Annual Water Deficit Research Articles

Comparison of the water budget for the typical cropland and pear orchard ecosystems in the North China Plain

The North China Plain (NCP) has a severe water shortage. About 70% groundwater has been exploited for irrigation. Winter wheat – summer maize and pears are typical representative cereal crops and commercial fruit trees in this area, respectively. Water budget for the typical cropland and orchard ecosystems has a significant importance for agricultural production, especially in the NCP. Therefore, evapotranspiration (ET) and water balance were studied in the annual winter wheat – summer maize rotation (cropland) and pear orchard. Latent and sensible heat fluxes were measured by eddy covariance. Annual ET for pear trees was 764 mm and for both crops was 690 mm. The difference of ET between these two ecosystems was about equal to one irrigation. Transpiration was the main loss with the mean proportion of 63% for crops and 76% for pear trees. Wheat growth period is in the dry season and requires much more irrigation than maize. Mainly transpiration (80%) occurred from April through September in the both ecosystems which was also the growing period for pear trees. The annual precipitation was 469 mm and 444 mm in the pear orchard and cropland, respectively, although 80% of it occurred from June to September. Compared with the precipitation, annual mean water deficit was 294 mm for the pear trees and 244 mm for crops. The water shortage was severe in May while surplus water presented in July and August. Energy and ET fluxes were determined by atmospheric demand and the response of plants as controlled by plant phenology and crop selection. As the water shortage situation becomes more serious in the NCP, sustainability of the agricultural ecosystems could be improved by changing crop planting patterns, specifically, increasing the area ratio of maize to pear trees.

Agroclimatic zoning for coffee crop in Angola

ABSTRACT The Angolan Government intends to recover its 1970s expressive production of coffee by means of agricultural financing programs, mainly directed to family farmers. This study aimed to perform the agroclimatic zoning for the coffee crop in the Angolan territory. Data or estimates of annual temperature, effective and total rainfall rates, climatic water balance and annual water deficit were evaluated for all the 163 Angolan municipalities. The effective and total precipitation data were used for the agroclimatic zoning of the coffee crop in the country. Based on the effective precipitation data, 1 %, 20 % and 79 % of the Angolan territory were respectively considered suitable, marginal and unsuitable for the Arabica coffee, while, for the Robusta coffee, the same rates were, respectively, 1 %, 8 % and 91 %. Based on the total precipitation data, these rates were 2 %, 27.5 % and 70.5 % for the Arabica coffee and 1 %, 11.8 % and 87.2 % for the Robusta coffee. The areas considered marginal and unsuitable for the coffee crop in Angola are related to water deficit conditions, mainly in the southwestern region and along the coastal strip. The results obtained from the climatic water balance show that most part of the Angolan territory is marginal or unsuitable for the coffee crop.

Rain Water Deficit and Irrigation Demand of Major Row Crops in the Mississippi Delta

Abstract. The Mississippi Delta is an important agricultural area, producing 67% of the soybean, corn, and cotton grown in the state of Mississippi. Because irrigation can stabilize and increase crop yields and economic returns, approximately 80% of the water withdrawn from the alluvial aquifer is used for irrigation. This region is experiencing severe declines in groundwater level, which threaten the sustainability of irrigated agriculture. Therefore, better irrigation management practices must be developed, but there is lack of knowledge regarding crop water requirements, rain water deficits, and irrigation demand to improve rain and irrigation water use efficiencies of these crops. The objective of this study was to determine the crop water requirements, rain water deficits, and irrigation demand of the three crops using the RZWQM2 model based on a 100-year representative weather data series from the Stoneville weather station for improving irrigation management in the Mississippi Delta. The analysis indicated that mean monthly precipitation in the crop non-growing season from November to the following April was 127 mm, while only 82 mm on average was received during the crop growing season. Soybean, corn, and cotton are typically planted in early May, late March, and late May and harvested in mid-September, late August, and late October, respectively. Rainfall during the growing seasons for soybean, corn, and cotton was 400, 510, and 435 mm and accounted for 31%, 40%, and 34% of annual rainfall, respectively, over the 100-year period. Early seeding can allow crops to receive more early season rainfall and reduce the number of days of water stress during the growing season. Average crop evapotranspiration of soybean, corn, and cotton was 546, 588, and 552 mm, respectively. Rainfall was found to be insufficient to meet the crop water requirements beginning in the 5th, 7th, and 6th weeks after planting. Weekly effective rain water deficits greater than 20 mm were found in weeks 7 through 16 (22 to 29 mm) for soybean, in weeks 11 through 20 (20 to 26 mm) for corn, and in weeks 11 through 16 (20 to 30 mm) for cotton. The RZWQM2 model estimated a range of annual effective rain water deficits in soybean of 0 to 622 mm, with an average deficit of 340 mm. Deficits in corn ranged from 32 to 685 mm, with an average deficit of 355 mm, while deficits in cotton ranged from 169 to 650 mm, with an average deficit of 395 mm. Results obtained from the 100-year historical weather data can be applied to improve irrigation scheduling, water resources planning, and design of irrigation and cropping systems in the Mississippi Delta. Keywords: Corn, Cotton, Crop water requirement, Irrigation demand, Mississippi Delta, Rain water deficit, Soil water balance, Soybean.

Water scarcity in Beijing and countermeasures to solve the problem at river basins scale

Beijing has been subject to water scarcity in recent decades. Over-exploitation of water resources reduced water availability, and water-saving measures were not enough to mitigate the water scarcity. To address this problem, water transfer projects across river basins are being built. This paper assessed water scarcity in Beijing and the feasibility of solving the problem at river basins scale. The results indicate that there was an average annual water deficit of 13×108 m3 y-1 in Beijing, which totaled 208.9 ×108 m3 for 1998–2014, despite the adoption of various measures to alleviate water scarcity. Three of the adjacent four sub-river basins suffered a serious water deficit from 1998–2014. It was therefore impossible to transfer enough water from the adjacent river basins to mitigate the water scarcity in Beijing. However, the annual water deficit will be eliminated after the comprehensive operation of the world’s largest water transfer project (the South-to-North Water Transfer Project, SNWTP) in 2020, but it will take approximately 200 years before Beijing’s water resources are restored to the 1998 levels.

Evaluation of the CropSyst Model during Wheat-Maize Rotations on the North China Plain for Identifying Soil Evaporation Losses.

The North China Plain (NCP) is a major grain production zone that plays a critical role in ensuring China's food supply. Irrigation is commonly used during grain production; however, the high annual water deficit [precipitation (P) minus evapotranspiration (ET)] in typical irrigated cropland does not support double cropping systems (such as maize and wheat) and this has resulted in the steep decline in the water table (~0.8 m year−1 at the Luancheng station) that has taken place since the 1970s. The current study aimed to adapt and check the ability of the CropSyst model (Suite-4) to simulate actual evapotranspiration (ETa), biomass, and grain yield, and to identify major evaporation (E) losses from winter wheat (WW) and summer maize (SM) rotations. Field experiments were conducted at the Luancheng Agro-ecosystem station, NCP, in 2010–2011 to 2012–2013. The CropSyst model was calibrated on wheat/maize (from weekly leaf area/biomass data available for 2012–2013) and validated onto measured ETa, biomass, and grain yield at the experimental station from 2010–2011 to 2011–2012, by using model calibration parameters. The revalidation was performed with the ETa, biomass, grain yield, and simulated ETa partition for 2008–2009 WW [ETa partition was measured by the Micro-lysimeter (MLM) and isotopes approach available for this year]. For the WW crop, E was 30% of total ETa; but from 2010–11 to 2013, the annual average E was ~40% of ETa for the WW and SM rotation. Furthermore, the WW and SM rotation from 2010–2011 to 2012–2013 was divided into three growth periods; (i) pre-sowing irrigation (PSI; sowing at field capacity) to emergence period (EP), (ii) EP to canopy cover period (CC) and (iii) CC to harvesting period (HP), and E from each growth period was ~10, 60, and 30%, respectively. In general, error statistics such as RMSE, Willmott's d, and NRMSE in the model evaluation for wheat ETa (maize ETa) were 38.3 mm, 0.81, and 9.24% (31.74 mm, 0.73, and 11.89%); for wheat biomass (maize biomass) they were 1.25 Mg ha−1, 0.83, and 9.64% (0.78 Mg ha−1, 0.96, and 7.96%); and for wheat grain yield (maize grain yield) they were 0.65 Mg ha−1, 0.82, and 9.87% (0.2 Mg ha−1, 0.99, and 3.79%). The results showed that CropSyst is a valid model that can be use with a reliable degree of accuracy for optimizing WW and SM grain yield production and water requirement on the NCP.

Assessing anthropogenic impacts on limited water resources under semi-arid conditions: three-dimensional transient regional modelling in Jordan

Both increasing aridity and population growth strongly stress freshwater resources in semi-arid areas such as Jordan. The country’s second largest governorate, Irbid, with over 1 million inhabitants, is already suffering from an annual water deficit of 25 million cubic meters (MCM). The population is expected to double within the next 20 years. Even without the large number of refugees from Syria, the deficit will likely increase to more then 50 MCM per year by 2035 The Governorate’s exclusive resource is groundwater, abstracted by the extensive Al Arab and Kufr Asad well fields. This study presents the first three-dimensional transient regional groundwater flow model of the entire Wadi al Arab to answer important questions regarding the dynamic quality and availability of water within the catchment. Emphasis is given to the calculation and validation of the dynamic groundwater recharge, derived from a multi-proxy approach, including (1) a hydrological model covering a 30-years dataset, (2) groundwater level measurements and (3) information about springs. The model enables evaluation of the impact of abstraction on the flow regime and the groundwater budget of the resource. Sensitivity analyses of controlling parameters indicate that intense abstraction in the southern part of the Wadi al Arab system can result in critical water-level drops of 10 m at a distance of 16 km from the production wells. Moreover, modelling results suggest that observed head fluctuations are strongly controlled by anthropogenic abstraction rather than variable recharge rates due to climate changes.

Impact of Climate and Bioclimate Factors on Apricot (Prunus armeniaca L.) Yield to Increase Economy and Achieve Maintaining Food Security of Palestine

Apricot (Prunus armeniaca L.) is one of the most important export crops in Hebron of Palestine. In this work, we analyzed the mean monthly temperature and precipitation using data from one weather station of the Palestine Meteoro-logical Department, recorded in the period from 1993-2014, with the same years of plant production (rain-fed) from the Palestinian Central Bureau of Statistics (PCBS). Statistical analysis included a bioclimatic analysis of Palestinian meteorological station for the period previous by using bioclimatic classification of the Earth of Rivas Martinez Salvador, with regard to simple continentality index, compensated thermicity index, annual ombrothermic index, water deficit and soil water reserve. In concluded, climate and bioclimatic factors play a key role in apricot production, when we analyzed of variance (ANOVA), with a standard coefficients (95% confidence interval), reveals significant differences, in case of the bioclimate factors as simple thermicity index and climate factors as precipitation, whereas there are no significant differences between the apricot yield and the reset of climate, bioclimate factors. However, the optimum of the plant production is achieved with values of simple thermicity index between (14-18), annual ombrothermic index (2.5-4.5), compensated thermicity index (250-450), precipitation more than 750 mm, mean monthly temperature (15.4℃ - 20℃), and inframediterranean, thermomediterranean and mesomediterranean of thermotype in Hebron of Palestine.

Long-term climate and competition explain forest mortality patterns under extreme drought.

Rising temperatures are amplifying drought-induced stress and mortality in forests globally. It remains uncertain, however, whether tree mortality across drought-stricken landscapes will be concentrated in particular climatic and competitive environments. We investigated the effects of long-term average climate [i.e. 35-year mean annual climatic water deficit (CWD)] and competition (i.e. tree basal area) on tree mortality patterns, using extensive aerial mortality surveys conducted throughout the forests of California during a 4-year statewide extreme drought lasting from 2012 to 2015. During this period, tree mortality increased by an order of magnitude, typically from tens to hundreds of dead trees per km2 , rising dramatically during the fourth year of drought. Mortality rates increased independently with average CWD and with basal area, and they increased disproportionately in areas that were both dry and dense. These results can assist forest managers and policy-makers in identifying the most drought-vulnerable forests across broad geographic areas.

Climatic Water Balance of Annapurna, Langtang and Khumbu regions of Nepal Himalaya

For the protection of the environment, climatic water balance studies play key role. This study attempts to assess the potential water availability at the Annapurna, Langtang and Khumbu regions of Nepal Himalaya. Potential evapotranspitration (PET) is calculated by CROPWAT 8 with the help of maximum and minimum temperature, relative humidity, wind speed and sunshine hour. The climatic water balance of water bodies is calculated on the basis of Thornthwait procedure. These calculations help to examine annual water surplus (WS) and water deficit (WD) periods. Potential water surplus at three selected station is calculated by above techniques after averaging the data of time period from 1987 to 2008. The main aim of this study is to compare the obtained result from the climatic water balance for the selected sites of the Nepal Himalaya region. This study will provide climatic water balance information of the given area which will be useful for sustainable management of water resources in local and small area of the Nepal Himalaya.Journal of Hydrology and Meteorology, Vol. 8(1) p.47-57

Climate, soil and land-use based land suitability evaluation for oil palm production in Ghana

Abstract In the past decade, oil palm (Elaeis guineensis Jacq.) has become the world’s most important oil crop. The large demand for palm oil has resulted in a rapid expansion of oil palm cultivation across the globe. Because of the dwindling availability of land in Southeast Asia, most expansion of the industry is expected in Central and South America and sub-Saharan Africa, where land with suitable agro-ecological conditions is available. Using Ghana as a case study, a method for evaluating areas that are both suitable and available for oil palm production is presented. Our assessment used spatial data and GIS techniques, and showed that areas with suitable climatic conditions (annual average water deficit

Erratum

Erratum

Climate predicts the proportion of divaricate plant species in New Zealand arborescent assemblages

AbstractAimPuzzling features of plants are sometimes explained as legacies of co‐evolution with extinct herbivores. One example is the convergent evolution of a small‐leaved, twiggy ‘divaricate’ form in > 50 woody species in New Zealand. This growth form was first interpreted as a response to the Plio‐Pleistocene onset of frosty, droughty environments, but opinion now favours the hypothesis that it arose as a defence against large herbivorous birds (moa). It has been argued that the extinction of moa during the last millennium has left divaricate plants at risk of being out‐competed by faster growing broadleaved competitors, yet their current abundance in some habitats suggests this growth form might confer other advantages besides protection against avian browsing. We aimed to clarify the adaptive significance of the divaricate growth form by identifying environmental correlates of its geographic distribution in New Zealand.LocationThe main islands of the New Zealand archipelago, spanning latitude c. 34.5–47° S.MethodsWe used generalized additive models to examine the environmental correlates of the proportion of local tree and shrub assemblages contributed by divaricate species, on 1152 0.04 ha plots distributed across a wide range of climate and landforms.ResultsA model with four climatic variables explained 37% of the observed variation. Mean minimum temperature of the coldest month was the single best predictor of the proportion of divaricate species in arborescent assemblages, with annual solar radiation, vapour pressure deficit and annual water deficit also contributing to the final model. Divaricates made their largest contributions to assemblages in the rain shadow of the Southern Alps, on sites with cold winters, low solar radiation and significant vapour pressure deficits, where potential evapotranspiration exceeds precipitation by > 130 mm. No physiographic variables (e.g. slope) contributed to the final model.Main conclusionsThe distribution of divaricate plants suggests they cope with frosty, droughty environments better than most other elements of New Zealand's arborescent flora. This may reflect selection for both (1) physiological resistance to frost and drought and (2) deterrence of herbivores, as climatic constraints on plant growth rates probably leave seedlings exposed for longer to ground‐dwelling browsers. However, the widespread persistence of divaricate plants during the c. 450‐year hiatus between the extinction of moa and the onset of widespread browsing by introduced ungulates suggests that even in the absence of large herbivores, divaricates are well adapted to frosty, droughty environments.

A Middle Pleistocene intense monsoonal episode from the Kapthurin Formation, Kenya: Stable isotopic evidence from bovid teeth and pedogenic carbonates

Carbon and oxygen isotope values of bovid tooth enamel and pedogenic carbonates were used to reconstruct the paleoenvironments associated with Middle Pleistocene archeological and paleontological sites from the Kapthurin Formation, Kenya. Fossil teeth and pedogenic carbonates were collected from lacustrine and fluvial facies (K3 and K3’) of the Kapthurin Formation (~543–509ka). Twenty teeth from six bovid tribes and twenty four pedogenic carbonates were sequentially sampled for stable oxygen and carbon analysis. The primary aims of this work are to reconstruct the vegetative habitats of bovids and environmental landscapes from the Kapthurin Formation, assessing the presence of C3, C4, or mixed vegetation and foragers. We also assess general paleoclimate factors, such as overall aridity, seasonal shifts in water availability, and broad habitat reconstructions. Carbon isotope values suggest a wide range of foraging strategies were available to bovids, and are characterized by both C3 dominated and C4 dominated diets, with little evidence for mixed feeders, while pedogenic carbonates suggest the landscape combined a mix of C3 and C4 vegetation sources, structurally similar to wooded grasslands. Paleoclimatic conditions, based on the reconstructed mean annual water deficit from δ18Oenamel values suggest a hyper mesic environment, most comparable to the modern Ituri rainforest, indicating a much wetter climate than the modern Lake Baringo Basin. This environment coincides with an intensified Middle Pleistocene African monsoonal system at the onset of Marine Isotope Stage 13 (~533ka). The Middle Pleistocene Lake Baringo regional habitat appears to have been one dominated by woodland areas, perennially active streams, marsh and sumpland environments, and a surrounding grassland ecosystem. This lush basin would have provided hominins with a diverse and productive ecosystem. Perhaps not surprisingly, archeological sites are found in all habitats, including wet, forested, and grassland environments.

Functionally relevant climate variables for arid lands: a climatic water deficit approach for modelling desert shrub distributions

AbstractAimWe have three goals. (1) To develop a suite of functionally relevant climate variables for modelling vegetation distribution on arid and semi‐arid landscapes of the Great Basin, USA. (2) To compare the predictive power of vegetation distribution models based on mechanistically proximate factors (water deficit variables) and factors that are more mechanistically removed from a plant's use of water (precipitation). (3) To quantify the climate gradients that control shrub distributions in a cold desert environment.LocationThe central basin and range ecoregion of the western USA (36–42°N).MethodsWe used a modified Thornthwaite method to derive monthly water balance variables and to depict them using a water balance climograph. Eighteen variables were calculated from the climograph, representing different components of the seasonal water balance. These were used in boosted regression tree models to derive distribution models for 18 desert shrub species. The water balance approach was compared with an approach that used bioclimatic variables derived from the PRISM (Parameter‐elevation Relationships on Independent Slopes Model) climate data.ResultsThe water balance and bioclimatic approaches yielded models with similar performance in predicting the geographical distribution of most shrub species. Cumulative annual climatic water deficit was consistently the most important water balance variable for predicting shrub type distributions, although predictions were improved by the inclusion of variables that describe the seasonal distribution of water balance such as water supply in the spring, fall actual evapotranspiration, monsoonality and summer decline in actual evapotranspiration.Main conclusionsThe water balance and bioclimatic approaches to species distribution modelling both yielded similar prediction accuracies. However, the water balance approach offers advantages over the bioclimatic approach because it is mechanistically derived to approximate physical processes important for plant growth.

Woodland recovery following drought-induced tree mortality across an environmental stress gradient.

Recent droughts and increasing temperatures have resulted in extensive tree mortality across the globe. Understanding the environmental controls on tree regeneration following these drought events will allow for better predictions of how these ecosystems may shift under a warmer, drier climate. Within the widely distributed piñon-juniper woodlands of the southwestern USA, a multiyear drought in 2002-2004 resulted in extensive adult piñon mortality and shifted adult woodland composition to a juniper-dominated, more savannah-type ecosystem. Here, we used pre- (1998-2001) and 10-year post- (2014) drought stand structure data of individually mapped trees at 42 sites to assess the effects of this drought on tree regeneration across a gradient of environmental stress. We found declines in piñon juvenile densities since the multiyear drought due to limited new recruitment and high (>50%) juvenile mortality. This is in contrast to juniper juvenile densities, which increased over this time period. Across the landscape, piñon recruitment was positively associated with live adult piñon densities and soil available water capacity, likely due to their respective effects on seed and water availability. Juvenile piñon survival was strongly facilitated by certain types of nurse trees and shrubs. These nurse plants also moderated the effects of environmental stress on piñon survival: Survival of interspace piñon juveniles was positively associated with soil available water capacity, whereas survival of nursed piñon juveniles was negatively associated with perennial grass cover. Thus, nurse plants had a greater facilitative effect on survival at sites with higher soil available water capacity and perennial grass cover. Notably, mean annual climatic water deficit and elevation were not associated with piñon recruitment or survival across the landscape. Our findings reveal a clear shift in successional trajectories toward a more juniper-dominated woodland and highlight the importance of incorporating biotic interactions and soil properties into species distribution modeling approaches.

Precipitation trends and variability from 1950 to 2000 in arid lands of Central Asia

Climate warming will cause differences in precipitation distribution and changes in hydrological cycle both at regional and global scales. Arid lands of Central Asia (ALCA), one of the largest arid regions at the middle latitudes in the world, is likely to be strongly influenced by climate warming. Understanding the precipitation variations in the past is an important prerequisite for predicting future precipitation trends and thus managing regional water resources in such an arid region. In this study, we used run theory, displacement, extreme deviation theory, precipitation concentration index (PCI), Mann-Kendall rank correlation and climatic trend coefficient methods to analyze the precipitation in wet and dry years, changes in precipitation over multiple-time scales, variability of precipitation and its rate of change based on the monthly precipitation data during 1950–2000 from 344 meteorological stations in the ALCA. The occurrence probability of a single year with abundant precipitation was higher than that of a single year with less precipitation. The average duration of extreme drought in the entire area was 5 years, with an average annual water deficit of 34.6 mm (accounting for 11.2% of the average annual precipitation over the duration). The occurrence probability of a single wet year was slightly higher than that of a single dry year. The occurrence probability of more than 5 consecutive wet years was 5.8%, while the occurrence probability of more than 5 consecutive dry years was 6.2%. In the center of the study area, the distribution of precipitation was stable at an intra-annual timescale, with small changes at an inter-annual timescale. In the western part of the study area, the monthly variation of precipitation was high at an inter-annual timescale. There were clear seasonal changes in precipitation (PCI=12–36) in the ALCA. Precipitation in spring and winter accounted for 37.7% and 24.4% of the annual precipitation, respectively. There was a significant inter-annual change in precipitation in the arid Northwest China (PCI=24–34). Annual precipitation increased significantly (P=0.05) in 17.4% of all the meteorological stations over the study period. The probability of an increase in annual precipitation was 75.6%, with this increase being significant (P=0.05) at 34.0% of all the meteorological stations. The average increasing rate in annual precipitation was 3.9 mm/10a (P=0.01) in the ALCA. There were significant increasing trends (P=0.01) in precipitation in Kazakhstan, Kyrgyzstan and Tajikistan, with rates of 2.6, 3.1 and 3.7 mm/10a, respectively.

How drought severity constrains gross primary production(GPP) and its partitioning among carbon pools in a <i>Quercus ilex</i> coppice?

Abstract. The partitioning of photosynthates toward biomass compartments plays a crucial role in the carbon (C) sink function of forests. Few studies have examined how carbon is allocated toward plant compartments in drought-prone forests. We analyzed the fate of gross primary production (GPP) in relation to yearly water deficit in an old evergreen Mediterranean Quercus ilex coppice severely affected by water limitations. Carbon fluxes between the ecosystem and the atmosphere were measured with an eddy covariance flux tower running continuously since 2001. Discrete measurements of litterfall, stem growth and fAPAR allowed us to derive annual productions of leaves, wood, flowers and acorns, and an isometric relationship between stem and belowground biomass has been used to estimate perennial belowground growth. By combining eddy covariance fluxes with annual net primary productions (NPP), we managed to close a C budget and derive values of autotrophic, heterotrophic respirations and carbon-use efficiency (CUE; the ratio between NPP and GPP). Average values of yearly net ecosystem production (NEP), GPP and Reco were 282, 1259 and 977 g C m−2. The corresponding aboveground net primary production (ANPP) components were 142.5, 26.4 and 69.6 g C m−2 for leaves, reproductive effort (flowers and fruits) and stems, respectively. NEP, GPP and Reco were affected by annual water deficit. Partitioning to the different plant compartments was also impacted by drought, with a hierarchy of responses going from the most affected – the stem growth – to the least affected – the leaf production. The average CUE was 0.40, which is well in the range for Mediterranean-type forest ecosystems. CUE tended to decrease less drastically in response to drought than GPP and NPP did, probably due to drought acclimation of autotrophic respiration. Overall, our results provide a baseline for modeling the inter-annual variations of carbon fluxes and allocation in this widespread Mediterranean ecosystem, and they highlight the value of maintaining continuous experimental measurements over the long term.

Climate change and water resources management in the Upper Santa Cruz River, Arizona

Episodic streamflow events in the Upper Santa Cruz River recharge a shallow alluvial aquifer that is an essential water resource for the surrounding communities. The complex natural variability of the rainfall-driven streamflow events introduces a water resources management challenge for the region. In this study, we assessed the impact of projected climate change on regional water resources management. We analyzed climate change projections of precipitation for the Upper Santa Cruz River from eight dynamically downscaled Global Circulation Models (GCMs). Our analysis indicates an increase (decrease) in the frequency of occurrence of dry (wet) summers. The winter rainfall projections indicate an increased frequency of both dry and wet winter seasons, which implies lower chance for medium-precipitation winters. The climate analysis results were also compared with resampled coarse GCMs and bias adjusted and statistically downscaled CMIP3 and CMIP5 projections readily available for the contiguous U.S. The impact of the projected climatic change was assessed through a water resources management case study. The hydrologic framework utilized includes a rainfall generator of likely scenarios and a series of hydrologic models that estimate the groundwater recharge and the change in groundwater storage. We conclude that climatic change projections increase the uncertainty and further exacerbate the already complicated water resources management task. The ability to attain an annual water supply goal, the accrued annual water deficit and the potential for replenishment of the aquifer depend considerably on the selected management regime.

Zoneamento agroclimático da cultura da videira no estado do Paraná

The state of Paraná is located in a climate transition region, with different thermal regimes and variations in the risk of frost. Knowledge of the climate risks to which grapevine (Vitis sp.) will be exposed is important to the success of the vineyard. The objective of this study was to perform the agroclimatic zoning for the growing vines in the state of Paraná. Historical data from 21 conventional weather stations of Instituto Agronômico do Paraná were used in different regions of the state with observation periods from 1976 to 2010. Three groups of grapes were considered: rustic grapes, fine table grapes and fine grapes for winemaking. For each group it was evaluated: the annual water deficit, the risk of late frosts, the average annual temperature, the volume of annual precipitation and relative humidity. The main climate risk is the high relative humidity which, combined with high temperature, may favor the occurrence of fungal diseases and compromise the vineyard. For rustic grapes, only the coast of the state of Paraná was not suitable for cultivation. For the cultivation of fine table grapes, only the northern, northwestern and western regions are apt, and for fine grapes for winemaking, only the coast and east are not considered suitable, according to established criteria.

Zoneamento agroclimático da cultura do abacaxizeiro no Estado do Paraná

O estado do Paraná localiza-se em uma região de transição climática, abrangendo regimes térmicos diferentes e variações no risco de geadas. O abacaxizeiro ( Ananas comosus L.) é uma cultura sensível às condições climáticas e o conhecimento dos riscos a que a cultura estará exposta é importante para o seu sucesso. O objetivo deste trabalho foi efetuar o zoneamento agroclimático para o cultivo do abacaxizeiro no estado do Paraná. Foram verificados os limites adequados das variáveis climáticas e avaliadas a temperatura média anual, a temperatura do mês mais frio, o risco anual de geadas, o risco de deficiência hídrica, o número de horas de insolação anual e o fotoperíodo no Estado. O Paraná possui áreas com baixo risco climático para a cultura do abacaxizeiro. A temperatura média anual acima de 19°C, a temperatura média do mês mais frio superior a 15,5°C e a altitude inferior a 600 m permitiram delimitar áreas aptas ao cultivo do abacaxizeiro no Paraná. A deficiência hídrica anual não é limitante ao cultivo do abacaxi no Estado. A temperatura média anual e o fotoperíodo podem induzir naturalmente o florescimento do abacaxi no Estado. Destacam-se as regiões Oeste, Noroeste e Norte, com temperatura média anual superior a 22°C, que são as mais recomendadas ao cultivo. Nas regiões com temperatura média anual entre 19 e 22°C, a escolha do local de cultivo deve ser criteriosa, levando-se em conta o risco de geada local. As regiões Centro, Sul e Leste não são recomendadas, por apresentarem faixas de temperatura abaixo do mínimo exigido.