OBSERVATION ON THE RÂMNIC PLAIN TERRACES BETWEEN BUZĂU AND RÂMNICU SĂRAT RIVERS

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1 Department of Geography. Valahia University of Targoviste Annals of Valahia University of Targoviste. Geographical Series Tome 14/2014 Issues 1: OBSERVATION ON THE RÂMNIC PLAIN TERRACES BETWEEN BUZĂU AND RÂMNICU SĂRAT RIVERS Ion FLOROIU International Computer High School of Bucharest, Bucharest, Abstract In this study were analyzed three rivers (Buzău, Râmnicu Sărat and Câlnău) located in Plain Râmnic between Buzău and Râmnicu Sărat rivers. Generally observed a two terraces on these rivers: T6-8m and T2-3m (flood plain terraces). Based on topographic maps (1981), the orthophotomaps (2005) supplemented with personal information who targeted localization and measurement terraces. Extending flood plain terrace (2-3m) along the river Buzău and Râmnicu Sărat show a reduced evolution of courses in these directions. Terrace T6-8m found at the confluence Buzău-Câlnău (Gura Câlnăului), in many points can be located on the rivers Râmnicul Sărat (Rubla,Măcrina) and Câlnău (Potârnicheşti, Poşta Câlnău). During the Holocene have been many changes in the courses of these rivers in the Romanian Plain. Keywords: terrace, Râmnicu Sărat, tectonic, meandering, Buzău, flood plain terrace 1. INTRODUCTION Râmnic Plain between Buzău and Râmnicu Sărat rivers is located in the north east of the Romanian Plain. Relief characteristics are strongly influenced by tectonics movements, positive in western half and negative in eastern (Polonic et al., 2005). Previous research on terraces have been undertaken by Ielenicz (1968, 1988), Visan & Cârstea (1978), and Voicu (2004), the study being integrated into the complex characterization of relief, river basins but also on larger areas of plain. Existing terraces along the river and Buzău, Râmnicu Sărat and Câlnău reflect the changes which have taken place during the Quaternary and especially Holocene in this territory at the hydrographic network (Popp, 1963). A common characteristic of these rivers is the existence a small number of terraces (between two and three terraces). 2. METHODOLOGY Thys study aimed to analize the river terrace location, mapping and morphometric quantification of these elements. Different materials were used, from thopographic maps (1981), continuing with orthophotomap (2005 edition), and drawing plans (1917, 1929, 1955, 1956). For a more detailed analysis and in orrde to achieve the higer accuracy of cross section, we used topographic plans (scale 1:5000). Identification of terrace deposits and their continuity in some points was facilitated by analysis of hydrogeological drilling depth executed by Romanian Waters (Directorate Buzău- Ialomiţa) in the southern part of the of the locality Potârnicheşti. Digital mapping of the different components and making maps was made with the program Arc GIS 10, interpolation to obtain digital terrain elevation model and some drawings with the program surfer 8. 33

2 The sections have been made using the program Global Mapper 10.All information obtained from these sources has been compared and supplemented by field information in order to achieve some correlation on wider spaces of the evolution of the hydrographic network both in Râmnic Plain between Buzău and Râmnicu Sărat rivers as well as its adjecent territory. 3. DISCUSSIONS 3.1. Buzău river terraces Buzău river valley (in the sector between localities Gura Câlnăului and Racoviţa, on the left-hand side, in the edge southern and south-eastern Râmnic Plain) has two terraces: T 2-3 m and T 6-8 m. Terrace 6-8 m emerges from the confluence with the Câlnău river to Vadu Paşii where is unitary, with widths ranging between 300 m (within the perimeter Focşănei locality) and 500 m at Gura Câlnăului, these two villages occupying most part of terrace surface (fig. 1). Also here is recorded the highest altitude (approximately 8 m) reported to Buzău river bed, south relative altitude is progressively reduced (approximately 4-5 m) appearing more fragmented (localities Scurteşti and Stănceşti). On the right side of the Buzău valley occupies large areas (to Calmăţui valley today) closely related to course deviation produced during the Holocene. Contact with the surface of the Râmnic Plain is well evidenced by steep slopes of 6-10 meters height. In the sectors where this level of terrace is missing (between localities Focşănei and Vadu Paşii) transition to flood plain terrace (2-3meters) is done by steep slopes meters height. (fig. 2). Figure 1. Profile south west-north east from flood plain (2-3m) Buzău river to Râmnic Plain surface (near locality Gura Câlnăului) Terrace 2-3 m has unitary character between Gura Câlnăului and Racoviţa, is characteristic of the sector in wich the course of the Buzău river was later estabilished on the current direction therefore its upper terrace levels are missing. Between confluence Câlnău river and the railway bridge from Vadu Paşii has widths of meters distinguishing cleary from Buzău riverbed by banks of 3 meters. In these can be observed structure of deposits formed at the base of gravel deposit (well rolled) in a mixture with coarse, sand (it is noted in the opening at the top of the deposits in thickness of 0,5 meters) more than they are silty and sandy deposits with few intercalation of small gravel. 34

3 Figure 2 Râmnic Plain and contact with flood plain terrace in the north-east of the locality Vadu Paşii Terrace surface between localities Gura Câlnăului and Vadu Paşii is coverd with grass and representing an area for grazing; near confluence with Câlnău river is affected by exploitation of mineral aggregates Gura Câlnăului. Downstream of the Săgeata terrace 2-3 meteres has character of meander terrace (Vişan & Cârstea, 1978) appearing in the sinuosity of the river in localities Beilic and Găvăneşti (fig. 3). Figure 3. Flood plain terrace (2-3m) at Beilic, Buzau river 35

4 3.2. Râmnicu Sărat river terraces Between localities Poşta and Ciorăşti, Râmnicu Sărat presents on the right hand side two level of terrace: T5-6 meters and T 2-3 meters. Terrace of 5-6 meters begins to take shape near the locality Valea Râmnicului, specifically in south-eastern, it is slightly recessed in deposits that clogs the nortern part of the valley Jirlău, here are heading to the east, parallel with the road conecting localities Valea Râmnicului and Râmnicelu. Downstream of the railway bridge over Râmnicu Sărat river increases in surface and width (in the northen locality Rubla from meters to meters in width), then its presence its interrupt in the north-west of the locality Râmnicelu. Up to locality Ştiubei has a uniform appearance along river Râmnicu Sărat, the width is generaly reduced (aproximately 150 meters), beyond wich is fragmented in the sector where Vâlsan (1915), indicate that possible was a watercourse toward Boldu valley. From the point called La Roata Sârbului (near locality Lunca previously called Hoinari), this terrace has the highest development. This accompanies river Râmnicu Sărat downstream, but from this point terrace is a clear deviation to the south east towards the forest Spătaru, contact with the surface of plain is difficult observe, beyond the road wich connect localities Vâlcelele and Nicoleşti (fig. 4). The structure of terrace can be traced in many outcrops (north of the locality Rubla and Ştiubei). In existing outcrops in the right side of the bank of Râmnicu Sărat river, about meters downstream of the railway bridge at the bottom to the top of the terrace can be seen folowing sequence:from basic (between 0,5-0,75meters) appear rolled gravel over wich is yellow sandy loesslike deposit (in its mass is found small gravel interspersed) at its level can identify a fossil soil horizon. Figure 4. Terrace 5-6m in area Măcrina-Dăscăleşti T2-3 meters is an almost all the sectors analyzed presenting a higer level of the river bed. It has width meters between Oreavu and northern Valea Râmnicului where it is in contact with the surface of glacis Plain of Râmnic, by stepp slopes of meters height along the braided riverbed of Râmnicu Sărat (fig. 5). In this sector there is a clear distinction betweeen this and riverbed of Râmnicu Sărat, is protected from river floods and much of it is grown. 36

5 Figure 5. Terrace 2-3m between localities Oreavu and Valea Râmnicului, Râmnicu Sărat river Between localities Valea Râmnicului and Măcrina has a fragmented appearance and can be located at several points (Râmnicelu,Stiubei), width is between meters. Downstream, up to Ciorăşti is surrounded by steep slopes between 4-10 meters heigt; its developments is evident in the sinuosity of the river where it has asymetricall character Câlnău river terrace Between locality Fundeni and the confluence with the Buzău river, Câlnău river terrace has tree levels: T1 (2-3 meters), T2 (6-8 meters), T3 (15-20 meters). Their development is mainly on the left side of the river, determined by the arrangement of Quaternary deposits north west to south east, asymmetric valley has a strong structural character. T15-20 meters occupies the largest areas in Râmnic Plain, plain surface contact is achieved by steep slopes of 20-25m height in the sector Fundeni-Suditi, to the south they are reduced to 15m (in the north of Poşta Câlnău) beyond wich contact is low marked in plain topography, transition to plain surface is slow on the line: Movila Poşta (167 meters) - Movila Mare (153 meters) - Movila Moroianu (137meters) - Movila Cojocaru (137meters). Figure 6. Digital terrain elevation model, view 3d Câlnău and Buzău terraces (near confluence Câlnău and Buzău rivers) 37

6 European road E 85 between road bridge over Câlnău river and north of locality Potârnichesti is located on the terrace surface (fig. 6). The width increases from north to south, so at Fundeni generally measured meters, at Aliceni meters, at Potârnichesti meters. Its structure can be followed into outcrops (Poşta Câlnău, Potârnicheşti) but also in the hydrogeological drilling at Potârnicheşti where it was intercepted cobbles and gravels (thickness aproximately 3meters) between 9,60-12,60 meters, is based on a yellowish clay (fig. 7). Figure 7. Hydrogeological drilling at Potârnicheşti, Romanian Waters (Directorate Buzău- Ialomiţa) Terrace surface has an absolute altitude wich decreases from 190 meters (Fundeni) to 120 meters at the intersection European road (E 85) with country road 203K (Focşănei-Jirlău) in the north of the locality Gura Câlnăului. Transition from negative vertical movements (in the north west of Râmnic Plain) to the slow rise movements determined juxtaposition aluvial cones in the lower course the Câlnău river (Rădulescu & Grumăzescu, 1962). The third terrace is sculpted into the alluvial cone, the altitude decreased to Buzău river, contact with surface of Râmnic Plain is less clear. Terrace 6-8 m can be observed near the confluene with the Buzău river, has a fragmented distribution on the left side of the Câlnău river. Starting from the north-east of the locality Gura Câlnăului (where is connected to the second terrace of Buzău river) its surface (where missing terrace 2-3 meters) is subject to strong erosion in sectors with banks concave. By comparing situation on the plans 1:20000 (1920), topographic map (1981) and ortophotomap (2005) by cutting a portion of the second terrace (located on the right) in the southern road bridge over river. This change is not natural but is result of antropic intervention wich followed channeling Câlnău river (Voicu, 2004). Terrace 2-3 meteres has discontinuos unfolding near the confluence Câlnău and Buzău river to Fundeni; large areas are near intersection European road (E85) with country road 203 K and western and south western locality Potârnicheşti (fig. 8). 3. CONCLUSIONS Râmnic Plain between Buzău and Râmnicu Sărat presents a relief influenced by the location in an area where there is contrary tendency regarding its vertical movements (positive movements in the western half and negative movements in the eastern half on the plain) wich is reflected and the overall patern of evolution hydrographic network. During the Holocene changes taken place of the courses along Râmnicu Sărat river and Buzău river in plain area, current valleys have two terraces (terrace 2-3 meters, terrace 6-8 meters on the Buzău river and terrace 5-6 meters on the Râmnicu Sărat), of wich for the most part on the river flood plain terrace is encountered, wich confirm the late fixing route in the lower course. Câlnău river beside the two menciond terraces has 38

7 developed and a third terrace in glacis Plain of Râmnic (T15-20 meters) wich is progressively lost in the plain, situation wich is found and the valley of Buzău river. Figure 8. Câlnău river terrace near intersection European road (E 85) with country road (203K) REFERENCES 1. Ielenicz M., 1968, Câmpia Buzăului, consideratii geomorfologice, Studii şi cercetări de Geografie, Bucureşti, pp Ielenicz M.,1988, Câmpia Vrancei, Analele Univ. Buc.,Geografie, Bucureşti, pp Polonic Gabriela, Zugrăvescu D., Toma I., 2005, Dinamica recentă a blocurilor tectonice din zonele de amplasament al construcţiilor hidroenergetice din Romania, St. şi cerc.de Geofizică, 43: 79-93, Bucureşti 4. Popp,N., 1963, Schimbari hidrografice in Câmpia Română de nord-est (Băraganul nordic), Meteorologia, Hidrologia si Gospodarirea Apelor, nr.1: 20-28, Bucureşti. 5. Rădulescu, I. & Grumăzescu H., 1962, Descifrarea mişcărilor tectonice din Cuaternar de pe teritoriul R.P.Române prin metoda geomorfologică, Probleme de Geografie, IX: 9-19, Bucureşti 6. Vâlsan G. 1915, Câmpia Română, Buletinul Societăţii Regale de Geografie, Bucureşti, pp Vişan, Gh. & Cârstea A., 1978, Câmpia Râmnicului-Consideraţii geomorfologice, Studii de Geografie, Bucureşti, pp Voicu, M., 2004, Bazinul Câlnăului, studiu de geografie fizică, Bucureşti, Teză de doctorat 39