An Overview of the Hydrology of the Zayandeh Rud Basin, Iran

Document Type : Research Paper


1 Esfahan Agricultural & Natural Resources Research

2 International Water Management Institute, Colimbo, Sri Lanka


This paper provides an overview of the hydrology and water use in the Zayandeh Rud basin based on the data available over the 11- years period 1988-1998. The inflows into Chadegan reservoir, the releases from the reservoir, and the extractions along the river for irrigation and other purposes are considered, and a rapid water balance of the basin is performed. Inflows to the Chadegan reservoir, which serves to collect and regulate the runoff from the upper catchment of the basin to better meet the downstream water requirements for irrigation, urban and industrial uses, follow a regular pattern with moderate variability. But the limited year-to-year storage in the reservoir makes the basin vulnerable to prolonged periods of drought. Water releases from the Chadegan reservoir also  show a predictable pattern, with the only deviations occurring during flood events. There is a high reliability of meeting the water requirements during periods of peak demand. But releases during the winter months, at the end of the irrigation season, are lower and more variable. This results in low discharges in the Zayandeh Rud and reduced water quality, especially in the lower reaches of the river. A simple water-balance approach was used to estimate the proportion of return flows in the basin. An average annual value of 30% was obtained, with the magnitude of return flows being particularly important in the lower reaches of the basin. But more investigation, especially including groundwater and water quality aspects, needs to be carried out before a definitive value can be advanced. Given the limited supply of fresh water in the Zayandeh Rud basin, further water resources development and water management improvements can only be envisaged in there is scope for real water savings in the basin. This can be assessed if a basin-wide approach, leading to a good understanding of water use (and reuse) at the farm, system and basin levels, is adopted.

1-    Droogers, P., Salemi, H.R., and Mamanpoush, H.R., (2000). “Exploring Basin Scale Salinity Problems Using a Simplified Water Accounting Model: the Example of Zayandeh Rud Basin, Iran”, IAERI-IWMI Research Report 5. IRAN.
2-    Gieske, A., Miranzadeh, M. and Mamanpoush, A., (2000). “Groundwater Chemistry of the Lenjanat District, Esfahan Province”, IEARI-EARC-IWMI Research Report 4. IRAN.
3-    Keller, A., Keller, J. and Seckler, D.W., (1996). “Integrated Water Resources Systems: Theory and Policy Implications”. IWMI, Research Report 3, Colombo, Lanka: International Water Management Institute. Srilanka.
4-    Modlen, D.J., (1997). “Accounting for Water Use and Productivity”, SWIM, Paper 1. Colombo, Srilanka: International Irrigation Management Institute.
5-    Modlen, D.J. and Sakthivadivel, R., (1999). “Water Accounting to Assess Use and Productivity of Water”, International Journal of Water Resources Development Special Double Issue: Research from the International water Management Institute (IWMI)]. 15(1/2): 55-71.
6-    Perry, C.J., (1996). “The IIMI Water Balance Framework: A Model for Project Level Analysis”, IWMI Research Report 5. Colombo, Srilanka: Irrigation Manangement Institute.
7-    Perry, C.J., (1999). “The IWM Iwater Resources paradigm: Definitions and Implications”, Agricultural Water Management, 40(1): 45-50.
8-    Salemi, H.R., Mamanpoush, A., Miranzadeh, M., Akbari, Torabi, M., Toomanian, N., Murray-Rust, H., Droogers, P., Sally, H., Gieske. A., (2000). “Water management for Sustainable Irrigated Agriculture in the Zayandeh Rud Basin, Esfahan Province, Iran”, IAERI-EARC-IWMI Research, Report 1.