In this field, works of several authors show that these models inspired of biological neurons functioning, are very performing for simulation and flows forecasting on the watersheds. Several studies conducted in America , in Europe [4, 5], in Africa  and in Algeria [7, 8] confirm the best simulation results and forecasting with neural networks. This research work will allow checking efficiency of formal neural networks for flows simulation in semi-aridzone (case of Oued Ouahrane’s basin). In fact, this study will allow optimizing and comparing neuronal models and a global conceptual model (GR4J) for floods flow simulation of wadi
Study of rainfall intensities for micro-scales in a semi-aridzone (Tunis) by FIF model 7 corresponding to 2 h 30 min. We are interesting in the first one which correspond to high frequencies and which is not conservative and corresponds to a FIF (H> 0). This result is important because it means that rain rate is not a pure multiplicative cascade but should be (fractionally) integrated to reconstruct the cascade itself. According to Table III, which summarizes the parameter estimates H for the three stations, they behave in the same way. These results are generally consistent with those found in the spectral analysis of rainfall data series. For multifractal analysis that follows, the necessity of working only with a number of samples that is a power of 2 will lead us to consider the break at 2h40min, the length of the sequence is 2 5 * 5 minutes. As we have just seen, these results confirm that there is a regime of micro-scale rain process, which is not conservative as reflected by a spectral slope greater than 1 and a non-conservation parameter H nonzero that is in agreement with the work of Fraedrich and Lardner (1993). They found, a spectral slope of 1 for increment of scale repectively lower then 2.4 hours and 1 hour.
In this study, we evaluate the soil erosion and solid transport in the oued Mekerra watershed in north-west Algeria. The study area is subject to a semi-arid climate characterized by irregular rainfall and showers, which are often accompanied by significant floods. These floods of large volumes transport large amounts of solid input to the Sarno dam, which is in the outlet of oued Mekerra. Therefore, the water storage capacity of this dam is gradually decreasing, and it might reach the volume of dead water. For this study, we utilized the hydrometric database provided by the National Agency of Water Resources (ANRH). The operating period was 24 years, from 1988 to 2012. This period was extended by classic regression to 65 years, which allowed extracting a series of annual maximum instantaneous flow rates (Q IXA ) and subsequently quanti- fied the sediment yield during floods. The specific degradation mean created by the 11 floods was quite high, in the order of 20 t km 2 year −1 . The highest value of solid contribution was observed during the floods of October 2000 (250,000 t), and
corresponding author: Ph. Orban, firstname.lastname@example.org
The Oulmès plateau (mid-Atlas in Morocco) is known for its groundwater resources in this semi-arid region. In the studied zone (approximately 80 km 2 ), the mineral water of ‘Sidi Ali’ is exploited as well as the naturally semi-sparkling ‘mineral water of Oulmès’ which are main mineral waters marketed in Morocco. Their sources are located at less than four kilometers from each other. In the same time, the drinking water supply to the local rural populations is not sufficient. In addition the plateau is also the place where many fruit-bearing cultures have been undertaken for a few years. Irrigation and the use of pesticide and herbicide compounds as wel l as fertilizers could constitute threats for the groundwater quantity and quality and unpleasant consequences are expected for all dependent groundwater end-users. Thus, in this semi-aridzone, an acute problem of sustainable development arises in terms of groundwater quantity and quality.
Key words | Algeria, hydrogeochemistry, multivariate statistical analysis, semi-aridzone, water quality
Groundwater chemistry is largely determined by natural processes (aquifer lithology, ﬂow direction, water–rock/ soil interactions in the unsaturated and saturated zones, and residence time), and anthropogenic activities (agricul- ture, industry, urban development, and overexploitation of groundwater resources) ( Li et al. ). Understanding the principal processes that control groundwater chemistry is important for sustainable development and effective man- agement of groundwater resources in any area ( Wu et al. ). The plain of Ain Oussera, located in the central part of northern Algeria, is characterized by a semi-arid cli- mate ( Kettab et al. ). Groundwater is a signi ﬁcant source for drinking water supply and irrigation of agricul- tural land in many parts of this area. Continuously increasing abstraction of groundwater resources to meet
Received: 19 Mars 2017 / Accepted: 27 July 2017 / Published online: 01 September 2017
This investigation is falls within the framework of conservation agriculture. Indeed, twenty- five years after the first of zero tillage farming experiences, this new method was named crop conservation agriculture because it helps preserve soil nutrients, water absorption enhancing and infiltration and biodiversity by maintaining the natural equilibrium in the soil. The objective of this is study is to compare the impact of the tillage (conventional work and the direct sowing) on water properties of the soil, especially the water-holding capacity of the soil in semi-aridzone (case of Tiaret region). According to the results, the comparative analysis between the two types of tillage (direct drilling sowing and conventional tillage) shows that water parameters studied such as moisture equivalent (He), of holding capacity (Cr), wilting point (Pf) and AWR (UK) are higher in the useful reserve case of direct seeding than in the case of conventional labor.
P. reticulatum leaf biomass applied as a mulch at 1.25 or 2.25 t DM ha −1 on a tropical ferruginous soil (Lixisol) in Burkina Faso increased sorghum grain yields by 14 and 28%, respectively, compared to a non-mulched control treat- ment (Yélémou et al. 2014 ). A study in semi-arid Niger re- ported that applying 2 t DM ha −1 of G. senegalensis mulch during two consecutive years resulted in increased millet grain yields by 76% during the first year and by 94% during the second year as compared to the non-mulch control (Wezel and Böcker 1999 ). Another experiment conducted on sandy-loam soils in Burkina Faso showed that yields decreased over the years on continuously cultivated plots, declining drastically during the second and third year for all treatments and control (Barthès et al. 2015 ). In that experiment, the use of 1.5 t DM ha −1 of P. reticulatum leaf and branch material as mulch did not significantly increase sorghum yields as compared to the control. The addition of RW does not automatically trans- late into increased crop yields, but the effects of RW use are rarely negative on crops (Figs. 5 and 6 ).
Thymus is a large genus of Lamiaceae comprising about 215 to 350 species and particularly widely distributed in North Africa. The systematics of species remains difficult because of the interspecific hybridization and morphological similarities among species. T. algeriensis is proliphic in the mediterranean, mostely in North Africa and is endemic of semi-arid and arid areas of Algeria, Tunisia, Lybia and Morocco. The wide range of its geographical distribution lead to several morphological and ecophysiological differentiation.
This deterioration in the groundwater quality of the Tarf basin has been the subject of several local studies [4-5]. Studies on the hydrochemical behavior of water in arid and semi-arid zones have been adopted by several authors [6-7-8].
In the Tarf basin, the supply of drinking water comes mainly from the groundwater, which makes this resource vulnerable in quantity as well as in quality. This work contributes to a characterization of this resource which aims to identify the processes that participate in the increase of mineralization.
that the magnitudes of the Australian semi-arid sink associated with wet-extremes will increase in coming dec- ades. The consequence of this trend will have important implications for global carbon cycling, as shown during the 2011 global land carbon sink anomaly period 8,9 .
In summary, multiple independent lines of evidence create a compelling argument that extreme wet year driven, semi-arid land carbon sink events are transient and dissipate rapidly under ensuing drought. The efficien- cies of these semi-arid carbon sinks are highly sensitive to hydroclimatic variations and are particularly vulnerable to drought. The spatial attribution of the land carbon sink to tropical savannas and grasslands refines previous attributions to semi-arid ecosystems 7,8 . The finding of large variations in rainfall use efficiency among biomes for
ing (95.5), plant height (94.9), number of internodes (94.5), internode length (90.2), panicle length (90.2), stalk diameter (83.9), dry stalk weight (82.1), and perultimate leaf width (81.0). The lowest heritability was scored for potential yield (64.8), panicle grain weight (64.8), panicle weight (61.5) and panicle width (58.6).
Other traits (see Supplementary Table 1) showed significant variability with some Chadian accessions per- forming better than the ICRISAT checks. Compared to the average of ICRISAT checks, 22 Chadian accessions were taller, 63 had shorter days to heading, 54 had shorter days to flowering, 46 had higher number of internodes, 20 had longer internode lengths, 16 had longer perultimate leaf, 7 had wider perultimate leaf, 19 had longer panicle, 48 with wider panicle, 41 with higher fresh stalk biomass, 74 with higher dry stalk biomass, and 33 with broader stem diameter. Five of the 105 accessions screened had potential grain yields equal to or higher than the average 1.0 t ha −1 of grain sorghum production in semi-arid Chad.
Also, the study is based on an advanced method of sensitivity analysis of various design variables. EnergyPlus was used for simulation and modelling, and jEPlus was used to create input data sets for EnergyPlus, while results were simplified using SimLab 2.2. The LHS sampling was used for sensitivity analysis, and the results were ranked based on SRC ranking. Initially, the simulation was run using DesignBuilder together with EnergyPlus. Each iteration took around 3 m and 40 s to minimise the time jEPlus was used together with EnergyPlus for simulation. In total, 100 LHS cases were created using SimLab 2.2. The total simulation time of these 1100 cases was reduced to 21 h using an Intel Core i7 CPU workstation with the speed of 2.9 GHz. The simple use of sensitivity analysis tools helped to identify influential design variables for the climate of Quetta. The study provides informed decision support and saves time for local architects and practitioners to identify better passive design solutions for the construction of houses in Quetta, and perhaps in other cold semi-arid areas worldwide (See Figure 1).
Received 26 April 2000, accepted 23 May 2001.
In order to assess the status of pigeonpea (Cajanus cajan (L.) Millsp.) production in Kenya, two surveys were carried out in Makueni and Mbeere Districts in areas representative of the main agro-ecological pigeonpea producing zone of the country (Mid-altitude ASAL). Participatory Rural Appraisal (PRA) approach was chosen as research method and was completed by household interviews based on a semi-structured questionnaire. The main points developed are the presentation of the different farming systems in which pigeonpea is considered as an important legume crop, the identification of the factors explaining pigeonpea production variations, the quantification of the use of improved varieties and improved production practices, and the analysis of the major patterns and trends in pigeonpea production, consumption and marketing.
POTENTIAL OF SORGHUM FOR IMPROVING FOOD SECURITY IN KENYA Sorghum (Sorghum bicolor L. Moench) is native to the
tropical areas of Africa. The oldest cultivation records date back to 3000 B.C. in Egypt. Sorghum is produced throughout the tropical, semi-tropical and arid regions of the world. The crop is a self- pollinating plant and its drought tolerance is higher than that of corn. It is a member of the grass family graminea and can be categorized into four groups by application, i.e. grain, sweet, broom sorghum or grass sorghum. Grain sorghum is mainly used as a principal food in tropical areas and often used as raw material for alcoholic beverages, sweets and glucose. Broom sorghum on the other hand is for making brooms while sweet and grass sorghum is used to make sweetener syrup and green feed (U.S Grain Council, 2010). Sorghum is one of the most important drought tolerant crops and is often referred to as the camel of the plant kingdom (Fetene et al., 2011). The plant has for a long time been noted to be the most important cereal for human consumption surpassed only by maize, wheat, rice and barley (Dicko et al., 2006; Akram et al., 2007). It is reported to be one of the main staple food crops for the world’s poorest and food insecure people (Timu et al., 2012). Sorghum is a globally cultivated cereal unique due to its tolerance to drought, water logging and saline-alkali infertile soils and high temperature (Taylor, 2003). It has for a long time been
Using the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) seasonal metrics computed with TIMESAT software and agrometeorological variables retrieved from the GeoWRSI program, we established three Cubist models for estimating herbaceous yield at the end of the season in the semi-arid areas of Senegal: (a) the VI-model with FAPAR metrics; (b) the AGRO-model with agrometeorological variables; and (c) the VIAGRO-model with both FAPAR and agrometeorological variables. All three models gave reasonable estimations of herbaceous yield over time and across land cover classes, among which those herbaceous areas with low woody cover showed the highest inter-annual variability and those in the south with higher woody cover showed lower variability over time. The VIAGRO-model gave the best estimation performance and indicated that the simultaneous use of agrometeorological data and FAPAR metrics improved the estimation accuracy and mitigated problems encountered with the sole use of FAPAR metrics (i.e., VI-model): (1) the saturation affecting optical remotely sensed vegetation data in areas of high vegetation productivity was attenuated; (2) the discrepancy between herbaceous mass and greenness (caused by species with high greenness and low mass production, or vice versa) was attenuated, with a weaker scattering around the low and high values closer to the 1:1 line (the additional use of agrometeorological data corrected for underestimations with the VI-model, particularly in sparsely vegetated areas); (3) the onset of the rainy season calculated from rainfall data was shown to be well suited for herbaceous mass assessment, in contrast to the onset of the growing season retrieved from FAPAR satellite data, which was not significantly related to herbaceous yields. Nevertheless, these metrics should be further investigated in order to improve our understanding of their temporal patterns and determine future setting parameters across Sahelian ecosystems.
Ces régions semi-arides, caractérisées par une pluviométrie variant entre 700 et 1 500 mm, sont propices à l’élevage . Cinquante-sept pour cent de la popula- tion des ruminants en Afrique sub- saharienne est localisée dans les zones arides et semi-arides qui représentent 54 % de la superficie totale de la région . La présente étude a été menée au Nord-Cameroun, au sud-ouest du Tchad et au nord-ouest de la RCA. Dans cette région, l’élevage côtoie étroitement la cul- ture du coton qui est la première activité économique. L’extension de l’activité agricole due à la poussée démographique importante entraîne la réduction des aires de parcours. Les espaces qui autrefois étaient réservés à l’élevage sont convertis en parcs naturels ou réserves. Cette concurrence accrue sur l’utilisation des terres par l’élevage, l’agriculture et les réserves contribue à la dégradation de l’environnement par une surexploitation de la couverture végétale.
La zone d’étude est dotée par deux stations de relevage SR1 et SR2. La station SR1 recevait les eaux en provenance de deux zones urbaines de Hassi Bounif et une partie de l’agglomération Chahid Mohamoud. Ces eaux sont transportées par une conduite de diamètre de 150 mm en amiante ciment vers la station SR2 située près du cimetière chrétien, à partir de cette dernière elles sont acheminées par la conduite de diamètre de 200mm en amiante ciment vers le canal de Hassi Ameur par l’intermédiaire d’une conduite de diamètre de 300mm, enfin toutes ces eaux sont transportées vers le canal de Hassi Ameur qui déverse dans le lac Télamine. Le problème que s’est posé ensuite est l’implantation illicite de Hai Eddoum sur la conduite de diamètre de 200 mm reliant SR2 SR3 ce qui a provoqué la détérioration de cette dernière d’où la réflexion de créer un nouveau réseau dont la description est la suivante :
204 P. Hublart et al.: Reliability of a conceptual hydrological model
Figure 1. The Claro River catchment in Chile: (a) location of the cultivated areas in the valley floors, and (b) long term evolution of irrigated areas as estimated from national cadastral surveys conducted from 1980 to 2010 for two main varieties cultivated in the catchment.
standing of the hydrological processes should not necessarily translate into more complex models used in impact studies”. Indeed, maintaining low-dimensional, holistic modeling ap- proaches is essential to constrain parameter uncertainty and help the modelers focus on understanding the main drivers of hydrological change. This paper investigates one possible way of incorporating the effects of changes in crop types and irrigated areas over time into the parsimonious GR4J hydro- logical model. Particular attention is paid to the modeling of temperature effects on crop phenology so as to improve model reliability and usefulness under future climate condi- tions. The method is tested in a semi-arid catchment of the Chilean Andes, where recent studies have noticed a decline in water availability for irrigation purposes (e.g. Ribeiro et al., 2014).