8 research outputs found
PRELIMINARY EVALUATION ON THE RATIO BETWEEN THE SURFACE AND UNDERGROUND RIVER SUPPLY IN EASTERN ROMANIA
In the last decades, the classic methodology for evaluating the base flow index (BFI), as the characteristic medium hydrograph, was replaced by new specialized algorithms, as HYSEP, PART, BFLOW, Eckhardt ș.a. The goal of this study is to determine the base flow index (BFI) within four hydrometric stations located on few rivers characterized by different phisical-geographic conditions from Eastern Romania (Lepșa – Lepșa river, Cuejdiu – Cuejdiu river, Băcești – Bârlad river and Tg. Frumos – Bhlueț river). The calculations were made both by using the classical methodology, and by a new algorithm proposed by Eckhardt in 2005 and 2008. Through comparing results, it is proved that the new determination methods for the underground intake reveal in a more accurate manner the climatic and geologic relations of the analyzed rivers (BFI - Lepșa 35%; Cuejdiu 45%; Băcești >50%; Târgu Frumos >50%). As a result, the higher underground intake for the rivers flow modifies the method of calculation of hydrological balances, and thus, changes in water resources management
Satellite images survey for the identification of the coastal sedimentary system changes and associated vulnerability along the western bay of the Gulf of Tunis (northern Africa)
The aim of this study consists in testing the effectiveness of
satellite data in order to monitoring shoreline and sedimentary features
changes, especially the rapidly changing of Gulf of Tunis coast. The study
area is located in the Gulf of Tunis western bay (Southern Mediterranean Sea)
which is characterized by sandy beaches of Ghar Melah and Raoued (Medjerda
Delta area). The aerial photographs and satellite imageries were used for
mapping the evolution of shoreline. Diachronic data (satellite imagery,
aerial photography and topographic maps) were used to monitor and to
quantify, the evolution of the coastal areas. These thematic data were
digitally overlaid and vectorised for highlighting the shoreline changes
between 1936 and 2016, in order to map the rate of erosion and accretion
along the shoreline. Results show that the accretion and degradation are
related to the Medjerda: change of outlet in 1973 and impoundment of the Sidi
Salem dam in 1982. We found that the general trend of the coastal geomorphic
processes can be monitored with satellite imageries (such as Sentinel A2,
Spots 4 and 5), due to its repetitive coverage along the time and their high
quality concerning the spectral contrast between land and sea areas. Improved
satellite imageries with high resolution should be a valuable tool for
complementing traditional methods for mapping and assessing the sedimentary
structures (such as shoreline, delta, marine bars), and monitoring especially
the lowlands coastal areas (slightly eroded)