نتایج جستجو برای: riprap

تعداد نتایج: 109  

2006
Gretchen G. Alexander David Allan

Restoration activities intended to improve the condition of streams and rivers are widespread throughout the Upper Midwest, U.S.A. As with other regions, however, little information exists regarding types of activities and their effectiveness. We developed a database of 1,345 stream restoration projects implemented from the years 1970 to 2004 for the states of Michigan, Ohio, and Wisconsin in o...

2002
J. L. D. Davis L. A. Levin S. M. Walther

Artificial hard substrates have been used to stabilize naturally soft bay shorelines for centuries. Despite the loss of over half of the natural shoreline in many bays, little attention has been paid to the communities inhabiting armored shorelines and to the ecological implications of armoring. The goal of the present study was to examine factors affecting spatial and temporal variation of int...

Journal: :San Francisco Estuary and Watershed Science 2021

The San Francisco Estuary is an incredibly diverse ecosystem with a mosaic of aquatic habitats inhabited by number economically, culturally, and ecologically important fish species. To monitor the temporal spatial trends this rich community, long-term monitoring programs within estuary use variety gear types to capture species across life stages habitats. However, concerns have been raised that...

Journal: :North American Journal of Fisheries Management 2022

Habitats may become unavailable to fish in reservoirs at different water elevations. Coves are particularly vulnerable habitat loss, as these peripheral zones isolated from the main reservoir. Quantifying loss elevation reductions and estimating cost of replacing specific types or maintaining a target percentage total cover can help fisheries managers plan for restoration projects reservoirs. W...

Journal: :Frontiers in Marine Science 2021

Healthy coral communities can be found on artificial structures (concrete walls and riprap) within the Port of Miami (PoM), Florida. These feature an unusually high abundance brain corals, which have almost entirely vanished from nearby offshore reefs. corals appear to thriving in very low-quality waters influenced by dense ship boat traffic, dredging, numerous residential industrial developmen...

ژورنال: مرتع و آبخیزداری 2019

با توجه به اینکه پایش و ارزیابی تغییرات بدنۀ سدهای خاکی با استفاده از روش­های نقشه­برداری زمینی وقت­گیر و پرهزینه است، لذا با بررسی­های به­عمل آمده در مشکلات مشابه در سطح دنیا روش تداخل سنجی راداری به­عنوان یک روش نوین جهت بررسی جابجایی بدنۀ سد معرفی شده است. بدین منظور در این تحقیق با هدف بررسی تغییرات بدنۀ سد طالقان از 68 تصویر Sentinel1-Aدر بازۀ زمانی 2018- 2014 از نرم­افزا...

Journal: :Estuaries and Coasts 2022

Abstract Understanding the spatiotemporal dynamics of trophic structures, or trophodynamics, is important for assessing overall condition and function estuarine ecosystems. We examined spatial seasonal trophodynamics nekton assemblages across seascape a subtropical estuary (Charlotte Harbor, FL, USA) using historical data from an ongoing monitoring program. also relationships between distributi...

Journal: :مهندسی عمران فردوسی 0
عبدا... اردشیر روح ا... چراغچی حجت کرمی

local scour around the abutment is of utmost importance in bridge failures. numerous methods such as riprap have been proposed to reduce the destructive effects of scouring; one of the ways to harness and reduce the local scour depth is installed protective collars around the abutment. in this paper effect of collar elevation (upper level, bed level and lower level), collar geometry and its siz...

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