Spring Rainfall Research Articles

Extensive gypsy moth defoliation in Southern New England characterized using Landsat satellite observations

Southern New England is currently experiencing the first major gypsy moth (Lymantria dispar) defoliation event in nearly 30 years. Using a novel approach based on time series of Landsat satellite observations, we generated consistent maps of gypsy moth defoliation for 2015 (first year of the outbreak), 2016 (second year of outbreak), and 2017 (third year of outbreak). Our mapped results demonstrate that the defoliation event continued through the 2017 growing season. Moreover, the affected area more than doubled in extent each year and expanded radially to encompass 4386 km2 of forested area in Rhode Island, eastern Connecticut, and central Massachusetts. The current gypsy moth outbreak is believed to be the result of a series of unusually dry springs in 2014, 2015, and 2016, which suppressed Entomophaga maimaiga, a fungal mortality agent that has historically reduced gypsy moth impacts in this region. The continuation and marked expansion of the outbreak in 2017 despite average spring rainfall suggests that caterpillars were active early in the growing season, and mortality from the fungus likely peaked after significant defoliation had already occurred. Our Landsat time series approach represents an important new source of data on spatial and temporal patterns in gypsy moth defoliation, and continued satellite-based monitoring will be essential for tracking the progress of this and other gypsy moth outbreaks.

A Bayesian hierarchical spatio-temporal model for extreme rainfall in Extremadura (Spain)

ABSTRACTA statistical study was made of the temporal trend in extreme rainfall in the region of Extremadura (Spain) during the period 1961–2009. A hierarchical spatio-temporal Bayesian model with a GEV parameterization of the extreme data was employed. The Bayesian model was implemented in a Markov chain Monte Carlo framework that allows the posterior distribution of the parameters that intervene in the model to be estimated. The results show a decrease of extreme rainfall in winter and spring and a slight increase in autumn. The uncertainty in the trend parameters obtained with the hierarchical approach is much smaller than the uncertainties obtained from the GEV model applied locally. Also found was a negative relationship between the NAO index and the extreme rainfall in Extremadura during winter. An increase was observed in the intensity of the NAO index in winter and spring, and a slight decrease in autumn.

Long-term seasonal rainfall forecasting: efficiency of linear modelling technique

Using the lagged (past) climate indices, including El Nino–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) as input parameters and long-term spring rainfall as outputs, calibration and validation of the linear multiple regression (MR) models have been performed. Since Australian rainfall varies both temporally and spatially, the analysis on the linear MR models was performed on regional scale. These models show the capability of linear MR technique for long-term predictions of Western Australian spring rainfall. The emphasis was given to assess the statistical correlations between Western Australian spring rainfall and dominating large-scale climate modes. The efficiency of linear modelling technique was evaluated to predict seasonal rainfall forecasting. At the same time, the Pearson correlation (R), mean absolute error, root-mean-square error and Willmott index agreement (d) were used to assess the capability of MR models. The models which fulfilled the limits of statistical significances were used for the prediction of future spring rainfall using independent data set. The results indicate that during calibration periods maximum achievable correlations varied from 0.47 to 0.53 for the selected stations. In regard to predict peaks and troughs of rainfall time series, it was found that correlations between predicted and actual peaks varied from 0.82 to 0.94 and between predicted and actual troughs varied from 0.53 to 0.91.

The investigation of the quality of water resources of decentralized water-supply of rural areas in Berezhany district

The main anthropogenic factors of chemical and toxicological pollution of decentralized water-supply sources in rural settlements are examined. Complex estimation of water pollution level is made and the dependence of subsoil waters quality from season changes is elicited on the example of countryside within Berezany district Ternopil region. Berezhany district is mostly agricultural and that’s why agriculture becomes one of the biggest polluters of water resources especially subsoil. Dangerous source of water pollution, especially in the period of spring flooding and rainfall flooding are diffuse runoffs from agricultural areas/ in three to four times more nutrients and suspended solids are imposed from them than from natural areas. In the qualitative composition (cation and anions content mineralization ) among subsoil’s waters of Ternopil region, that are used for water-supply, essentially dominate bicarbonate-sulfate calcium-sodium waters with mineralization 0.2–0.8 g/dm3. Especially in Berezhany district subsoil fresh waters have bicarbonate-sulfate calcium-sodium composition with common mineralization of 0.5–0.7 g/dm3. There are 3432 artesian wells in the region, including 2679 in the countryside and 753 in towns and 74296 mine pits. It is found that on this territory low concentrations of nitrites during the whole period of research are marked. Except for isolated cases of its growth: in the village Zhukiv (to 0.02 mg/dm3) in autumn and Posurhiv (to 0.04 mg/dm3) in spring, that are explained by the increasing of quantity of fall-outs and respectively, growth of runoff from agricultural lands. Small concentrations of nitrites in groundwater’s on the district territory (less more than 0.01 mg/dm3) are due to their extreme instability. They are oxidized, moving to the most stable inorganic nitrogen – nitrates. Concerning nitrates, their high levels with gradual growth from spring to autumn is found. In the village Zhukiv the figure does not exceed the norm, except in autumn, where it is 52.35mg/dm3. Significant increase of nitrates concentration on the territory of these villages in autumns is explained by the fact, than during the rains polluting substances penetrated into groundwater’s, that drained from fields, where nitrogen fertilizers were given. In summer this increase can be explained by fertilization. Receiver results speak about poor state of ground waters as the sources of decentralized water-supply due to increasing of nitrate contents in these objects. It is shown that effluents and fertilizers that are given into the soil, make the most influence on the quality of water from underground sources. It is also founded the increasing of contents of nitrites, nitrates, chlorides, sulphates in spring during snowmelting and in autumn during rains. Considering the excess of nitrates norm in ground water it is necessarily control making of nitrogen fertilizers into soil. It is necessary to conduct purification of drinking water before its usage. It is obviously that on the areas with higher percentage of “unstandard” water the morbidity of cancer is higher. The effect of influence of water with higher contents of nitrates increases against the background of malnutrition that is particularly in the current crisis period of life.

Spatially and temporally variable urinary N loads deposited by lactating cows on a grazing system dairy farm

Feed nitrogen (N) intakes in Australian grazing systems average 545 g cow−1 day−1, indicating that urinary N is likely to be the dominant form excreted. Grazing animals spend disproportionate amounts of time in places on dairy farms where N accumulation is likely to occur. We attached to grazing cows sensors that measure urine volume and N concentration, as well as global positioning systems sensors used to monitor the times the cows spent in different places on a farm and the location of urination events. The cows were monitored for up to 72 h in each of two seasons.More urination events and greater urine volumes per event were recorded in spring 2014 (3.1 L) compared with winter 2015 (1.4 L), most likely influenced by environmental conditions and the greater spring rainfall observed. Mean (range) N concentration (0.71%; 0.02 to 1.52%) and N load (12.8 g cow−1 event−1; 0.3 to 64.5 g cow−1 event−1) did not differ over the two monitoring periods. However, mean (range) daily N load was greater in spring (277 g cow−1 day−1; 200 to 346 g cow−1 day−1) than in winter (90 g cow−1 day−1; 44 to 116 g cow−1 day−1) due to the influence of urine volume. Relatively greater time was spent in paddocks overnight (13.3 h) than in paddocks between morning and evening milking (6.4 h), compared with the mean numbers of urinations in these places (6.4 and 3.8 respectively). The mean N load deposited overnight in paddocks (89.6 g cow−1) was more than twice that deposited in paddocks during the day (43.8 g cow−1), due to the greater N load per event overnight, and was more closely linked to the relative difference in time spent in paddocks than in the number of urination events. These data suggest that routinely holding cows in the same paddocks overnight will lead to high urinary N depositions, increasing the potential for N losses from these places. Further research using this technology is required to acquire farm and environment specific urinary data to improve N management.

Impacts of rainfall extremes on wheat yield in semi-arid cropping systems in eastern Australia

Investigating the relationships between climate extremes and crop yield can help us understand how unfavourable climatic conditions affect crop production. In this study, two statistical models, multiple linear regression and random forest, were used to identify rainfall extremes indices affecting wheat yield in three different regions of the New South Wales wheat belt. The results show that the random forest model explained 41–67% of the year-to-year yield variation, whereas the multiple linear regression model explained 34–58%. In the two models, 3-month timescale standardized precipitation index of Jun.–Aug. (SPIJJA), Sep.–Nov. (SPISON), and consecutive dry days (CDDs) were identified as the three most important indices which can explain yield variability for most of the wheat belt. Our results indicated that the inter-annual variability of rainfall in winter and spring was largely responsible for wheat yield variation, and pre-growing season rainfall played a secondary role. Frequent shortages of rainfall posed a greater threat to crop growth than excessive rainfall in eastern Australia. We concluded that the comparison between multiple linear regression and machine learning algorithm proposed in the present study would be useful to provide robust prediction of yields and new insights of the effects of various rainfall extremes, when suitable climate and yield datasets are available.

A land use suitability model for rainfed farming by Multi-criteria Decision-making Analysis (MCDA) and Geographic Information System (GIS)

This study was carried out to analyze the land use suitability of Golestan Province, located in the northeast of Iran, for rainfed farming performance using Geographic Information System (GIS) and Multi-criteria Decision-making Analysis (MCDA) in 2016. First, thematic maps of several environmental variables including soil, climate and topographic variables were obtained. After preparing the raster layers, the environmental requirements of rainfed farming were identified from a comprehensive literature review and asking local experts’ opinions; then they were classified according to FAO (Food and Agriculture Organization of the UN) requirements. In the next step, AHP (Analytic Hierarchy Process)-acquired weights were assigned to the criteria. Then, digital layers were overlaid using Weighted Overlay Analysis (WOA) in ArcGIS. According to the results of land suitability analysis, development of rainfed farming is possible for up to 56 percent of the current land of Golestan Province (about 396,550.5 ha) in the southern and central areas as a long belt from east to west. The results showed that some climatic variables such as temperature, annual rainfall, and sunshine hours were not limiting factors for rainfed farming in this region. However, other environmental variables such as salinity, organic matter, soil erosion, soil texture classes, and the autumn, spring, May and June rainfalls were identified as limiting factors for rainfed farming performance in the northern and northeastern regions of Golestan Province. We also found that slope was a limiting cause in the southern part of this province. Generally, the use of specific management practices such as increasing soil organic matter, saline reduction of lands, conservation tillage, and supplementary irrigation canimprove the quality class of low capability lands to higher suitability classes and increase the quality of environmental resources.

Variability of cool seasonal rainfall associated with Indo-Pacific climate modes: case study of Victoria, Australia

AbstractThis study focused on diagnosing the relative and independent role of El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on austral cool seasonal rainfall by stratifying the cool seasonal rainfall into winter (June–August) and spring (September–November). Partial regression and classification analysis was used to investigate the effect of the climate modes on rainfall in the state of Victoria in southeast Australia. Partial regression analyses revealed that when the influence of IOD is removed from ENSO, sea surface temperature (SST) anomalies in the Pacific Ocean have no significant effect on spring rainfall across Victoria and affect winter rainfall mildly in west Victoria. By removing the inter-correlations between ENSO and IOD, SST anomalies in the Indian Ocean and SLP anomalies in the Pacific Ocean showed weak relationships with Victoria's spring and winter rainfall. Classification analysis demonstrated the effects of phases of ENSO and IOD on Victoria's seasonal rainfall; the dry phases of the climate modes have more effect on spring rainfall compared to the wet phases and both show no significant effect on winter rainfalls. It is recommended that for water availability forecasting in Victoria, water managers should focus on the effect of climate modes on spring rainfalls, particularly during the dry phases of ENSO and IOD.

Dendrochronological analyses and climatic signals of Alchornea triplinervia in subtropical forest of southern Brazil

AbstractThe predominance of secondary forest‐species in Brazilian subtropical forests highlights the importance of understanding the ecology of these taxa, and dendrochronology provides valuable information about the growth and climate response of tree species. The wide distribution of Alchornea triplinervia (Spreng.) Mull. Arg. (Euphorbiaceae), and the presence of growth rings in its wood, leds to its selection for this study. Samples were collected from 34 trees growing in rainy dense forest fragments in the cities of Blumenau and Brusque, in southern Brazil, and subjected to standard dendrochronological techniques. The local chronology spanned from 1889 to 2013 and the age of the trees ranged from 32 to 125 years. The mean age was 73 years and annual increment was 1.13 mm year−1; the diameter and age showed a weak correlation. The results suggest that A. triplinervia growth responded negatively to hot summers and increased rainfall in the previous spring and winter. The high perdiodicity trend characteristic of ENSO activity was reflected in wavelet power spectra of A. triplinervia chronology, affecting positively its growth after strong ENSO events (1970–2009). Negative influences occurred before 1970 during normal ENSO events. Also, there is evidence of the existence of a connection between Pacific and Atlantic sea surface temperatures influencing on tree growth.

Spatiotemporal Characteristics of Winter Wheat Waterlogging in the Middle and Lower Reaches of the Yangtze River, China

The waterlogging is a serious agrometeorological disaster caused by excessive soil water during crop growth stages. The middle and lower reaches of the Yangtze River are one of the major winter wheat growing regions in China and at the same time they are waterlogging-prone due to their specific climatic conditions. In this study, we integrated a set of tools to analyze the spatiotemporal features of winter wheat waterlogging in this region. We proposed a waterlogging precipitation index (WPI) based on winter wheat yield loss rate and precipitation anomaly percentage and analyzed the frequency, scope, and intensity of winter wheat waterlogging. The results showed that the spring rainfall had a direct and significant effect on winter wheat yield, and the meteorological yield of winter wheat was negatively correlated with precipitation abnormal event from jointing to maturity stages (March to May) across the whole study area. The matching between the waterlogging severity identified by the WPI and historical winter wheat waterlogging records was relatively high. We also discussed the influences of the other nonmeteorological factors, for example, soil texture, topographic and geomorphic conditions, and local disaster-resisting ability, on the extent of waterlogging damage.

Flowering Phenology and Observations on the Pollination Biology of South American Cacti. 3. Temporally Robust Sequential “Big Bang” Flowering of Two Unrelated Sympatric Globular Cacti in Northern Argentina

Sequential flowering of sympatric plant species is a commonly observed phenomenon and is thought to contribute towards maintaining the pollinator community. Sequential flowering is also interpreted as a potential way to reduce competition for pollinators and to reduce interspecific pollen transport.Within-season sequential flowering is well-known for many species assemblages and usually shows a staggering over weeks and months. Here, we report on the flowering behaviour of two unrelated sympatric cacti (both Cactaceae — Cactoideae) from N Argentina, Acanthocalycium thionanthum (Cereeae — Trichocereinae) and Parodia microsperma (Notocacteae). At the start of the flowering season, the two taxa exhibit a temporally stable sequential mass-flowering that is triggered by the first rainfall event after the dry season: On the 6th or 7th day after the rainfall, Parodia microsperma starts a 3-day “big-bang” flowering period, and on the 8th or 9th day after the rainfall, Acanthocalycium thionanthum also starts a 3-day “big-bang” flowering period, with 1 day of overlap with that of Parodia. The sequence and duration, including the 1-day overlap, has been found to be temporally stable in all study years, with c. 90% of all flowers buds of a population opening synchronously in years with average spring rainfall. Later in the season, after the fruits derived from these initial flowerings have ripened, opportunistic flowering (including sporadic local small-scale mass flowerings) is exhibited by both species with no apparent synchronization or sequence. Only once was a second “big bang” flowering observed, likely caused by above-average dry conditions. The species pair is notable for the massive “big-bang” flowering triggered by rainfall with a tightly staggered synchronization, as well as for the change in flowering strategy later in the season.

Influence of tillage, vertical seed distribution, and pyroxasulfone application timing and rate on control of wild oat (Avena fatua L.)

Tillage and new herbicide options may be necessary for the control of herbicide-resistant wild oat. The efficacy of soil-applied herbicides such as pyroxasulfone can be influenced by edaphic factors and weed seed recruitment depth, which varies with tillage system. We investigated the effect of tillage and pyroxasulfone rate when applied in the fall and spring on wild oat biomass at three locations in Alberta in 2014–2015. The vertical position of wild oat seeds, with and without tillage, was examined at each site. Wild oat biomass was greater in untilled plots compared with plots with fall tillage at all locations. In two out of three locations, pyroxasulfone efficacy was superior when applied in the fall compared with spring, possibly influenced by low spring rainfall. A single tillage pass at the Edmonton and Kinsella locations did not affect wild oat seed distribution, but there was an increase in seeds present in the surface layer in the untilled treatment at Lacombe. Tillage, used in combination with soil-applied herbicides, may be an option to achieve acceptable control of herbicide-resistant wild oat.

Spatial and interannual variations of spring rainfall over eastern China in association with PDO–ENSO events

The spatio-temporal variations of eastern China spring rainfall are identified via empirical orthogonal function (EOF) analysis of rain-gauge (gridded) precipitation datasets for the period 1958–2013 (1920–2013). The interannual variations of the first two leading EOF modes are linked with the El Nino–Southern Oscillation (ENSO), with this linkage being modulated by the Pacific Decadal Oscillation (PDO). The EOF1 mode, characterized by predominant rainfall anomalies from the Yangtze River to North China (YNC), is more likely associated with out-of-phase PDO–ENSO events [i.e., El Nino during cold PDO (EN_CPDO) and La Nina during warm PDO (LN_WPDO)]. The sea surface temperature anomaly (SSTA) distributions of EN_CPDO (LN_WPDO) events induce a significant anomalous anticyclone (cyclone) over the western North Pacific stretching northward to the Korean Peninsula and southern Japan, resulting in anomalous southwesterlies (northeasterlies) prevailing over eastern China and above-normal (below-normal) rainfall over YNC. In contrast, EOF2 exhibits a dipole pattern with predominantly positive rainfall anomalies over southern China along with negative anomalies over YNC, which is more likely connected to in-phase PDO–ENSO events [i.e., El Nino during warm PDO (EN_WPDO) and La Nina during cold PDO (LN_CPDO)]. EN_WPDO (LN_CPDO) events force a southwest–northeast oriented dipole-like circulation pattern leading to significant anomalous southwesterlies (northeasterlies) and above-normal (below-normal) rainfall over southern China. Numerical experiments with the CAM5 model forced by the SSTA patterns of EN_WPDO and EN_CPDO events reproduce reasonably well the corresponding anomalous atmospheric circulation patterns and spring rainfall modes over eastern China, validating the related mechanisms.

Meteorological factors affecting seroconversion of Akabane disease in sentinel calves in the subtropical Okinawa Islands of Japan.

Akabane virus, the pathogen-causing Akabane disease, is an arthropod-borne virus (arbovirus) transmitted by the Culicoides biting midge. A nationwide serological surveillance program for bovine arboviral diseases, including Akabane disease, has been established in Japan to monitor the circulation of arboviruses by targeting sentinel calves. Okinawa, which is located in the southwestern-most region of Japan, is a high-risk area for incursion of arboviruses. The aim of the present study was to identify the meteorological factors related to farm-level seroconversion of Akabane virus by analyzing the serological surveillance data for sentinel calves collected in Okinawa between 2007 and 2015. Rainfall in winter, spring, and autumn was positively associated with seroconversion. Adequate rainfall seems to keep the soil in a suitably moist state for growth and survival of biting midges. Maximum temperature in winter was also positively associated with seroconversion in sentinel calves. The warmer temperatures in winter may provide conditions suitable for shortening the larval development cycle and increase production of adult midges. Our findings indicate that meteorological factors such as temperature and rainfall may be important factors that produce circumstances conducive to effective transmission of the virus between vectors and the host. The results of this study provide a better understanding of the circulation of arboviruses and offer suggestions for developing better surveillance and measures to prevent arboviral disease.

MULTI-YEAR MONITORING OF RADON IN BOREHOLES AT THE MODRA GEOPHYSICAL OBSERVATORY, SLOVAKIA.

Long-term radon monitoring was performed in two boreholes, at a depth of 13 m in the 40 m deep V-2 borehole (August 2003-September 2005), and at 3 m depth in the 10 m deep V-3 borehole (August 2003-April 2008). Diurnal, multi-day and annual variations in radon time-series were observed. Daily average of radon activity in V-2 borehole was significantly higher and ranged from 6.5 to 383.7 kBq/m3, while in V-3 borehole only between 1.2 and 139.4 kBq/m3. The seasonal pattern was more pronounced in V-3 time series, with the maximum occurring from October to March. Multi-day variations (2-10 days) were registered in V-2 and V-3 mostly simultaneously, with higher discrepancy in spring and summer periods, when radon activity in V-3 borehole was low. Diurnal radon variations with two maxima and two minima per day were registered in both boreholes. The influence of meteorological parameters on radon concentrations was investigated. The overall impression is that seasonal variation in radon in V-3 borehole seems to be connected with the temperature variation. Multi-day variations of radon in both boreholes coincided with the atmospheric pressure changes. An increase in radon activity was observed in V-3 borehole after the rainfall in spring and summer seasons.

Characterizing changes in rainfall: a case study for New South Wales, Australia

ABSTRACTThis paper examines changes in rainfall in New South Wales (NSW), Australia using daily rainfall data from 200 rainfall stations covering the period of 1945–2014. The Mann–Kendall test is applied to identify trends in the selected rainfall indices, while the Pettitt change point test is employed to determine the direction and timing of a change point. Van Bell and Hughes homogeneity test is applied to examine homogeneity of the observed trends. It is found that the southern half of NSW is dominated by a negative trend in annual total rainfall, and autumn and spring rainfall. Based on the Pettitt change point test, it is found that annual maximum 24‐h rainfall data in NSW is dominated by a negative shift. Based on the Van Belle and Hughes method, it is found that NSW is dominated by non‐homogeneous trends in monthly maximum daily rainfall data. Overall, the results do not show any consistent pattern of rainfall trends in NSW. The findings of this study contribute towards the growing body of knowledge on the nature of changes in rainfall based on the latest data in NSW.

A spring rainfall pulse causes greater in situ photosynthetic upregulation for Bromus tectorum compared to co-occurring native herbaceous species

The invasive grass Bromus tectorum fuels fires, displaces native species, and reduces wildlife habitat on sagebrush steppe throughout the western United States. Recently, it has spread from the Great Basin Desert into higher elevations of the eastern Sierra Nevada, where it coexists with natives but has not yet altered fire regimes. We evaluated effects of a springtime water pulse (+10mm) in a drought year on photosynthesis for B. tectorum and co-occurring shallow-rooted native perennials Achnatherum hymenoides, Elymus elymoides, and Lupinus argenteus near the range limit of B. tectorum at ∼2175m in California. Watered B. tectorum had the largest increase in stomatal conductance (27%) of the four species. Watering increased CO2 assimilation for B. tectorum by 78% over controls, compared to 17% for A. hymenoides, 2% for E. elymoides, and 29% for L. argenteus. Electron transport rate within Photosystem II increased for watered B. tectorum and A. hymenoides, but not for E. elymoides and L. argenteus. Instantaneous electron transport rate and carbon assimilation were more responsive for B. tectorum than natives following a spring water pulse during drought. Rapid upregulation of carbon uptake in spring in response to soil re-wetting during drought could facilitate B. tectorum spread at high elevation.

High-resolution long-term WRF climate simulations over Volta Basin. Part 1: validation analysis for temperature and precipitation

A 26-year simulation (1980–2005) was performed with the Weather Research and Forecast (WRF) model over the Volta Basin in West Africa. This was to investigate the ability of a climate version of WRF to reproduce present day temperature and precipitation over the Volta Basin. The ERA-Interim reanalysis and one realization of the ECHAM6 global circulation model (GCM) data were dynamically downscaled using two nested domains within the WRF model. The outer domain had a horizontal resolution of 50 km and covered the whole of West Africa while the inner domain had a horizontal resolution of 10 km. It was observed that biases in the respective forcing data were carried over to the RCM, but also the RCM itself contributed to the mean bias of the model. Also, the biases in the 50-km domain were transferred unchanged, especially in the case of temperature, to the 10-km domain, but, for precipitation, the higher-resolution simulations increased the mean bias in some cases. While in general, WRF underestimated temperature in both the outer (mean biases of −1.6 and −2.3 K for ERA-Interim and ECHAM6, respectively) and the inner (mean biases of −0.9 K for the reanalysis and −1.8 K for the GCM) domains, WRF slightly underestimated precipitation in the coarser domain but overestimated precipitation in the finer domain over the Volta Basin. The performance of the GCM, in general, is good, particularly for temperature with mean bias of −0.7 K over the outer domain. However, for precipitation, the added value of the RCM cannot be overlooked, especially over the whole West African region on the annual time scale (mean biases of −3% for WRF and −8% for ECHAM6). Over the whole Volta Basin and the Soudano-Sahel for the month of April and spring (MAM) rainfall, respectively, mean bias close to 0% was simulated. Biases in the interannual variability in both temperature and precipitation over the basin were smaller in the WRF than the ECHAM6. High spatial pattern correlations between 0.7 and 0.8 were achieved for the autumn precipitation and low spatial correlation in the range of 0.0 and 0.2 for the winter season precipitation over the whole basin and all the three belts over the basin.

Analysis of the Hydrogeological and Hydrochemical Characteristics of an Immature Karst Aquifer System

This study intends, using classic and new techniques (e.g., Time Series Analysis, TSA), and hydrogeological data for the period February 2008 - May 2011, to improve the existing knowledge on the hydrogeology of the immature karst Philippi aquifer system (PHAS), Northeast Greece, in order to introduce the sustainable integrated water management of this system. The PHAS catchment consists of Mesozoic fissured and slightly karstified marbles, and covers an area of 121.7 km2. It discharges through the perennial, fault-controlled, overflow Voirani spring, which serves the needs of 85,000 inhabitants. Source of recharge is direct diffuse infiltration of precipitation. The Voirani spring mean discharge rate is 1.48 m3/s and ranges from 1 to 2.1 m3/s. Its variability index ranges from 1.73 to 2.07 m3/s. Auto- and cross-correlation and spectral analyses were used in combination with PHAS hydrogeological characteristics to study the interrelationship of daily spring discharge and rainfall, and provided useful information about the PHAS memory effect. PHAS baseflow prevailed greatly and had a behavior similar to a porous aquifer. The catchment area recharges and stores deep circulating water, while its karstification is poorly developed with high storages. The Voirani spring water is of Ca-HCO3 chemical type, of high quality, and oversaturated with respect to calcite. Examination of hydrograph and chemograph data revealed that PHAS is dominated by diffuse flow of stable hydrochemical composition. The application of TSA combined with classic hydrogeological techniques can be used in order to achieve a sustainable integrated water management of this system.

The interplay of climate, intervention and imported cases as determinants of the 2014 dengue outbreak in Guangzhou.

Dengue is a fast spreading mosquito-borne disease that affects more than half of the population worldwide. An unprecedented outbreak happened in Guangzhou, China in 2014, which contributed 52 percent of all dengue cases that occurred in mainland China between 1990 and 2015. Our previous analysis, based on a deterministic model, concluded that the early timing of the first imported case that triggered local transmission and the excessive rainfall thereafter were the most important determinants of the large final epidemic size in 2014. However, the deterministic model did not allow us to explore the driving force of the early local transmission. Here, we expand the model to include stochastic elements and calculate the successful invasion rate of cases that entered Guangzhou at different times under different climate and intervention scenarios. The conclusion is that the higher number of imported cases in May and June was responsible for the early outbreak instead of climate. Although the excessive rainfall in 2014 did increase the success rate, this effect was offset by the low initial water level caused by interventions in late 2013. The success rate is strongly dependent on mosquito abundance during the recovery period of the imported case, since the first step of a successful invasion is infecting at least one local mosquito. The average final epidemic size of successful invasion decreases exponentially with introduction time, which means if an imported case in early summer initiates the infection process, the final number infected can be extremely large. Therefore, dengue outbreaks occurring in Thailand, Singapore, Malaysia and Vietnam in early summer merit greater attention, since the travel volumes between Guangzhou and these countries are large. As the climate changes, destroying mosquito breeding sites in Guangzhou can mitigate the detrimental effects of the probable increase in rainfall in spring and summer.