نتایج جستجو برای: point nitrogen pollution and soil erosion

تعداد نتایج: 16946384  

2003
Berit Arheimer Jonas Olsson

Conceptual watershed model developed to examine water quality as it is affected by soil erosion from agriculture and urban areas (Young et al., 1987). AGNPS has three major components: hydrology, soil erosion and nutrient pollution. The hydrological function provides prediction of runoff volume and peak flow rate. The soil erosion function includes soil erosion and sedimentation. The nutrient f...

2017
Xuekai Chen Xiaobo Liu Wenqi Peng Fei Dong Zhihua Huang Ruonan Wang

To enhance the quantitative simulation and integrated assessment of non-point source (NPS) pollution in plateau lakes in data-poor regions, a simple and practical NPS assessment method is developed by combining the improved export coefficient model (ECM) and the revised universal soil loss equation (RUSLE). This method is evaluated via application to the Chenghai Lake watershed (Yunnan Province...

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One of the most important main environmental problems is soil erosion and its affects. Eutrophication, low oxygen levels and `high nutrient (nitrogen and phosphorus) concentrations in reservoirs, channel and other water courses, is a common water pollution feature. Phosphorus (P) is one of the major plant nutrients and also the major nutrients controlling eutrophication of surface water. The ai...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده علوم انسانی 1389

rivers and runoff have always been of interest to human beings. in order to make use of the proper water resources, human societies, industrial and agricultural centers, etc. have usually been established near rivers. as the time goes on, these societies developed, and therefore water resources were extracted more and more. consequently, conditions of water quality of the rivers experienced rap...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علوم کشاورزی و منابع طبیعی گرگان - دانشکده جنگلداری و مهندسی چوب و کاغذ 1391

درک الگوی توزیع مکانی ماکروفون خاک بدلیل اثرات آن روی فرآیندهای اکوسیستم بسیار مهم است. لیکن اطلاعات کمی در این خصوص وجود دارد. درمورد تنوع زیستی ارگانیسم ها وجانداران خاکزی که ازاجزای مهم وکلیدی درهرسیستم اکولوژیکی هستند و در بهبود حاصلخیزی خاک و تولیدات زمین وپایداری اکوسیستم ها(ازطریق فرآیندهای بیولوژیک)نقش عمده دارند تحقیقات کمی انجام شده است. این تحقیق جهت بررسی الگوی مکانی پارامترهای تنوع...

Journal: :Scientific reports 2015
Chunjian Tan Xue Cao Shuai Yuan Weiyu Wang Yongzhong Feng Bo Qiao

Conservation tillage is commonly used in regions affected by water and wind erosion. To understand the effects of conservation tillage on soil nutrients and yield, a long-term experiment was set up in a region affected by water and wind erosion on the Loess Plateau. The treatments used were traditional tillage (CK), no tillage (NT), straw mulching (SM), plastic-film mulching (PM), ridging and p...

2008
A. N. Sharpley

The current emphasis on sustainable agricultural systems has led to a renewed interest in the use of cover crops to reduce soil erosion losses and retain soluble nutrients during the dormant season. Cover crop choices include a broad range of plant material, such as ryegrass (Secufe cereale L.), winter wheat (Triticum aestivum L.), forage grasses, and legumes. Historically, cover crops were use...

Journal: :Environmental management 2014
Kathryn R Kidd W Michael Aust Carolyn A Copenheaver

Trail-based recreation has increased over recent decades, raising the environmental management issue of soil erosion that originates from unsurfaced, recreational trail systems. Trail-based soil erosion that occurs near stream crossings represents a non-point source of pollution to streams. We modeled soil erosion rates along multiple-use (hiking, mountain biking, and horseback riding) recreati...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1392

gol-e-gohar iron ore mine of sirjan in southern part of iran is a large open pit that operates below the groundwater table and during mining operation, dewatering is required to prevent operation processes from flooding. current operation is going on by digging wells in or out of the pit and pumping to prevent flooding. as a result of the former dewatering operation a vast deep cone of depressi...

Journal: :Water 2021

As one of the most important causes water quality deterioration, NPS (non-point source) pollution has become an urgent environmental and livelihood issue. To date, there have been only a few studies focusing on conforming to estimation, sources are mainly concentrated in nitrogen phosphorus nutrients. Unlike that consider intensity loads, risk for China’s Fuxian Lake Basin was evaluated this st...

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