Knowledge Resource Center for Ecological Environment in Arid Area
| Basin-scale change in water availability and water quality under intensified irrigated agriculture | |
| Törnqvist;Rebecka | |
| 出版年 | 2013 |
| 学位授予单位 | Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm University |
| 英文摘要 | 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. At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript. |
| 英文关键词 | 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 |
| 语种 | 英语 |
| URL | http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-93214 |
| 来源机构 | Stockholms universitet |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/247959 |
| 推荐引用方式 GB/T 7714 | Törnqvist;Rebecka. Basin-scale change in water availability and water quality under intensified irrigated agriculture[D]. Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm University,2013. |
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