was dominant,and the change of annual average temperature could well correspond to the change in the number of very hot days.In the context of climate warming,the number of cold days tended to decline generally,but it was larger in the years with fewer very cold days.Under the background of climate warming,there was no obvious change in the number of days of the overall comfort of human body.The number of hot days was closely related to the duration of summer,and the number of days of grade 8 rose significantly in the years with an increase in the duration of summer.

Response of drought to climate extremes in a semi-arid inland river basin in China

Against the backdrop of global warming,climate extremes and drought events have become more severe,especially in arid and semi-arid areas.This study forecasted the characteristics of climate extremes in the Xilin River Basin(a semi-arid inland river basin)of China for the period of 2021–2100 by employing a multi-model ensemble approach based on three climate Shared Socioeconomic Pathway(SSP)scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5)from the latest Coupled Model Intercomparison Project Phase 6(CMIP6).Furthermore,a linear regression,a wavelet analysis,and the correlation analysis were conducted to explore the response of climate extremes to the Standardized Precipitation Evapotranspiration Index(SPEI)and Streamflow Drought Index(SDI),as well as their respective trends during the historical period from 1970 to 2020 and during the future period from 2021 to 2070.The results indicated that extreme high temperatures and extreme precipitation will further intensify under the higher forcing scenarios(SSP5-8.5>SSP2-4.5>SSP1-2.6)in the future.The SPEI trends under the SSP1-2.6,SSP2-4.5,and SSP5-8.5 scenarios were estimated as–0.003/a,–0.004/a,and–0.008/a,respectively,indicating a drier future climate.During the historical period(1970–2020),the SPEI and SDI trends were–0.003/a and–0.016/a,respectively,with significant cycles of 15 and 22 a,and abrupt changes occurring in 1995 and 1996,respectively.The next abrupt change in the SPEI was projected to occur in the 2040s.The SPEI had a significant positive correlation with both summer days(SU)and heavy precipitation days(R10mm),while the SDI was only significantly positively correlated with R10mm.Additionally,the SPEI and SDI exhibited a strong and consistent positive correlation at a cycle of 4–6 a,indicating a robust interdependence between the two indices.These findings have important implications for policy makers,enabling them to improve water resource management of inland river basins in arid and semi-arid areas under future climate uncertainty.

Regional Climate Models in the Simulation of the Drought of the 1970’s and 1980’s Years in Senegal (In West Africa)

West Africa was hit by an unprecedented drought in the 1970’s and 1980’s years, with dramatic consequences for surface and groundwater resources. In the context of climate change, there are many studies for the prediction of the increase in the occurrence of these droughts. To predict this situation in the Senegalese region, it is necessary to use regional climate models, which carrying out the study. This work deals with the interest to examine the capacity of the RCMs (regional climate models) in order to reproduce the deficit on the 1970’s year rainfall in Senegal. In this work, we used daily precipitation data from five (5) regional climate models to characterize the droughts in Senegal by using the SPI (Standardized Precipitation Index) on different time scales (3, 6, 12 and 24 months). For this purpose, the index was calculated over two distinct periods: 1951-1969 and 1970-1990. The results show that the period 1970-1990 was drier than the period 1951-1969. For the zonal average, the results show that the North of Senegal was more affected by this deficit rainfall than the South part. The analysis of the interannual variability of rainfall for some stations in Senegal shows that the drought did not start at the same time throughout the zone.

Spatial distribution characteristics of climate-induced landslides in the Eastern Himalayas

Climate warming is constantly causing hydro-meteorological perturbations,especially in high-altitude mountainous regions,which lead to the occurrences of landslides.The impact of climatic variables(i.e.,precipitation and temperature)on the distribution of landslides in the eastern regions of the Himalayas is poorly understood.To address this,the current study analyzes the relationship between the spatial distribution of landslide characteristics and climatic variables from 2013 to 2021.Google Earth Engine(GEE)was employed to make landslide inventories using satellite data.The results show that 2163,6927,and 9601 landslides were heterogeneously distributed across the study area in 2013,2017,and 2021,respectively.The maximum annual temperature was positively correlated with the distribution of landslides,whereas precipitation was found to have a non-significant impact on the landslide distribution.Spatially,most of the landslides occurred in areas with maximum annual precipitation ranging from 800 to 1600 mm and maximum annual temperature above 15℃.However,in certain regions,earthquake disruptions marginally affected the occurrence of landslides.Landslides were highly distributed in areas with elevations ranging between 3000 and 5000 m above sea level,and many landslides occurred near the lower permafrost limit and close to glaciers.The latter indicates that temperature change-induced freeze-thaw action influences landslides in the region.Temperature changes have shown a positive correlation with the number of landslides within elevations,indicating that temperature affects their spatial distribution.Various climate projections suggest that the region will experience further warming,which will increase the likelihood of landslides in the future.Thus,it is crucial to enhance ground observation capabilities and climate datasets to effectively monitor and mitigate landslide risks.

Effects of nitrogen deposition on the carbon budget and water stress in Central Asia under climate change

Atmospheric deposition of nitrogen(N)plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide.However,the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly uncertain.In this study,a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition(DNDC)model.Results showed that total vegetation carbon(C)in Central Asia was 0.35(±0.09)Pg C/a and the averaged water stress index(WSI)was 0.20(±0.02)for the whole area.Increasing N deposition led to an increase in the vegetation C of 65.56(±83.03)Tg C and slightly decreased water stress in Central Asia.Findings of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition,and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.

Coupled effects of climate change and human activities on vegetation dynamics in the Southwestern Alpine Canyon Region of China

The driving effects of climate change and human activities on vegetation change have always been a focal point of research.However,the coupling mechanisms of these driving factors across different temporal and spatial scales remain controversial.The Southwestern Alpine Canyon Region of China(SACR),as an ecologically fragile area,is highly sensitive to the impacts of climate change and human activities.This study constructed a vegetation cover dataset for the SACR based on the Enhanced Vegetation Index(EVI)from 2000 to 2020.Spatial autocorrelation,Theil-Sen trend,and Mann-Kendall tests were used to analyze the spatiotemporal characteristics of vegetation cover changes.The main drivers of spatial heterogeneity in vegetation cover were identified using the optimal parameter geographic detector,and an improved residual analysis model was employed to quantify the relative contributions of climate change and human activities to interannual vegetation cover changes.The main findings are as follows:Spatially,vegetation cover exceeds 60%in most areas,especially in the southern part of the study area.However,the border area between Linzhi and Changdu exhibits lower vegetation cover.Climate factors are the primary drivers of spatial heterogeneity in vegetation cover,with temperature having the most significant influence,as indicated by its q-value,which far exceeds that of other factors.Additionally,the interaction q-value between the two factors significantly increases,showing a relationship of bivariate enhancement and nonlinear enhancement.In terms of temporal changes,vegetation cover shows an overall improving trend from 2000 to 2020,with significant increases observed in 68.93%of the study area.Among these,human activities are the main factors driving vegetation cover change,with a relative contribution rate of 41.31%,while climate change and residual factors contribute 35.66%and 23.53%,respectively.By thoroughly exploring the coupled mechanisms of vegetation change,this study provides important references for the sustainable management and conservation of the vegetation ecosystem in the SACR.

Response of vegetation variation to climate change and human activities in the Shiyang River Basin of China during 2001-2022

Understanding the response of vegetation variation to climate change and human activities is critical for addressing future conflicts between humans and the environment,and maintaining ecosystem stability.Here,we aimed to identify the determining factors of vegetation variation and explore the sensitivity of vegetation to temperature(SVT)and the sensitivity of vegetation to precipitation(SVP)in the Shiyang River Basin(SYRB)of China during 2001-2022.The climate data from climatic research unit(CRU),vegetation index data from Moderate Resolution Imaging Spectroradiometer(MODIS),and land use data from Landsat images were used to analyze the spatial-temporal changes in vegetation indices,climate,and land use in the SYRB and its sub-basins(i.e.,upstream,midstream,and downstream basins)during 2001-2022.Linear regression analysis and correlation analysis were used to explore the SVT and SVP,revealing the driving factors of vegetation variation.Significant increasing trends(P<0.05)were detected for the enhanced vegetation index(EVI)and normalized difference vegetation index(NDVI)in the SYRB during 2001-2022,with most regions(84%)experiencing significant variation in vegetation,and land use change was determined as the dominant factor of vegetation variation.Non-significant decreasing trends were detected in the SVT and SVP of the SYRB during 2001-2022.There were spatial differences in vegetation variation,SVT,and SVP.Although NDVI and EVI exhibited increasing trends in the upstream,midstream,and downstream basins,the change slope in the downstream basin was lower than those in the upstream and midstream basins,the SVT in the upstream basin was higher than those in the midstream and downstream basins,and the SVP in the downstream basin was lower than those in the upstream and midstream basins.Temperature and precipitation changes controlled vegetation variation in the upstream and midstream basins while human activities(land use change)dominated vegetation variation in the downstream basin.We concluded that there is a spatial heterogeneity in the response of vegetation variation to climate change and human activities across different sub-basins of the SYRB.These findings can enhance our understanding of the relationship among vegetation variation,climate change,and human activities,and provide a reference for addressing future conflicts between humans and the environment in the arid inland river basins.

Climate-Vegetation Coverage Interactions in the Hengduan Mountains Area, Southeastern Tibetan Plateau, and Their Downstream Effects

Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.

Impacts of climate change and human activities on vegetation dynamics on the Mongolian Plateau, East Asia from 2000 to 2023

The Mongolian Plateau in East Asia is one of the largest contingent arid and semi-arid areas of the world.Under the impacts of climate change and human activities,desertification is becoming increasingly severe on the Mongolian Plateau.Understanding the vegetation dynamics in this region can better characterize its ecological changes.In this study,based on Moderate Resolution Imaging Spectroradiometer(MODIS)images,we calculated the kernel normalized difference vegetation index(kNDVI)on the Mongolian Plateau from 2000 to 2023,and analyzed the changes in kNDVI using the Theil-Sen median trend analysis and Mann-Kendall significance test.We further investigated the impact of climate change on kNDVI change using partial correlation analysis and composite correlation analysis,and quantified the effects of climate change and human activities on kNDVI change by residual analysis.The results showed that kNDVI on the Mongolian Plateau was increasing overall,and the vegetation recovery area in the southern region was significantly larger than that in the northern region.About 50.99%of the plateau showed dominant climate-driven effects of temperature,precipitation,and wind speed on kNDVI change.Residual analysis showed that climate change and human activities together contributed to 94.79%of the areas with vegetation improvement.Appropriate human activities promoted the recovery of local vegetation,and climate change inhibited vegetation growth in the northern part of the Mongolian Plateau.This study provides scientific data for understanding the regional ecological environment status and future changes and developing effective ecological protection measures on the Mongolian Plateau.

A CMIP6-based assessment of regional climate change in the Chinese Tianshan Mountains

Climate warming profoundly affects hydrological changes,agricultural production,and human society.Arid and semi-arid areas of China are currently displaying a marked trend of warming and wetting.The Chinese Tianshan Mountains(CTM)have a high climate sensitivity,rendering the region particularly vulnerable to the effects of climate warming.In this study,we used monthly average temperature and monthly precipitation data from the CN05.1 gridded dataset(1961-2014)and 24 global climate models(GCMs)of the Coupled Model Intercomparison Project Phase 6(CMIP6)to assess the applicability of the CMIP6 GCMs in the CTM at the regional scale.Based on this,we conducted a systematic review of the interannual trends,dry-wet transitions(based on the standardized precipitation index(SPI)),and spatial distribution patterns of climate change in the CTM during 1961-2014.We further projected future temperature and precipitation changes over three terms(near-term(2021-2040),mid-term(2041-2060),and long-term(2081-2100))relative to the historical period(1961-2014)under four shared socio-economic pathway(SSP)scenarios(i.e.,SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5).It was found that the CTM had experienced significant warming and wetting from 1961 to 2014,and will also experience warming in the future(2021-2100).Substantial warming in 1997 was captured by both the CN05.1 derived from interpolating meteorological station data and the multi-model ensemble(MME)from the CMIP6 GCMs.The MME simulation results indicated an apparent wetting in 2008,which occurred later than the wetting observed from the CN05.1 in 1989.The GCMs generally underestimated spring temperature and overestimated both winter temperature and spring precipitation in the CTM.Warming and wetting are more rapid in the northern part of the CTM.By the end of the 21st century,all the four SSP scenarios project warmer and wetter conditions in the CTM with multiple dry-wet transitions.However,the rise in precipitation fails to counterbalance the drought induced by escalating temperature in the future,so the nature of the drought in the CTM will not change at all.Additionally,the projected summer precipitation shows negative correlation with the radiative forcing.This study holds practical implications for the awareness of climate change and subsequent research in the CTM.

基于TerraClimate数据集的1960—2019年中国干湿气候变化特征

考虑地理地形和下垫面等因素的影响,选用高空间分辨率TerraClimate数据集分析中国干湿气候变化特征具有重要意义。以该数据集1960—2019年的降水和蒸散月度数据为基础,基于降水量和湿润指数对中国各干湿区范围、干湿气候界线以气候变化趋势进行了分析。结果表明:前后30 a相比,基于两种指标划分的干旱区和湿润区面积负增长,半干旱区和半湿润区面积正增长;各区分界线主要在黑龙江、内蒙古中部和东北部、淮河以及黑龙江等地按年代波动;近60 a来,我国的降水量和湿润指数变化趋势不显著,均在西部和东南部趋于增大,气候变湿,在中部和东北部趋于减小,气候变干。与利用气象站点观测资料的研究结果进行对比评价,TerraClimate数据集能够很好反映中国区域的干湿状况及其变化特征,且降水数据的适用性更为突出。

Heterogeneity and non-linearity of ecosystem responses to climate change in the Qilian Mountains National Park, China

Ecosystem responses to climate change,particularly in arid environments,is an understudied topic.This study conducted a spatial analysis of ecosystem responses to short-term variability in temperature,precipitation,and solar radiation in the Qilian Mountains National Park,an arid mountainous region in Northwest China.We collected precipitation and temperature data from the National Science and Technology Infrastructure Platform,solar radiation data from the China Meteorological Forcing Dataset,and vegetation cover remote-sensing data from the Moderate Resolution Imaging Spectroradiometer.We used the vegetation sensitivity index to identify areas sensitive to climate change and to determine which climatic factors were significant in this regard.The findings revealed a high degree of heterogeneity and non-linearity of ecosystem responses to climate change.Four types of heterogeneity were identified:longitude,altitude,ecosystem,and climate disturbance.Furthermore,the characteristics of nonlinear ecosystem responses to climate change included:(1)inconsistency in the controlling climatic factors for the same ecosystems in different geographical settings;(2)the interaction between different climatic factors results in varying weights that affect ecosystem stability and makes them difficult to determine;and(3)the hysteresis effect of vegetation increases the uncertainty of ecosystem responses to climate change.The findings are significant because they highlight the complexity of ecosystem responses to climate change.Furthermore,the identification of areas that are particularly sensitive to climate change and the influencing factors has important implications for predicting and managing the impacts of climate change on ecosystems,which can help protect the stability of ecosystems in the Qilian Mountains National Park.

Interannual Variability of the Normalized Difference Vegetation Index on the Tibetan Plateau and Its Relationship with Climate Change

The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index （NDVI） dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982-2002. The temporal variation also exhibits striking regional differences： an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.

An assessment of the climatic suitability of Afriski Mountain Resort for outdoor tourism using the Tourism Climate Index(TCI)

Tourism Climatic Indices(TCIs)are widely used in the global North to quantify the climatic suitability of a destination for tourism.Only one such study has been conducted in southern Africa to date.It is in a chronic shortage of research on tourism and climate change in the southern hemisphere.This study presents the application of the TCI in Lesotho,calculated for the eastern Lesotho Highlands.The region has an emerging tourism sector,which primarily comprises outdoor activities.These include hiking,horse-riding,music festivals,mountain biking,cultural visits,sightseeing,and at the Afriski lodge,skiing and snowboarding.These activities are reliant on climatic conditions that are conducive to the activity taking place,prolonged periods outdoors,and tourist satisfaction of the activity.Climate is a major determinant of both the length of season for these activities and the timing of peak tourist arrivals.Rising temperatures and changes in relative humidity and precipitation pose real threats to hiking,sightseeing and snow tourism at Afriski.The reliance of tourism in the region on specific climatic conditions for successful tourism prompted the use of the TCI.TCI results classify the eastern Lesotho Highlands as having‘good'climatic conditions with an overall TCI score of 64 for the period 2012-2017.Monthly TCI scores for the eastern Lesotho reveal a bimodal-shoulder,meaning the peak climatic conditions are in the regional summer months(December to February).This conflicts with the peak tourist seasons of summer and winter,which align with South African school holidays,and the timing of the most profitable tourism activity(skiing)which occurs during the winter months of June,July and August.Lesotho is landlocked by South Africa.TCI analysis for South Africa reveals more suitable climatic conditions for tourism than Lesotho,with significantly higher scores of 80-89.

Early Cretaceous Climate Changes Recorded in Magnetic Susceptibility and Color Index Variations of the Lower Liupanshan Group, Central China

This study carried out comprehensive analysis on sedimentology, magnetic susceptibility （7of） and color data of the continental sediments of the Liupanshan Group in Central China so as to obtain climatic change information during the 129.14-122.98 Ma interval. Based on the results of the Xlf and of the redness （a＊）, the section can be divided into two segments： （1） 129.14-126.3 Ma, with the lowest Xlf values and strongly variable relatively high values of redness and （2） 126.3-122.98 Ma, with high Elf values and relatively low redness. Analysis of the lithology and facies as well as the magnetic minerals and their contents points to a detrital origin of the magnetic minerals and this allow us to interpret the relationship between magnetic susceptibility variations and climate changes. Our study shows that the climate was significantly dry and hot during the whole studied interval although the interval between 126.3 Ma and 122.98 was a little bit cooler with increased humidity.

THE EAST ASIAN SUBTROPICAL SUMMER MONSOON INDEX AND ITS RELATION WITH THE CLIMATE ANOMALIES IN CHINA

A new East Asian subtropical summer monsoon circulation index is defined, where the barotropic and baroclinic components of circulation are included. Results show that this index can well indicate the interannual variability of summer precipitation and temperature anomalies in China. A strong monsoon is characterized by more rainfall in the Yellow River basin and northern China, less rainfall in the Yangtze River basin, and more rainfall in south and southeast China, in association with higher temperature in most areas of China. Furthermore, comparison is made between the index proposed in this paper and other monsoon indexes in representing climate anomalies in China.

Future meteorological drought conditions in southwestern Iran based on the NEX-GDDP climate dataset

Investigation of the climate change effects on drought is required to develop management strategies for minimizing adverse social and economic impacts.Therefore,studying the future meteorological drought conditions at a local scale is vital.In this study,we assessed the efficiency of seven downscaled Global Climate Models(GCMs)provided by the NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP),and investigated the impacts of climate change on future meteorological drought using Standard Precipitation Index(SPI)in the Karoun River Basin(KRB)of southwestern Iran under two Representative Concentration Pathway(RCP)emission scenarios,i.e.,RCP4.5 and RCP8.5.The results demonstrated that SPI estimated based on the Meteorological Research Institute Coupled Global Climate Model version 3(MRI-CGCM3)is consistent with the one estimated by synoptic stations during the historical period(1990-2005).The root mean square error(RMSE)value is less than 0.75 in 77%of the synoptic stations.GCMs have high uncertainty in most synoptic stations except those located in the plain.Using the average of a few GCMs to improve performance and reduce uncertainty is suggested by the results.The results revealed that with the areas affected by wetness decreasing in the KRB,drought frequency in the North KRB is likely to increase at the end of the 21st century under RCP4.5 and RCP8.5 scenarios.At the seasonal scale,the decreasing trend for SPI in spring,summer,and winter shows a drought tendency in this region.The climate-induced drought hazard can have vast consequences,especially in agriculture and rural livelihoods.Accordingly,an increasing trend in drought during the growing seasons under RCP scenarios is vital for water managers and farmers to adopt strategies to reduce the damages.The results of this study are of great value for formulating sustainable water resources management plans affected by climate change.

Projections of the impacts of climate change on the water deficit and on the precipitation erosive indexes in Mantaro River Basin, Peru

Projections of climate change are essential to guide sustainable development plans in the tropical Andean countries such as Peru. This study assessed the projections of precipitation and potential evaporation, rain erosive potential, and precipitation concentration in the Mantaro River Basin, in the Peruvian Andes, which is important for agriculture and energy production in Peru. We assumed the Intergovernmental Panel on Climate Change （IPCC） AIB greenhouse gas emission scenario and simulated the global climate change by the HadCM3 global climate model. Due to the steepness of the mountain slopes and the narrowness of the river valley, this study uses the downscaling of the global model simulations by the regional Eta model down to 2o-km resolution. The downscaling projections show decrease in the monthly precipitation with respect to the baseline period, especially during the rainy season, between February and April, until the end of the 21st century. Meanwhile, a progressive increase in the monthly evaporation from the baseline period is projected. The Modified Fournier Index （MFI） shows a statistically significant downward trend in the Mantaro River Basin, whieh suggests a possible reduction in the rain erosive potential. The Precipitation Concentration Index （PCI） shows a statistically significant increasing trend, which indicates increasingly more irregular temporal distribution of precipitation towards the end of the century. The results of this study allow us to conclude that there should be a gradual increase in water deficit and precipitation concentration. Both changes can be negative for agriculture, power generation, and water supply in the Mantaro River Basin in Peru.