气候变化领域集成服务门户(CCPortal): Assessment of hydrological pathways in East African montane catchments under different land use

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DOI	10.5194/hess-22-4981-2018
	Assessment of hydrological pathways in East African montane catchments under different land use
	Jacobs S.R.; Timbe E.; Weeser B.; Rufino M.C.; Butterbach-Bahl K.; Breuer L.
发表日期	2018
ISSN	1027-5606
起始页码	4981
结束页码	5000
卷号	22 期号:9
英文摘要	Conversion of natural forest (NF) to other land uses could lead to significant changes in catchment hydrology, but the nature of these changes has been insufficiently investigated in tropical montane catchments, especially in Africa. To address this knowledge gap, we aimed to identify stream water (RV) sources and flow paths in three tropical montane sub-catchments (27-36 km2) with different land use (natural forest, NF; smallholder agriculture, SHA; and commercial tea and tree plantations, TTP) within a 1021 km2 catchment in the Mau Forest complex, Kenya. Weekly samples were collected from stream water, precipitation (PC) and mobile soil water for 75 weeks and analysed for stable isotopes of water (δ2H and δ18O) for mean transit time (MTT) estimation with two lumped parameter models (gamma model, GM; and exponential piston flow model, EPM) and for the calculation of the young water fraction. Weekly samples from stream water and potential endmembers were collected over a period of 55 weeks and analysed for Li, Na, Mg, K, Rb, Sr and Ba for endmember mixing analysis (EMMA). Solute concentrations in precipitation were lower than in stream water in all catchments (p < 0.05), whereas concentrations in springs, shallow wells and wetlands were generally more similar to stream water. The stream water isotope signal was considerably damped compared to the isotope signal in precipitation. Mean transit time analysis suggested long transit times for stream water (up to 4 years) in the three sub-catchments, but model efficiencies were very low. The young water fraction ranged from 13 % in the smallholder agriculture sub-catchment to 15 % in the tea plantation sub-catchment. Mean transit times of mobile soil water ranged from 3.2-3.3 weeks in forest soils and 4.5-7.9 weeks in pasture soils at 15 cm depth to 10.4-10.8 weeks in pasture soils at 50 cm depth. The contribution of springs and wetlands to stream discharge increased from a median of 16.5 (95 % confidence interval: 11.3-22.9), 2.1 (-3.0-24.2) and 50.2 (30.5-65.5) % during low flow to 20.7 (15.2-34.7), 53.0 (23.0-91.3) and 69.4 (43.0-123.9) % during high flow in the natural forest, smallholder agriculture and tea plantation sub-catchments, respectively. Our results indicate that groundwater is an important component of stream water, irrespective of land use. The results further suggest that the selected transit time models and tracers might not be appropriate in tropical catchments with highly damped stream water isotope signatures. A more in-depth investigation of the discharge dependence of the young water fraction and transit time estimation using other tracers, such as tritium, could therefore shed more light on potential land use effects on the hydrological behaviour of tropical montane catchments. © 2018 Author(s).
语种	英语
scopus关键词	Forestry; Groundwater; Isotopes; Land use; Rivers; Runoff; Soil moisture; Tropics; Wetlands; Catchment hydrology; Confidence interval; End-member mixing analysis; Lumped parameter models; Mean transit time; Model efficiency; Solute concentrations; Stable isotopes of water; Catchments
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159906
作者单位	Jacobs, S.R., Centre for International Development and Environmental Research (ZEU), Justus Liebig University, Senckenbergstr. 3, Giessen, 35390, Germany, Institute for Landscape Ecology and Resources Management (ILR), Justus Liebig University, Heinrich-Buff-Ring 26, Giessen, 35392, Germany, Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (KIT/IMK-IFU), Kreuzeckbahnstr. 19, Garmisch-Partenkirchen, 82467, Germany, Centre for International Forestry Research (CIFOR), C/o World Agroforestry Centre, United Nations Avenue, Nairobi, 00100, Kenya; Timbe, E., Facultad de Ciencias Agropecuarias, Carrera de Ingeniería Agronómica, Universidad de Cuenca, Cuenca, 010111, Ecuador; Weeser, B., Centre for International Development and Environmental Research (ZEU), Justus Liebig University, Senckenbergstr. 3, Giessen, 35390, Germany, Institute for Landscape Ecology and Resources Management (ILR), Justus Liebig University, Heinrich-Buff-Ring 26, Giessen, 3...
推荐引用方式 GB/T 7714	Jacobs S.R.,Timbe E.,Weeser B.,et al. Assessment of hydrological pathways in East African montane catchments under different land use[J],2018,22(9).
APA	Jacobs S.R.,Timbe E.,Weeser B.,Rufino M.C.,Butterbach-Bahl K.,&Breuer L..(2018).Assessment of hydrological pathways in East African montane catchments under different land use.Hydrology and Earth System Sciences,22(9).
MLA	Jacobs S.R.,et al."Assessment of hydrological pathways in East African montane catchments under different land use".Hydrology and Earth System Sciences 22.9(2018).