Hydrology in Cyprus

(August '97 update)

1.0 Introduction

In Cyprus the hydrological and meteorological activities were initiated back in the year 1881.

The hydrological activities are carried out by the Department of Water Development and the meteorological by the Department of Meteorological Service. Both departments belong to the Ministry of Agriculture, Water Resources and Environment.

1.1 The Water Resources of the Island

Cyprus has always been confronted with the problem of inadequate water both for its domestic and its irrigation needs. This is due to its semi-arid climate, the average annual rainfall being about 500 mm, and its traditional inclination towards agriculture whilst the booming tourism industry is pressing for more water.

Of the estimated 900 Mm³ total average annual water resource some 300 Mm³ naturally replenish the aquifers most of which are in the coastal areas and which in turn are pumped and utilized mainly for irrigation and 600 Mm³ appear as surface runoff. The water cycle for Cyprus is shown on the attached figure.

Groundwater was the first to be developed in the island since surface water is available only between November and April when it is least needed.

At first, springs were used and developed followed by hand-dug wells and chains-of-wells (Qanats) in shallow aquifers. With the introduction of drilling machines and pumping equipment the aquifers were fully developed to the extent that certain aquifers have either been exhausted by ´mining´ or sea-intrusion took over extensive parts of them.

Until the early 1970´s the 270 Mm³/year of groundwater use pumped from the aquifers and from springs represented about 80% of the water used in the country. Of this quantity, some 40 Mm³ represented overpumping mainly in three of the main aquifers whilst some additional 70 Mm³ per year are estimated as being lost to the sea.

The last 33 years have seen a revolution in the water supply industry. Since 1960, the year of Independence, the number of dams has risen from 21 to 96 and of these the major dams increased from 10 in 1962 to 47 in 1993. In 1960 most villages relied on communal water fountains but since then around 600 villages have had domestic water supplies installed and their sources developed. Schemes have been more numerous and larger as time has gone on storage capacity in 1960 being 6.1 Mm³ and at present, 291 Mm³. The area irrigated has risen from 1,600 hectares to almost 21,000 hectares. Figure 1 presents a map of Cyprus with its physical features and the location of major water development projects.

With the high dams built not far from the coast the groundwater replenishing regime in most areas has been modified and downstream aquifers depend more and more on artificial groundwater recharge either through controlled releases from the dams directly onto the downstream riverbeds or through purposely built spreading grounds at strategic points on the aquifers. This trend will continue as long as existing domestic supply schemes continue to operate on the basis of groundwater extraction and until the planned water supply treatment plants are completed.

This also holds true for irrigation as long as the existing dependence on the aquifers is maintained and until direct supplies are provided from the dams to substitute an equal amount of groundwater.

Even with the water resources development described above, by which almost two-thirds of the annual water crop has been harnessed, the seriousness of the shortage of water in Cyprus is illustrated by the fact that only 12 - 13% of arable land is currently being irrigated, yet over-pumping is occurring.

1.2 Demand and Supply

The total water consumption in Cyprus is currently about 305 Mm³ annually, of which 65 Mm³ for Municipal and Industrial (M & I) purposes and 240 Mm³ for irrigation.

In a normal year the current water balance for Cyprus as a whole is favourable. The drought, however of 1989/91 demonstrated quite convincingly how critical the water situation might be even at the current water use level. During the summer of 1991 stored water reached the record low of 8.7% of the total storage capacity. Water supply to municipal systems was on average reduced by 25% while permanent crops were allocated 80% of the normal demand. Annual crops were limited to as much as 70% of the area irrigated in a normal year.

Advanced water management principles based on low water supply lasting for two consecutive years are and should be used for satisfying the spatial and temporal varying demand.

1.3. Future water resources plan

Demand for water is expected to increase in the years to come. This stems directly from the need of providing adequate and suitable water supplies for all the sectors of the economy as the economy and population expand. On the very conservative assumption that no further land will be developed for irrigation than that presently planned, it is projected that irrigation water demand would increase from 240 Mm³ in 1995 to 295 Mm³ in 2010 and remain rather stable thereafter. Similarly water for M & I would increase from 65 Mm³ in 1995 to 105 Mm³ in 2020. There is an increase of 95 Mm³ in the time span between 1995 and 2020 which corresponds to 31 percent of the present gross demand.

Augmenting the supply so as to satisfy the increasing demand for water is an arduous undertaking. The Government policy for achieving this goal is based on the following three components:

Development of New Water Source

Water Demand Management

1.4 The Water Resources Management Set up in Cyprus

Policy

The policy control of the Water Industry in Cyprus is divided between the Ministry of the Interior, the Ministry of Agriculture, Natural Resources and Environment, the Ministry of Finance, the Ministry of Commerce and Industry and the Planning Bureau.

Executive Level

At executive level the industry is mainly in the hands of the Water Development Department of the Ministry of Agriculture but usually only in an advisory capacity. Legal power lies with the District Officers of the Ministry of the Interior. The Department of Agriculture is closely concerned with irrigation matters, the Geological Department with the development of boreholes, the Land Surveys Department with the registration of water rights, the Accountant General with finance, loans and tenders and the Planning Bureau with budgets.

User Level

Domestic Water Supplies are managed by the Town Water Boards in the major towns of Nicosia, Larnaca and Limassol, and by Municipal, Improvement Board or Village Water Committees elsewhere.

Irrigation Water Supplies are managed by local Irrigation Divisions formed of landowners or Irrigation Associations, formed of water-rights owners. Recent Government Irrigation Schemes supply water direct to the farmer and are managed by Project Water Committees chaired by the District Officer.

1.5. Description of the Institutions for Hydro-Meteorological measurements

The Water Development Department of the Ministry of Agriculture, Natural Resources and Environment

The Department of Water Development of the Ministry of Agriculture, Natural Resources and Environment, is responsible for formulating and executing the Government´s overall policy on water resources, planning, design and construction on the Island. It cooperates in the management of water resources and water development projects together with other Departments, Ministries and water distribution organizations. It normally has no contact with the individual consumer. Since 1982 the Department also undertakes the design and construction of sewerage and sewage disposal works for Town Sewage Boards and Village Public Health Committees.

The Water Development Department is made up of ten Divisions. Pertinent to water resources for collection and interpretation of hydrological and hydrogeological data both for surface and groundwater are the Divisions of Water Resources and of Hydrology.

The Division of Hydrology operates as a central unit with minimal purpose-selected staff making use of the staff available at the Regional Offices for field data and observations.

The Division consists of four major branches:

The basic tasks of the Division aim to provide the Director and the Department the following: The Division of Water Resources is mainly responsible for field measurements of surface runoff and sediments, groundwater levels and quality, mesurements of springs, issue of drilling permits and evaluation of groundwater extraction.

The Department of Meteorology of the Ministry of Agriculture, Natural Resources and Environment

The Meteorology Department is responsible for monitoring rainfall, evaporation and other climatologic parameters in the Island beyond its responsibility for climatologic evaluation reports for air and marine travel.

2.0 The hydrological approach, data collection and practice

Rainfall

The longest hydrologic record available in the island and with the most wide distribution is that of rainfall. For some 63 rainfall gauges the record extends back to 1916/17 ( see Table below).
 

Altitude
(m)
Island
area
coverage
(%)
Non Recording Gauges
(Years of record)
< 26 26 - 75 76 - 100 > 100 Total
0 - 500 80 54 31 28 5 118
501 - 1000 15 14 17 16 0 47
1001 - 1500 4 3 6 7 0 16
1501 - 2000 1 0 0 1 0 1
Total 71 54 52 5 182
Altitude
(m)
Island
area
coverage
(%)
Recording Gauges
(Years of record)
< 6 6 - 10 11 - 30 > 30 Total
0 - 500 80 3 13 26 2 44
501 - 1000 15 1 1 12 0 14
1001 - 1500 4 0 0 2 3 5
1501 - 2000 1 0 0 1 0 1
Total 4 14 41 5 64

Evaporation

The evaporation is measured at 29 stations most of which have a record of 10 to 30 years. The Table below lists the observation network for evaporation measurements.
 

Altitude
(m)
Island
area
coverage
(%)
Evaporation Pans
(Years of record)
< 6 6 - 10 11 - 30 > 30 Total
0 - 500 80 1 5 20 0 26
501 - 1000 15 2 0 5 0 7
1001 - 1500 4 0 0 3 0 3
1501 - 2000 1 0 0 0 0 0
Total 3 5 28 0 36

Surface runoff

The surface runoff is recorded at some 65 weirs spread throughout the island and especially concentrated around the Troodos Mountains from which the major streams issue. For more than 40 weirs, the record extends between 10 and 30 years.
 

Altitude
(m)
Island
area
coverage
(%)
Discharge Recording stations
(Years of record)
< 6 6 - 10 11 - 30 > 30 Total
0 - 500 80 38 18 51 0 107
501 - 1000 15 3 2 6 0 11
1001 - 1500 4 0 0 0 0 0
1501 - 2000 1 0 0 0 0 0
Total 41 20 57 0 118

Groundwater

Groundwater levels and quality are monitored on a monthly basis from some 100 observation wells whilst some 1200 wells and boreholes are monitored twice-a- year. Groundwater extraction estimates are made on more than 13 000 wells on the basis of land use and method of irrigation.

Surface runoff simulation

The existing record of observed stream flows in itself is not sufficiently long (10 -20 years) to enable a meaningful application of operation studies such as reservoir operation studies, etc. This is often the case in most developing countries. Cyprus is fortunate to have a long rainfall record (80 years) derived from a sufficiently dense raingauge-network. This long rainfall record combined with the relatively short record of stream-flows is used through a catchment model which generates an extended runoff record using the long history of climatic data. The calibration of this model is based on the available runoff record.

The rainfall-runoff model, adapted to local conditions is a conceptual one and it is a simplified version of the Stanford Model, which basically uses the hydrological cycle process and involves most of its parameters. It is of the storage type. The input consists of the 24-hour area-precipitation data and mean daily evaporation. The model synthesizes daily stream flow whilst the output is expressed as monthly runoff as well as daily flow duration.

On the basis of these simulated flows all the feasibility studies for reservoir design and operation have been carried out. The runoff simulation is reviewed as the observed record becomes larger.

Hydrological Surveys

Hydrological Surveys of the groundwater bearing systems starting with the most important ones were initiated in a small scale in 1954 by the Water Development Department. After 1960 these surveys were accelerated in scale until all the aquifers were covered. Until recently these surveys covered an area of 3700 sq. km and more than 45 000 wells, boreholes, springs and chains-of-wells have been registered.

The Survey includes, the registration and plotting on Land Registry maps of all the existing wells and boreholes, together with other information like the owner, the pumping plant used, the area irrigated and type of crop, irrigation method etc.

A dense network of private wells as well as a number of purposely drilled observation boreholes are topographically leveled.

Water Balance studies and groundwater modeling

The result of the hydrologic surveys, the hydrologic observations and hydrogeological evaluation of the main aquifers has resulted to water balance studies and safe yield definition. This led to the development of groundwater models for most of the aquifers which allow the study of the performance of the aquifer to various stresses of pumping or recharge. The mathematical groundwater model solves the general groundwater flow equation for a two-dimensional flow over a nodal grid by replacing it with an equivalent system of finite difference equations, the simultaneous solution of which gives the water levels at a finite number of nodes within the boundaries of the aquifer.

A calibrated groundwater model of an aquifer is a useful tool for evaluating the effects that may result from management decisions regarding the abstraction or operation of artificial recharge etc. on the water - table configuration.

The groundwater models have played an important role in the overall understanding of the aquifer systems, their water-balance and the overall management of the groundwater resources in conjunction with surface water development.

3.0 Existing databases for hydrological data and information

Although a large amount of hydrometeorological and hydrogeological data exist in Cyprus and are kept in ledgers, and files still only a small proportion is available in a digital form which can be used directly on Personal Computer applications. Even this information which is available in a digital form is not under a formal database encompassing all types of data.

What actually exist in effect is data in spreadsheet files such as MS-Excel, Quattro, Lotus and other commercial software which are collated as "study specific" files prepared at the time of particular studies and research being carried out. These files are used in their form or modified to suit other studies as the need arises.

These study specific sets of data files constitute in effect smaller databases and are available at the Water Development Dept. and more specifically at the Division of Hydrology and are used for various studies and research activities being updated at the time of need.

Such databank applications exist for the following:

Rainfall Data Bank

For some 60 stations the daily rainfall is available in a digital form since 1916. This dataset is being used for rainfall - runoff simulation, flood studies and other research activities and studies. The information is in ASCII format and is easily transferable to other software for the various applications.

Observed runoff Data Banks

Mean daily observed runoff for the period of 1965 onwards is kept in files and in digital form used mainly for rainfall - runoff simulations and reservoir operation studies or groundwater balance evaluations.

Practically all the observed runoff record is in a digital form. A more formal database is available for the monthly observed runoff for the period of 1965 to 1995 called "Flogasta". Through this database monthly observed flows can be edited, analyzed statistically, printed out and graphs can be created. On the same database, area-rainfall values are incorporated for each catchment together with maximum and minimum instantaneous flows.

Groundwater Data Banks

The abundance of information obtained through the Hydrological Surveys is being introduced into a computer data bank for easy reference.

The information contains among other, the location of each well, the name of owner and his address, the depth, the pumping equipment and the area and kind of crop irrigated and the irrigation method.

Already, data for 8500 wells and boreholes have been introduced with 88 fields of information for each one of them.

Feasibility and water balance studies as well as the issue of annual pumping permits are greatly facilitated through the use of this data bank. Using dBase IV such databanks are available for two major aquifers in the island, The Akrotiri and Kokkinochoria aquifers.

The data fields contain amongst other, information on the location of each well, the name owner and address, the depth, the pumping equipment and the irrigation method used, the extent of are irrigated by each well and the type of crop, the yield of each well and in the case of Akrotiri (500 boreholes) the monthly reading of the watermeter showing the water extracted.

Feasibility and water balance studies as well as the issuing of annual permits are greatly facilitated through the use of this data bank.

More recently, the chemical analysis of groundwater started being introduced into a database and already the Akrotiri aquifer is practically completed with about 1000 analysis reports having been introduced.

Ground water level data are also available for most of the aquifers in a digitized form (spreadsheet files) covering monthly networks involving more than 150 wells throughout the island and spanning over a 20 year period.

Other information also exists on individual data files ( mainly spreadsheets) such as water demands, springs, population census, irrigated areas etc.

4.0 Internet and web site

No web - site has been developed as yet within the Water Development Dept. although Internet connection exists.