THE EVOLUTION OF THE AREA BETWEEN VALEA CHINTĂULUI AND VALEA CALDĂ FOLLOWING THE WORKS MITIGATING SOIL EROSION

Abstract

The study area is located on the left slope of the Someșul Mic River, in the northern part of Cluj-Napoca and is bounded on the north and east by the watershed that separates it from the Valea Caldă River basin, south of the agricultural road that separates the slope from Someșul Mic floodplain and west of the orchard border. The area is called Sfântu Gheorghe Hill, the homonymous peak bordering it to the west, and Țigla Hill to the east. In 1986, the Institute for Studies and Design for Land Improvements implemented a plan to mitigate soil erosion on an area of 600 hectares within the mentioned limits. Of these, 300 hectares represented the arrangement of terraces, 200 hectares the arrangement of landslides and 100 hectares of drainage on slopes. The execution of the works mitigating soil erosion aimed at reducing the annual soil losses, the possibility of applying appropriate agrotechniques in the fruit plantations to be established. The arrangement of the slippery surfaces was done by modeling, eliminating the excess moisture, terracing, grassing or planting and had the purpose of bringing significant areas of land back in the economic circuit. Elimination of excessive water through drains was made for the proper development of future tree plantations. The purpose of this study is to analyze the temporal evolution, over a period of 30 years, of the efficiency of the arrangement works on the slope performed in 1986, first of all. The estimation of the effectiveness of the works executed at that moment was made by the comparative morphometric and morphological analysis of the landslides and the forms of deep erosion on the slopes. Second, the study examines the vulnerability of landslide risk factors in this area, in particular residential and public buildings, road infrastructure and agricultural land. The study starts from the following premises: the geomorphology of the southern slope of Sfântu Gheorghe Hill has been studied over time, as attested by bibliographical sources; 30 years ago, the destination of the lands related to the area was mainly agricultural, and the land use plans included mainly measures for agricultural development; in recent years, there has been an accelerated expansion of Cluj-Napoca, including on the northern slope of Someșul Mic, both from the base of the slope to the watershed, and along the base of the slope, to the eastern outskirts of the city. The questions that arise are: how did the landslides evolve and how did the slope evolve after the development carried out in 1986? How many of the built elements are located in areas with acceptable risk and how many are located in areas with high risk in terms of slope stability?