CRTC for ITCAMP: Coastal Profiles. I.R.Iran

I.R.Iran

1.4.1. Quality and quantity for Groundwater

According to the latest available data, in 1995-6, the total surface water volume of the country has been estimated at 110 billion m3. This is distributed in the major watersheds as follows:

1. Caspian Basin	19.4 billion m3
2. Persian Gulf and Sea of Oman	60.0 billion m3
3. Lake Urumieh	4.8 billion m3
4. Central Basin	22.2 billion m3
5. Hamoon and Sarakhs	3.3 billion m3

There has been an 8.2% increase in present surface water levels compared to the data of the last 30 years. Gilan, Mazandaran and Golestan provinces contain only 3.5% of the country’s surface area but receive about 10% of total precipitation, or some 40 billion m3 per year. About 30% of the aggregate water resources of the region are found in rivers. After being used for agriculture or other purposes, these waters reach the sea. The other two-thirds evaporate and sink into ground water reservoirs. The total groundwater resources in three littoral provinces of Caspian Sea are estimated to be about 4.23 billion m3. 0.72 in Gilan (17%), 2.16 billion m3 in Mazandaran (51%) and 1.35 billion m3 (32%) in Golestan province.

Groundwater is accessed in a number of ways, including wells, Qantas (manmade underground irrigation channels) and springs. The amount of each is shown in Table 3.

Accordingly, from a yearly total consumption of about 3.8 billion m3 of groundwater, about 48% of the total is taken from springs, 27% through deep wells and 22% via semi-deep wells or 49% and the remaining 3% is utilized through qanats. Groundwater is primarily used for agriculture (87%) industrial (1%) and drinking water (12%).

Wells provide a primary source of drinking water for human consumption. They are also used for agricultural and industrial purposes and contribute about 50% of the total water supply.

Well waters used for human consumption are generally shallow, therefore subject to various pollutant leakages entering the ground, and hence water sources. Among these, pesticides are the most important source of pollution. Extensive and even illegal use of these substances pollutes surface and groundwater. Since groundwater is found close to the surface, the water table can easily be contaminated by polluted surface waters.

Domestic sewage is another source of contamination for groundwater. This type of pollution is threatening the quality of groundwater in villages and cities. The gentle slope of the land and low natural drainage potential has created vulnerable ecosystems. This is particularly true of Gilan province. A large proportion of sewage is carried by rivers to the sea. Cesspools containing polluted waters leak into underground water sources and the water table. As a result, epidemic intestinal disease is particularly prevalent in villages and small urban areas.

The pollution of water by nitrogen compounds is caused by various point and non-point sources including chemical fertilizers, animal manure and effluent from factories. Sewage containing human feces and effluent carrying a variety of household detergents eventually find their way into the groundwater. Unfortunately, drinking water is also contaminated in the process and is the origin of a number of diseases.

Expansion and over population of cities and rural areas, lack of adequate environmental protection policies, as well as a lack of water conservation schemes only accelerate water source pollution both on land, at the surface and underground.