The effect of different meteorological parameters on the temporal variations of reference evapotranspiration

Temporal changes of meteorological variables can affect reference evapotranspiration (ET₀). The goal of the present research is to analyze the changes of ET₀ and identify the impact of effective meteorological parameters to the changes of ET₀. For this purpose, daily meteorological data recorded in 30 synoptic stations of Iran during 1960–2014 were used. The annual and seasonal values of ET₀ were calculated by the recorded data. To calculate ET₀, FAO56 Penman–Monteith method (standard method) was used. The annual and seasonal trends of ET₀ and its eight effective parameters were analyzed. Then the contributions of effective parameters changes on ET₀ were determined. To analyze ET₀ trend at annual and seasonal scales, two common methods, Spearman’s Rho and Mann–Kendall tests, were used. The R ² = 0.99 showed that the results of the mentioned methods were similar and on the basis of T-statistic <0.057, their difference was not significant (95% confidence level). Therefore, only one method’s results (Spearman’s Rho) were reported. On the basis of Spearman’s Rho results, the annual and seasonal values of ET₀ had negative trend in most of arid and semi-arid stations while the trend of this parameter was positive in humid and very humid stations. At annual and seasonal scales, decreasing in wind speed (W), temperature (T), sunshine hours (n), minimum temperature (TN), dew point temperature (TD), maximum temperature (TX), saturation vapor pressure deficit (SVPD) and solar radiation (RS) was observed in 58, 54, 39, 43, 56, 65, 65 and 37% studied stations, respectively. In many scales, the results showed that TX and W were the most effective meteorological variables on ET₀ changes and then SVPD was located in second step in arid and semi-arid stations. In humid and very humid stations, W was the first effective parameter at all scales, except autumn.     

Observation of abnormal thermal and infrasound signals prior to the earthquakes: a study on Bonin Island earthquake M7.8 (May 30, 2015)

Scientists from all over the world try to incorporate multi-disciplinary precursors to forecast the earthquake on a short-term basis. The authors here have analyzed outgoing longwave radiations acquired from polar-orbiting National Oceanic and Atmospheric Adminstration (NOAA) satellites and long-period infrasound waves recorded by the ground observatories in China prior to the recent Bonin Islands, Japan region earthquake which occurred on May 30, 2015 with the magnitude of 7.8. The anomalous outgoing longwave radiation (OLR) was observed on May 15, 2015, and was recorded by “NOAA 18” satellite during its “night pass.” Similarly, an abnormal infrasound spike was recorded at the Beijing station on May 17, 2015. The delay in observing anomalous infrasound waves compared to the OLR anomaly is due to these low-frequency waves traveling at low speed with the velocity range of 10–15 m/s. From the analysis of the results, it can be inferred that there is a substantial relation between parameters like OLR and infrasound waves; hence, the authors conclude that it is possible to forecast the earthquake on a short-term basis with reasonable accuracy.     

Changes in soil organic carbon and its active fractions in different desertification stages of alpine-cold grassland in the eastern Qinghai–Tibet Plateau

In recent years, the desertification of alpine-cold grasslands has become increasingly serious in the Qinghai–Tibet Plateau in China, but it has not received the same amount of attention as has desertification in (semi)arid areas. Little is thus known about the change in soil organic carbon (SOC) during alpine-cold grassland desertification. To quantify the impacts of desertification on vegetation, SOC and its active fractions in alpine-cold grasslands, areas of light desertified grassland, medium desertified grassland, heavy desertified grassland, serious desertified grassland, and nondesertified grassland were selected as experimental sites in the eastern Qinghai–Tibet Plateau in China. The species number, height and coverage of vegetation were surveyed, and the soil particle fractions, SOC and SOC active fractions (including dissolved organic carbon (DOC), microbial biomass carbon (MBC), and labile organic carbon (LOC) were measured to a depth of 0–100 cm. The results showed that alpine-cold grassland desertification resulted in a significant reduction in vegetation cover, plant biomass, fine soil particles, SOC, DOC, LOC and MBC. The decreases in DOC, LOC and MBC were more rapid and apparent than were those in SOC, and the decrease in MBC was the most obvious among them. The rates of reduction in SOC concentrations accelerated as desertification progressed; most of the SOC was lost in the middle and later desertification stages, with lower losses during early desertification. The results indicate that active SOC fractions, particularly MBC, are more sensitive to desertification and can be used as sensitive indicators of desertification. Efforts to limit desertification and reduce SOC loss in alpine-cold grasslands should focus on early desertification stages and adopt strategies to prevent overgrazing and control the erosion of soil by wind.     

Soil contamination by metals with high ecological risk in urban and rural areas

Industrial development, intensive agriculture and fast urbanization have caused the metal contents of soils to increase to many times the allowable limits. To assess this impact on urban and rural soils, we quantified the Cd, Cr, Cu, Pb, Ni and Zn contents of 258 soil samples from the Recife metropolitan region (RMR). The objectives of the study were to estimate the probability of ecological risk, to determine the spatial pattern of the metals’ accumulation in the soil and to identify potential sources for the metals using a multivariate geostatistical approach. Mean concentrations of Zn, Cr, Pb, Cu, Ni and Cd in soils were 65.2, 17.9, 16.5, 12.8, 6.3 and 1.5 mg kg^?1, respectively. The results demonstrated that the Cd was anthropogenic in origin, the Cr and Ni were lithogenic (natural) in origin and the Cu, Pb and Zn were mixed in origin. Cd contaminated 91% of the samples; the median content of Cd (1.4 mg kg^?1) was three times the quality reference value for soil. The Cd contents of sugarcane fields exceeded the allowable limit (3.0 mg kg^?1) for agricultural areas. The spatial variability of the metals in the RMR showed that metallurgy, cement production, vehicle exhaust and vehicular traffic were the main sources of metals in urban areas, while phosphate-based fertilizers were the main sources in rural areas. More than 80% of the metropolitan region surveyed in the study was at moderate to high ecological risk.     

Improved barometric and loading efficiency estimates using packers in monitoring wells

Measurement of barometric efficiency (BE) from open monitoring wells or loading efficiency (LE) from formation pore pressures provides valuable information about the hydraulic properties and confinement of a formation. Drained compressibility (α) can be calculated from LE (or BE) in confined and semi-confined formations and used to calculate specific storage (S _s). S _s and α are important for predicting the effects of groundwater extraction and therefore for sustainable extraction management. However, in low hydraulic conductivity (K) formations or large diameter monitoring wells, time lags caused by well storage may be so long that BE cannot be properly assessed in open monitoring wells in confined or unconfined settings. This study demonstrates the use of packers to reduce monitoring-well time lags and enable reliable assessments of LE. In one example from a confined, high-K formation, estimates of BE in the open monitoring well were in good agreement with shut-in LE estimates. In a second example, from a low-K confining clay layer, BE could not be adequately assessed in the open monitoring well due to time lag. Sealing the monitoring well with a packer reduced the time lag sufficiently that a reliable assessment of LE could be made from a 24-day monitoring period. The shut-in response confirmed confined conditions at the well screen and provided confidence in the assessment of hydraulic parameters. A short (time-lag-dependent) period of high-frequency shut-in monitoring can therefore enhance understanding of hydrogeological systems and potentially provide hydraulic parameters to improve conceptual/numerical groundwater models.     

Local rainfall thresholds for forecasting landslide occurrence: Taipingshan landslide triggered by Typhoon Saola

This paper presents a case study of the Taipingshan landslide, which was triggered by Typhoon Saola in 2012. Taipingshan villa is one of the most famous scenic locations within the Taipingshan National Forest Recreation Area in northern Taiwan. Since the early 1990s, evidence of recent landslide activity appeared throughout the Taipingshan villa and included features such as tension cracks, ground settlement, and cracking in manmade structures. In response, a series of geological investigations and in-site/laboratory tests were conducted in 2010 to estimate slope stability and predict critical rainfall thresholds (event accumulated rainfall) for landslide activity. Results revealed that the critical rainfall threshold for the Taipingshan National Forest Recreation Area is 1765 mm. In 2012, that threshold was tested when Typhoon Saola brought tremendous rainfall to northern and eastern Taiwan and triggered activity along the main scarp of sliding mass B located near the History Exhibition Hall. According to in situ extensometer readings and on-site precipitation data, the extensometer was severed at an accumulated rainfall 1694 mm. Field monitoring data during the typhoon event are in good agreement with the rainfall threshold. These preliminary results suggest that the threshold may be useful for assessing the rainfall threshold of other landslides and a good reference for establishing early warning systems for landslides.     

Performance of a Pier Group Foundation in Swelling Rock

Foundations on claystone with swell potential may experience upward movement and failure. In this case study, the cause of 58 mm upward movement of drilled-in piers is analyzed using survey data, extensometer readings, and moisture content monitoring of claystone at the site. Laboratory swell tests were conducted to characterize the swelling characteristics of the weathered rock. A swell potential analysis for the pier group foundations is presented. The interaction of the pier group with the swelling rock is considered in analyzing the initiation of the upward movement. Furthermore, a novel inverse analysis method is presented to integrate the laboratory swell test results and numerical modeling to identify the representative swell pressures acting on the pier group as well as upward movement of the pier system. The numerical analysis indicates that the studied pier system is expected to have 135 mm heave and its rate of upward movement is compared with field observations. The behavior of the pier group foundation in swelling rock under various pier spacings and superstructure pressures shows that the uplift is considerably less for piers with smaller center-to-center spacing. The results of pier group numerical modeling provide the correlation of upward deformation changes due to center-to-center spacing of the piers, pier diameters and superstructure pressures.     

Analysis and prediction of a catastrophic Indian coastal heat wave of 2015

Heat wave of 2015 over India, a natural disaster with 2500 human deaths, was studied to understand the characteristics, associated atmospheric circulation patterns and to evaluate its predictability. Although temperatures are highest in May over India, occurrence of heat wave conditions over southeast coastal parts of India in May 2015 had been unanticipated. Analyses revealed that isolated region of Andhra Pradesh (AP) had experienced severe heat wave conditions during May 23–27, 2015, with temperatures above 42 °C and the sudden escalation by 7–10 °C within a short span of 2–3 days. Short-range weather predictions with Advanced Research Weather Research and Forecasting model at 3-km resolution, up to 72-h lead time, have been found accurate with statistical metrics of small mean absolute error and root-mean-square error and high index of agreement confirming the predictability of the heat wave evolution. Analyses have indicated that regional atmospheric pressure disparities within the Eurasia region, i.e., increased pressure gradient between the Middle East and India, had been responsible for increased northwest wind flow over to northwest India and to southeast India which have advected higher temperatures. Estimates of warm air advection have shown heat accumulation over AP region, due to sea breeze effect. The study led to the conclusion that changing pressure gradients between Middle East and India, enhancement of northwest wind flow with warm air advection and sea breeze effect along southeast coast blocking the free flow have contributed to the observed heat wave episode over coastal Andhra Pradesh.     

Characteristics analysis of spatial and temporal variation on extreme weather events in Anhui Province for recent 50 years

To mitigate the impact of natural or man-made hazards on the services of an infrastructure facility, it is important to quantitatively assess its available capacity. For example, in a post-disaster scenario, critical infrastructure is likely to experience (i) excessive demand for the service of an infrastructure and/or (ii) compromised capacity because of damage to the infrastructure and the failure of infrastructure interdependencies. As the demand grows and nears the capacity limit of an infrastructure facility, a shortage of services required for the community’s recovery will occur. The development of mitigation strategies and an assessment of their effectiveness require a systematic approach. In this paper, a functional stress–strain principle for infrastructure facilities is proposed to quantitatively assess their serviceability in post-disaster scenarios. Functional stress in infrastructure management represents a service-related demand on an infrastructure facility, while strain indicates its coping capacity. The dynamic nature of infrastructure services will be considered depending on the relationship between demand and available capacity. The allowable range of functional stress is then defined, considering plastic and elastic patterns of responses of a facility during recovery to explore strain capacity variations. The proposed principle facilitates a systematic understanding of how infrastructure facilities can adapt themselves to growing stress and the maximum level of stress they can handle. The application of the proposed functional stress–strain principle is demonstrated through case studies of two infrastructure facilities in a post-earthquake scenario: a medical facility and a power facility.