Presentation of IWA Groundwater Specialist Conference 8-10 September 2011, Belgrade, Serbia - page 6

 

Raeisi (2011) presented ancient and present groundwater management practices in Iran. Most of the agricultural lands in Iran are located in arid and semi-arid climates with no precipitation during the summers. The use of the groundwater is unavoidable due to the lack of permanent rivers and the seasonality of precipitation. Iranians invented "qanats" to transfer groundwater by gravity to the surface without energy costs and evaporation. In addition, qanats do not cause overexploitation problems. They are also capable of draining considerable amounts of aquitard water, compared to the negligible discharge of pumping wells. Population growth, urbanisation, modernisation of agricultural technologies, economic development, social and cultural changes, and the absence of big industries in rural areas to employ the number of farmers' offspring in excess of the farms' labour demands, have all lead farmers to extend their cultivated lands by constructing unauthorised pumping wells or withdrawing water over the permissible levels. The resulting impacts include water table drop, desolation of numerous qanats, reduction of discharge of downstream springs and wells, increased energy costs, increased groundwater contamination, and the intensification of water scarcity in draught years.

Remediation methods include reduction of exploitation from aquifers by use of intelligent meters, providing agricultural water from other sources, increasing water prices, using drip irrigation without extending farm areas, increasing dry grain yield per unit volume of applied water, and integrating research to encourage farmers to further cooperation for optimum groundwater management. New water supplies include desalinisation of seawater or saline aquifers, prevention of intrusion of evaporate formations and salt diaper brines into karstic and fresh water aquifers, treatment of municipal and industrial wastewater, and the use of fossil and virtual water. Drip and sprinkler irrigations are recommended only if the farm area is not extended as a result of the saved water from return, as return is being used by downstream wells for irrigation. Using the saved water of return flow for cultivating new land only intensifies the water crisis in the basins. The transfer of water from other basins is no longer an option, because there is simply no excess water left. Cloud seeding is also not recommended, because it has severe impacts on the other parts of Iran with very low precipitation."

McBean (2011) gives an assessment of sustainability of groundwater in the developing world, in a climate changing world. Globally, ground water use has undergone dramatic expansion over the past 50 years, with global abstraction rates increasing from an estimated 100-150 cubic kilometres in 1950 to 950-1000 cubic kilometres in the year 2000. Much of this growth is the result of agriculture where, for example, in Bangladesh, the area irrigated by groundwater (as a fraction of total irrigated area) grew from 4% to 70% between 1972 and 1999. Additional concerns are that increasing water demands are also in response to urban growth and the population explosion. The result is that the growth in demands for water has been so large in the developing world in particular, that serious questions exist in terms of sustainability. Currently it is estimated that 8.2% of annually renewable groundwater on a global scale is being extracted for human use but the regionality of the withdrawals are such that some regions are experiencing declining groundwater levels. While there are many advantages to use of groundwater as a water supply source, when available, globally only about 2% of all worldwide precipitation goes to groundwater. The bulk of global groundwater use is concentrated in relatively few nations, namely Bangladesh, China, India, Iran, Pakistan, and the U.S.A., which accounts for approximately 80% of global groundwater use. Groundwater withdrawals over the last four decades have been substantial and important, in meeting the burgeoning needs of the agricultural sector and increasingly so, the needs of the urban sectors. However, the ability to respond to the existing and projected increased needs, including the increasing populations, has limits. The situation, in light of climate change, however, is even more foreboding as the ability to rely on groundwater resources is going to be severely limiting. While issues of the challenges to sustainability were only demonstrated using one country (Bangladesh), the message is consistent across many parts of the world. The potential to use increased groundwater withdrawals as the response to climate change, is very limited in most countries.