ORIGINAL ARTICLE Qanat hazard in Iranian urban areas: explanation and remedies Ahmad Abbasnejad 1 • Behnam Abbasnejad 2 • Reza Derakhshani 1 • Alireza Hemmati Sarapardeh 3 Received: 6 November 2015 / Accepted: 7 September 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Abstract This article explains the qanat hazard in Iranian urban areas. Each qanat consists of an underground gallery (tunnel) which conveys groundwater to the surface, and several to tens of vertical wells (shafts) which provide access to the gallery. It is estimated that about 10,000 km qanats with 300,000 wells lie under Iranian urban areas. Their number under urban areas of the other countries containing it seems to be significant as well. In Iran, sub- sidence and other problems related to shafts and galleries of hidden qanats impose millions of dollars damage annually. Despite the importance of the qanat hazard, it has not yet received enough attention from scholars. In this article, qanat hazard as a special kind of geological hazard is explained from such aspects as the causes, the extents, the impacts and the various remedies to combat this hazard. Remedies to abate this hazard should include hazard assessment, risk assessment and risk reduction phases. Generally, the most efficient strategy is to detect qanats using aerial photos, maps or inquiring local people and construct the buildings in hazard-prone areas with spread footing foundations. However, this is not applicable in all occasions. So, depending on conditions, some other strategies which are provided in the text may be more effective. Keywords Ground subsidence Á Water management Á Urban geology Á Overpumpage Á Sinkhole Á Groundwater mismanagement Introduction As a kind of groundwater extraction, a qanat (also known as a Kariz) consists of an underground gallery (or tunnel) which conveys groundwater to the surface, and several to tens of vertical shafts (or wells), often 20–30 m apart, which provide access and help to excavate and ventilate the gallery (Fig. 1). Hence, a qanat can be considered as a form of subsurface canal which collects groundwater and con- veys it to the surface for human use (Saghafian 2005). The length of qanats, which depends on the gradient of topog- raphy and the depth and gradient of water table, varies from several tens of meters to more than 70 km, and the majority are 10–16 km long (Wulff 1968). Typically, the cross section of a qanat gallery is 1.5 m high and about 1 m wide, which is sufficient to allow the diggers and cleaners to move in (Saghafian 2005). The gradient of gallery is commonly in the range of 1:500–1:1500. The first and the deepest shaft, which is called the main shaft or mother well, is usually sunk into the unconsolidated coarse alluvial deposits near the mountain front to some depths below the water table. The mother well is often 30–100 m in depth. Soils excavated from the shafts are piled around their collar and create a line of mounds reminiscent of paternoster beads from above. Qanats may have several benefits (Table 1). & Ahmad Abbasnejad aabbas@uk.ac.ir Behnam Abbasnejad B.Abbasnejad@shirazu.ac.ir Reza Derakhshani Derakhshani@uk.ac.ir Alireza Hemmati Sarapardeh Alirezahemmati67@yahoo.com 1 Shahid Bahonar University of Kerman, Kerman, Iran 2 Shiraz University, Shiraz, Iran 3 Kerman, Iran 123 Environ Earth Sci (2016)75:1306 DOI 10.1007/s12665-016-6067-6