scholarly journals Trade-off between reservoir yield and evaporation losses as a function of lake morphology in semi-arid Brazil

2016 ◽  
Vol 88 (2) ◽  
pp. 1113-1125 ◽  
Author(s):  
José N.B. Campos ◽  
Iran E. Lima Neto ◽  
Ticiana M.C. Studart ◽  
Luiz S.V. Nascimento
Keyword(s):  
Water Yield ◽  
Prediction Errors ◽  
Arid Environments ◽  
Triangle Diagram ◽  
Trade Off ◽  
The Real ◽  
Lake Morphology ◽  
Evaporation Losses ◽  
Semi Arid ◽  
Reservoir Yield

This study investigates the relationships between yield and evaporation as a function of lake morphology in semi-arid Brazil. First, a new methodology was proposed to classify the morphology of 40 reservoirs in the Ceará State, with storage capacities ranging from approximately 5 to 4500 hm3. Then, Monte Carlo simulations were conducted to study the effect of reservoir morphology (including real and simplified conical forms) on the water storage process at different reliability levels. The reservoirs were categorized as convex (60.0%), slightly convex (27.5%) or linear (12.5%). When the conical approximation was used instead of the real lake form, a trade-off occurred between reservoir yield and evaporation losses, with different trends for the convex, slightly convex and linear reservoirs. Using the conical approximation, the water yield prediction errors reached approximately 5% of the mean annual inflow, which is negligible for large reservoirs. However, for smaller reservoirs, this error became important. Therefore, this paper presents a new procedure for correcting the yield-evaporation relationships that were obtained by assuming a conical approximation rather than the real reservoir morphology. The combination of this correction with the Regulation Triangle Diagram is useful for rapidly and objectively predicting reservoir yield and evaporation losses in semi-arid environments.

scholarly journals Representations of farmers' in social systems and their agro-pastoral choices in semi-arid environments in Morocco, a comparative study of the regions of Doukkala- Abda: تمثلات الفلاحين للأنظمة الاجتماعية وعلاقتها باختياراتهم الرعي- زراعية بالبيئات شبه الجافة- دراسة مقارنة لمنطقتي دكالة وعبدة بالمغرب

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Assmaa Bassir, Mohammed El- Assaad
Keyword(s):  
Real Estate ◽  
Comparative Study ◽  
Null Hypothesis ◽  
Social Systems ◽  
Age Groups ◽  
Arid Environments ◽  
The Real ◽  
The Real Estate ◽  
Urban Rural ◽  
Semi Arid

This research deals with the subject "Representations of farmers' in social systems and their agro- pastoral choices in semi- arid environments in Morocco, a comparative study of the regions of Doukkala- Abda".The research also aims to achieve the following objectives: Firstly, it provides a description and interpretation of the structure of the farmers' society in relation to their agro- pastoral choices (essential plantations and sheep farming).Secondly, the research gives a description and interpretation of the status of the real estate system in relation to agro- pastoral choices of farmers' (essential plantations and sheep farming). Thirdly, the study introduces a description and interpretation of the importance of urban- rural solidarity in relation to agro- pastoral choices of the farmers’ (essential plantations and sheep farming). This research is based on the following null hypothesis: «There are no statistically significant differences (H0) in the agro- pastoral choices of the farmers’ (essential plantations and sheep farming) in the two units Had Hrara (Abda region) and Tnine Lgharbia (Doukkala region), according to the representations of social systems (age groups, types of holdings, solidarity between urban and rural, status of the real estate system) ». We have adopted a quantitative and statistical verification strategy, which includes parametric and non- parametric data based on two methods: one on documents and archives (monographs, statistics ...), and the other on field observation based on the selection of a random sample of 465 farmers' distributed between the following two regions: 227 farmers in the Doukkala region (Tnine Lgharbia) and 238 farmers in Abda (Had Hrara) during 2016 and the questionnaire. Research has stressed the importance of the middle age groups [45- 54 years] and the types of small and medium holdings [4- 19 Ha] to guide the farmers’ agro- pastoral choices in the regions of Doukkala and Abda with the importance of the Melk lands, in addition to the important aid farmers receive in the framework of urban- rural solidarity. The research has also concluded the rejection of the null hypothesis (H0) and confirmation of the alternative hypothesis (H1) "there are statistically significant differences (H1) in the agro- pastoral choices of farmers according to the representations of social systems". Finally, the research adopted the "IMRAD" method based on four scientific qualities: introduction (I), methodology (M), results (R) and discussion (D).

scholarly journals Exogenously Used 24-Epibrassinolide Promotes Drought Tolerance in Maize Hybrids by Improving Plant and Water Productivity in an Arid Environment

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 354
Author(s):  
El-Sayed M. Desoky ◽  
Elsayed Mansour ◽  
Mohamed M. A. Ali ◽  
Mohamed A. T. Yasin ◽  
Mohamed I. E. Abdul-Hamid ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Agronomic Traits ◽  
Water Productivity ◽  
Positive Association ◽  
Net Photosynthesis ◽  
Antioxidant Enzyme Activities ◽  
Severe Drought ◽  
Arid Environments ◽  
Maize Hybrids ◽  
Semi Arid

The influence of 24-epibrassinolide (EBR24), applied to leaves at a concentration of 5 μM, on plant physio-biochemistry and its reflection on crop water productivity (CWP) and other agronomic traits of six maize hybrids was field-evaluated under semi-arid conditions. Two levels of irrigation water deficiency (IWD) (moderate and severe droughts; 6000 and 3000 m3 water ha−1, respectively) were applied versus a control (well-watering; 9000 m3 water ha−1). IWD reduced the relative water content, membrane stability index, photosynthetic efficiency, stomatal conductance, and rates of transpiration and net photosynthesis. Conversely, antioxidant enzyme activities and osmolyte contents were significantly increased as a result of the increased malondialdehyde content and electrolyte leakage compared to the control. These negative influences of IWD led to a reduction in CWP and grain yield-related traits. However, EBR24 detoxified the IWD stress effects and enhanced all the above-mentioned parameters. The evaluated hybrids varied in drought tolerance; Giza-168 was the best under moderate drought, while Fine-276 was the best under severe drought. Under IWD, certain physiological traits exhibited a highly positive association with yield and yield-contributing traits or CWP. Thus, exogenously using EBR24 for these hybrids could be an effective approach to improve plant and water productivity under reduced available water in semi-arid environments.

Changing perceptions of the effect of plant phenolics on nutrient supply in the ruminant

1996 ◽  
Vol 47 (6) ◽  
pp. 829 ◽  
Author(s):  
JB Lowry ◽  
CS McSweeney ◽  
B Palmer
Keyword(s):  
Phenolic Compounds ◽  
Acute Toxicity ◽  
Protein Interactions ◽  
Nutrient Supply ◽  
Arid Environments ◽  
Plant Phenolics ◽  
Ruminant Nutrition ◽  
Forage Plants ◽  
Hydrolysable Tannins ◽  
Semi Arid

Mammalian metabolism of plant phenolics, initially studied in monogastric animals, gave an emphasis to their toxic and antinutrient effects. Subsequent studies in tropical ruminants and wild herbivores have highlighted the high levels than can occur in some diets and the extensive microbial modification and degradation that can occur in the tract. This paper reviews aspects of plant phenolics as they relate to ruminant nutrition in tropical or semi-arid environments in which some forage plants contain high levels of phenolic compounds. Effects range from occasional acute toxicity of hydrolysable tannins, to acetate-releasing microbial degradations that apparently enable certain phenolics to act as nutrients. The most important and complex effects are those due to tannin-protein interactions. Although these can clearly reduce feed intake, nutrient digestibilities, and protein availability, many of the interactions are still not understood. The diverse effects of plant phenolics on nutrient flow probably result from the balance between adverse effects on some organisms and the rate at which they are degraded or inactivated by other organisms, and improved animal performance can likely be obtained by manipulation of rumen microbial metabolism.

scholarly journals Modelling water utilization patterns in apple orchards with varying canopy sizes and different growth stages in semi-arid environments

2021 ◽  
Vol 283 ◽  
pp. 110051
Author(s):  
Nompumelelo Thelma Mobe ◽  
Sebinasi Dzikiti ◽  
Timothy Dube ◽  
Dominic Mazvimavi ◽  
Zanele Ntshidi
Keyword(s):  
Growth Stages ◽  
Arid Environments ◽  
Apple Orchards ◽  
Water Utilization ◽  
Utilization Patterns ◽  
Different Growth Stages ◽  
Semi Arid

Adaptation of sulla cultivars to contrasting Mediterranean environments

2008 ◽  
Vol 59 (8) ◽  
pp. 702 ◽  
Author(s):  
P. Annicchiarico ◽  
A. Abdelguerfi ◽  
M. Ben Younes ◽  
H. Bouzerzour ◽  
A. M. Carroni ◽  
...  
Keyword(s):  
Dry Matter ◽  
Mediterranean Climate ◽  
Western Mediterranean ◽  
Arid Environments ◽  
Ge Interaction ◽  
Interaction Modelling ◽  
Breeding Programmes ◽  
Crop Cycle ◽  
Main Effects ◽  
Semi Arid

Sulla coronaria (L.) Choi & Ohashi (syn. Hedysarum coronarium L.) may become a major forage species in various Mediterranean-climate areas. This study aimed to assess the extent of genotype × environment (GE) interaction in the western Mediterranean region and its implications for breeding programmes. The milestone Italian varieties Grimaldi and Sparacia, one recent Italian variety, and the Tunisian cv. D’Italie (evolved under moderately favourable conditions from Italian germplasm introduced about 40 years ago) were evaluated in three environments of Tunisia (of which two were irrigated), two of Algeria, and one of Sardinia (Italy). Water available over the crop cycle (rainfall + possible irrigation from October 2004 to June 2006), ranging from 881 to 1906 mm, accounted for 85% of the variation among environments and 72% of the GE interaction variation for dry matter yield. The latter was adequately described by one-covariate factorial regression, which was preferable to joint regression and additive main effects and multiplicative interaction modelling. D’Italie was specifically adapted to environments with available water exceeding 1200 mm, Grimaldi was top-ranking between 950 and 1200 mm, and Sparacia below 950 mm. The crossover GE interaction between top-yielding material (P < 0.05) has implications for adaptation targets, genetic resources, selection environments, and opportunities for international co-operation between breeding programmes. It suggests breeding either for rainfed cropping in semi-arid or near semi-arid environments, or for definitely subhumid or irrigated environments.

scholarly journals Effects of maquis clearing on the properties of the soil and on the near-surface hydrological processes in a semi-arid Mediterranean environment

2014 ◽  
Vol 45 (4) ◽  
pp. 176 ◽  
Author(s):  
Mario Pirastru ◽  
Marcello Niedda ◽  
Mirko Castellini
Keyword(s):  
Land Use ◽  
Hydraulic Properties ◽  
Water Infiltration ◽  
Hydrological Processes ◽  
Soil Water Storage ◽  
Water Yield ◽  
Mediterranean Environment ◽  
Canopy Interception ◽  
Near Surface ◽  
Semi Arid

Many hillslopes covered with maquis in the semi-arid Mediterranean environment have been cleared in recent decades. There is little information on what effect this has on the hydrology of the soil. We compared the hydraulic properties of the soil and the subsurface hydrological dynamics on two adjacent sites on a hillslope. One site was covered with maquis, the other with grass. The grass started to grow some 10 years ago, after the maquis had been cleared and the soil had been ploughed. Our study found that the hydraulic properties and the hydrological dynamics of the maquis and the grassed soil differed greatly. The grassed soil had less organic matter and higher apparent density than did the soil covered in maquis. Moreover, the maquis soil retained more water than the grassed soil in the tension range from saturation to 50 cm of water. Infiltration tests performed in summer and in winter indicated that the field saturated hydraulic conductivity (K<sub>fs</sub>) of the maquis soil was higher than that of the grassy soil. However the data showed that the K<sub>fs</sub> of the two soils changed with the season. In the maquis soil the K<sub>fs</sub> increased from summer to winter. This was assumed to be due to water flowing more efficiently through wet soil. By contrast, in the grassy soil the K<sub>fs</sub> decreased from summer to winter. This was because the desiccation cracks closed in the wet soil. As result, the influence of the land use change was clear from the K<sub>fs</sub> measurements in winter, but less so from those in the summer. Changes in land use altered the dynamics of the infiltration, subsurface drainage and soil water storage of the soil. The maquis soil profile never saturated completely, and only short-lived, event based perched water tables were observed. By contrast, soil saturation and a shallow water table were observed in the grass covered site throughout the wet season. The differences were assumed to be due to the high canopy interception of the maquis cover, and to the macropores in the grassed soil being destroyed after the maquis had been cleared and the soil ploughed. The results of this work are helpful for predicting the changes in the hydraulic properties of the soil and in the near-surface hydrological processes in similar Mediterranean environments where the natural vegetation has been cleared. These changes must be taken into consideration when developing rainfall-runoff models for flood forecasting and water yield evaluation.

Sign in / Sign up

Export Citation Format

Share Document