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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]