water Article Evolution of Cretan Aqueducts and Their Potential for Hydroelectric Exploitation Triantafyllia G. Nikolaou 1,*, Ioannis Christodoulakos 2, Panagiotis G. Piperidis 1 and Andreas N. Angelakis 3,4 1 Organization for the Development of Crete S.A., 73100 Chania, Greece; [email protected] 2 Ministry of Culture and Sports, Ephorate of Antiquities of Chania, 73134 Chania, Greece; [email protected] 3 Institute of Crete, National Foundation for Agricultural Research (N.AG.RE.F.), 71307 Iraklion, Greece; [email protected] 4 Hellenic Union of Municipal Enterprises for Water Supply and Sewerage, 41222 Larissa, Greece * Correspondence: [email protected]; Tel.: +30-28210-29311 Academic Editor: Ashok K. Chapagain Received: 6 October 2016; Accepted: 28 December 2016; Published: 7 January 2017 Abstract: In this article, several archaeological, historical and other aspects of aqueducts in Crete, Greece, since the prehistoric times until today, are reviewed and presented. In Crete, since the Minoan era, various water management techniques that are found in modern water technologies were developed and applied. One of the most significant features of the Minoan civilization was the architecture of water supply systems in the palaces and other settlements. These technologies were continued and improved mainly during the Classical, Hellenistic and Roman periods and at the same time spread to other towns in the mainland and islands. The aqueduct technologies developed during the Classical and Hellenistic periods were further developed by Romans, mainly by enlarging their application scale (e.g., water bridges). Several paradigms of Cretan aqueducts are considered by which the significance of those technologies for water supply in areas with limited water resources is justified. A brief presentation and discussion of climatic conditions, the karst hydrogeology and the water resources management in Crete is also included. The article also describes the present water management profile of the island, in terms of the water plants, water supply–irrigation networks, and water renewable energy exploitation of dams and water pipelines. Keywords: aqueducts; Minoan era; Classical–Hellenistic periods; Roman–Ottoman period; modern times; hydroelectric exploitation 1. Introduction The Island of Crete is located in the eastern Mediterranean area and is characterized by low water availability due to the intense spatial and temporal variation of precipitation. The island is a rather mountainous region with three main mountains (i.e., White, Ida, and Dikti) which play an important role to the hydrogeology of the island [1,2]. Thus, the technology of transporting of water from the higher watersheds to the urban areas located in downhill areas with low water availability has been known since prehistoric times. The mean atmospheric precipitation ranges from 1800 mm in the mountainous areas of western Crete to about 300 mm in the southeastern coastal areas [3]. The Island of Crete was the center of Europe’s first advanced civilization, the Minoan [4]. In Crete, the earliest human settlements on the island date back to the Neolithic period (ca. 7000–3200 BC). However, Crete was the center of Europe during the Bronze Age when the Minoan civilization developed (ca. 3200–1100 BC), one of the most important civilizations of mankind and the first European civilization. At that time, several localities on the island grew to cities, which further Water 2017, 9, 31; doi:10.3390/w9010031 www.mdpi.com/journal/water Water 2017, 9, 31 2 of 19 developed into centers of commerce and craftsmanship. Minoan was peaceful and equal cultural society, characterized by Evans [5] as pax minoica (i.e., Minoan peace) a period that cities did not have walls. Thus, Minoans were concentrated to arts, cultures and technologies. One of the major achievements of the Minoans was the advanced water resources technologies developed in Crete at that time [6]. Archaeological and other evidence reveal that, in the Island of Crete since the Minoan times, various water management techniques (water networks; construction, exploitation and use of surface water; sanitation; and irrigation), that are found in modern scientific fields of water resources, waste water and hydrology of groundwater, were developed and applied. Angelakis et al. [7] suggested that the advanced water distribution systems in Minoan “palaces” and other settlements located in areas of pure water sources, i.e., aqueduct technology, was originally developed by Minoans (e.g., Knossos, Malia, Gournia, Tylissos and Mochlos). In the structures of most Minoan palaces and towns are remarkably complex and highly functional water supply systems. Thereafter, aqueducts were used by the Mycenaens in continental Greece. These technologies were continued and improved during Classical and Hellenistic Crete (ca. 490–67 BC) and Roman (ca. 67 BC–330 AC) periods and at the same time spread to other towns in the mainland and islands. Typical examples are the aqueducts, cisterns and other water supply plants in Polyrrhinia, Eleuthera, Falassarna, Elyros, Chersonisos, Lyttos, Gortys, Minoa (Marathi), Kissamos, and other sites [8–10]. Nowadays, the bodies related to water in Crete are: the Direction of Water of the Decentralized Administration of Crete; the Organization for the Development of Crete (OAK, sa), which has continued to be active in the water infrastructures and networks since 1979; and municipalities and research institutes, which are responsible for the optimal implementation of the approved Water Management Plan of Crete, in terms of the development, construction and improvement of water plants and networks, in order to meet the water needs in Crete in the most efficient and environmentally friendly way [11,12]. In this article, several characteristic examples in selected archeological sites that chronologically extend from the prehistoric times to the present times are presented and discussed. By those examples, the evolution of the aqueduct technology on the Island of Crete through its long history is presented. In addition, some of significant recent renewable energy projects, based on water exploitation, are presented in the article, pointing out another significant role of water resources in “green development” [13–15]. The article is organized as follows: In Section2, the historical variation of climate of Crete, as well as the water resource status is presented. Section3 deals with presentation of the characteristics of major aqueducts in Minoan Crete. In Section4, the known aqueducts in Crete from the Classical and Historical periods and Roman period are presented. Section5 refers to Byzantine period, while Section6 deals with the modern times, focusing on present large hydraulic infrastructure like dams, reservoirs, water treatment plants and the water supply–irrigation networks in the Island of Crete. In Section7, some renewable energy projects that are based on the exploitation of water infrastructures and networks are analyzed and presented. Section8 summarizes the historical evolution of Cretan aqueducts and indicates the most significant future water measures that have to be planned for the most efficient exploitation of water resources on the Island of Crete. 2. Physical Settings Crete is a mountainous island in the eastern Mediterranean, located in the southern part of the Aegean Sea, separating the Aegean Sea from the Libyan Sea. Crete, the largest Greek island and the fifth largest in the Mediterranean, washed North from Cretan Sea and south of the Aegean Sea, located 160 km south of the Greek mainland, is the southernmost border of the EU and is surrounded by numerous small islands (Gavdos, Gavdopoula, Golden, Koufonisia, Dia, Dionysases, etc.), which are uninhabited, except the island of Gavdos. The total area of the island is 8335 km2. It is 260 km long, with width ranging from 12 to 57 km and a coastline of 1306 km (including the islands) [11,12]. Water 2017, 9, 31 3 of 19 Water 2017Crete, 9, forms31 an important bridge between Europe, Asia, and Africa. The unique geographical3 of 18 position of Crete in the eastern Mediterranean basin has determined its historical course throughout Inthe addition, centuries. more The than total 4.5 population million tourists of Crete visited is 623,065 Crete or in 5.8% 2013. of A the further total increase population is expected of the country. in the comingIn addition, years more [16]. than 4.5 million tourists visited Crete in 2013. A further increase is expected in the coming years [16]. 2.1. Climate of the Island of Crete 2.1. Climate of the Island of Crete In eastern Mediterranean, and especially in the Island of Crete, climatic fluctuations during the last 10In thousand eastern Mediterranean, years were recorded and especially [17]. These in fluctuations the Island of show Crete, increasing climatic fluctuations and decreasing during cycles the oflast climatic 10 thousand conditions years werealternating recorded chronologically, [17]. These fluctuations lasting from show a increasing few decades and decreasingto over centuries. cycles of Recently,climatic conditions Markonis alternating [18] summarize chronologically, all available lasting sources from and a few presented decades to a overpicture centuries. of the Recently,climatic variabilityMarkonis [in18 ]the summarize eastern Mediterranean all available sources and more and specifically presented ain picture Crete during of the climatic the last variability10 thousand in yearsthe eastern which Mediterranean showed alternating