Impact of critical source area on AnnAGNPS simulation

2011 ◽  
Vol 64 (9) ◽  
pp. 1767-1773 ◽  
Author(s):  
Wang Xiaoyan ◽  
Lin Qinhui
Keyword(s):  
Source Area ◽  
Prediction Errors ◽  
Nutrient Loads ◽  
Watershed Scale ◽  
Point Source Pollution ◽  
Terrain Attributes ◽  
Average Slope ◽  
Nitrogen Yields ◽  
The Impact ◽  
Total Phosphorus Load

The objective of this paper is to study the impact of critical source area (CSA) within an Annualized AGricultural Non-Point Source pollution models (AnnAGNPS) simulation at medium- large watershed scale. The impact of CSA on terrain attributes is examined by comparing six sets of CSA (0.5, 1, 2, 4, 6 and 8 km2). The accuracy of AnnAGNPS stimulation on runoff, sediment and nutrient loads on these sets of CSA is further suggested in this paper. The results are as followed: (1) CSA has little effect on watershed area, and terrain altitude. The number of cell and reach decreases with the increase of CSA in power function regression curve. (2) The variation of CSA will lead to the uncertainty of average slope which increase the generalization of land characteristics. At the CSA range of 0.5–1 km2, there is little impact of CSA on slope. (3) Runoff amount does not vary so much with the variation of CSA whereas soil erosion and total nitrogen (TN) load change prominently. An increase of sediment yield is observed firstly then a decrease following later. There is evident decrease of TN load, especially when CSA is bigger than 6 km2. Total phosphorus load has little variation with the change of CSA. Results for Dage watershed show that CSA of 1 km2 is desired to avoid large underestimates of loads. Increasing the CSA beyond this threshold will affect the computed runoff flux but generate prediction errors for nitrogen yields. So the appropriate CSA will control error and make simulation at acceptable level.

scholarly journals Environmental Changes and Cultural Transitions in SW Iberia during the Early-Mid Holocene

2021 ◽  
Vol 11 (8) ◽  
pp. 3580
Author(s):  
Cristina Val-Peón ◽  
Juan I. Santisteban ◽  
José A. López-Sáez ◽  
Gerd-Christian Weniger ◽  
Klaus Reicherter
Keyword(s):  
Dietary Habits ◽  
Environmental Changes ◽  
Source Area ◽  
Direct Access ◽  
Special Focus ◽  
Early Neolithic ◽  
Archaeological Data ◽  
Local Resources ◽  
Climate Events ◽  
The Impact

The SW coast of the Iberian Peninsula experiences a lack of palaeoenvironmental and archaeological data. With the aim to fill this gap, we contribute with a new palynological and geochemical dataset obtained from a sediment core drilled in the continental shelf of the Algarve coast. Archaeological data have been correlated with our multi-proxy dataset to understand how human groups adapted to environmental changes during the Early-Mid Holocene, with special focus on the Mesolithic to Neolithic transition. Vegetation trends indicate warm conditions at the onset of the Holocene followed by increased moisture and forest development ca. 10–7 ka BP, after which woodlands are progressively replaced by heaths. Peaks of aridity were identified at 8.2 and 7. 5 ka BP. Compositional, textural, redox state, and weathering of source area geochemical proxies indicates abrupt palaeoceanographic modifications and gradual terrestrial changes at 8.2 ka BP, while the 7.5 ka BP event mirrors a decrease in land moisture availability. Mesolithic sites are mainly composed of seasonal camps with direct access to the coast for the exploitation of local resources. This pattern extends into the Early Neolithic, when these sites coexist with seasonal and permanent occupations located in inland areas near rivers. Changes in settlement patterns and dietary habits may be influenced by changes in coastal environments caused by the sea-level rise and the impact of the 8.2 and 7.5 ka BP climate events.

Watershed-Scale Simulation of Sediment and Nutrient Loads in Georgia Coastal Plain Streams using the Annualized AGNPS Model

2002 ◽  
Author(s):  
Jennifer B. Suttles ◽  
George Vellidis ◽  
David Bosch ◽  
Richard Lowrance ◽  
E. Lynn Usery ◽  
...  
Keyword(s):  
Coastal Plain ◽  
Nutrient Loads ◽  
Watershed Scale ◽  
Plain Streams ◽  
Coastal Plain Streams

scholarly journals The use of groundwater crustacean communities as indicators for aquifers quality in the semi-arid region of north-central Chile

2018 ◽  
Vol 1 ◽  
Author(s):  
Sanda Iepure ◽  
Nicolas Gouin ◽  
Angeline Bertin ◽  
Ana Camacho ◽  
Antonio González-Ramón ◽  
...  
Keyword(s):  
Negative Impact ◽  
Groundwater Resources ◽  
Economic Benefits ◽  
Nutrient Loads ◽  
Groundwater Temperature ◽  
Groundwater Levels ◽  
Water Abstraction ◽  
Over Exploitation ◽  
The Impact ◽  
Semi Arid

Chile has large extensions of arid and semi-arid regions throughout the whole country, where the intensive demands and use of water resources, especially groundwater for irrigations and mining activities, increased dramatically over the last decades. The aquifer depletions due to water abstraction for irrigation and nutrient loads, exert major alterations of water quality, groundwater recharge and the natural renewal rate. All these factors diminish the aquifer value for the users and contribute to the degradation of groundwater as environment and habitat for fauna. This intensive use of groundwater resources in Chile brought to significant social and economic benefits, but their inadequate management resulted in negative environmental, legal and socioeconomic consequences. In this study, we aimed at providing a first assessment of environmental alterations of groundwater ecosystems from agricultural watersheds in northern Chile by specifically evaluating the effects of nitrogen and pesticide loads on groundwater communities and identifing the ecosystem service alterations due to agricultural activities. The study has been performed in a glacial aquifer from Coquimbo region; 250 km north of Santiago de Chile, the floodplain of which is dominated by agriculture (fruits tress, vineyards). Due to low regional precipitations (100-240 mm/year) the aquifer is primarily recharged by snowmelt from the Andean chain and surface runoff. The relative groundwater levels, groundwater temperature, chemical analysis of nitrogen and total phosphorus and pesticide concentrations were examined, along with the evaluation of crustacean biodiversity and spatial distribution pattern. Stygofauna taxonomic richness and the presence of stygobites have been related more to groundwater level stability than to chemical water parameters indicating that over-exploitation has a negative impact on habitat suitability for groundwater invertebrates. Groundwater biota assessment is essential in understanding the impact produced by agriculture activities on groundwater as a resource and as ecosystem, a nexus that becomes more and more widely recognized. The rationale and the preliminary results of this study are summarized in the Suppl. material 1.

scholarly journals Study on the Causes of Water Environmental Pollution of Important Rivers in Haihe River Basin and Countermeasures

2021 ◽  
Vol 261 ◽  
pp. 04023
Author(s):  
Xu He ◽  
Hou Siyan
Keyword(s):  
Water Quality ◽  
Point Source ◽  
Environmental Pollution ◽  
River Basin ◽  
River Regulation ◽  
Haihe River Basin ◽  
Point Source Pollution ◽  
Haihe River ◽  
The Impact

The water quality of six important rivers in Haihe River Basin, including Yongding River, Luanhe River, North Canal, Daqing River, South Canal and Chaobai River, was evaluated. The influence of point source and non-point source on water quality was analyzed. The causes of water environmental pollution in the major rivers were preliminarily revealed. The results show that the water quality of Chaobai River is good, and the impact of point source and non-point source discharge on the water body is small. Other rivers are affected by different degrees of point source and non-point source pollution. Based on the analysis results, the engineering measures and management countermeasures for river regulation are put forward.

scholarly journals Implicit signals in small group settings and their impact on the expression of cognitive capacity and associated brain responses

2012 ◽  
Vol 367 (1589) ◽  
pp. 704-716 ◽  
Author(s):  
Kenneth T. Kishida ◽  
Dongni Yang ◽  
Karen Hunter Quartz ◽  
Steven R. Quartz ◽  
P. Read Montague
Keyword(s):  
Social Status ◽  
Small Group ◽  
Cognitive Capacity ◽  
Cultural Norms ◽  
Prediction Errors ◽  
Group Setting ◽  
Group Settings ◽  
Brain Responses ◽  
Dorsolateral Prefrontal ◽  
The Impact

Measures of intelligence, when broadcast, serve as salient signals of social status, which may be used to unjustly reinforce low-status stereotypes about out-groups' cultural norms. Herein, we investigate neurobehavioural signals manifest in small ( n = 5) groups using functional magnetic resonance imaging and a ‘ranked group IQ task’ where implicit signals of social status are broadcast and differentiate individuals based on their expression of cognitive capacity. We report an initial overall decrease in the expression of cognitive capacity in the small group setting. However, the environment of the ‘ranked group IQ task’ eventually stratifies the population into two groups (‘high performers’, HP and ‘low performers’, LP) identifiable based on changes in estimated intelligence quotient and brain responses in the amygdala and dorsolateral prefrontal cortex. In addition, we demonstrate signals in the nucleus accumbens consistent with prediction errors in expected changes in status regardless of group membership. Our results suggest that individuals express diminished cognitive capacity in small groups, an effect that is exacerbated by perceived lower status within the group and correlated with specific neurobehavioural responses. The impact these reactions have on intergroup divisions and conflict resolution requires further investigation, but suggests that low-status groups may develop diminished capacity to mitigate conflict using non-violent means.

A comparison among approaches for recommending learning objects through collaborative filtering algorithms

2017 ◽  
Vol 51 (1) ◽  
pp. 35-51
Author(s):  
Henrique Lemos dos Santos ◽  
Cristian Cechinel ◽  
Ricardo Matsumura Araújo
Keyword(s):  
Collaborative Filtering ◽  
Learning Objects ◽  
Learning Goals ◽  
Average Error ◽  
Neighborhood Size ◽  
Relevant Parameter ◽  
Prediction Errors ◽  
Content Type ◽  
User Coverage ◽  
The Impact

Purpose The purpose of this paper is to present the results of a comparison among three different approaches for recommending learning objects (LO) inside a repository. The comparison focuses not only on prediction errors but also on the coverage of each tested configuration. Design/methodology/approach The authors compared the offline evaluation by using pure collaborative filtering (CF) algorithms with two other different combinations of pre-processed data. The first approach for pre-processing data consisted of clustering users according to their disciplines resemblance, while the second approach consisted of clustering LO according to their textual similarity regarding title and description. The three methods were compared with respect to the mean average error between predicted values and real values. Moreover, we evaluated the impact of the number of clusters and neighborhood size on the user-coverage. Findings Clustering LO has improved the prediction error measure with a small loss on user-coverage when compared to the pure CF approach. On the other hand, the approach of clustering users failed in both the error and in user-space coverage. It also became clear that the neighborhood size is the most relevant parameter to determine how large the coverage will be. Research limitations The methods proposed here were not yet evaluated in a real-world scenario, with real users opinions about the recommendations and their respective learning goals. Future work is still required to evaluate users opinions. Originality/value This research provides evidence toward new recommendation methods directed toward LO repositories.

Using Arc GIS to explore the impact of environmental and ecological factors on water body

2021 ◽  
Vol 7 (6) ◽  
pp. 6247-6261
Author(s):  
Xiaoqing Liu ◽  
Juanfen Wang
Keyword(s):  
Water Quality ◽  
Numerical Model ◽  
Point Source ◽  
River Water ◽  
Ecological Factors ◽  
River Water Quality ◽  
Pollution Sources ◽  
Point Source Pollution ◽  
The Impact ◽  
Non Point Source Pollution

As water pollution is more and more serious, ArcGIS is proposed to explore the impact of environmental and ecological factors on water. Taking the river water quality as the research object, this paper simulates and analyzes the endogenous and non-point source pollution and water quality through indoor physical model experiment, hydrological and water quality numerical model and water quality numerical model, and analyzes the impact of different environmental changes on river water quality and pollution sources from micro and macro perspectives. The main contents include: experimental study on the influence mechanism of overlying water velocity, disturbance and water temperature on sediment endogenous release, construction and simulation of watershed non-point source pollution model, construction and simulation of watershed river water quality model, as well as the impact of environmental change on river water quality and quantitative analysis of river pollution sources.

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