Geogaphica Timisiensis, vol. 19, nr.1, 2010 (pp. 371-386) ● THE ROLE OF THE ANTHROPIC FACTOR IN THE FORMATION AND EVOLUTION OF WATER RESOURCES IN THE EASTERN PART OF ROMANIA. CASE STUDY: BAHLUI DRAINAGE BASIN IonuŃ MINEA, IonuŃ VASILINIUC University „Al.I.Cuza” Iaşi Abstract: Anthropic activities have, mainly in the last decades, a main role in the formation and evolution of water resources from Bahlui basin. Land use, the construction of reservoirs (used in different purposes) and ponds or enclosures, flood control works, dams and bank consolidation, land improvement or water alimentation, to which adds the settlements and transportation networks, have decisively hall-marked the formation of surface and underground water resources, their quality and regime, Bahlui hydrographic basin being considered one of the most (hydrologically) human- managed basins from the country. Rezumat: Rolul factorului antropic în formarea şi evoluŃia resurselor de apă în partea de est a României. Studiu de caz: bazinul hidrografic Bahlui. ActivităŃile antropice au, mai ales în ultimele decenii, un rol primordial în formarea şi evoluŃia resurselor de apă din bazinul Bahlui. Modul de utilizare a terenului, construcŃia de lacuri de acumulare (utilizate în diferite scopuri) şi iazuri sau incinte piscicole, lucrările de regularizare, îndiguire şi consolidări de maluri, de îmbunătăŃiri funciare sau cele legate de alimentarea cu apă (a populaŃiei şi zonelor industriale), la care se adaugă reŃeaua de localităŃi şi căi de transport, şi-au pus amprenta decisiv în formarea resurselor de apă de suprafaŃă şi din subteran, în calitatea şi regimul acestora, bazinul hidrografic Bahlui, fiind considerat unul dintre cele mai „antropizate” bazine (din punct de vedere hidrologic) din Ńara noastră. Keywords : water resources, hydrographic basin, evolution, management Cuvinte cheie: resurse de apă, bazin hidrografic, evoluŃie, management 1. INTRODUCTION In Romania, Bahlui basin is situated in the north-eastern part, covering an area with central-north-eastern position in the Moldavian Plateau, entering the hydrographic system of Middle Prut River (Fig 1). In this idea, Bahlui is a right tributary of Jijia, in its sector of common floodplain with Prut. This situation gives Bahlui basin a certain genetic, evolutional and hydrological autonomy in relation to those of Jijia and Prut, manifested during time and in the mode of water resources’ formation and evolution, as well as in the role of the human factor in their management. 372 ● The role of the anthropic factor in the formation and evolution of water resources Fig. 1 The geographic position of Bahlui basin in Romania PoziŃia geografică a bazinului hidrografic Bahlui în cadrul României Being considered one of the most human-managed basins in the country, 71% hydrotechnically managed ( Savin Nicoleta, 1998), Bahlui basin may be considered as model in the efficient management of water resources in the eastern part of Romania, model that may be extended at the level of the entire space between Prut and Siret. In this sense we had in view the analysis of the human factor’s impact in the formation and evolution of water resources in this basin, by closely monitoring: land use, the formation of reservoirs and ponds, the realization of some hydrotechnical works (regularization, damming, bank consolidation), of land improvements or of those regarding water alimentation (of population and industrial areas), to which add the settlements and transportation networks. 2. LAND USE The socio-economic activities have led to changes in the geographical landscape from Bahlui basin through the process of terrains’ agricultural use, through the action of development and industrialization of the human settlements and transportation’ networks. The changes induced in the landscape influence directly or indirectly river discharge and the hydrologic balance at the level of the entire basin. The agricultural use of the terrains produced most and the profoundest changes in the landscape of Bahlui basin. Analyzing the structure of the land use fund at the level of year 2000 (Fig. 2) we see that arable terrains occupy over 35% of the basin, followed by pastures (17%) and forests (14%). A high percentage is detained by agriculturally complex- used surfaces (10.5) and by settlements (9%). IonuŃ MINEA, IonuŃ VASILINIUC ● 373 The effect of this distribution is manifested on field through the intensification of erosion processes at the level of high slopes, where the soil cover is gradually removed, fact that favors the increase in the flash flood potential of small rivers and in the solid discharge (fig. 2 a and b). Fig. 2 a Main land use types in Bahlui drainage basin in 1984 Principalele tipuri de utilizare a terenului în bazinul hidrografic Bahlui în 1984 Fig. 2b Main land use types in Bahlui drainage basin in 2000 Principalele tipuri de utilizare a terenului în bazinul hidrografic Bahlui în 2000 In the present study we tried to evidence the changes brought in the structure of land use in the last 30 years. In this idea we departed from the topographic maps scale 1:25.000, edition 1984, as well as from a series of Landsat TM satellite images from 2000. 374 ● The role of the anthropic factor in the formation and evolution of water resources We applied the methodology proposed by European Environmental Agency in the analysis of terrain utilization in the Corine Land Cover projects (with certain modifications), identifying 10 main classes of land use. The classes identified have been extrapolated to the entire succession of topographic maps, satellite images and aerial photos. The statistical data obtained regarding the distribution of areas with different land use at certain time intervals allowed for a spatio-temporal analysis at the level of the entire basin. At the same time have been obtained a series of correlations between the different land use categories, terrain altitude and slope declivity, from which conclusions were drawn regarding land use improvement. Analyzing the evolution of land use categories at the basin level during the last 30 years, we notice a different spatial dynamics of surfaces occupied by settlements. Their increase occurred in the disadvantage of quasi-natural surfaces, mainly of those with hygrophille vegetation (very many constructions have been emplaced in the floodplain of Bahlui, mainly after 1990, but also of its tributary Nicolina). This dynamic was accentuated during 2000-2009, when this sector took a special impetus. As a consequence of the implementation of Law 18/1991, increased also the percentage of surfaces occupied by arable terrains (less in the case of complex agriculture) and of pastures, in the disadvantage of those occupied by forests (that suffered a decrease of over 2500 ha at the level of the entire basin), orchards and vineyards or areas with hygrophille vegetation. After Romania’s adhesion to the European Union in 2007 and the realization (in the future) of some programs /projects of territorial planning on the basis of European funds, there is the possibility of modifying the spatial structure of use categories by restraining the fragmentation degree in the case of agricultural terrains, and through a better monitoring of the extension in constructed areas. At the level of 2000, with altitude (Fig. 4) may be seen an accentuated diminishment of agricultural surfaces. The positioning of Bahlui basin at the contact of three physico-geographical sub-units of the Moldavian Plateau: Jijia Hilly Plain (under 150 m) and Sucevei Plateau in west, and respectively “Coasta Iaşilor” to south (over 150 m altitude), leads to a situation where agricultural terrains have a large extension between 35 and 200 m. In the same span enter also pastures, which often are emplaced on the cuesta fronts affected by geomorphologic processes ( Cojocaru, 2008). Areas occupied by forests have a high percentage at altitudes over 200 m, where occur natural forests specific to the Moldavian Plateau (in which dominate associations of Quercus and Fagus). Under this limit, these areas occur rarely, being in fact forestry plantations of fir and acacia, with role in slope protection. IonuŃ MINEA, IonuŃ VASILINIUC ● 375 bazinul / Utilizarea terenului, la nivelul anului 1984, în hidrografic Bahlui Fig. 3 Land use in 1984 in Bahlui drainage basin 376 ● The role of the anthropic factor in the formation and evolution of water resources zinul hidrografic Bahlui Utilizarea terenului, la nivelul anului 2006, în ba Fig. 4 Land use in 2006 in Bahlui drainage basin/ If we have in mind the distribution of land use classes according to slope, we notice in general that all classes occupy surfaces that increase progressively disregarding the slope (with the exception of the areas with slopes over 18 0, where may be found patches of IonuŃ MINEA, IonuŃ VASILINIUC ● 377 forests with role of protection and for grazing, which cover the cuesta foreheads of high declivity), respecting the percentage they have in relation to the basin’s total surface. The same situation is found when correlating land use classes with slope exposition, when only the presence of forests (the same protection plantations) on certain slopes of western or north-western exposition does not respect this rule, due to the forestations conducted on cuesta foreheads. Fig. 5 Distribution of land use types in 2000 according to altitude classes DistribuŃia utilizării terenului, la nivelul anului 2000, în funcŃie de clasele de altitudine Fig. 6 Distribution of land use types in 2000 according to slope classes in Bahlui basin DistribuŃia utilizării terenului, la nivelul anului 2000, în funcŃie de clasele de pantă 378 ● The role of the anthropic factor in the formation and evolution of water resources 3. RESERVOIRS AND PONDS In Bahlui basin have been realized a series of direct interventions on the hydrographic network and the regime of river discharge. These interventions have an organized character and had in view the realization of: - reservoirs with multiple utilization; - impermanent accumulations for attenuating flood waves and protection against inundations for urban and industrial areas (polders).