Print ISSN: 2077-5822

Online ISSN: 2618-1479

Author : Smadhi, Dalila

Improvement of Interpolation Using Information From Rainfall Stations and Comparison of Hydroclimate Changes (1913-1938)/(1986-2016)

Hakim Bachir; Souheila Kezouh; M‘hamed Ait-oubelli; Ahcène Semar; Dalila Smadhi; Karim Ouamer-ali

Al-Qadisiyah Journal For Agriculture Sciences, 2021, Volume 11, Issue 1, Pages 54-67
DOI: 10.33794/qjas.2021.129350.1002

The primary objective of this study is to use a better method for rainfall mapping in areas with low density rain gauge networks. Secondly, to identify and study hydro-climatic change in the semi-arid high plains of eastern Algeria on the basis of a comparative mapping approach. The latter concerns the annual rainfall map produced by the authors of this paper for the period studied (1986/2016) and the annual rainfall map for the period 1913/1938, prepared by Chaumont and Paquin (1971). The results of this analysis show that isohyets between 300 mm and 350 mm cover a large part of the study area, they occupy an area of 14444 Km², followed by isohyets between 200 mm and 300 mm with an area of 5298 Km². In addition, the comparative analysis between the periods showed that hydro-climatic change was clear for the 200 mm, 300 mm and 400 mm isohyets, whereas there are no major changes for the 500 mm and above isohyets. Data processing based on a combination of statistical and geostatistical analysis (multiple linear regression and kriging) has once again shown the value of taking into account other parameters in the design of rainfall maps, such as geomorphological and geographical parameters.

Rainfall Trends in Semi-Arid Cereal Regions of Algeria

Mawhoub Amirouche; Dalila Smadhi; Lakhdar Zella; Hakim Bachir

Al-Qadisiyah Journal For Agriculture Sciences, 2021, Volume 11, Issue 1, Pages 36-44
DOI: 10.33794/qjas.2021.129187.1000

The study focuses on rainfall, number of rainy days and droughts, on an annual time step basis, over the period (1940-2019). Each parameter is analysed by the average behavior of 1,817 variables representative of 23 semi-arid wilayas. The approach helps to characterise the rainfall climate of cereal-growing regions, where production and yields per hectare are unstable for decades.The average rainfall, estimated at 423 mm, shows a cyclical evolution, reflected by a change in averages: 430, 405, 440 mm. These averages reproduce two relatively rainy cycles (1940-1970) and (2000-2019), separated by a dry cycle (1970-2000). The frequency of cyclical rains, however, shows that rains above 400 mm remain less dominant over 79 years. The averages of observations decrease progressively with the increase of the quantities of rains, that is to say, percentages that do not exceed 14, 13 and 9%. These characteristics underline interannual droughts, which fluctuate between 0.8 and -2.5, showing a progressively decreasing number of rainy days. The results obtained do not seem to explain all the variations in cereal production and yield. However, the correlation coefficients below 35% reflect the efficient use of rainfall during the crop growth cycle, which is subject to other production factors.