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Watershed

About: Watershed is a(n) research topic. Over the lifetime, 18596 publication(s) have been published within this topic receiving 283402 citation(s).

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Journal ArticleDOI: 10.1007/BF01867358
Abstract: Classification of streams and stream habitats is useful for research involving establishment of monitoring stations, determination of local impacts of land-use practices, generalization from site-specific data, and assessment of basin-wide, cumulative impacts of human activities on streams and their biota. This article presents a frame-work for a hierarchical classification system, entailing an organized view of spatial and temporal variation among and within stream systems. Stream habitat systems, defined and classified on several spatiotemporal scales, are associated with watershed geomorphic features and events. Variables selected for classification define relative long-term capacities of systems, not simply short-term states. Streams and their watershed environments are classified within the context of a regional biogeoclimatic landscape classification. The framework is a perspective that should allow more systematic interpretation and description of watershed-stream relationships.

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Topics: Watershed (51%), Context (language use) (50%)

2,140 Citations


Journal ArticleDOI: 10.2307/1939127
01 Oct 1984-Ecology
Abstract: Nutrient (C, N, and P) concentration changes were measured in surface runoff and shallow groundwater as they moved through a small agricultural (cropland) watershed located in Maryland. During the study period (March 1981 to March 1982), dramatic changes in water-borne nutrient loads occurred in the riparian forest of the watershed. From surface runoff waters that had transited : 50 m of riparian forest, an estimated 4.1 Mg of particulates, 1I kg of particulate organic-N, 0.83 kg of ammonium-N, 2.7 kg of nitrate-N and 3.0 kg of total particulate-P per ha of riparian forest were removed during the study year. In addition, an estimated removal of 45 kg ha- yr-t of nitrate- N occurred in subsurface flow as it moved through the riparian zone. Nutrient uptake rates for the cropland and riparian forest were estimated. These systems were then compared with respect to their pathways of nutrient flow and ability to retain nutrients. The cropland appeared to retain fewer nutrients than the riparian forest and is thought to incur the majority of its nutrient losses in harvested crop. The dominant pathway of total-N loss from the riparian forest seemed to be subsurface flux. Total phosphorus loss from the riparian forest appeared almost evenly divided between surface and subsurface losses. Nutrient removals in the riparian forest are thought to be of ecological significance to receiving waters and indicate that coupling natural systems and managed habitats within a watershed may reduce diffuse-source pollution.

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Topics: Riparian zone (72%), Riparian forest (69%), Riparian buffer (62%) ...read more

1,531 Citations


Open accessJournal ArticleDOI: 10.3233/FI-2000-411207
Abstract: The watershed transform is the method of choice for image segmentation in the field of mathematical morphology. We present a critical review of several definitions of the watershed transform and the associated sequential algorithms, and discuss various issues which often cause confusion in the literature. The need to distinguish between definition, algorithm specification and algorithm implementation is pointed out. Various examples are given which illustrate differences between watershed transforms based on different definitions and/or implementations. The second part of the paper surveys approaches for parallel implementation of sequential watershed algorithms.

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Topics: Sequential algorithm (56%), Watershed (51%), Image segmentation (50%)

1,337 Citations


Journal ArticleDOI: 10.1016/J.AGEE.2004.01.015
L.A. Bruijnzeel1Institutions (1)
Abstract: Differing perceptions of the impacts on hydrological functions of tropical forest clearance and conversion to other land uses have given rise to growing and often heated debate about directions of public environmental policy in southeast Asia. In order to help bring more balance and clarity to such debate, this paper reviews a wide range of available scientific evidence with respect to the influence exerted by the presence or absence of a good forest cover on regional climate (rainfall), total and seasonal water yield (floods, low flows), as well as on different forms of erosion and catchment sediment yield under humid tropical conditions in general and in southeast Asia in particular. It is concluded that effects of forest disturbance and conversion on rainfall will be smaller than the average decrease of 8% predicted for a complete conversion to grassland in southeast Asia because the radiative properties of secondary regrowth quickly resemble those of the original forest again. In addition, under the prevailing ‘maritime’ climatic conditions, effects of land-cover change on climate can be expected to be less pronounced than those of changes in sea-surface temperatures. Total annual water yield is seen to increase with the percentage of forest biomass removed, with maximum gains in water yield upon total clearing. Actual amounts differ between sites and years due to differences in rainfall and degree of surface disturbance. As long as surface disturbance remains limited, the bulk of the annual increase in water yield occurs as baseflow (low flows), but often rainfall infiltration opportunities are reduced to the extent that groundwater reserves are replenished insufficiently during the rainy season, with strong declines in dry season flows as a result. Although reforestation and soil conservation measures are capable of reducing the enhanced peak flows and stormflows associated with soil degradation, no well-documented case exists where this has also produced a corresponding increase in low flows. To some extent this will reflect the higher water use of the newly planted trees but it cannot be ruled out that soil water storage opportunities may have declined too much as a result of soil erosion during the post-clearing phase for remediation to have a net positive effect. A good plant cover is generally capable of preventing surface erosion and, in the case of a well-developed tree cover, shallow landsliding as well, but more deep-seated (>3 m) slides are determined rather by geological and climatic factors. A survey of over 60 catchment sediment yield studies from southeast Asia demonstrates the very considerable effects of such common forest disturbances as selective logging and clearing for agriculture or plantations, and, above all, urbanisation, mining and road construction. The ‘low flow problem’ is identified as the single most important ‘watershed’ issue requiring further research, along with the evaluation of the time lag between upland soil conservation measures and any resulting changes in sediment yield at increasingly large distances downstream. It is recommended to conduct such future work within the context of the traditional paired catchment approach, complemented with process-based measuring and modelling techniques. Finally, more attention should be paid to the underlying geological

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Topics: Soil retrogression and degradation (58%), Deforestation (56%), Erosion (55%) ...read more

1,295 Citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202216
2021915
2020893
2019906
2018946
2017861

Top Attributes

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Topic's top 5 most impactful authors

Raghavan Srinivasan

51 papers, 4.3K citations

Tammo S. Steenhuis

31 papers, 1.4K citations

Timothy O. Randhir

26 papers, 761 citations

Seong-Joon Kim

25 papers, 241 citations

Ronald L. Bingner

24 papers, 614 citations

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