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Water Savings Through Improved Irrigation Techniques: Basin-Scale Quantification in Semi-Arid Environments
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
2012 (English)In: Water resources management, ISSN 0920-4741, E-ISSN 1573-1650, Vol. 26, no 4, 949-962 p.Article in journal (Refereed) Published
Abstract [en]

In many semi-arid and arid regions of the world, water saving strategies need to be implemented in the agricultural sector in order to increase the resilience to water scarcity. We investigate basin-scale hydrological impacts of possible irrigation technique improvements, considering extensive cotton fields in the Aral Sea drainage basin (ASDB), Central Asia. We use a distributed hydrologic model that combines basin-scale, calibrated discharge and evapotranspiration quantifications with experimental results of (on-farm) water application needs for different irrigation techniques. This allows for quantification of how return flows contribute to river discharge through coupled groundwater-surface water-systems at the basin scale, under different regional climatic conditions. Results show that an implementation of improved irrigation techniques can yield water savings that increase the discharge to the Aral Sea by between 1 and 6 km3/year. Such water savings could contribute to mitigation of the acute water scarcity in the lower ASDB. The basin-scale water savings are about 60% lower than corresponding on-farm reductions in irrigation water application, since water is re-used and, hence, return flows decrease when less water is applied. Spatial analysis of regional differences in climatic conditions shows that implementation of more efficient irrigation systems would result in much larger (up to a factor 4) water savings in the more arid downstream regions than in the colder, upstream mountainous regions.

Place, publisher, year, edition, pages
2012. Vol. 26, no 4, 949-962 p.
Keyword [en]
Irrigation, Return flows, Semi-arid, Basin-scale modelling, Central Asia
National Category
Oceanography, Hydrology, Water Resources
Identifiers
URN: urn:nbn:se:su:diva-67752DOI: 10.1007/s11269-011-9819-9ISI: 000301748200007OAI: oai:DiVA.org:su-67752DiVA: diva2:471110
Note

2

Available from: 2012-01-01 Created: 2012-01-01 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Basin-scale change in water availability and water quality under intensified irrigated agriculture
Open this publication in new window or tab >>Basin-scale change in water availability and water quality under intensified irrigated agriculture
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Changes in land use and water use can greatly impact the cycling of water and water-borne substances. Increased redistribution of river water to irrigated fields can cause enhanced evapotranspiration and decreased river discharge. Additionally, the water quality can be affected by the external input of fertilisers and pesticides, and by changed pollutant transport pathways in expansive irrigation canal systems. This thesis examines basin-scale changes in water use, river discharge, water quality and nitrogen (N) loading under conditions of intensified irrigated agriculture, using the Aral Sea drainage basin (ASDB) with its two large rivers Syr Darya and Amu Darya in Central Asia as study area. Results show that more efficient irrigation techniques could reduce outtake of river water to the cotton fields in the ASDB by about 10 km3/year, while the corresponding river water saving at the outlet would be 60% lower. The result illustrates the importance of accounting for return flows of irrigation water in basin-scale water saving assessments. Moreover, a decrease in riverine N concentrations at the outlet of the Amu Darya River Basin (ADRB) was observed during a 40-year period of increasing N fertiliser input. The decrease was identified to be primarily caused by increased recirculation of river water in the irrigation system, leading to increased flow-path lengths and enhanced N attenuation. Decreasing N loads were shown to be primarily related to reduced discharge. N export from the basin may further decrease due to projected discharge reductions related to climate change. Furthermore, nutrients and metals were occasionally found at concentrations above drinking water guideline values in surface waters in the ADRB. However, metal concentrations in groundwater in the lower ADRB were subject to orders of magnitude higher health hazards. Projected decrease in downstream surface water availability would thus imply decreased access to water suitable for drinking.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography and Quaternary Geology, Stockholm University, 2013. 34 p.
Series
Dissertations from the Department of Physical Geography and Quaternary Geology, ISSN 1653-7211 ; 38
Keyword
Irrigation, Hydrology, Land-use change, Basin-scale, Central Asia, Aral Sea, Semi-arid, Return flow, Water saving, Health risk, Water quality, Surface water, Groundwater, Nitrogen, Attenuation, Recirculation, Climate change
National Category
Oceanography, Hydrology, Water Resources
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-93214 (URN)978-91-7447-724-5 (ISBN)
Public defence
2013-10-18, William-Olssonsalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript.

Available from: 2013-09-26 Created: 2013-09-04 Last updated: 2013-09-25Bibliographically approved

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