scholarly journals How to determine the effective discharge and its return period in a semi-arid basin? The case of the Wadi Sebdou, Algeria (1973–2004)

2018 ◽  
Author(s):  
Abdesselam Megnounif ◽  
Sylvain Ouillon
Keyword(s):  
Arid Environment ◽  
Sediment Supply ◽  
Annual Series ◽  
North West ◽  
Sediment Rating Curve ◽  
Effective Discharge ◽  
The One ◽  
Log Normal ◽  
Load Discharge ◽  
Semi Arid

Abstract. Over a long multi-year period, flood events can be classified according to their effectiveness in moving sediments. Efficiency depends both on the magnitude and frequency with which events occur. In this study, the efficiency of the Wadi Sebdou (North-West Algeria), in a semi-arid environment, is examined through its histogram of sediment supply by discharge classes, established from 31-years of measurements. The effective (or dominant) discharge is the one whose class corresponds to the maximum sediment supply. Three types of subdivisions into discharge classes were compared. The subdivision in classes of equal amplitudes and the subdivision with equivalent discharges were those which allowed a correct distribution of frequencies and supplies of water and sediments. The effective discharges for these two subdivisions were close and almost equal to the half load discharge, i.e. to the flow rate corresponding to 50% of the cumulative sediment yield. The substitution of the flow histogram by a probability relationship and the use of a sediment rating curve enable to infer a theoretical value of the effective discharge. In this basin with strongly irregular flows, the introduction of a probability distribution was tested and assessed, analytical solutions are provided, but the Log-normal and Log-Gumbel laws highly underestimated the effective discharge. Return periods, estimated from the annual series of maximum discharge and half-load discharge, were compared. The former gives the period between hydrological years with discharges higher than the effective discharge (around 2 years), and the latter shows that more than half of the yearly sediment supply is carried by flows higher than the effective discharge only every 7 hydrological years. The study finally emphasized that the distribution of suspended load as a function of liquid discharge was sensitive to the basin and its forcings. On the Wadi Sebdou, the distribution of the sediment load, bimodal before 1988, became essentially monomodal after this date.

scholarly journals Empirical and analytical methods to characterize the efficiency of floods to move sediment in a small semi-arid basin

2018 ◽  
Vol 22 (12) ◽  
pp. 6335-6355 ◽  
Author(s):  
Abdesselam Megnounif ◽  
Sylvain Ouillon
Keyword(s):  
Water Discharge ◽  
Analytical Calculation ◽  
Empirical Method ◽  
Sediment Supply ◽  
Annual Series ◽  
North West ◽  
Sediment Rating Curve ◽  
Effective Discharge ◽  
Load Discharge ◽  
Semi Arid

Abstract. Over a long multi-year period, flood events can be classified according to their effectiveness in moving sediments. Efficiency depends both on the magnitude and frequency with which events occur. The effective (or dominant) discharge is the water discharge which corresponds to the maximum sediment supply. If its calculation is well documented in temperate or humid climates and large basins, it is much more difficult in small and semi-arid basins in which short floods with high sediment supplies occur. Using the example of 31 years of measurements in the Wadi Sebdou (north-west Algeria), this paper compares the two main statistical approaches to calculate the effective discharge (the empirical method based on histograms of sediment supply by discharge classes and an analytical calculation based on a hydrological probability distribution and on a sediment rating curve) to a very simple proxy: the half-load discharge, i.e. the flow rate corresponding to 50 % of the cumulative sediment yield. Three types of discharge subdivisions were tested. In the empirical approach, two subdivisions provided effective discharge close to the half-load discharge. Analytical solutions based on log-normal and log-Gumbel probability distributions were assessed but they highly underestimated the effective discharge, whatever the subdivision used to adjust the flow frequency distribution. Furthermore, annual series of maximum discharge and half-load discharge enabled the return period of hydrological years with discharge higher than the effective discharge (around 2 years) to be inferred and showed that more than half of the yearly sediment supply is carried by flows higher than the effective discharge only every 7 hydrological years. This study was the first to adapt the analytical approach in a semi-arid basin and to show the potentiality and limits of each method in a such climate.

Response of wheat cultivars to dates of sowing under dryland conditions

1983 ◽  
Vol 101 (3) ◽  
pp. 727-733 ◽  
Author(s):  
R. De ◽  
G. Saran ◽  
B. B. Turkhede ◽  
R. B. Lal ◽  
R. K. Singh ◽  
...  
Keyword(s):  
High Temperatures ◽  
Spring Wheat ◽  
Vegetative Growth ◽  
Field Experiments ◽  
Arid Environment ◽  
Seedling Stage ◽  
Wheat Cultivars ◽  
North West ◽  
Early Differentiation ◽  
Semi Arid

SUMMARYField experiments made for 4 years between 1976–7 and 1979–80 in a semi-arid environment of north-west India showed that the productivity of dryland unirrigated wheat can be increased considerably by adjusting the date of sowing to conducive atmospheric temperatures. Sowing in the middle of November when daily mean temperatures ranged between 19 and 21 °C produced yields ranging between 2·6and 3·5t/ha (averaged over the 4 years) compared with 1·4–3·3 t/ha obtained from the crop sown by mid-October when the daily mean temperature ranged between 24 and 26 °C. The tall cultivar C 306, a derivative of winter x spring wheat cross, could withstand sowing at higher temperatures (mid-October) more than the spring wheats. High temperatures prevailing during the seedling stage of spring wheats shortened their vegetative growth and initiated early differentiation. Night temperatures above 13 °C coupled with day temperatures of 33–35 °C in the last fortnight of October adversely affected the tillering of spring wheats sown on 15 October and produced smaller spikes with few fertile spikelets.

Effect of Haemonchus contortus on productivity of ewes, lambs and weaners in a semi-arid environment

1992 ◽  
Vol 118 (2) ◽  
pp. 245-248 ◽  
Author(s):  
D. H. Cobon ◽  
B. M. O'Sullivan
Keyword(s):  
Milk Yield ◽  
Haemonchus Contortus ◽  
Clinical Signs ◽  
Arid Environment ◽  
Treated Group ◽  
North West ◽  
Wool Growth ◽  
Third Stage ◽  
Lamb Growth ◽  
Semi Arid

SUMMARYLactating ewes, ewes that had lambed but subsequently lost their lambs (dry) and weaners were either artificially infested with 2000–3000 third-stage Haemonchus contortus larvae (parasitized) or drenched with levamisole (treated) and run under extensive grazing conditions in north-west Queensland. Worm egg counts in parasitized lactating, dry and weaner sheep ranged from 860–2830 eggs per gram of faeces. These levels of infestation significantly (P < 0·01) reduced liveweight gain of all three sheep classes, milk yield of ewes and wool growth of weaners compared to their treated counterparts. The lower milk yield of the parasitized ewes significantly (P < 0·01) reduced lamb growth rate. Survival of lambs to weaning was 26% higher in the treated group. The experiments showed that moderate levels of H. contortus, that did not produce clinical signs of infestation, reduce productivity of sheep in this semi-arid environment.

scholarly journals Evaluation of sensory properties of Kilishi prepared from fermented cattle and camel beef in Semi-arid Nigeria

2021 ◽  
Vol 48 (5) ◽  
pp. 113-123
Author(s):  
S.K. Inusa ◽  
B. F. Muhammad
Keyword(s):  
Polyvinyl Chloride ◽  
Starter Culture ◽  
Arid Environment ◽  
Sensory Properties ◽  
Randomized Design ◽  
Important Processing ◽  
The One ◽  
Meat Samples ◽  
Meat Fermentation ◽  
Semi Arid

Meat fermentation is an important processing method with enormous nutritional and health benefits. A study was conducted to examine the sensory properties of fermented cattle and camel beef Kilishi. The effects of meat type, age and packaging on this meat quality attribute were evaluated. The experimental meat samples were fermented before utilized in Kilishi processing. The chunks of meat were sliced and then inoculated with lactic meat starter culture at three concentrations (2.5, 5.0 and 7.5 g /100 ml w/v). Kilishi samples for the sensory assessment were taken from each product lot. The experiment for the second trial was laid in a 2 x 3 x 4 factorial arrangement in a completely randomized design. The factors are two animal species (cattle and camel) aged 3, 5 and 8 years and above and four packaging arrangements: brown paper (B), polyvinyl chloride (P), aluminium foil and polyvinyl chloride (AP), brown paper and polyvinyl chloride (BP). Data generated were analysed by analysis of variance using SPSS Version 20.0 and GraphPad Instat while significantly different means were separated with Tukey HSD test. The result of sensory evaluation of the experimental Kilishi indicated that colour was ranked high and the product prepared from animals aged 5 years (middle age) and packaged in polyvinyl chloride material was the one preferred. It was concluded that fermentation and packaging improved the sensory quality of the product. Fermentation of cattle and camel beef of animals aged 5 years using 2.5% meat starter culture and the use of PVC-based package were recommended in semi-arid environment of Nigeria.     La fermentation de la viande est une méthode de traitement importante avec d'énormes avantages nutritionnels et de santé. Cette étude a été menée pour examiner les propriétés sensorielles des bovins fermentés et du Kilishi de bovins à base de chameaux. Les effets du type de viande, de l'âge et de l'emballage sur cet attribut de qualité de la viande ont été évalués. Les échantillons de viande expérimentaux étaient fermentés avant l'utilisation de la transformation du Kilishi. Les morceaux de viande ont été tranchés puis inoculés avec une culture de démarreur de la viande lactique à trois concentrations (2,5, 5,0 et 7,5 g / 100 ml w/v). Les échantillons de Kilishi pour l'évaluation sensorielle ont été prélevés sur chaque lot de produit. L'expérience du deuxième essai a été déposée dans un arrangement factoriel de 2 x 3 x 4 dans une conception complètement randomisée. Les facteurs sont deux espèces animales (bovins et chameaux) âgés de 3, 5 et 8 ans et plus et quatre arrangementsd'emballage: papier brun (P), chlorure de polyvinyle (C), feuille d'aluminium et chlorure de polyvinyle (FC), papier brun et polyvinyle chlorure (PC). Les données générées ont été analysées par analyse de la variance à l'aide de SPSS version 20.0 et du graphique PadinStat, tandis que des moyens nettement différents ont été séparés avec un test de Tukey DFS. Le résultat de l'évaluation sensorielle des Kilishi expérimentaux a indiqué que la couleur était élevée et le produit préparé à partir d'animaux âgés de 5 ans (âge moyen) et emballé dans des matériaux de chlorure de polyvinyle était celui préféré. Il a été conclu que la fermentation et l'emballage ont amélioré la qualité sensorielle du produit. Fermentation du bétail et du bœuf à base de chameaux d'animaux âgés de 5 ans en utilisant une culture de démarrage de 2,5% de la viande et l'utilisation de colis à base de PVC ont été recommandées dans un environnement semi-aride du Nigéria.

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