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WATER RESOURCES *

The Sultanate of Oman lies in an arid region of the world, but due to its size and the configuration of its topography there are considerable variations of climatic conditions within the country. Only in the extreme south where the seaward facing slopes of the mountains and the coastal plain have the benefit of light summer monsoons extending from June to September is rainfall regular. In the north of Oman heavy and very localised thunderstorms occur over the Hajar range of moun tains during the summer months, and in the winter occasional depres sions sweeping across the Arabian Peninsula bring rain to the Interior and coastal regions. Nevertheless, rainfall is sparse and sporadic, and lengthy periods of drought are frequent On rare occasions majority clonic storms sweep into Oman from the Indian Ocean to produce large volumes of rainfall in Southern and Central regions.

Exploring Water

The art of exploiting available water resources to the best advan tage has been perfected by Omanis over the centuries. An example of this is the falaj (plur. aflaj) system, which was introduced into Oman about a thousand years ago, and used throughout the Interior as a means of irrigation. Water is tapped at the water table in the mountains and in wadis, and is led by man-made subterranean channels or by channels that skirt and cling to mountain sides to areas of settle ment where at the surface it is used for irrigation and domestic pur poses. Elsewhere, and especially in the coastal regions, water for irri gation is obtained from wells.

 

Raising Water Demand and MWR

In recent years the balance achieved over the centuries has been upset by the introduction of modern methods of extracting subterranean sources of water and the subsequent increase in the areas under culti vation. Diesel and electrical pumps have replaced animal power as a means of raising water from wells. Other pressures on available water resources arise from increasing agricultural productivity, the increas ing demands of a developing industrial sector, which was previously non-existent, and the mounting demands for domestic water as popu lation and living standards rise. Desalinated sea water now meets an increasing proportion of the domestic requirement in some coastal re gions.

Since the start of the renaissance in 1970 the Government, under the leadership of His Majesty Sultan Qaboos bin Said, has been keenly aware of the need to conserve available water resources and to use them to the best advantage. In 1975, the Water Resources Council was formed. This was followed by the formation of a Public Authority for Water Resources, charged with identifying and assessing the natural water resources. In 1986, two Councils concerned with the environment and water resources were merged into the Council for the Con senation of the Environment and Water Resources, of which His Majesty the Sultan was the Chairman. In 1988 the country's water resources were declared "natural wealth" by Royal Decree. In 1989 it was decided that water was of such paramount importance that the Ministry of Water Resources (MWR) was established by Royal Decree. In January 1994, a Royal Decree was issued making the development and maintenance and the jurisdiction and records of dams and aflaj the responsibility of the Ministry of Water Resources.

The principal aim of the MWR is to conserve and develop the natural water resources of the Sultanate, and to initiate long-term policies for these resources to support the economic and social development of the country. Initial emphasis was given to the development of the in frastructure of the Ministry, regulation of water use, the expansion of the water monitoring network, and water resources assessment projects. More recently the Ministry has broadened its scope by giving priority to the assessment of projects that support expanding municipal demands, that can identify all possible new resources, that evaluate development schemes to ease water shortages in some areas, and also to the initiation of other water management projects.

The Ministry has met the major challenge of water use regulation by a national campaign of well registration. By July 1990,167,000 wells had been registered by citizens. In the past few years 24,000 ap plications have been received by regional Water Resource departments for the sinking of new or replacement wells, the deepening of existing wells and the repair of wells and aflaj. Violations of regulations and appeals against Ministry decisions are also handled by Water Resource departments. Since 1991,1,800 violations have been investigated, but the numbers have been declining through greater Ministry vigilance and cooperation of the general public.

Well Inventory

A national well inventory currently being conducted is confirming well registrations and collecting information required to support current permit policy and future policies for water usage. The inventory was commenced in 1992 following evaluation of one-year pilot projects in three regions. Work initially concentrated in the Batinah coast of northern Oman where 50% of wells were registered in 1990 and where the adverse effects of the sa line intrusion are most severe. Inventory on the Salalah Plain and Al Wusta areas were completed last year.

By last year 50,000 wells had been inventoried, in the course of which water samples have been col lected and analysed providing baseline data for environmental monitoring, which will be consolidated in a national water quality database. Work has now extended into the Interior, and the major part of the project should be completed by the end of this year. To carry out its aim of planning a long-term strategy to develop the water resources of the Sultanate, the Ministry needs to establish how much natural water is available, 97% of which exists as groundwater. Virtually all monitoring of rainfall, wadi flows, groundwater levels and chemistry have been carried out within the last twenty years, so Oman has few measurements or records extending back into the past from which it can infer trends on water availability, except for areas such as Muscat, Salalah and Nizwa. As a result, the Ministry has expanded its groundwater, surface water and meteorological monitoring networks. All the data from these networks is stored in the Ministry's growing technical database to form a national water resources data bank.

Water Avaiability

Among the Ministry's major tasks has been the need to refine knowledge of available water resources, evaluate stocks, and search for new sources. A most significant find so far has been an aquifer in north western Oman, the Al Massarat aquifer as revealed by His Majesty Sultan Qaboos during his armual tour of the Wilayats in January 1994. Phased development of this aquifer will bring relief to areas around Ibri, Dank/Yanqul and Bahla which have seen the quali ty and quantity of their natural water deteriorate over the past few years. Rapid assessments have been carried out over the whole country, which have enabled the Ministry to estimate water balances for the nine major catchment regions. More detailed studies are focusing on areas which are known to be experiencing particular problems of water supply and which are also undergoing more rapid growth.

The southern Batinah, where groundwaters have been affected by sea wa ter intrusion, is the subject of a groundwater modelling study. This will help to show the rate at which the aquifers are being affected by water of higher salinity, and their response to changes in rainfall, re charge and pumping from boreholes. A detailed drilling programme is currently proceeding in the Sumail Gap which marks the route be tween the capital area and Nizwa along which there are several grow ing centres of population. Drilling programmes at Adam were com pleted almost two years ago. Detailed geological and hydrogeological studies have been carried out in Wadi Dayqah near Muscat, which is one of the few perennially flowing wadis in the country. The assessment report on these studies was submitted in 1994. Further southeast, extensive research is being carried out in Wadi Al Batha, which lies between the northern moun tains and the northern edge of the Wahiba Sands. Assessment pro grammes aim to quantify just how much water can be relied on to sup port future developments. A study was undertaken in the Nejd of northern Dhofar in 1993 to estimate the quantities of groundwater available, and to explore differ ent methods for its development.

Recharge Dams

Most of the water is brackish and fossil water, meaning that there is no, or very little, recharge to the aquifer in the present day, as it derives from a past age when the climate was much wetter, so any development has to be carefully controlled. The Ministry has made significant progress in planning and development of schemes to increase recharge, provide surface water storage and to improve aflaj water use efficiency. Recharge dams are designed to intercept flood flows in wadis, which would otherwise run to waste in the sea or inland into the desert. Water is released at a reduced rate of flow often through culverts in the dam and infiltrates the ground water aquifer beyond the dams in controlled flow. This recharged water moves gradually in the aquifer to replenish boreholes downstream of the dams.

Sixteen dams have so far been completed and several small dams and water structures have been built in Jebel Akhdar. Monitoring networks of rain gauges, wadi flow gauges and boreholes are installed at strategic sites behind and downstream of the dams. When there have been significant periods of wadi flow, water levels in boreholes downstream of the dams rise significantly. Over periods of many months, observations of water levels from over the whole net work show that this recharged water diffuses to other zones in the aquifers.

The Ministry of Agriculture and Fisheries prepared a master plan for building recharge dams in 1986. The original intention was to build 58 dams in preliminary identified sites, mostly on the coastal and Interior sides of the northern mountains. During each 5-year develop ment planning period progress towards this aim is assessed and modi fications are made in the light of experience. Broadly speaking, the master plan is still being followed and discussions are now under way for the next 5-year planning period starting at the end of 1996. The feasibility of building water conservation structures and their potential for operating successfully is evaluated fully before building begins. Issues that must be taken into account in deciding between re charge and retention structures include estimations of aquifer capacity (how much groundwater the aquifer underlying the site of the struc ture can hold) and recharge potential (how much of the intercepted flood flows will actually infiltrate the aquifer, rather than just be evaporated). Where there is no suitable aquifer, usually in mountain ous areas with small valleys, a retention structure is more viable.

Water Salinity

The assessment of sea-water intrusion on the Batinah Coast has been examined through several studies. The most important of these so far was the production of a series of maps comparing the extent of saline water intrusion and falls in groundwater levels during the peri od 1983 to 1991. This showed that significant levels of saline intrusion are taking place along the entire coastal strip, but particularly in the south from Suwaiq to Seeb.

Here, average long-term decline in the groundwater level is in the order of 0.5 metres per year. Similar maps have been produced for the Salalah coastal plain, where saline intru sion is also increasing. Similar investigations formed part of the studies of the feasibility of recharge dams in wadis Sumail and Rusayl. National well inventory data together with preliminary assessments of the southern Batinah, completed early last year, have also helped to define the landward ex tent of saline and brackish waters, and the amount of groundwater abstractions in excess of recharge. These studies confirm that sea water intrusion is generally increasing along the Batinah. Management options which have been proposed to alleviate the situation include the removal of large fodder farms from the Batinah, the introduction of metering to measure water use, continued well inven tory work, improved monitoring and several engineering initiatives that will control use and the intrusion it causes.

MWR Structure

The Ministry operates through four Directorate-Generals, which are respectively responsible for water resources assessment, water resources management, regional affairs and administration and finance. Staffing levels have increased more than eight-fold since the creation of the Ministry, which reflects its increasing activity. 93% of the 1,200 staff are Omani. The Ministry provides training, ranging from locally based administrative and language courses to technical MSc courses overseas. Since 1992, 114 staff have studied abroad, while an average of 500 a year have attended local courses. The Ministry's headquarters are at present in Ruwi, and there are 11 water resource departments in the regions. The number of regional departments has doubled in five years. To celebrate the 25th anniversary of His Majesty's accession and the fifth anniversary of its founding, the Ministry, helped by the Interna tional Water Resources Association, held an international conference on Water Resources Management in Arid Countries in Muscat during March 1995. Two hundred and forty delegates representing 39 coun tries attended 15 sessions of scientific presentations. 86 papers and 19 posters were presented on 11 topics:

Regional water management · water resources development · agricultural water consenation · desalination and brackish water utilisation · wastewater re-use · saline intrusion · hydrology · hydrogeology · groundwater recharge · hydrologic modelling · hydraulic structures.

In his opening statement, Professor G.O.P. Obasi, Secretary General of the World Meteorological Organisation, praised the Sultanate's achievements in the area of water resources, adding that arid regions could learn much from Oman. Eminent speakers from the World Meteorological Organisation, UNESCO, the United Nations Environmental Programme and the Arab Organisation for Agricultural Development gave keynote papers. The closing statement of the Conference recommended: conserving water use in agriculture through modern management methods inventorising all water sources and usages in detail undertaking more research on non-conventional water sources undertaking further assessment and monitoring of groundwater recharge and flow undertaking more research on the links between climate and water resources protecting water sources from pollution integrating water resources plans and strategies within national policy emphasising demand management for water emphasising water supply management through water re-use, water harvesting and water transfer increasing public awareness of water resources issues. The Ministry was recognised as being well advanced in many of these areas. The Ministry mounted a technical exhibition describing the work it is doing, which was very well received by participants of the conference.

© Adapted from Oman'95, Ministry of Information. Nizwa.NET is not responsible for accuracy or errors.



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