Base Information

Topography

Karkhe River, in the above of hydrometer station of Paypol, passes from the middle of the hills and high grounds and enters in to the Khuzestan plain. Karkhe River, at the upstream of the dam axis, changes its direction about 90° and the dam lake is located at the right side of the axis. From the viewpoint of River slight steep, dam lake has a remarkable volume. The steep of reservoir is mild. Steep of the left abutment is too harsh but at the right side it became mild. In the left coast, at the distance of 200 Km to the dam axis, a relatively great flood channel enters into the river and in the downstream also there is a smaller flood channel that the dam power station is located in the left side of it. Besides, there is another flood channel in the upstream of the dam axis, on the right side.

Meteorology

Catchment area of the Karkhe River, for its great extension, has various climates. Khuzestan plain and southern area of the Catchment is semi-dry with mild winters and long and hot summers, whereas northern parts and alpine regions have cold winters and mild summers. Temperature degree in this area changes from -25° to maximum 50°C. Annual average of rainfall in this area changes from 300 milliliter to 800 milliliter. Karkhe catchment area generally has Mediterranean climate. Annual average rainfall amount in dam location is about 290.6 milliliter. The annual average of temperature in dam location is about 24.6 degrees centigrade and the highest and lowest temperatures are -4.2 and 53.6 degrees centigrade. Annual evaporation of the water free level is about 2079 millimeter and the amount of Annual average humidity is 45.5%. The annual average of freezing days in the project location is 4.5. Average velocity of wind is 2.5 M/S and the maximum is 41.2 m/s directing west. The annual average of sunny hours is 2762.7.

Hydrology

There are 47 hydrometric stations on the Karkhe River. The area of Karkhe catchment area in Paypol station is about 42239 square kilometer. The average annual discharge volume in Paypol station is more than 5916 Million m3 and the average annual long-term outflow in this station is equal to 188 m3/s. More than 64% of annual water flow occurs in January to May.

Flood

Generally, floods occur in humid months of the year, tha is October to April. Big floods mostly occur in March, April and May.

Return period (Year)	5	10	20	50	100	200	1000	10000	P.M.F
Discharge (m3/s)	2900	3735	4665	6075	7240	8465	11690	17560	23670

Water quality

Samples quality shows that the water of this area is healthy potable. But in dry months, when the outflow of the river reaches to its minimum amount, the TDS amount is high and causes some limitations for agricultural usage.

Sedimentation

For normal figures of 220 masl, total sedimentation in a period of 50 years is estimated about 1730.5 million tones and in case a 100-year hydrograph is considered, the total amount of sedimentation for a 50-year period will reach to 2147.3 million tons. The reservoir suitable lost volume, caused by the above sedimentation is equal to 1443 million square meters.

Planning the water resources

Total potential of irrigating lands in Karkhe dam system is about 340000 hectares. The annual average volume of regulated water is about 3306.42 million m3. The average amount of hydro-electric potential energy of Karkhe dam power-station is 934 GW/h in a year and functional coefficient of Karkhe power-station is equal to 27%.

Geology

Karkhe dam is located in south western of Zagros Chain Mountains. High hills of this region consist of soft sediments of Aghajary and Bakhtiary Conglomerates. The main parts of the upstream of the reservoir consist of Aghajary components which is a combination of sand stone layers and lichen. The upper parts of this component consist of sandstone and lichen which made this area suitable for creation of under-pressure reservoirs.

Seismicity

Karkhe Dam structure is located in Zagros, which is one of the most active seismocity regions of Iran. Around the dam structure there are several faults that Lahbory fault has the maximum amount of quaking potential in this project.

Area of ground quake	DBL	MDE
Maximum horizontal velocity (according to g)	0.23	0.28
Maximum horizontal velocity (according to g)	0.12	0.18

Dam reservoir

Reservoir volume on operation level of 220 meter: 5.6 Billion m3 (before sedimentation)
Usable volume of reservoir is 3.9 Billion m3 (after sedimentation)
Water level at the time of flood occurrence is at most 230.9
Lake area at operation level of 220 m is 162.47 km2
Length of the lake at operation level of 220 m is about 60 km

Karkhe Project