Supplemental irrigation potential and impact on downstream flow of Karkheh River basin in Iran
Open Access
- 12 May 2016
- journal article
- Published by Copernicus GmbH in Hydrology and Earth System Sciences
- Vol. 20 (5), 1903-1910
- https://doi.org/10.5194/hess-20-1903-2016
Abstract
Supplemental irrigation of rainfed winter crops improves and stabilises crop yield and water productivity. Although yield increases by supplemental irrigation are well established at the field level, its potential extent and impact on water resources at the basin level are less researched. This work presents a Geographic Information Systems (GIS)-based methodology for identifying areas that are potentially suitable for supplemental irrigation and a computer routine for allocating streamflow for supplemental irrigation in different sub-basins. A case study is presented for the 42 908 km2 upper Karkheh River basin (KRB) in Iran, which has 15 840 km2 of rainfed crop areas. Rainfed crop areas within 1 km from the streams, with slope classes 0–5, 0–8, 0–12, and 0–20 %, were assumed to be suitable for supplemental irrigation. Four streamflow conditions (normal, normal with environmental flow requirements, drought and drought with environmental flow) were considered for the allocation of water resources. Thirty-seven percent (5801 km2) of the rainfed croplands had slopes less than 5 %; 61 % (3559 km2) of this land was suitable for supplemental irrigation, but only 22 % (1278 km2) could be served with irrigation in both autumn (75 mm) and spring (100 mm), under normal flow conditions. If irrigation would be allocated to all suitable land with slopes up to 20 %, 2057 km2 could be irrigated. This would reduce the average annual outflow of the upper KRB by 9 %. If environmental flow requirements are considered, a maximum (0–20 % slopes) of 1444 km2 could receive supplemental irrigation. Under drought conditions a maximum of 1013 km2 could be irrigated, while the outflow would again be reduced by 9 %. Thus, the withdrawal of streamflow for supplemental irrigation has relatively little effect on the outflow of the upper KRB. However, if the main policy goal would be to improve rainfed areas throughout the upper KRB, options for storing surface water need to be developed.Keywords
This publication has 15 references indexed in Scilit:
- Impact of upstream changes in rain-fed agriculture on downstream flow in a semi-arid basinAgricultural Water Management, 2011
- Assessment of Water Availability and Consumption in the Karkheh River Basin, Iran—Using Remote Sensing and Geo-statisticsWater Resources Management, 2009
- Estimating potential costs and gains from an aquifer storage and recovery program in AustraliaAgricultural Water Management, 2008
- Assessment of environmental flow requirements for river basin planning in ZimbabwePhysics and Chemistry of the Earth, Parts A/B/C, 2007
- Water harvesting and supplemental irrigation for improved water productivity of dry farming systems in West Asia and North AfricaAgricultural Water Management, 2006
- Supplemental irrigation for dry-spell mitigation of rainfed agriculture in the SahelAgricultural Water Management, 2003
- A desktop model used to provide an initial estimate of the ecological instream flow requirements of rivers in South AfricaJournal of Hydrology, 2003
- Water Use Efficiency of Rainfed and Irrigated Bread Wheat in a Mediterranean EnvironmentAgronomy Journal, 2000
- Stabilizing Rainfed Wheat Yields with Supplemental Irrigation and Nitrogen in a Mediterranean ClimateAgronomy Journal, 1998
- Use of a water deficit sensitivity index for partial irrigation scheduling of wheat and barleyIrrigation Science, 1997