نتایج جستجو برای: drainage depth control

تعداد نتایج: 1511160  

2010
P. J. Shouse J. E. Ayars

In the irrigated western U.S. disposal of drainage water has become a significant economic and environmental liability. Development of irrigation water management practices that reduce drainage water volumes is essential. One strategy combines restricted drainage outflow (by plugging the drains) with deficit irrigation to maximize shallow groundwater consumption by crops, thus reducing drainage...

Journal: :Global change biology 2016
Kristina Konecny Uwe Ballhorn Peter Navratil Juilson Jubanski Susan E Page Kevin Tansey Aljosja Hooijer Ronald Vernimmen Florian Siegert

Tropical peatland fires play a significant role in the context of global warming through emissions of substantial amounts of greenhouse gases. However, the state of knowledge on carbon loss from these fires is still poorly developed with few studies reporting the associated mass of peat consumed. Furthermore, spatial and temporal variations in burn depth have not been previously quantified. Thi...

2002
Xiuying Wang Rabi H. Mohtar

This study was conducted to evaluate the performance of DRAINMOD /DRAINMOD-N on an experimental drainage field at Southeast Purdue Agricultural Center (SEPAC), based on the comparison between observed and predicted subsurface drain flows and nitrate-nitrogen losses via drainage. The site was under conventional drainage management, consisting of two replications of three tile drain spacings—5m, ...

Journal: :آب و خاک 0
حسین مولوی مسعود پارسی نژاد عبدالمجید لیاقت

abstract one of the ways to increase economic and environmental efficiency of drainage systems is water table management. water table management consists of, controlled drainage and subirrigation. this study examines the effect of controlled drainage on yield, root distribution pattern and water use efficiency of maize (sc 704) in karaj. the experiment was performed as a randomized complete des...

Journal: :Geofluids 2022

In view of the high gas pressure and low permeability deep coal seam, it is difficult to control gas, which affects safety production mine. The technical scheme hydraulic fracturing improve seam put forward, drainage technology used emission seam. effect under different water pressure, gradient times, in situ stress analyzed by using 3DEC (3-Dimensional Distinct Element Code) discrete element s...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
Ying Fan Gonzalo Miguez-Macho Esteban G Jobbágy Robert B Jackson Carlos Otero-Casal

Plant rooting depth affects ecosystem resilience to environmental stress such as drought. Deep roots connect deep soil/groundwater to the atmosphere, thus influencing the hydrologic cycle and climate. Deep roots enhance bedrock weathering, thus regulating the long-term carbon cycle. However, we know little about how deep roots go and why. Here, we present a global synthesis of 2,200 root observ...

Journal: :journal of hydraulic structures 2014
mina sadat seyedjavad mahmoud mashaal aliasghar montazar

measuring sensitivity of hydraulic structures is considered as an approach for evaluation of water projects performance, due to lower distribution efficiency in irrigation and drainage project schemes. sensitivity analysis approach for irrigation structures is one of flow analysis methods which are developed in recent years in order to measure the behavior of flow in hydraulic structures in an ...

Journal: :فیزیک زمین و فضا 0
اصغر کوهپیما کارشناس ارشد آبخیزداری، گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، ایران سادات فیض نیا استاد، گروه گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، ایران حسن احمدی استاد، گروه گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، ایران محمد معظمی دانشجوی دکتری آبخیزداری، گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، ایران

designing effective strategies for sediment management and control is closely related to identification of sediment sources in a drainage basin. one of the methods for investigating sediment sources is using magnetic tracers for erosion and sediment yield studies. sediment source identification using magnetic characteristics is a simple, inexpensive, quick and non-destructive method having appl...

The momentum equation in the kinematic wave model is a power-law equation with two parameters. These parameters, which relate the discharge to the flow area, are commonly derived using Manning’s equation. In general, the values of these parameters depend on the flow depth except for some special cross sections. In this paper, improved estimates of the kinematic wave parameters for circular chan...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی عمران 1391

in this study, scour of mashkid bridge pier located in mashkid river of saravan county has been studied and to measure the scour rate, the numerical model hec-ras 4.0 has been used. upon selection of mashkid river as the case study and whereas the studied zone is important with respect to the climatic conditions and showery monsoon raining and flowing the great and destructive floodwaters, ther...

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