Darreh Shahr County () is in Ilam province, Iran. Its capital is the city of Darreh Shahr.
At the 2006 census, the county's population was 56,346 in 11,487 households. The following census in 2011 counted 59,551 people in 14,867 households. At the 2016 census, the county's population was 43,708 in 12,012 households, by which time Badreh District had been separated from the county to form Badreh County.
Administrative divisions
The population history and structural changes of Darreh Shahr County's administrative divisions over three consecutive censuses are shown in the following table. The latest census shows two districts, four rural districts, and two cities.
Abdanan County and Badreh County used to be districts of Darreh Shahr County before 1995 and 2013, respectively, after which they were upgraded to county status themselves.
Neighboring counties
Abdanan – south
Badreh – northwest
Rumeshkhan County, Lorestan – north
Pol-e Dokhtar County, Lorestan – east
Geography
Darreh Shahr county has an area of . Darreh Shahr is bounded by Kabir Kuh range to the south and Seymareh and Karkheh rivers to the north. The plains between the mountains and the rivers are fertile farmlands being cultivated for millennia. There are about of woodlands in the county, most of which are on the higher altitudes of the Kabir Kouh range to the south. The Kabir Kouh Protected Area is the most important conservation area in the county. It was established in 2001 and has an area of between the elevations of 950-2790m on the northern, greener, side of Kabir Kouh.
Rivers
Seymareh River
Karkheh River
Darreh Shahr River
Sikan River
Lakes
Seymareh Dam Lake
Climate
Darreh Shahr County has a warm climate with hot dry summers and mild wet winters. July–August maximum daily temperature can as high as during heat waves, which are frequent in summer due to proximity to the Iraqi desert. Winters are generally mild but occasionally goes below freezing.
The long-term average annual precipitation is at Darreh Shahr Weather Station. The lowest annual precipitation happened during the farming season of 2007–2008 with a figure as low as . The highest annual precipitation used to be in 1990–1991, after which, a deadly flood ensued. This record was broken in 2018–2019 with , which again resulted in a heavy flooding in southwestern Iran.
There is almost no precipitation through the months of June to September. Darreh Shahr used to receive snow once or twice a year in the past, but nowadays it has become less and less likely thanks to global warming. Hail and lightning storms are not uncommon in Fall and Spring and have devastating effects on crops and the farming-dependent economy of the county.
Western air masses from the Mediterranean and Black Sea are cause autumn and winter rains in the province, and Sudanese and Red Sea and Saudi Arabia currents are also effective in winter and spring rains and cause warm weather in summer. The vast plains of Iraq create a low-pressure high-temperature low-humidity weather cell over the area.
Seymareh Landslide
In prehistoric times, a huge landslide occurred in the south eastern parts of Kabir Kuh range. The incident is described in an article on Royal Geographical Society, published in 1937 by Harrison and Falcon. Based on their observations, the landslide is in area and in thickness; amounting to a body of material of about , some of which is found around from their original location. The reason for this colossal event is very likely to have been a catastrophic earthquake. Due to its enormity, the Seymareh Landslide is believed to be the largest one recorded in the eastern hemisphere.
Economy
The economy of Darreh Shahr is mostly based on agriculture and animal husbandry. As of February 2018, Darreh Shahr farmers produce more than 190,000 tons of agricultural and 23,000 tons of livestock products annually. Darreh Shahr has about of farming irrigated and dry lands. The agriculture market in Darreh Shahr is worth around US$17.7m.
Darreh Shahr is a large producer of daffodils with about of cultivated farms and an average annual production of 7 million flowers, most of which is marketed in cities of Tehran, Isfahan, Ahvaz and Arak.
The majority of the people living in urban areas, especially Darreh Shahr, work in construction and services trades sector. As the county seat, Darreh Shahr hosts almost all of the government offices of the county, therefore many people work for the government.