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Study area

Climate

Meteorology

This chapter offers a short overview the annual precipitation data received in July 2017 by the Department of Agricultural Development and Veterinary of Samos district.

We concentrate on data of 2 meteorological stations as indicated below:

Meteorological station X in EGSA 87 Y in EGSA 87 X in WGS 84 Y in WGS 84 Elevation (m)
I. Myloi 753643.257 4174071.479 37.681352 26.877926 20
II. Airport 756883.443 4175132.323 37.690000 26.915000 6

Main statistics for each station are indicated below:

Myloi Airport
count 43 37
mean 868.64 698.15
std 251.22 207.44
min 450.10 333.60
25% 680.35 596.40
50% 839.90 661.00
75% 1030.90 795.20
max 1381.10 1268.30

When plotting these data-sets we can follow the trend of decrease of precipitation in the Aegean, as well as the overlap of data.

For further analysis please check here.

rainfall_4_meteostations_samos_01.pdf

Geology

The island of Samos is located on the eastern edge of central Aegean. It’s shape is elongated with maximum axis E-W, a surface of 476 km2 and a coastline of 120 km 1) [Dies ist nur ein Test, des Zitiermechanismus mit 'refnote'].

Its main mountains are Kerketeas (1.433 m), in the west part of Samos, Ampelos (1.150 m) located at the central part of the island and Zoodochos Pigi (433 m) in the eastern part. These mountains are separated by the two main neogene basins of Karlovassi and Mytilini.

Fig. 1: Physical map of Samos with main mountains and basins (Used basemap under the licence OpenStreetMap contributors)

The metamorphic cluster of Samos belongs to the west border of the Menderes Massif and is divided in 4 tectonic sections the Kerketeas section, the Ampelos section and the Vourliotes section, which mainly consist of marble, phyllites, mica schist and the Agios Ioannis section, which interjects a tectonic wedge between the Kerketeas and Ampelos sections. The Agios Ioannis section consists of metamorphic igneous rocks. The only non metamorphic section is the Kallithea section, which lies on the northern steep side of the western part of Samos. It consists of spilites, diabasic, chert and Triassic- Jurassic limestones.

During the Neogene, Samos and western Anatolia belonged to an extended terrestrial area that was periodically connected to Euboea and Attica. Both the neogene intermont basins of Karlovassi and Mytilini follow a parallel development under the continental conditions of sedimentation. Two fluvial-lacustrine sedimentation periods can be identified, separated by a shorter phase of uplift and erosion. Both basins consist of a lower Neogene series of lacustrine deposits, tuffs and tuffites, followed by an interstitial clastic series of terrestrial and torrential deposits and, finally, a younger Neogene series of lake-water deposits. For both basins, sedimentation begins during the Middle Miocene and extends during the Neogene.

Further on, there are four deformation phases of the metamorphic formations. The first phase takes place during the Upper Eocene - Lower Miocene in a direction of N 60° - 80°, while the next three phases, in a direction of N 110° - 130°, N 150° - 190°, originate in the Middle-Upper Miocene and Pliocene. There exists a phase of compaction which is contemporaneous with the sediment of the lower clastic series. In addition, there is a tension phase of Paleocene – Pleistocene origin.

Fig. 2: Geological map of Samos (Theodoropoulos, Bornovas, Apostolides, IGME,1979

The following geological formations belong to the Quaternary period:

Sliding area

Coastal deposits (cd,dn): sand and sand dunes

Alluvial deposits (al2): plain deposits of clayey-sandy material, loam, sand, pebbles, gravels. Recent material of sand and gravel at torrent beds and torrent terraces 1-3 m.

Small interior basins alluvial deposits (al1): of fine material, terra rossa with grits and coarse torrential material.

Recent scree and talus cones (sc2,cs2): of various angular fragments, unconsolidated or weakly cemented with clayey-sandy matrix.

Weathering of the surrounding rocks eluvial (el).

Old scree and talus cones (sc1,cs1): of strongly cemented agglomerate and red fine-grained material, at places. These formations are commonly intersected by faults (area of Mortia bay).

Torrential terrace: about 10 m., loose, clayey sand with pebbles and intercalations of cohesive conglomerates.

The following geological formations belong to the Neogene period:

Mytilini basin

Upper series of Mytilini basin formations (pl.km2): lacustrine limestones, travertine-like and in places marly, medium to thick-bedded, sometimes pseudoolithic, whitish to gray and sometimes yellowish, with lenticular intercalations of loose marls, loam and tuffitic bodies, enclosing disperse pebbles. At places, pure conglomeratic breccia intercalations, generally of small thickness. These formations overlie the clastic series of Mytilini which enclose the known Pikermian fauna of Mammals. Their thickness is approximately 250 m and they are younger than Pontian, certainly Pliocene in regard to the dating.

Clastic series of Mytilini basin (M4,c2 - km): fluvial-lacustrine deposits, consisting of alternating beds of medium cohesiveness, breccia, conglomerates, grit, red and yellowish loam, clays and tuffs with intercalations locally, of sandy marls and sometimes of marly limestones (km), in the upper members of the series. The pebbles and fragments are from volcanites, marls and marly limestones of the lower series of the Neogene formations. Pebbles and fragments of crystalline rocks participate, at places. The size varies not exceeding 10 cm. Rare fragments up to 50 cm. Generally the size of pebbles and gravels is larger at the middle sections of the series. The maximum deposits thickness is estimated at about 400 m. NE of Mytilini village, at “Tsarouchis” site of “Stephanidis” torrent, within the fluvial-lacustrine sediments and tuffs of the upper half of the series, the known Pikermian Mammal fauna of rhinoceros, monkeys, antilopes, Hipparion a.o. has been found. Some representatives of this fauna are: Hipparion proboscideum (STUDER), Hipparion dietrichi, Hipparion matthewi, Palaeotragus, Samotherium boissieri, Criotherium, Palaeoryx, Machairodus aphanistus, Mastodon pentelici, Dinotherium, Dicerorhinus orientalis, Struthio karatheodoris.

Lower series of Mytilini basin formations (M.(k,m)2): lacustrine, medium to thick-bedded, travertine-like limestones and whitish to yellowish, thin-bedded marls, generally of monotonous sedimentation, with intercalations of read loam and gray or greenish clay and beds of tuffs and tuffites. The thickness of this series is quite significant. Generally, the clastic materials are absent or they occur scarcely. The sediment of this sequence are folded very intensively and occupy the western part of Mytilini basin as well as the areas Pagonda and Pyrgos. Generally, at Pythagorion area dominate thin and well-bedded, hard marls and marly limestones. The marls of the upper members of the series are thin-bedded to foliated (1-5 cm). Many times in the lower part of this series basaltic lavas are intercalated accompanied by tuffs as sills within the sediments. Sometimes, in the vicinity of the lavas the lacustrine sediments are silicified as it can be seen in Pyrgos area. Locally, the sediments of the series enclose plant relics, mainly parts of Hydrophytes. The maximum thickness of the series is estimated at about 650 m. The age is Miocene, as it is concluded from the age of the overlying clastic series which include the known Pikermian fauna.

Karlovassi basin

Upper series of Karlovassi basin formations (pl,km1): the formations of this series are found, mainly, in the area between the public road of Karlovassi - Bathi port and the coast, overlying comformably the clastic series of Karlovassi basin. They consist mainly, of marly and travertine-like, lacustrine limestones with intercalations of low cohesion marls, sometimes enclosing disperse pebbles. The above formations are very possibly analogous to the formations of Mytilini basin, with a thickness of about 120 m. The age is probably Pliocene.

Clastic series of Karlovassi basin (M4,c1): the typical formations appear at the area of the village Hydroussa (formerly Fourni). It is also found in Pyrgos area. It consists of fluvial-lacustrine deposits overlying comformably the lacustrine sediments of Karlovassi lower series and discomformably the marly limestones of Pyrgos area. Possibly they are deposits analogous to the clastic ones of Mytilini series. They are mainly conglomeratic-breccia unbedded, of low cohesiveness, with pebbles and fragments from volcanites, Neogene marly limestones, metamorphic rocks, as marbles, quartzites, and schists varying in size from 1-10 cm. and sometimes to 30 cm, generally without orientation. Many times the conglomeratic-breccia alternate or pass laterally to finer detrital deposits of grit and sandstones with a marly matrix. Locally, sandy marls and red loam with disperse grits and pebbles within them, are also found. The thickness of this series fluctuates between 50-200 m. in Karlovassi basin area and it is about 150 m. at Pyrgos area. Its age is probably Pontian.

Lower series of Karlovassi basin:

Hard marls (M.m1) whitish, gray or yellowish, well- and thin-bedded or sometimes foliated, (beds of a thickness 1-5 cm.), alternating with friable once, with intercalations of clays, sandy marls, breccia with components from the Neogene sediments and of conglomerates. Also, bedding of fine tuffic material and tuffites of brown or greenish colour can be found within the whole series. Many times these sediments are folded. Folds with fold axis striking N 30° E have been observed. Maximum thickness is estimated at about 400 m.

Travertine - like, thick - bedded limestones (M.(k,m)1) locally with tuffic materials, they constitute the lateral transition of marls of the lower series of Karlovassi basin formations. Sometimes, they also occur as intercalations within the marls. Their thickness at Skoureika village area exceeds the 150 m. Age is Miocene.

The following formation (prc1) occurs within Karlovassi basin and consists of:

Pyroclastic material consisting mainly of rubbles deriving from Neogene sediments, volcanites and from the rocks of the metamorphic basement with fine tuffitic material. Unbedded, of low cohesiveness and at places opalized.

Silicified Neogene sediments of marls and manly limestones of the lower Karlovassi basin series.

Silicified conglomeratic breccia red coloured, of the Neogene sediments base, constituting the sheer area above Kontakeika and Hydroussa villages, sitting on the metamorphic system.

Volcanic bodies of small size, not separated during the geological mapping.

Small deposits of saponites (clays), deriving from the metavolcanic hydrothermal action. Maximum thickness of the formation, about 200 m.

The age of this formation is probably Miocene, as indicated by the fact that these formations are found with the lower sediments series of Neogene, the age of which has been already accepted as Miocene.

Silicified sediments ((m,mk)1): of marls and manly limestones of the lower series of Karlovassi basin. They commonly occur in the vicinity of volcanites from which they cannot be distinguished.

Paleocastron basin

Medium to thick-bedded, travertine-like limestones (M.k→tv), with intercalations of marls and loose, fine material. They constitute the upper and partly the lateral transition of the above mentioned marls. Their thickness is estimated at about 80 m and their age is probably Miocene.

Marls of low cohesion (M L-m.m), mainly sand-bearing, with disperse pebbles-rubbles, alternating with tuffs and tuffites. Sometimes with intercalations of conglomerates. Generally they constitute the lower members of the basin’s Neogene formations and their thickness varies from a few to about 50 m.

Conglomerates of the Neogene sediments base (Ng,c) of fluvial-terrestrial origin, commonly red-ruby colored, consisting totally of pebbles from metamorphic rocks mainly from quartzites, marbles and schists. Generally the pebbles have small rounding and varying size reaches 30 cm. The matrix is clayey-sandy and it participates in a small percentage. Their maximum thickness is about 75 m.

Volcanic rocks: occurring, mainly, in the eastern and western side of Ampelos mountain, which coincide with the tectonic lines of Karlovassi and Mytilini Neogene basins, either within the lower series of Neogene sediments as sills, or intersecting or overlying the crystalline rocks. They are mainly basalts, rhyolites, trachites and dacitoids. These volcanites have created the genesis of one disperse but very extensive mineralization of sulfid mixed ores (mainly galena). Volcanites have been noticed at western piedmonts of Karlovassi basin and at Pyrgos area. The age of volcanites is probably Miocene. This is concluded from the fact that many volcanic masses are intercalated in the lower series of Neogene sediments, the age of which is accepted as Miocene.

Volcanic tuffs (tf): basalt tuffs overlying the great basalt mass, that occurs as sill within the lower series of Neogene sediments of Mytilini basin. They mainly consist of fine material, unbedded or partly bedded often mixed with sediments. Locally they are intersected by veins of Fe-oxides. Their thickness is estimated at 15-30 m.

Nappe sequence

Upper Triassic - Jurassic limestones (Js.k): commonly they are sitting on the horizons of basic intrusive rocks of Kallithea-Drakea area, with which they overthrust, very possibly, the metamorphic system. At the base they are white or rose, unbedded, fine-crystalline and generally strongly tectonized. At higher stratigraphic positions, they locally pass to dolomitic, compact to fine-crystalline, strongly karstic, bituminous, medium — to thick — bedded, gray — black gray and sometimes ankeritized limestones. Around Kallithea village, they enclose Megalodon sp., of a size up to 12 cm. which is of upper Triassic age. In these limestones have also been found not determinable Lamellibranches and Gastropods, and in thin sections Ostracods and Radiolaria. Also in thin sections of samples, taken from the upper parts of this limestone horizon, have been found Valvulinidae of Jurassic age. Their maximum thickness is estimated at 150 m.

Basic intrusive rocks (σπ,δ): great masses of submarine extrusions (pillow lavas), mainly of spilites and diabasic type rocks, in greenish or red-ruby color, commonly widely altered and locally schistose. Generally, these rocks show a secondary pseudobedding and only in few cases are unbedded. Often limestones and sandstones of small thickness are intercalated within these rocks. In thin sections of the limestones a microfauna of Middle- Upper Triassic age has been found. The age of submarine extrusions is determined also by this microfauna : Ostracods, Radiolaria, small sized Gastropods, fragments of macrofossils, Involutina sp., Codiaceae, I)iplopora sp., Thaumatoporella sp., Frondiailaria. The thickness of the basic intrusive rocks is estimated about 250 m.

Peridotitic mass (π) of limited dimensions, appeared within the elastic sediments of the overthrusted series. It is a fairly preserved peridotite with easily distinguished pyroxenes.

Clastic rocks (st): small outcrops of sandstones at the base of the overthrusted basic intrusive rocks of Kallithea-Drakea villages, area. The sandstones are fine to medium — grained, with intercalations of coarse-grained ones and grits. Maximum observed thickness about 50 m.

Metamorphic system

Zoodochos Pigi marbles (mr4- sch.mu): occurring at the eastern part of the island, overlying the schists of Kotsikia-Psili Ammos. They are, commonly, medium to thick- bedded and locally thin-bedded, mainly at their upper parts where they pass into cipoline marbles, light gray to gray-black and sometimes white or gray-black, fine-crystalline and locally coarse-crystalline, sometimes with intercalations or lenses of chert. Many times the marbles enclose intercalations of dolomitic marbles and schists (sch.mu), mainly micaschist through out their stratigraphic range. In some cases the thickness of these intercalations reaches 50 m. In the lower parts of the marbles deposits of emery occur. The maximum observed thickness of Zoodochos Pigi marbles reaches 500 m.

Kotsikia – Psilli Ammos schists (mr,sp-sch3): mainly chloritic, muscovite schist, sericite, quartz schist and calcareous schist, alternating vertically and passing laterally from the one lithological type to the other, with intercalations of quartzites. Many times within the schists, occur intercalations of marbles, cipoline marbles (mr), ankerites and in one case intercalations of breccia marbles (Kotsikia area) 10 m. thick. Sometimes they are strongly folded with strike of folding axis N 65° E. Maximum visible thickness about 400 m located at Psilli Ammos area.

Vourliotes - “Syrrachos” marbles (sch.mi-mr3): they constitute, almost totally, the eastern side mountainous block of the central island section and the SE area of the eastern island section, where the tectonic horn of “Syrrachos” occurs. Their thickness, at the eastern part of the central section of the island, exceeds the 1.000 m., but at “Syrrachos” area reaches about 400 m. (visible thickness). The precise stratigraphic correlation of the marbles between central and eastern island sections is not possible because of the intercalations of the Mytilini Neogene basin sediments. However, it is accepted that these marbles are of the same stratigraphic sequence and that “Syrrachos” marbles constitute the upper members of it. These marbles in central section area are generally light-colored, usually gray-white, medium- to thick- bedded, fine-crystalline, often saccha-roidal, very commonly dolomitic, partly karstic and microfolded, with strike of folding axis N 50° E. In the eastern section area, they are whitish to gray-white, well - and medium - bedded, medium-to coarse- crystalline with local chert intercalations. In these marbles and mainly in the marbles of the island's central section there are many intercalations of schist (sch.mi) mainly mica schist, with a considerable eventually thickness.

Ampelos marbles (mr2): they occur as intercalations or great banks of various thickness, within the schists of Ampelos. Various colored as whitish, light gray or dark gray, fine — and sometimes coarse — crystalline, medium-bedded, partly karstic. At Spatharei area, where their thickness exceeds 300 m., they are medium to coarse-bedded, gray-white or gray and at the tower members, black-gray. Many times, they are dolomitic and sometimes pure crystalline dolomites. In some cases intercalations of breccia-marbles occur e.g. between Dendria and Platanos area. Generally their thickness increases and decreases rapidly, with synchronous lateral passing to cipolines and calcareous schists. Commonly, they are strongly folded and faulted.

Ampelos schists (sch2): they constitute the larger part of island's central section and more or less the upper extension of the Marathokampos-Kosmadei schists, of western island's part. They have various mineralogical composition, as mica schist (where muscovite dominate in relation to biotite), muscovite schist, quartz:muscovite schists and quartz schists. Epidote amphibolites, chloritic schists, epidote-muscovite-glaucophane schists, hematite schists and phyllites, also occur within them. Locally there are found intercalations of ultramafic igneous rocks, often schistose (Myli village area). Sometimes quartz-schists and quartzites with a thickness exceeding 100 m. in cases, dominate within the schists (Western side of Ampelos mountainous block). Total thickness of Ampelos schists is more than 2.500 m.

Ampelos schists with many small volcanic bodies, not mapped (vol-sch2). They occur around the great volcanic mass of Ampelos village. Small volcanic bodies existing within schists of the area. Frequently within the schists, big sized garnet crystalls occur. Also, many mineral occurrences (mainly of pyrite and galena) are outcropping, which must become subject of further research.

Peridotites – serpentines of island’s central section (σ) generally small sized bodies as sills within the Ampelos schists. Locally, they are schistose and many times serpentinized. These ultramafic masses enclose sporadic asbestos veins of small thickness been in the past, subject of small exploitation (mining).

Ophiolite rocks (ο): ophiolitic masses within Ampelos schists, partly schistose, usually gabbro-type.

Marbles of Kerketeas’ piedmonts (mr1): they occur either overlying on Marathokambos- Kosmadei schists of island's western section as distinguished horizons of about 200 m. thickness (Aghia Kyriaki and Karlovassi areas) or as intercalations within these schists. They are gray to black gray and sometimes white-gray, fine-crystalline, in some cases coarse-crystalline, very commonly dolomitic, thin to medium-bedded, karstic and sometimes with chert intercalations. The thickness of the marbles varies from a few to 200 m.

Cipolines – cipoline marble – angerites of Kerketeas piedmonts (sp): occuring as intercalations within the Marathokampos-Kosmadei schists of western island's section. Grey-brown and sometimes greenish. These intercalations are generally of small thickness (except one with a thickness reaching 150 m.), laterally passing into calcareous schists. Within the cipolines of top-line, south of Kosmadei, limonite as lenticular intercalation of 0,5 m. thickness and 10 m. length, outcrops.

Marathokambos – Kosmadei schists (sch1): overlying comformably Kerketeas 370 marbles. They are mainly muscovite schists, quartz schists, chlorite and calcareous schists, frequently alternating in vertical and horizontal direction with local intercalations of prasinites, marbles and cipolines of various thickness. The thickness of the schists, in the area of Palaeochori (western side of Kerketeas), is about 600 m., in Marathokambos area (eastern side of Kerketeas) is more than 1.500 m.

Kerketeas marbles (mr): white to white-gray, locally gray at the upper members, very commonly dolomitic, medium -to thick- bedded and sometimes unbedded, coarse-crystalline, strongly faulted, karstic and as a rule without schist intercalations. Many times enclose chert interstratifications. Mountainous block of Kerketeas at the western part of the island, consists almost totally, of these marbles. They also appear at Aghios Minas of Fourni islet. The visible thickness exceeds 1.500 m.

Dyke igneous rock of Kallithea (γ,η): occuring at the cliffs of the northern coast, in the area of Kallithea village in the western part of the island. It is a system of dykes intersecting one another with a thickness from a few cms to 2 m., and cutting from the one side the upper parts of Kerketeas marbles and from the other the overlying Marathokambos—Kosmadei schists. They are mainly dykes of granitic, granodioritic, dioritic and aplitic rocks constituting, very possibly, apophyses of one not outcropping at the surface, intrusive mass. Dykes injection has been occurred in metamorphic rocks and before the upthrust of non metamorphic mesozoic formations of the area.

Coast of Samos

The coast of Samos is generally steep on the west and eastern part, since the mountains of Kerketeas, Ampelos and Zoodochos Pigi form cliffs towards the sea, largely impeding the formation of a wide seashore. The formation of a mild terrain as well as seashores is present in the north and south endings of the Neogene basins, where both the Neogene and Quaternary sediments extend smoothly towards the sea.

The southern coast, eastern and western of Tsopeloa cape, retains two Holocene coast lines. One emerged at a height of 0,20 m and the other submerged to a depth of 0,20 m. The beach rocks on the east and west side of the cape smoothly sink to a depth of 0,20 m. At the sunk part of the formation a lot of ceramic elements have been found, proving its younger age. Further on, along the eastern part of the coast there has been a sunk coast-line to a depth of 0,50 m, indicating a corresponding lift of 0,50 m.

Fig. 3: Main tectonic sections of Samos (Moutzas-Kollaiti, 1994)

 

Soils

 

Palaeoenvironment at Samos - A literature review

 

Results

Reconnaissance

 

Drainage basin

 

Soil

 

Land use

 

Geology

 

Groundwater

 

Springs

 

Water analysis

 

Hydrology and Rivers

 

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Groundwater model of the coastal area of Kampos

Conceptual model

Delineation of model area

The ground water model (GWM) concerns the coastal area at the south part of Neogene Mytilini basin and has an area of 20 km2 and a perimeter of 26 km. The archaeological site of Heraion, geographically belongs to the coastal basin and it is located at the south-western side of the study area. The geology of the area consists mainly of tertiary scree slopes (sc2,cs2) (9 km2) and alluvial deposits (al2) (11 km2), laying upon the neogene formations of Mytilini basin, while there are some intercalations of travertine limestones and marls (M(k,m)2).

Northern edge of our study area consists of scree slope and has a highest point of aprox. 224 m above sea level. At that point the elevation decreases dramatically up to 40 m. The scree slope formation constitutes a plane stretch with its elevation varying between 20 to 40 m. Alluvium deposits covers the southern part forming mainly a plain area at an elevation of 0 to 20 m above sea level. The alluvium has an upward-fining thickness (higher thickness towards the coast).

The GWM area gets affected by 11 basins. The geology of the total area of these basins varies between three main categories: 15% marble , 31% schist and 52% travertine . The remaining 1% consists mainly of intercalations of volcanic and ophiolite rocks.

Water basin Area (km2)
135,8
212,8
39,1
44,5
51,6
61,1
71,2
80,5
912,2
103,9
112,3

The GWM area is surrounded by these geological formations ending up to the sea with a coast line of 6,3 km. These geological units extend along our study area as following:

  • Travertine limestones and marls (M (k,m)2) at a length of 20.7 km
  • Schist of Ampelos (sch2) at a length of 1.6 km
  • Schist of Kotsikias - Psili Ammos (sch3) at a length of 1.2 km
  • Marbels of Ampelos (mr2) at a length of 0.6 km
  • Marbles of Vourlioti - Syrrachos (mr3) at a length of 2.8 km

The alluvium deposits (al2) of Mytilini basin bears a free water table. The limits of this table extend up to the limits of the strata itself. The substrata of these deposits are the Neogene formations, that bear the deeper water table in the basin.

Furthermore, Ampelos marbles (mr2) form a hydro-system that leads to numerous sources of different dynamic and water discharge, varying between 0.5 to 5.5 l/s. Vourliotes marbles (mr3) is the most important hydro-system of Samos, covering the area between Nerotrivias source and Mana source, to the eastern side of Karvounis mountain. Vourliotes marbles do not form a united hydrosystem but rather consist of several water systems leading to various sources, including Nerotrivias and Mana source.

The lowest series of Neogene (M.(k.m)2) form a remarkable water system that leads to water discharges up to 22 l/s. The combination of both series (Ampelos marbles and Vourliotis marbles) within our basins lead to numerous sources, such as Fleva, Kryo Nero, Karitsa, Megali Vrissi. Further more, the intercallation of volcanic formations among this series, mostly west of Mytilini village lead to a high concentration of arsenic (As).

(EEF:Giannopoulos, P. & Lappa, I. (2009). Hydro-geological identification and survey of water supply of Pythagoreion Municipality at Samos (43). I.G.M.E.)

The ground water model simulates the aquifer system within the coastal area. It includes two main parts, the alluvial deposits at the south (1) and the scree slope at the north (2).

Part 1 consists of 3 unconfined (convertible) layers as following:

  1. Alluvium deposits of an aprox. 20 m depth which bears an unsaturated aquifer
  2. Scree slope of an aprox. 50 m depth which bears a saturated aquifer
  3. Marle and travertine limestones of approx. 600 m depth which bears a saturated aquifer

Part 2 consists of 3 unconfined (convertible) layers as following:

  1. Thin soil layer of 2 m depth (Alluvium deposits)
  2. Scree slope of an aprox. 50 m depth which bears a unsaturated aquifer
  3. Marle and travertine limestones of aprox. 600 m depth which bears a saturated aquifer

Hydrolological and Hydraulic Parameters of the different layers

The hydraulic parameters of these layers are the following:

Layer Thickness Part 1 (m) Thickness Part 2 (m) Hydraulic conductivity (m/s) Porosity Specific yield Specific storage (1/m)
Alluvium 20 2 2.7*10-5 0.3 0.3 6.3*10-5
Scree Slope 50 50 4.5*10-6 0.23 ~1*10-4-1.1*10-3 2.2*10-5
Travertine (Marl) <600 <600 2.7*10-9 0.05 ~1*10-4-3*10-3 5.1*10-6

All layers are considered to be homogenous and isotropic, while vertically the hydraulic conductivity factor is a 10% of the horizontal.

Boundary and Initial Conditions

A constant head is set at the coastal boundary at 0 mNN and the boundary conditions at the periphery of the modeled area are set to the discharge rates of the lateral flows into GWM area. The respective flow rates are defined as inflows from the adjustent aquifers into the modeled area aquifers.

Recharge at the GWM area has been estimated at 2*10-9 m3/s as following: given the local mean precipitation (recorded at Myloi rainfall Station) of 875 mm, the potential evapotranspiration of 1576 mm (5*10-8 m3/s) and the actual evapotranspiration of 788 mm which takes place at a root depth between 0.5 m to 1 m. The surplus flow is at around 86 mm whereas the infiltration (recharge) is at 70% of the surplus (≈60 mm) and the other 30% builds the runoff. Hence the recharge in the model is defined at 60 mm/yr or 2*10-9 m3/s.

The inflow rates are used to set the initial boundary conditions of the model. These are intially estimated according to Darcy formula taking into account the gradient, thickness, contact length and hydraulic conductivity of the each of the adjasent aquifers. The effective thickness of the aquifers responsible for generating the discharge is intially set at ≈50m.

The discharge parameters of each layer are set as follows:

Layer Hydraulic conductivity (m/s) Gradient Length of contact segment (m) Discharge (m³/s)
Travertine (Marl) M(k,m)2 1*10-8 5*10-2 12370.75 3.1*10-4
Marble mr2 1*10-6 1*10-1 - -
Marble mr3 1*10-6 1*10-1 2946 1.5*10-2
Schist sch2 1*10-9 1*10-1 1215 6.1*10-6
Schist sch3 1*10-8 1*10-1 1104 5.5*10-5

A more precise boundary conditions are set for the modeling simulation. The boundary flows are defined along segments of interlinkings between the watersheds beyond (lateral flows discharge) and the boundary of the area of modelling. The respective discharge of the adjacent partial watersheds is calculated through the infiltration rate at the area of the responsible watershed multiplied by the area of the watershed.

Adjacent Partial Watersheds produce the following discharge rates:

Partial Watershed 109
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 17207761.87 4.8E-10 8.2E-3
Marble mr2 . 3.2E-9 .
Marble mr3 4463527.18 3.2E-9 1.4E-2
Schist sch2-outflow sc1 [outflow M(k,m)2] 11169158.81 [5767294.55] 9.5E-10 1.1E-2 [5.5E-3]
Schist sch3 . 9.5E-10 .
Partial Watershed 129
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 1303362.37 4.8E-10 6.2E-4
Marble mr2 . 3.2E-9 .
Marble mr3 4582377.29 3.2E-9 1.5E-2
Schist sch2 . 9.5E-10 .
Schist sch3 532922.25 9.5E-10 5.1E-4
Partial Watershed 102
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 3743233.49 4.8E-10 1.8E-3
Marble mr2 . 3.2E-9 .
Marble mr3 . 3.2E-9 .
Schist sch2 . 9.5E-10 .
Schist sch3 . 9.5E-10 .
Partial Watershed 178
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 8544725.69 4.8E-10 4.1E-3
Marble mr2 . 3.2E-9 .
Marble mr3 . 3.2E-9 .
Schist sch2 . 9.5E-10 .
Schist sch3 . 9.5E-10 .
Partial Watershed 146
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 4536086.51 4.8E-10 2.2E-3
Marble mr2 . 3.2E-9 .
Marble mr3 . 3.2E-9 .
Schist sch2 . 9.5E-10 .
Schist sch3 . 9.5E-10 .
Partial Watershed 183 West
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 7783378.97 4.8E-10 3.7E-3
Marble mr2 . 3.2E-9 .
Marble mr3 . 3.2E-9 .
Schist sch2 . 9.5E-10 .
Schist sch3 . 9.5E-10 .
Partial Watershed 183 Ost
Aquifer geological formation Area (m2) Infiltration rate (m3/s) Q (m3/s)
Travertine (Marl) M(k,m)2 6150671.14 4.8E-10 2.9E-3
Marble mr2 . 3.2E-9 .
Marble mr3 . 3.2E-9 .
Schist sch2 . 9.5E-10 .
Schist sch3 . 9.5E-10 .

These flows make the totals which flow into the aquifer formations of the model are then divided proportionally over the aquifers according to their transmitivity (kf*thickness) to provide the boundary flows that span the upper aquifer, the middle aquifer and the bottom aquifer of the model.

Layer 1 2 3
kf (m/s) 2.7E-5 4.5E-6 2.7E-09
Mächtigkeit Untergebiet (m) 20 50 600
Mächtigkeit Obergebiet (m) 2 50 600
Transmitivität Untergebiet (m2/s) 5.4E-4 22.5E-5 16.2E-7
Transmitivität Obergebiet (m2/s) 5.4E-5 22.5E-5 16.2E-7
Flows along segments of adjacent Watersheds (m3/s) Flowshare Layer 1 Flowshare Layer 2 Flowshare Layer 3 Total Discharge Discharge by Darcy Formula
Mkm2_Oberlinie_WB129_div 4.37E-04 1.82E-04 1.31E-06 6.20E-04 1.50E-05
Mkm2_Oberlinie_WB146_div 1.55E-03 6.46E-04 4.65E-06 2.20E-03 2.00E-05
Mkm2_Oberlinie_WB178_div 2.89E-03 1.20E-03 8.66E-06 4.10E-03 6.00E-05
Mkm2_Oberlinie_WB183_div 2.61E-03 1.09E-03 7.82E-06 3.70E-03 2.40E-05
Mkm2_UnterlinieOst206_189_183ost 5.58E-04 2.33E-03 1.67E-05 2.90E-03 7.70E-05
Mkm2_UnterlinieWestNew_WB102_95 3.46E-04 1.44E-03 1.04E-05 1.80E-03 3.30E-05
Mkm2_UnterlinieWestNew_WB109 1.58E-03 6.57E-03 4.73E-05 8.20E-03 8.00E-05
mr3_Oberlinie109 9.86E-03 4.11E-03 2.96E-05 1.40E-02 1.20E-02
mr3_Oberlinie129 1.06E-02 4.40E-03 3.17E-05 1.50E-02 2.50E-03
sch2_Oberlinie109 3.87E-03 1.61E-03 1.16E-05 5.50E-03 5.50E-03
sch3_Oberlinie129 3.59E-04 1.50E-04 1.08E-06 5.10E-04 5.50E-05

Rivers System

The Imbrassos river works as a natural drainage for the water within our basin. This element is included in the model as drain module. The conductance of the river bed of gravely loam is defined at 1*10-5 m2/s and the base level of 2 m depth.

Wells and Pumping rates

Wells have been integrated in the model from actual data register IGME for consumption rates and locations, including pumping rates, duration and usage (irrigation, drinkig water resource, etc.) and the depth of each borehole/well. These data are spatially presented on the following map. Pumping rate vary between 4E-3 m3/s and 4E-5 m3/s.

<olmap id=“olMapWells” width=“680px” height=“450px” lat=“37.666” lon=“26.883” zoom=“13” statusbar=“1” controls=“1” poihoverstyle=“0” baselyr=“terrain” summary=“Wells/Boreholes”> 37.6980,26.8726,-90,.8,marker-red.png,W1
Depth = 40 m 37.6911,26.8786,-90,.8,marker-red.png,W2
Depth = 40 m 37.6789,26.8685,-90,.8,marker-red.png,W3
Depth = 40 m 37.6985,26.8719,-90,.8,marker-red.png,W4
Depth = 40 m 37.6940,26.9031,-90,.8,marker-red.png,W5
Depth = 40 m 37.7013,26.9079,-90,.8,marker-red.png,W6
Depth = 40 m 37.6931,26.9196,-90,.8,marker-red.png,W7
Depth = 40 m </olmap> Fig4|Wells Locations lat:37.66666,lon:26.8351, alt:5 , placename:Heraion , country:Greece , region:Samos

Observation Data for Calibration

The measured waterlevels at the observation points are used as a standard to validate the model's simulated water levels and to calculate the standard deviations of the simulated values versus the observed values.

The observed values serve furthermore as the basis for running parameters estimation process (using UCODE) for calibrating several parameters like Recharge, Evapotranspiration, Hydraulic conductivity values of layers etc. Giving a well calibrated and tuned model that produce results near to reality values and conditions.

Calibration Results
Calibration I: Semi-complete Low-resolution Model; cell-size 100m*100m
Calibration II: High-resolution Model containing complete scale of pumping wells and side rivers; cell-size 10m*10m

The high-resolution model delivers refined grid value results which are essential in evaluating the groundwater-level situation of the Heraion site terrain showing vulnerabilities to partial scale or full scale flooding. These results deliver the fundamental information for developing the drainage system in preventing and remediating flooding.

Parameter Parameter values under calibration I Parameter values under calibration II
Hydraulic Conductivity kf (Layer 1): HK_Par1 1.5E-5 m/s 2.7E-5 m/s
Hydraulic Conductivity kf (Layer 2): HK_Par2 3.9E-6 m/s 4.5E-6 m/s
Hydraulic Conductivity kf (Layer 3): HK_Par3 1E-9 m/s 2.7E-9 m/s
Drainage Conductunce: DRN_Par1 1.3E-5 m2/s 7.8E-6 m2/s
Evapotranspiration Rate: EVT_Par1 4E-8 m3/s 2.5E-8 m3/s
Recharge Rate: RCH_Par1 3E-9 m3/s (95 mm/yr) 1.94E-9 m3/s (56.8 mm/yr)
Root Mean Square Error 2.9 2.5

Preliminary Results

Groundwater Levels

After running calibration II, where Rainfall measured at 875.5 mm and Recharge and Evapotranspiration respectively calibrated during modeling simulation at 61.2 mm and 787.9 mm, plausible hydrological relationships had been drawn out as follows:

Potential Evapotranspiration >= 0.9 * Rainfall
Recharge = 0.07 * Rainfall
Runoff (surplus) = 0.03 * Rainfall

These formulas serve as the basis for setting Scenario hydrological conditions and hence the parameterization of the model, giving the following palett of hydrological conditions and various stress periods.

Stress Periods Simulation

Stress Periods Calibrated (Steady-state) Dry Season (Transient) Wet Season (Transient) Normal Season (Transient)
Year of information 1984 1972-73 1960-61 All years Mean
Rainfall (mm) @ Myloi Rainfall Station 875.5 450 1044 874
Recharge (mm) 61.2 (1.94E-9 m3/s) 31.5 (9.98E-10 m3/s) 73 (2.23E-9 m3/s) 61.2 (1.94E-9 m3/s)
Potential Evapotranspiration (mm) 787.9 (2.5E-8 m3/s) 787.9 787.9 787.9
Discharge Fitting factor 1 0.51 1.19 0.99

Side Note: The discharge fitting factor is either a magnifying or a reducing factor of the boundary inflows proportional to the devition of Rainfall intensity in any given year in comparison to the year at calibration.

Simulations are run according to different cross-combination of these stress periods

Scenario III

Results of Waterlevels (m NN and m under terrain) at the Heraion Site (area under Investigation).

The areas where waterlevels under terrain less than 1 meter (dark blue) give an indication of the susceptability to soil waterlevel capillary ascending forces and potential salinization and show vulnerability to overflooding.

- End of Scenario III

At the end of the simulation, the scale of areas where waterlevels under terrain less than 1 meter is shown to be larger. Pathways are marked as shown.

Drainage System Design

The drainage system is designed within the framework to protect the Heraion Site against flooding and to provide an accessible site for uninterrupted archaeological work and visits.

The Drainage System is based on applying underground drainage pipes. A Drainage pipe has a Diameter of 0.25 m, pipe wall thickness of 2.5 mm, total Diameter 0.3 m and burried underground. The pathway of Drainage is assured to run in the allowed free zones taken into account the archeological significance.

The pathway of the Drainage is divided into Segments as shown in the diagram below. The slope is assigned to 0.007 (0.7cm/1m).

The following routine explains the design of Elevation and Depth of the pipe degments:

Slope = Delta h / Segment_Length; where Delta h is the height difference between the beginning and end of the Segment; S = 0.007.

Delta h = Slope * Segment_Length

hence Drainage_Elevation = Draiange_Elevation[previous] - Delta h; then Drainage_Depth = Elevation(Terrain) - Drainage_Elevation

if Drainage_Depth < 0.3 m; then Drainage_Depth is set to = 0.3 and Drainage_Elevation = Elevation(Terrain) - 0.3 m

therefore all pipe segements are assured to be Underground (under Terrain).

Side Note: in GWmodel the drainage higher z-height set above the drainage elevation is reduced by a factor (z = pi 0.15^2 /10 = 0.007 m) to compensate for the resized width of the cell. This allows the flowing of the same volume of drained water.

End of Simulation III after applying the Drainage System

Analyzing Water-levels at Heraion's Ancient Wells

Water-levels over Droughts and Floods have been simulated using our Groundwater Model. Results show the water-levels in each of the ancient wells and how it varied during floods and droughts up to 20 years-duration. The water-levels are shown within the higher and lower edges of each well. Some results show deviations of water-levels above the higher edge of the given well, this could be due to several reasons. One could be the current incomplete form of the ancient wells. Second, the severe paleo-environmental conditions that might have caused water-levels to be lower than usual, for example droughts that have lasted for hundreds of years. Third, the presence of irregularities due to for instance small scale formations of impermeable layers.

A map of locations of ancient wells at Heraion is shown below with water-levels values.

ancient_wells.xlsx

<olmap id=“olMap” width=“680px” height=“450px” lat=“37.6721908427” lon=“26.8869799167” zoom=“17” statusbar=“1” controls=“1” poihoverstyle=“0” baselyr=“terrain” summary=“Ancient Wells”> 37.6721908427,26.8869799167,-90,.8,marker-blue.png,

W23
37.6730537488,26.8864581157,-90,.8,marker-blue.png,W11
37.6721769829,26.8868854107,-90,.8,marker-blue.png,W25
37.6720368287,26.8861507932,-90,.8,marker-blue.png,W7
37.6712606758,26.8871156737,-90,.8,marker-blue.png,W15
37.671474643,26.887032226,-90,.8,marker-blue.png,W9
37.6713834193,26.8866173661,-90,.8,marker-blue.png,W13
37.6719499086,26.8866715935,-90,.8,marker-blue.png,W10
37.6728685081,26.8860904839,-90,.8,marker-blue.png,W17
37.6719813203,26.8866465864,-90,.8,marker-blue.png,W8
37.6719752961,26.8866052703,-90,.8,marker-blue.png,W3
37.6719929383,26.8866052703,-90,.8,marker-blue.png,W4
37.6718621277,26.8863823808,-90,.8,marker-blue.png,W14
37.671780371,26.8863638973,-90,.8,marker-blue.png,W6
37.6724044434,26.886924495,-90,.8,marker-blue.png,W12
</olmap> Fig. 4: Locations of Ancient Wells

lat:37.6724044434,lon:26.886924495, placename:Heraion , country:Greece , region:Samos

References

Giannopoulos, P. & Lappa, I. (2009). Hydro-geological identification and survey of water supply of Pythagoreion Municipality at Samos (43). I.G.M.E. .

projects/samos/reporting/start.txt · Last modified: 2020/08/01 15:16 (external edit)