نتایج جستجو برای: runoff yield

تعداد نتایج: 207970  

2008
P. A. Vadas A. N. Sharpley

Dissolved phosphorus (P) in runoff from surface-applied fertilizers can be relatively great, but commonly used, field or watershed-scale computer models often do not simulate direct transfer of fertilizer P to runoff. Using data from our own simulated rainfall experiments and published runoff studies, we developed a simplemodel to predict fertilizer P release during rain and the concentration o...

2017
J. D. Williams

Conservation tillage systems that reduce soil erosion and maintain or increase soil carbon offer long-term benefits for producers in the inland Pacific Northwestern United States but could result in reduced grain yields due to increased pressure from weeds, disease, and insect pests. Our objective was to compare runoff, soil erosion, and crop yields from a conventional tillage, wheat-fallow two...

Journal: :تحقیقات آب و خاک ایران 0
پریسا سادات آشفته دانشجوی دکتری مهندسی منابع آب، پردیس کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران امید بزرگ حداد دانشیار گروه مهندسی آبیاری و آبادانی، پردیس کشاورزی و منابع طبیعی دانشگاه تهران، کرج

in this study, long-term trends and abrupt changes of hydro-climatic variables was investigated in the observed period 1971-2000 for aidoghmoush basin using mann-kendall nonparametric test and cumulative curve of climatic variables-runoff, respectively. results show decrease trends for rainfall and runoff and increase trend for temperature by the mann-kendall test with a confidence level of 99%...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان 1390

a one dimensional dynamic model for a riser reactor in a fluidized bed catalytic cracking unit (fccu) for gasoil feed has been developed in two distinct conditions, one for industrial fccu and another for fccu using various frequencies of microwave energy spaced at the height of the riser reactor (fccu-mw). in addition, in order to increase the accuracy of component and bulk diffusion, instanta...

2016
Yungang Li Daming He Xue Li Yueyuan Zhang Liyan Yang Xixi Wang Xuefeng Chu Tingxi Liu Xiangju Cheng

Quantifying the effects of climate variability and human activities on runoff changes will contribute to regional water resource planning and management. This study aims to separate the effects of climate variability and human activities on runoff changes in the upper catchment of the Red River Basin in China. The Mann–Kendall test and Pettitt’s test methods were applied to identify the trends ...

2001
Douglas A. Burns Jeffrey J. McDonnell Richard P. Hooper Norman E. Peters James E. Freer Carol Kendall Keith Beven

The geographic sources and hydrologic flow paths of stormflow in small catchments are not well understood because of limitations in sampling methods and insufficient resolution of potential end members. To address these limitations, an extensive hydrologic dataset was collected at a 10 ha catchment at Panola Mountain Research Watershed near Atlanta, GA, to quantify the contribution of three geo...

2002
Assefa M. Melesse

The use of geographic information systems (GISs) and remote sensing to facilitate the estimation of runoff from watershed and agricultural fields has gained increasing attention in recent years. This is mainly due to the fact that rainfall-runoff models include both spatial and geomorphologic variations. The US Department of Agriculture, Natural Resources Conservation Service Curve Number (USDA...

2006
Jeanne M. Schneider Michael W. Van Liew

Conditions under which monthly rainfall forecasts translate into monthly runoff predictions that could support water resources planning and management activities were investigated on a small watershed in central Oklahoma. Runoff response to rainfall forecasts was simulated using the hydrologic model SWAT. Eighteen scenarios were examined that represented combinations of wet, average, and dry an...

2016
Lloyd Ling Zulkifli Yusop

Thorough understanding of the rainfall-runoff processes that influence watershed hydrological response is important and can be incorporated into the planning and management of watershed resources. Soft computing techniques and inferential statistics were used to assess 2 rainfall-runoff models and their runoff predictive accuracy in this article. The 1954 simplified SCS runoff model was found t...

Journal: :Annals of GIS 2001
Yong Q. Tian Peng Gong Richard P. Ibbitt Alexander E. Elliott

Rainfall, topography and soil characteristics are considered to control spatial redistribution of phosphorus in catchments. To advance this research, a hydrology model is needed to describe spatial variation of soil moisture dynamics and runoff source areas in multiple runoff events. This study examined whether the spatially distributed, topographically based rainfall-runoff model, TOPMODEL pro...

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