Reduction In Annual Precipitation Research Articles

Which contributes more in predictor of desert shrubs traits: Intra-annual or inter-annual precipitation change?

Considering the implications of future climatic shifts, mid-latitude desert ecosystems will experience pronounced changes in precipitation dynamics, as evidenced by the elevated inter-annual variability and escalated annual incidence of extreme rainfall events. Despite considerable research on vegetation response to intricate precipitation patterns at the community level, the physiological adaptations of individual plants within these assemblages are not well defined. This investigation employed simulations of diverse precipitation scenarios, utilising varying precipitation amounts (to simulate inter-annual variability) and intervals (to simulate intra-annual variability). A field-manipulated experiment was conducted to assess the responses of the leaf and stem hydraulic functional traits of Artemisia ordosica under different precipitation regimes. The results demonstrated that 1) the magnitude of inter-annual precipitation, rather than the intra-annual redistribution of precipitation, dominated the variability in the functional traits of A. ordosica, with diminished inter-annual precipitation inducing an array of functional trait alterations (e.g., specific leaf area, stomatal conductance, water use efficiency, and conduit diameter) to enhance water-use safety. Reallocating precipitation to low-frequency but high-intensity events during years with less inter-annual precipitation was more advantageous for the survival of A. ordosica. 2) A reduction in annual precipitation fostered a correlation between stem and leaf functional traits in A. ordosica (e.g., hydraulic conductance with photosynthetic rate, stomatal conductance, conduit diameter with transpiration rate, and water use efficiency), suggesting that under decreased precipitation, A. ordosica strengthens the coupling between hydraulics and photosynthesis to prevent hydraulic failure, demonstrating a safer survival strategy. Overall, the impact of global changes in precipitation patterns on the individual survival of A. ordosica primarily depended on the variation in inter-annual precipitation rather than the within-year redistribution. This study enhanced our understanding of the adaptability of dominant shrub species within desert shrub communities to altered precipitation patterns under climate change.

Leaf morpho-anatomical adjustments in a Quercus pubescens forest after 10 years of partial rain exclusion in the field.

In the Mediterranean region, a reduction of annual precipitation and a longer and drier summer season are expected with climate change by the end of the century, eventually endangering forest survival. To cope with such rapid changes, trees may modulate their morpho-anatomical and physiological traits. In the present study, we focused on the variation in leaf gas exchange and different leaf morpho-anatomical functional traits of Quercus pubescens Willd. in summer using a long-term drought experiment in natura consisting of a dynamic rainfall exclusion system where trees have been submitted to amplified drought (AD) (~-30% of annual precipitation) since April 2012 and compared them with trees under natural drought (ND) in a Mediterranean forest. During the study, we analyzed net CO2 assimilation (An), stomatal conductance (gs), transpiration (E), water-use efficiency (WUE), stomatal size and density, density of glandular trichomes and non-glandular trichomes, thickness of the different leaf tissues, specific leaf area and leaf surface. Under AD, tree functioning was slightly impacted, since only An exhibited a 49% drop, while gs, E and WUE remained stable. The decrease in An under AD was regulated by concomitant lower stomatal density and reduced leaf thickness. Trees under AD also featured leaves with a higher non-glandular trichome density and a lower glandular trichome density compared with ND, which simultaneously limits transpiration and production costs. This study points out that Q. pubescens exhibits adjustments of leaf morpho-anatomical traits which can help trees to acclimate to AD scenarios as those expected in the future in the Mediterranean region.

EVALUATION OF THE HYDROLOGICAL RESPONSE TO CLIMATE AND LAND USE CHANGE IN A WATERSHED

Climate change and land-use change influence hydrological processes in a basin, thereby affecting water production. The Cañar River basin originates in the Andean moors and flows into the Pacific Ocean, covering areas of great importance for conservation and agriculture. The basin exhibits a high degree of climatic and ecosystem variability. Two scenarios were proposed and studied using a semi-distributed hydrological model: a) a future climate scenario based on the projection of historical precipitation and temperature trends observed from 1985 to 2010 at 9 stations distributed throughout the basin, and b) a future soil use scenario derived from a multi-temporal analysis of land use, explanatory variables, and transition models. The analysis revealed an increase in precipitation during the rainy season and a decrease in precipitation during the dry season, resulting in a slight reduction in annual precipitation. During the study period, an increase in temperatures is observed in the low and high zones, while in the middle zone, there is a slight reduction in temperatures. The most significant land use changes were observed in natural vegetation, which experienced a significant reduction in area. If the observed climatic trends persist, precipitation would be expected to be concentrated mainly in the rainy season, leading to increased water availability during that period and a significant decrease during the dry season.

Climate change effects on bread wheat phenology and grain quality: A case study in the north of Italy.

Increasing temperatures, heat waves, and reduction of annual precipitation are all the expressions of climate change (CC), strongly affecting bread wheat (Triticum aestivum L.) grain yield in Southern Europe. Being temperature the major driving force of plants’ phenological development, these variations also have effects on wheat phenology, with possible consequences on grain quality, and gluten protein accumulation. Here, through a case study in the Bolognese Plain (North of Italy), we assessed the effects of CC in the area, the impacts on bread wheat phenological development, and the consequences on grain gluten quality. The increasing trend in mean annual air temperature in the area since 1952 was significant, with a breakpoint identified in 1989, rising from 12.7 to 14.1°C, accompanied by the signals of increasing aridity, i.e., increase in water table depth. Bread wheat phenological development was compared in two 15-year periods before and after the breakpoint, i.e., 1952–1966 (past period), and 2006–2020 (present period), the latest characterized by aridity and increased temperatures. A significant shortening of the chronological time necessary to reach the main phenological phases was observed for the present period compared to the past period, finally shortening the whole life cycle. This reduction, as well as the higher temperature regime, affected gluten accumulation during the grain-filling process, as emerged analyzing gluten composition in grain samples of the same variety harvested in the area both before and after the breakpoint in temperature. In particular, the proportion of gluten polymers (i.e., gliadins, high and low molecular weight glutenins, and their ratio) showed a strong and significant correlation with cumulative growing degree days (CGDDs) accumulated during the grain filling. Higher CGDD values during the period, typical of CC in Southern Europe, accounting for higher temperature and faster grain filling, correlated with gliadins, high molecular weight glutenins, and their proportion with low molecular weight glutenins. In summary, herein reported, data might contribute to assessing the effects of CC on wheat phenology and quality, representing a tool for both predictive purposes and decision supporting systems for farmers, as well as can guide future breeding choices for varietal innovation.

Understanding model diversity in future precipitation projections for South America

Precipitation patterns are expected to change in the future climate, affecting humans through a number of factors. Global climate models (GCM) are our best tools for projecting large-scale changes in climate, but they cannot make reliable projections locally. To abate this problem, we have downscaled three GCMs with the Weather Research and Forecasting (WRF) model to 50 km horizontal resolution over South America, and 10 km resolution for central Chile, Peru and southern Brazil. Historical simulations for years 1996–2005 generally compare well to precipitation observations and reanalyses. Future simulations for central Chile show reductions in annual precipitation and increases in the number of dry days at the end-of-the-century for a high greenhouse gas emission scenario, regardless of resolution and GCM boundary conditions used. However, future projections for Peru and southern Brazil are more uncertain, and simulations show that increasing the model resolution can switch the sign of precipitation projections. Differences in future precipitation changes between global/regional and high resolution (10 km) are only mildly influenced by the orography resolution, but linked to the convection parameterization, reflected in very different changes in dry static energy flux divergence, vertical velocity and boundary layer height. Our findings imply that using results directly from GCMs, and even from coarse-resolution (50 km) regional models, may give incorrect conclusions about regional-scale precipitation projections. While climate modelling at convection-permitting scales is computationally costly, we show that coarse-resolution regional simulations using a scale-aware convection parameterization, instead of a more conventional scheme, better mirror fine-resolution precipitation projections.

Appraising climate change impacts on future water resources and agricultural productivity in agro-urban river basins

Climate change can have an adverse effect on agricultural productivity and water availability in semi-arid regions, as changes in surface water availability lead to groundwater depletion and resultant losses in crop yield. These inter-relationships necessitate an integrated management approach for surface water, groundwater, and crop yield as a holistic system. This study quantifies the future availability of surface water and groundwater and associated crop production in a large semi-arid agro-urban river basin in which agricultural irrigation is a leader consumer of water. The region of study is the South Platte River Basin (72,000 km2), Colorado, USA. The coupled SWAT-MODFLOW modeling code is used as the hydrologic simulator and forced with five different CMIP5 climate models downscaled by Multivariate Adaptive Constructed Analogs (MACA), each for two climate scenarios, RCP4.5, and RCP8.5, for 1980–2100. The hydrologic model accounts for surface runoff, soil lateral flow, groundwater flow, groundwater-surface water interactions, irrigation from surface water and groundwater, and crop yield on a per-field basis. In all climate models and emission scenarios, an increase of 3 to 5 °C in annual average temperature is projected. Whereas, variation in the projected precipitation depends on topography and distances from mountains. Based on the results of this study, the worst-case climate model in the basin is IPSL-CM5A-MR-8.5. Under this climate scenario, for a 1 °C increase in temperature and the 1.3% reduction in annual precipitation, the basin will experience an 8.5% decrease in stream discharge, 2–5% decline in groundwater storage, and 11% reduction in crop yield. These results indicate the significant effect of climate change on water and food resources of a large river basin, pointing to the need for immediate implementation of conservation practices.

Safety margins and adaptive capacity of vegetation to climate change

Vegetation is composed of many individual species whose climatic tolerances can be integrated into spatial analyses of climate change risk. Here, we quantify climate change risk to vegetation at a continental scale by calculating the safety margins for warming and drying (i.e., tolerance to projected change in temperature and precipitation respectively) across plants sharing 100 km × 100 km grid cells (locations). These safety margins measure how much warmer, or drier, a location could become before its ‘typical’ species exceeds its observed climatic limit. We also analyse the potential adaptive capacity of vegetation to temperature and precipitation change (i.e., likelihood of in situ persistence) using median precipitation and temperature breadth across all species in each location. 47% of vegetation across Australia is potentially at risk from increases in mean annual temperature (MAT) by 2070, with tropical regions most vulnerable. Vegetation at high risk from climate change often also exhibited low adaptive capacity. By contrast, 2% of the continent is at risk from reductions in annual precipitation by 2070. Risk from precipitation change was isolated to the southwest of Western Australia where both the safety margin for drier conditions in the typical species is low, and substantial reductions in MAP are projected.

Speleothem δ13C record suggests enhanced spring/summer drought in south-eastern Spain between 9.7 and 7.8 ka – A circum-Western Mediterranean anomaly?

South-eastern Spain is one of the driest regions in Europe and thus, prone to drought. Terrestrial climate records covering the late Glacial and Holocene from this area are sparse. Here, we present a flowstone record from Cueva Victoria, south-eastern Spain, which covers the late Glacial (15 ka) to the mid-Holocene (7 ka) including the Younger Dryas (YD). Between the onset of the Bølling/Allerød (B/A) and the early Holocene, flowstone δ18O values progressively decrease in accordance with sea-surface temperatures in the Alboran Sea, indicating an increase in precipitation in south-eastern Spain and a supra-regional signal of North Atlantic temperature change. At the same time, decreasing δ13C values suggest progressively increasing precipitation and vegetation density. This trend is interrupted by both colder and drier conditions during the YD. Between 9.7 ± 0.3 and 7.8 ± 0.2 ka, a large positive excursion of the δ13C values indicates a strong reduction in vegetation density, probably as a consequence of very dry spring/summer conditions. In combination with the continuously low speleothem δ18O values and a nearly unchanged growth rate, this suggests increased seasonality (i.e. drier spring/summer conditions, but not a strong reduction in annual precipitation). This is consistent with several other climate records from the Western Mediterranean region, showing that the Western Mediterranean realm (Spain, Italy) experienced pronounced spring/summer drought during this time interval. Interestingly, the timing of this dry period coincided with the African Humid Period. This may be part of a teleconnection with the North African Monsoon via the Hadley cell circulation.

Extreme ENSO-driven torrential rainfalls at the southern edge of the Atacama Desert during the Late Holocene and their projection into the 21th century

Abstract Extreme precipitation events and multi-annual droughts, especially in arid to semi-arid subtropical regions, are among the most critical El Nino Southern Oscillation (ENSO) and global climate change impacts. Here, we assess the variability of torrential rainfall during the Late Holocene and its projection into the 21st century at the southern edge of the hyperarid Atacama Desert. The analysis of historical data since the beginning of the 20th century reveals that most (76.5%) alluvial disasters in the southern Atacama Desert (26–30°S) have resulted from extreme rainfall events occurring between March and September under El Nino conditions, and more frequently during the warm phase of the Pacific Decadal Oscillation. Particular rainfall events under these ocean-climate conditions are associated with the convective phase of the Madden-Julian Oscillation (MJO) near the central-equatorial Pacific, resulting in warmer sea surface temperature (SST) there and in the triggering of persistent/intense Pacific South America (PSA) tropical-extratropical teleconnection patterns which result in blocking of the westerly flow at high latitudes and the subsequent deviation of storm tracks towards central-northern Chile. On a longer timescale, marine sediments from Tongoy Bay (30°S) reveal an increasing trend of stronger runoff by torrential coastal rain since ca. 3500 cal yr BP and even stronger heavy rainfall since ca. 1700 cal yr BP. Highly variable coastal sea surface temperatures in the same time span deduced from the sedimentary record can be explained by intensified southerly winds in connection with stronger alongshore pressure gradients and reduced coastal low-cloud cover. Both storm intensification and increased intensity of upwelling-favorable winds point to a variable climate conditioned by strengthened interannual ENSO and interdecadal ENSO-like variability during the Late Holocene. Climate projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5) indicate a reduction in annual precipitation of 15–30% during the current century, together with an intensification of the storms, such as the alluvial disaster on March 25, 2015 in Atacama.

Climate change and its impact on Forest Fire in the state of Himachal Pradesh and Uttarakhand states of India: Remote Sensing and GIS Analysis

Abstract We have examined the climate and forest fire data using Remote Sensing and GIS in the state of Himachal Pradesh and Uttarakhand states of India. The significant high forest fire events were observed in district of Pauri Garhwal (22.4%) followed by Naini Tal (16.4%), Tehri Garhwal (8.5%), Almora (7.7%), Chamoli (5.8%), Dehra Dun (4.6%), Uttarkashi (4.3%), Champawat (4.2%), Haridwar (3.6%), Una (3.4%), Bageshwar (3.1%), Udham Singh Nagar (2.9%), Sirmaur (2.7%), Solan (2.3%), Kangra (2.1%), Pithoragarh (1.7%) and Shimla (1.2%). The LULC forest category “Deciduous Broadleaf Forest” occupied 17.2% of total forest area and retain significantly high forest fire percent equivalent to 44.7% of total forest fire events. The study revealed that 79% of forest fire incidence was found in the month of April and May. The fire frequency was found highest in the month of April (among all months) whereas it was spread over the five grids (in the count) where the fire frequencies were greater than 100. The average monthly analysis (from January to June) for maximum temperature (°C), precipitation (mm), solar radiation (MJ/m^2), wind velocity (meter/sec.), wet-days frequency (number of days) and evapotranspiration (mm/day) were found to be in the range of (9.90 to 26.44), (26.06 to 134.71), (11738 to 24119), (1.397 to 2.237), (1.46 to 5.12) and (3.96 to 8.46) respectively. Rapid climate/weather severities which significantly enhance the forest fire events were observed in the month of April and May. The analysis of the Pearson Correlation Coefficient (PCC) values of climate parameters showed a significant correlation with forest fire events. The analysis of predicted (2050) climate anomalies data (RCP-6) for the month of April and annual precipitation manifest the significant rise in April temperature and reduction in annual precipitation observed over large part of high forest fire grids will certainly impact adversely to the future forest fire scenario.

Assessing the effectiveness of Sustainable Land Management for large-scale climate change adaptation

Climate change will strongly affect essential ecosystem services, like the provision of freshwater, food production, soil erosion and flood control. Sustainable Land Management (SLM) practices are increasingly promoted to contribute to climate change mitigation and adaptation, but there is lack of evidence at scales most relevant for policymaking. We evaluated the effectiveness of SLM in a large Mediterranean catchment where climate change is projected to significantly reduce water security. We show that the on-site and off-site impacts of climate change are almost entirely reversed by the large-scale implementation of SLM under moderate climate change conditions, characterized by limited reductions in annual precipitation but significant increased precipitation intensity. Under more extreme reductions of annual precipitation, SLM implementation reduces the impacts on water security, but cannot prevent significant increased plant water stress and reduced water availability. Under these conditions, additional adaptation measures are required considering their interactions and trade-offs regarding water security.

Experimental throughfall reduction barely affects soil carbon dynamics in a warm-temperate oak forest, central China

Changing precipitation patterns could affect soil carbon (C) cycling in China’s forests. A throughfall reduction (TFR) experiment was conducted in a warm-temperate oak forest in central China to examine effects of reduced precipitation on total soil respiration (SR), heterotrophic soil respiration (HR), autotrophic soil respiration (AR), soil microbial biomass, and fine root biomass from 2013 to 2016. Rain-out shelters, excluding ~50% of throughfall, were applied between May and September, thereby simulating a ~30% reduction in annual precipitation. Although soil moisture was significantly reduced during TFR, microbial biomass and HR remained unaffected. SR, AR, as well as fine root biomass increased during TFR in a comparable dry year, but remained unaffected during all other years. Annual rates of SR, HR, and AR were all unaffected by TFR. Our results indicate that a mild, steady, reduction in growing season precipitation does not affect soil organic matter decomposition in the oak forest ecosystem studied. Low SR rates during a natural dry-spell indicate that SR can be significantly decreased under more severe drought than imposed by the TFR treatment. Our data suggest a low soil moisture threshold of about 10 vol% for SR in the studied soil.

Haihe River discharge to Bohai Bay, North China: trends, climate, and human activities

Trends in annual precipitation and river discharge (1956–2012) were analyzed using the Mann–Kendall test and Sen's method to evaluate the impact of climate variation and human activities on the Haihe River discharge to Bohai Bay. Compared to observations before 1965, two obvious decreases in annual river discharge occurred after 1965 and after 1980. Considering 1956–1965 as the baseline period, it was established that the reduction in Haihe River discharge to the Bohai Sea was 52.9% and 81.9% during 1966–1980 and 1981–2012, respectively. Compared to the baseline period, the reductions in annual precipitation in 1966–1980 and 1981–2012 were 7.1% and 14.2%, respectively. Following the increase in population, industrial activity, and irrigated areas, water consumption has increased rapidly, from 51.9 mm in 1965 to 124.8 mm in 1980 and 126.4 mm in 2000. These results indicate that the reduction in discharge in the Haihe River basin during 1966–1980 and 1981–2000 could be attributed to climatic variations (33.2% and 41.4%, respectively) and human activities (66.8% and 58.6%, respectively). The results also indicate that salinity in Bohai Bay increased following the decrease in discharge from the Haihe River.

Landscape and Climate Dynamics of the Upper Don River Basin in the Mid- and Late Holocene

The paper presents the new multy-proxy data from the Bolsheberezovskoye mire, the key-section for forest-steppe region in the Upper Don River basin (central part of European Russia), notably, the Kulikovo Battle-fi eld area. According to obtained results the studied area was covered by steppe (middle Atlantic, early Subatlantic) and forest-steppe vegetation (Subboreal, middle and late Subatlantic). Climatic reconstructions have shown that landscape dynamics of the region in the second half of the Holocene were determined by changes in effective moisture. Even small reductions in annual precipitation, accompanied by the rise of summer temperature by 1–3 °С comparing to their present values, were suffi cient to cause a shift from the forest-steppe to typical steppe communities and, probably, higher frequencies of fi res.

Amino acid and N mineralization dynamics in heathland soil after long-term warming and repetitive drought

Abstract. Monomeric organic nitrogen (N) compounds such as free amino acids (FAAs) are an important resource for both plants and soil microorganisms and a source of ammonium (NH4+) via microbial FAA mineralization. We compared gross FAA dynamics with gross N mineralization in a Dutch heathland soil using a 15N tracing technique. A special focus was made on the effects of climate change factors warming and drought, followed by rewetting. Our aims were to (1) compare FAA mineralization (NH4+ production from FAAs) with gross N mineralization, (2) assess gross FAA production rate (depolymerization) and turnover time relative to gross N mineralization rate, and (3) assess the effects of a 14 years of warming and drought treatment on these rates. The turnover of FAA in the soil was ca. 3 h, which is almost 2 orders of magnitude faster than that of NH4+ (i.e. ca. 4 days). This suggests that FAA is an extensively used resource by soil microorganisms. In control soil (i.e. no climatic treatment), the gross N mineralization rate (10 ± 2.9 μg N g−1 day−1) was 8 times smaller than the total gross FAA production rate of five AAs (alanine, valine, leucine, isoleucine, proline: 127.4 to 25.0 μg N g−1 day−1). Gross FAA mineralization (3.4 ± 0.2 μg N g−1 day−1) contributed 34% to the gross N mineralization rate and is therefore an important component of N mineralization. In the drought treatment, a 6–29% reduction in annual precipitation caused a decrease of gross FAA production by 65% and of gross FAA mineralization by 41% compared to control. On the other hand, gross N mineralization was unaffected by drought, indicating an increased mineralization of other soil organic nitrogen (SON) components. A 0.5–1.5 °C warming did not significantly affect N transformations, even though gross FAA production declined. Overall our results suggest that in heathland soil exposed to droughts a different type of SON pool is mineralized. Furthermore, compared to agricultural soils, FAA mineralization was relatively less important in the investigated heathland. This indicates more complex mineralization dynamics in semi-natural ecosystems.

Impacts of uplift of northern Tibetan Plateau and formation of Asian inland deserts on regional climate and environment

Based on the geological evidence that the northern Tibetan Plateau (NTP) had an uplift of a finite magnitude since the Miocene and the major Asian inland deserts formed in the early Pliocene, a regional climate model (RegCM4.1) with a horizontal resolution of 50 km was used to explore the effects of the NTP uplift and the related aridification of inland Asia on regional climate. We designed three numerical experiments including the control experiment representing the present-day condition, the high-mountain experiment representing the early Pliocene condition with uplifted NTP but absence of the Asian inland deserts, and the low-mountain experiment representing the mid-Miocene condition with reduced topography in the NTP (by as much as 2400 m) and also absence of the deserts. Our simulation results indicated that the NTP uplift caused significant reductions in annual precipitation in a broad region of inland Asia north of the Tibetan Plateau (TP) mainly due to the enhanced rain shadow effect of the mountains and changes in the regional circulations. However, four mountainous regions located in the uplift showed significant increases in precipitation, stretching from the Pamir Plateau in the west to the Qilian Mountains in the east. These mountainous areas also experienced different changes in the rainfall seasonality with the greatest increases occurring during the respective rainy seasons, predominantly resulted from the enhanced orographically forced upwind ascents. The appearance of the major deserts in the inland Asia further reduced precipitation in the region and led to increased dust emission and deposition fluxes, while the spatial patterns of dust deposition were also changed, not only in the regions of uplift-impacted topography, but also in the downwind regions. One major contribution from this study is the comparison of the simulation results with 11 existing geological records representing the moisture conditions from Miocene to Pliocene. The comparisons revealed good matches between the simulation results and the published geological records. Therefore, we conclude that the NTP uplift and the related formation of the major deserts played a controlling role in the evolution of regional climatic conditions in a broad region in inland Asia since the Miocene.

Water Resources Impact Assessment Under Climate Change Scenarios in Mediterranean Watersheds

Climate models project a reduction in annual precipitation and an increase in temperature, which may lead to runoff shortages and a consequent water availability reduction, in some Mediterranean regions, such as southern Portugal. The impacts on water availability under different climate change scenarios are assessed using SHETRAN, a physically-based and spatially-distributed hydrological model. SHETRAN is calibrated and validated against daily runoff measurements at outlet and internal sections and against phreatic surfaces using a multi-basin, multi-location and multi-response approach. Nash-Sutcliff efficiency, volume deviation and coefficient of determination ranged, respectively, from 0.58 to 0.76, 0.59 to 0.79 and −9 to 15 %, in the calibration period, and from 0.54 to 0.75, 0.54 to 0.77 and −14 to 12 %, in the validation period. Three GCM and two RCM are used for control (1961–1990) and scenario (2071–2100) periods, under the A2 SRES emission scenario. Observed bias in the climate models’ projected precipitation and temperature are corrected with three bias correction methods. For the scenario period the climate models project a change in precipitation from +1.5 to −65 % and an increase in temperature from +2.7 to +5.9 °C. This trend in climate change projection is reflected in the annual runoff that decreases drastically, between 13 and 90 %, in southern Portugal by the end of the century. The runoff reduction is greater in all watersheds in Autumn and Spring with higher agreement between models and bias correction methods. The runoff decrease seems greater in the Guadiana river basin which is already under significant water stress.

Water scarcity impact of climate change in semi-arid regions: a case study in Mujib basin, Jordan

Jordan is confronting a severe water scarcity because of its reliance on a highly fluctuating annual precipitation. The impact of climate change on freshwater resources is of primary concern as it may elevate water shortage problem. Therefore, climate change has to be adequately addressed in order to attain proper management and sustainable use of available water resources. In this paper, incremental scenarios of climate change have been deployed to assess foreseen impacts of climate change on water resources in Mujib, a groundwater basin in central Jordan by the aid of Soil and Water Assessment Tool hydrological model. Ten incremental scenarios representing dry, normal, and wet events are tried. Findings indicate that dry scenarios lead to about 20 to 50 % reduction in annual precipitation and surface runoff. However, wet scenarios estimate annual precipitation and surface runoff to increase up to fourfold the baseline values.

Spatial and Temporal Variation of Annual Precipitation in a River of the Loess Plateau in China

Empirical orthogonal function (EOF) decomposition and geostatistical (semivariogram) analysis are used to analyze the spatial and temporal patterns of annual precipitation in the Weihe basin based on the data from 1960 to 2011 at 30 national meteorological stations within and surrounding the Weihe basin area of the Loess Plateau in China. Then the Mann-Kendall method is used to discriminate the variation points of precipitation series at each station. The results show that, during the study period, there was an overall reduction in annual precipitation across the basin and there were two spatial patterns: increase in the northwest, decrease in southeast and increase in the west, decrease in east. Variation points in the annual precipitation series at each meteorological station in the basin were detected, and they occur earliest in the southeast and downstream, then progressively later in the northwest and upstream areas. These variations were most frequent during the 1970s and 1980s. The findings have significant implications for the variations research of runoff in the basin and formulate robust strategies to adapt to climate change and mitigate its effects.

Impact of climate change on the hydrogeology of two basins in northern France

This study presents an analysis of climate-change impacts on the water resources of two basins located in northern France, by integrating four sources of uncertainty: climate modelling, hydrological modelling, downscaling methods, and emission scenarios. The analysis focused on the evolution of the water budget, the river discharges and piezometric heads. Seven hydrological models were used, from lumped rainfall-discharge to distributed hydrogeological models, and led to quite different estimates of the water-balance components. One of the hydrological models, CLSM, was found to be unable to simulate the increased water stress and was, thus, considered as an outlier even though it gave fair results for the present day compared to observations. Although there were large differences in the results between the models, there was a marked tendency towards a decrease of the water resource in the rivers and aquifers (on average in 2050 about −14 % and −2.5 m, respectively), associated with global warming and a reduction in annual precipitation (on average in 2050 +2.1 K and −3 %, respectively). The uncertainty associated to climate models was shown to clearly dominate, while the three others were about the same order of magnitude and 3–4 times lower. In terms of impact, the results found in this work are rather different from those obtained in a previous study, even though two of the hydrological models and one of the climate models were used in both studies. This emphasizes the need for a survey of the climatic-change impact on the water resource.