Basic Physicogeographical Characteristics of the Rava Island in the Zadar Archipelago

Abstract

The island of Rava (3,62 km2 and 120 inhabitants, 1991) is one of those small islandssituated in the Zadar archipelago, on the eastern coast of the Adriatic. From the geographical point of view it has not been much elaborated so far. The paper gives physicogeographic characteristics, which is connected with the project on small Croatia’s islands. The first part of the paper treats the position of the island, its size and extent. According to its area, this is the 53rd island in Croatia,and the 37th with regard to the number of inhabitants (1991). The highest point is Babićovac (98m). The sea cliff of Ravica appertains to it. The island makes part of the middle range of Zadar islands and, administratively, belongs to the city of Zadar. It is an autonomous cadastral commune and Roman Catholic parish. The settlement consists of two separated nuclei along SW coast: Vela Rava in the central part of the island and Mala Rava in its NW part. Its geological structure is relatively simple. There is a predominance of nonlayered greyish lower-upper cretaceous dolomites, to 600m thickness. These are the oldest sediments in the Zadar archipelago. Their form is anticlinal. There are two smaller unexamined speleological objects in the NW part of the island. The island is well carved. The coast is 15.45 km in length. The coastline index is 2,29. There are many more coves and promontories in the central and SE parts. Larger coves are Lokvina, Vićabok, Paladinjica, Marnjica, Tanko, Vališina, Ivanoševica, Pavajsko, Pestehovac, Dražice, Golubovac, Martinjica, Grbavač and Grbačina. Relief features show dry dolinas and torrents with well expressed slope drainage and weathering. Along the coastthere is a shallow zone (1,5 m deep, called singular) large several metres, followed by deeper waters. There is a small number of flat superficies, which are used as gardens, while slopes serve for olives and less often as vineyards. The island surfaces are divided into properties by horizontal stone walls (mocira) and vertical ones (trmezal). The authors emphasize a numerous and interesting toponimy connected with the terrain geomorphology. From pedological point of view there are not remarkable soil zones. It is a question of shallow and poor reddish-brown soils originated from degraded dolomites. There is plenty of rocky soil and broken stones. There is no superficial running water on the island. There are several wells with brackish water, and potable water is found in a 40 metres deep pit on the nearby islet of Mrtovnjak. There is also a Pool in Vela Rava. Because of water deficiency, the inhabitants have built public cisterns in both settlements and the owners of new houses have their own cisterns. The authors study in particular the sea water surrounding the island. Physical properties of the sea (depth, sea bottom, temperatures, density, transparency, colour, currents, tides, waves) are elaborated in accordance with accessible data. Chemical characteristics follow (salinity, oxygenconcentration, pH factor, the quantity of silicate, phosphate and nitrate, ammoniac) and biological data (organic world: plankton, nekton, benthos). Climatic indicators connected with insolation, global radiation and cloudness are elaborated. Temperature data follow (annual t. ca 15oC; ca 23,5oC in July and ca 6,8oC in January), precipitation (ca 880 mm per annum), winds. Mediterranean climate conditions adequate vegetation. The island of Rava belongs to the climazonal association of holm oak (Quercus ilex). Mediterranean sorts are numerous. The present day high and low maquis and garigues predomine and, here and there, even larger specimens of trees grow. It is significant that cupresses can be seen on certain locations. The paper ends with elaborating the significance of physicogeographical basis for the social and economic development of the island. Consideration is given to the population since the oldest times of Mediterranean polyculture. Cultivation of olives, figs and grape vine (the latter till not long time ago) has considerable importance as well as breeding small cattle. Restrictive factors of development (lack of water and fertile soils, isolation, depopulation) are analysed too. The influence of regional centre Zadar is also important, as well as the prospects of tourist and aquaculture objects.