TEHRAN —Inter-basin water transfer or trans-basin diversion -man-made conveyance schemes which move water from one basin where it is available, to another basin where water is less available- is frequently referred to as an option to alleviate water scarcity in arid provinces of the country.

Waster transfer projects might solely aim at providing sufficient drinking water to the residents of an arid area or being used for industrial, and some agricultural practices as well. 

In some cases agricultural and industrial uses may possibly produce enough economic value to compensate for the expenses involved constructing facilities such as canals, pipelines, and pumping stations. Nonetheless, when water is removed from an area it inevitably causes economic and environmental impacts.

That’s why inter-basin transfers are often considered as controversial practices, as the environmental and socio-economic consequences for the donor basin can be catastrophic, and at the same time difficult to foresee. Therefore, it must be strictly regulated in many areas, and even banned in others.  

Therefore in case of implementation some certain conditions should be met, for example: only a limited amount of water can be transferred, water right of the donor basin must be observed, and environment conservation plans should be drawn up for both donor and recipient basins.

In order to divert water from the donor to the recipient watershed pipes and canals must be constructed and this highly entails technical expertise.

For instance, pipes, canals and other equipment should be regularly checked, dredged and repaired if necessary, to limit potential water loss and ensure maximum efficiency of resource use.  

In areas facing critical water shortages, water transfer schemes can lead to groundwater recharge in the recipient basin and mitigate the adverse effects of water scarcity in the region.    

Socioeconomically speaking the increase in water supply in the recipient basin can promote agricultural, domestic, and industrial practices as well as power generation.

However, implementing such schemes are usually costly and time-consuming, they could have negative socio-economic consequences for communities downstream from the donor basin, and meanwhile water transfer can negatively affect ecosystem balance, including water quality and  flora and fauna.

Inter-basin water transfers in Iran

Iran is an arid and semiarid country with scarce and sensitive water resources and the increasing demand for water has led to an alarming decrease in annual per capita renewable water resources. Due to the fact that available water resources are unevenly distributed in terms of both time and space, water resources in many areas are under pressure.

The reasons behind present shortage of water for urban and domestic uses are the uneven distribution of water across the country, the expansion of population centers as well as developments in unsustainable agricultural and industrial activities. 

In a chapter of the book Water Conservation, Reuse, and Recycling (2005) titled “Inter-basin Water Transfers in Iran” by Ahmad Abrishamchi and Massoud Tajrishy it is highlighted that water managers at both local and national levels find water transfer from humid zones to arid zones to be the only option to satisfy demand. Each year proposals are presented to the government for new inter-basin water transfer (IBWT) projects, which are normally backed by political pressure. These efforts occur even while efficient and effective use is not being made of the available water resources.
 
Iran, an arid country, has an average annual precipitation of about 250 mm; less than one-third of the world average.

The annual per capita water as a general index of the water resources status used to be about 7,000 m3 in 1956 when the population was only 19 million. In 2005, with a population that has grown to about 65 million, the index was estimated to be about 2,000 m3. With the increasing trend in population growth, it is predicted to sink further, to below 1,000 m3 in the year 2025.

And this, sadly, indicate that the future generations will most certainly face serious water shortages in the coming decades. 

The chapter on inter-basin water transfers continues: “Due to the present increase in water demand by an increasing population, as well as the economic status and desire for higher standards of living by the public, the conflicts of water supply and water demand are gradually getting more serious so that the available water must be shared among different regions in the country for different uses. 

“In most areas, local water resources have already been tapped, while demand remains beyond the capacity of existing water resources. Bridging the present and future gaps between demand and supply will require tremendous efforts to develop various supply enhancements and demand management options, among which construction of new dams on the remaining unexploited sites and inter-basin water transfer (IBWT) appear to water managers to be promising options. A number of IBWT schemes have accordingly been implemented or proposed in order to divert water mainly from northeastern basins into central arid regions.”

Conclusion

Usually one argument which is raised against such infrastructural solutions is that initiatives must be directed toward reducing water wastage before any efforts are made to justify costly investments that are associated with intervening in the natural hydrologic cycle.

Granted uneven water resource distribution and imbalanced water demand has made water transfer projects inexorable. The projects might resolve the urgent demand of water-deficient areas, but socioeconomic as well as ecological consequences are definitely not negligible.  

The positive impacts of inter-basin water transfer include improving meteorological conditions in the recipient basins, repairing the damaged ecological system, and preserving the endangered wild fauna and flora, according to the U.S. National Center for Biotechnology Information (NCBI).

On the contrary salinization and aridification of the donor basins, damage to the ecological environment of the donor basins and the both sides of the conveying channel system, increase of water consumption in the recipient basins, and spread of diseases are among the negative impacts.

With regards to the huge ecological risks of inter-basin water transfer schemes, it is necessary to comprehensively analyze the inter-basin water balance relationship, coordinate the possible conflicts and environmental quality problems between regions, and strengthen the argumentation of the ecological risk of water transfer and eco-compensation measures. 

Most importantly there are some effective alternative measures for inter-basin water transfer, such as attaching importance to water recycling practices, improving water use efficiency, developing sea water desalination, and advancing rainwater harvesting technology.

MQ/MG