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The occurrence of loess landslides is particularly closely related to rainfall. In order to deeply understand the promotional effect of rainfall infiltration on landslides, based on the investigation of “9?17” Baqiao landslide in Xi'an area of Shaanxi, the numerical simulation methods were used to systematically study the change response characteristics and spatial- temporal distribution laws of the relevant physical and mechanical parameters of the loess slope under the rainfall infiltration conditions, analyze the destabilization process of the slope from the perspective of the change of the safety factor of sliding surface, and reveal the initiation mechanism of this type of landslide. The results show that ① the action of rainfall causes a gradual decrease in the matrix suction of the slope soil, and the magnitude of the decrease varies at different distribution locations; ② before the initiation of the landslide, the range of high volume moisture of the slope body expands significantly with rainfall, and the volume moisture shows the law of decreasing from paleosoil layer to the adjacent loess layer; ③ the horizontal displacement of the slope is radially decreasing from the middle to the upper and lower parts of the slope body, while the vertical displacement gradually decreases from the top to the bottom, and the safety coefficient of its critical sliding surface gradually decreases with the process of rainfall infiltration; ④ the response time and magnitude of pore water pressure and the change of volume moisture in the soil at the nodal development site are earlier and stronger than those in other areas of the slope, and the regional distribution of the maximum shear strain within the slope is basically parallel to the slope surface, and the simulation results are consistent with the prototype landslide; ⑤ based on the unique water-sensitive nature of loess, and the influence of causal factors such as geological structure or human engineering activities, the existence of loess joints and fissures provides an advantageous channel for water infiltration and transport, and rainfall accelerates the process of loess subduction and slope structure destruction, changing the internal stress field, displacement field and hydrogeological conditions of the slope, which in turn promotes the occurrence of landslides. [ABSTRACT FROM AUTHOR]

Efforts to correct precipitation measurements have been ongoing for decades, but are scarce for tropical highlands. Four tipping-bucket (TB) rain gauges with different resolution that are commonly used in the Andean mountain region were compared-one DAVIS-RC-II, one HOBO-RG3-M, and two TE525MM TB gauges (with and without an Alter-Type wind screen). The relative performance of these rain gauges, installed side-by-side in the Zhurucay Ecohydrological Observatory, south Ecuador, at 3780 m a.s.l., was assessed using the TB with the highest resolution (0.1 mm) as reference, i.e. the TE525MM. The effect of rain intensity and wind conditions on gauge performance was estimated as well. Using 2 years of data, results reveal that (i) the precipitation amount for the reference TB is on average 5.6 to 7.2% higher than the rain gauges having a resolution of 0.2 mm and 0.254 mm respectively; (ii) relative underestimation of precipitation from the gauges with coarser resolution is higher during low-intensity rainfall mounting to a maximum deviation of 11% was observed for rain intensities ≤1 mm h-1; (iii) precipitation intensities of 2 mm h-1 or less that occur 75% of the time cannot be determined accurately for timescales shorter than 30 minutes because of the gauges' resolution, e.g. the absolute bias is >10%; and (iv) wind has a similar effect on all sensors. This analysis contributes to increase the accuracy and homogeneity of precipitation measurements throughout the Andean highlands, by quantifying the key role of rain-gauge resolution. [ABSTRACT FROM AUTHOR]

The region of Sidi Bel Abbes is periodically affected by floods and flooding. The city of Sidi Bel Abbes is exposed to very important and recurrent floods. This region is located at a lower level than the bed of Wadi Mekerra. It is equipped with three hydrometrics stations: Haçaiba Sidi Ali Benyoub and Sidi Bel Abbes. These stations have a long series: 43 years, 55 years and 64 years respectively. Statistical estimation of extreme flood has been carried out for the annual maxima. The choice the most appropriate class of law for modelling the annual maxima was made by the decision support (DSS ) of HYFRAN software system. Series of three stations belong to the class D. After classification of laws, on the basis of the posterior probability, the Bayesian information criterion ( BIC ) and the Akaike information criterion (AIC ), which take into account the statistical goodness of fit, the law gamma was selected to estimate the maximum flow frequency . [ABSTRACT FROM AUTHOR]

In Tunisia, olive tree is traditionally propagated using ovules that delays fruiting period. Using herbaceous cutting allows shortening juvenile period and enhancing productivity. The present study aims to understand the hydraulic characteristics of the conducting system of the olive-tree as related to plant material origin. Experiments were carried out within an olive grove "Chemlali", 17 years old conducted in rain-fed conditions on sandy soil in the arid region of Souassi, Gouvernorate of Mahdia (center-east Tunisia) receiving an average rainfall of 250 mm per year. Olive trees were propagated either by ovules or herbaceous cuttings and planted at 14m x 14m (51 trees/ha). Comparative study was made using parameters of water status (wood density and wood relative water contents) and anatomical observations (conducting vessels, hydraulic diameter, surface of the lumen and theoretical hydraulic conductivity). The dynamic of water use by olive shoots was also studied on both olive plant types under plastic house conditions. Results showed that conducting system characteristics of olive trees issued from herbaceous cuttings permitted a good adaptation to water stress. Those of trees issued from traditional propagating method allowed, relatively, more water loss and less water absorption. [ABSTRACT FROM AUTHOR]

The bulk sedimentary δ15N record of Alfonso Basin displayed changes both from a regional source possibly associated with changes in the isotopic signal of NO3 – dissolved in Subsurface Subtropical Water and from a climate source governed by solar forcing (total solar irradiance) over the strength of the North American monsoon (i.e., rainfall), causing intermediate water suboxia and promoting denitrification in the basin. High values of bulk sedimentary δ15N (maximum of 14.5‰) agree with increases in land-derived organic matter (from –14.8% to 49.2%) and with a decrease in terrigenous percentage (from 84.8% to 61.6%) during the Middle and Late Holocene, suggesting that increased rainfall and freshwater input promotes increased stratification of the water column, which inhibits vertical mixing and produces a reduction in oxygen content in an already oxygen-poor zone. [ABSTRACT FROM AUTHOR]