نتایج جستجو برای: catchments

تعداد نتایج: 4452  

2008
F. SABATER

1. Due to the hierarchical organization of stream networks, land use changes occurring at larger spatial scales (i.e. the catchment) can affect physical, chemical and biological characteristics at lower spatial scales, ultimately altering stream structure and function. Anthropogenic effects on streams have primarily been documented using structural metrics such as water chemistry, channel alter...

Journal: :روش های عددی در مهندسی (استقلال) 0
سید سعیداسلامیان s. s. eslmian احمد ابریشم چی و کیوان فرزام نیا a. abrishamchi and k. farzamnia

accurate estimate of flood flows at selected return periods is a fundamental step in flood control and design of hydraulic structures. due to the inadequacy or unavailability of flood flow records in several western catchments of iran, traditional regional flood frequency methods lead to remarkable estimate errors, particularly for long return periods. in this research, discriminant analysis is...

2006
M. Voss

Nitrate input to a river is largely controlled by land use in its catchment. We compared the information carried by the isotopic signatures of nitrate in 12 Baltic rivers, in relation to the vegetation cover, land use, and fertilization of agricultural land of their catchments. We found isotope values in nitrate ranging from −2 to 14‰ for δ15N and 8 to 25‰ for δ18O. The annual variability of ri...

Journal: :Environmental management 2005
Kelly O Maloney Patrick J Mulholland Jack W Feminella

We conducted a 3-year study designed to examine the relationship between disturbance from military land use and stream physical and organic matter variables within 12 small (<5.5 km2) Southeastern Plains catchments at the Fort Benning Military Installation, Georgia, USA. Primary land-use categories were based on percentages of bare ground and road cover and nonforested land (grasslands, sparse ...

2018
Mary C. Ockenden Wlodek Tych Keith J. Beven Adrian L. Collins Robert Evans Peter D. Falloon Kirsty J. Forber Kevin M. Hiscock Michael J. Hollaway Ron Kahana Christopher J. A. Macleod Martha L. Villamizar Catherine Wearing Paul J. A. Withers Jian G. Zhou Clare McW. H. Benskin Sean Burke Richard J. Cooper Jim E. Freer Philip M. Haygarth

Excess nutrients in surface waters, such as phosphorus (P) from agriculture, result in poor water quality, with adverse effects on ecological health and costs for remediation. However, understanding and prediction of P transfers in catchments have been limited by inadequate data and over-parameterised models with high uncertainty. We show that, with high temporal resolution data, we are able to...

2014
Silke Werth Christoph Scheidegger

One of the major distinctions of riparian habitats is their linearity. In linear habitats, gene flow is predicted to follow a one-dimensional stepping stone model, characterized by bidirectional gene flow between neighboring populations. Here, we studied the genetic structure of Myricaria germanica, a threatened riparian shrub which is capable of both wind and water dispersal. Our data led us t...

2003
H. Koivusalo T. Kokkonen A. Laurén M. Ahtiainen T. Karvonen H. Mannerkoski P. Seuna M. Starr P. Vakkilainen

This paper combines an empirical paired-catchment method with hydrological simulation techniques in quantifying and explaining the influence of forest removal on streamflow generation. The pair of catchments (56 and 29 ha) is located in a northern boreal zone in eastern Finland. As the first part of the study, measured streamflows from the two catchments, of which one has been partially clear-c...

2013

Streamflow (Q) estimation in ungauged catchments is perhaps the most fundamental challenge faced by hydrologists. A promising approach to calibrate hydrological models in ungauged catchments is to use estimated Q characteristics to identify acceptable model parameter sets. This study is the first to test this approach at the global scale using a large, heterogeneous catchment set. First, observ...

2010
Walter Boughton

A new method of calibration of the Australian Water Balance Model (AWBM) daily rainfall-runoff model allows for errors in the estimation of areal rainfall over the catchment. The result of applying the method to a group of gauged catchments is the production of a single set of parameter values for the AWBM that can be used with any catchment in the group, or used to estimate runoff on ungauged ...

2010
Sarah E. Godsey Wenche Aas Thomas A. Clair Heleen A. de Wit Ivan J. Fernandez J. Steve Kahl Iain A. Malcolm Colin Neal Margaret Neal Sarah J. Nelson Stephen A. Norton Marisa C. Palucis Brit Lisa Skjelkvåle Chris Soulsby Doerthe Tetzlaff James W. Kirchner

Catchment travel time distributions reflect how precipitation from different storms is stored and mixed as it is transported to the stream. Catchment travel time distributions can be described by the mean travel time and the shape of the distribution around the mean. Whereas mean travel times have been quantified in a range of catchment studies, only rarely has the shape of the distribution bee...

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