scholarly journals Sub-daily variability of suspended sediment fluxes in small mountainous catchments – implications for community-based river monitoring

2010 ◽  
Vol 7 (5) ◽  
pp. 8233-8263
Author(s):  
C. Duvert ◽  
N. Gratiot ◽  
J. Némery ◽  
A. Burgos ◽  
O. Navratil
Keyword(s):  
Suspended Sediment ◽  
Rural Areas ◽  
Temporal Variability ◽  
Fine Sediment ◽  
Community Based ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Monitoring Strategies ◽  
Mountainous Catchments ◽  
Daily Variability

Abstract. Accurate estimates of suspended sediment yields depend on effective monitoring strategies. In mountainous environments undergoing intense seasonal precipitation, the implementation of such monitoring programs relies primarily on a rigorous study of the temporal variability of fine sediment transport. This investigation focuses on seasonal and short-term sediment variability in a subhumid region of the Mexican Volcanic Belt. Intensive hydrosedimentary monitoring was conducted during one year on four contrasting catchments (3 to 630 km2). Analyses revealed significant temporal variability in suspended sediment export over various time scales, with between 63 and 97% of the annual load exported in as little as 2% of the time. Statistical techniques were used to evaluate the sampling frequency required to get reliable annual sediment yield estimates at the four sites. A bi-daily sampling would be required at the outlet of the 630-km2 catchment, whereas in the three smaller catchments (3–12 km2), the achievement of accurate estimates would inevitably require hourly monitoring. At the larger catchment scale, analysis of the sub-daily variability of fine sediment fluxes showed that the frequency of sampling could be lowered by up to 100% (i.e. from bi-daily to daily) if considering a specific and regular sampling time in the day. In contrast, conducting a similar sampling strategy at the three smaller catchments could lead to serious misinterpretation (i.e. up to 1000% error). Our findings emphasise the importance of an analysis of the sub-daily variability of sediment fluxes in mountainous catchments. Characterising this variability may offer useful insights for improving the effectiveness of community-based monitoring strategies in rural areas of developing countries. In regions where historical records based on discrete sampling are available, it may also help assessing the quality of past flux estimates. Finally, the study confirms the global necessity of acquiring more high frequency data in small mountainous catchments, especially in poorly gauged areas.

scholarly journals Sub-daily variability of suspended sediment fluxes in small mountainous catchments &ndash implications for community-based river monitoring

2011 ◽  
Vol 15 (3) ◽  
pp. 703-713 ◽  
Author(s):  
C. Duvert ◽  
N. Gratiot ◽  
J. Némery ◽  
A. Burgos ◽  
O. Navratil
Keyword(s):  
Suspended Sediment ◽  
Temporal Variability ◽  
Fine Sediment ◽  
Sediment Flux ◽  
Community Based ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Monitoring Strategies ◽  
Mountainous Catchments ◽  
Daily Variability

Abstract. Accurate estimates of suspended sediment yields depend on effective monitoring strategies. In mountainous environments undergoing intense seasonal precipitation, the implementation of such monitoring programs relies primarily on a rigorous study of the temporal variability of fine sediment transport. This investigation focuses on seasonal and short-term variability in suspended sediment flux in a subhumid region of the Mexican Volcanic Belt. Intensive monitoring was conducted during one year in four contrasting catchments (3 to 630 km2). Analyses revealed significant temporal variability in suspended sediment export over various time scales, with between 63 and 97% of the annual load exported in as little as 2% of the time. Statistical techniques were used to evaluate the sampling frequency required to get reliable estimates of annual sediment yield at the four sites. A bi-daily sampling scheme would be required at the outlet of the 630 km2 catchment, whereas in the three smaller catchments (3–12 km2), accurate estimates would inevitably require hourly monitoring. At the larger catchment scale, analysis of the sub-daily variability of fine sediment fluxes showed that the frequency of sampling could be lowered by up to 100% (i.e. from bi-daily to daily) if a specific and regular sampling time in the day was considered. In contrast, conducting a similar sampling strategy at the three smaller catchments could lead to serious misinterpretation (i.e. up to 1000% error). Our findings emphasise the importance of an analysis of the sub-daily variability of sediment fluxes in mountainous catchments. Characterising this variability may offer useful insights for improving the effectiveness of community-based monitoring strategies in rural areas of developing countries. In regions where historical records based on discrete sampling are available, it may also help assessing the quality of past flux estimates. Finally, the study confirms the global necessity of acquiring more high frequency data in small mountainous catchments, especially in poorly gauged areas.

Sediment fluxes and sinks for Magela Creek, Northern Territory, Australia

2018 ◽  
Vol 69 (7) ◽  
pp. 1018 ◽  
Author(s):  
Wayne D. Erskine ◽  
M. J. Saynor ◽  
J. M. Boyden ◽  
K. G. Evans
Keyword(s):  
Suspended Sediment ◽  
Sediment Load ◽  
Northern Territory ◽  
Bed Load ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Erosion Rates ◽  
Dry Tropics ◽  
The World ◽  
Total Sediment

Sediment fluxes and sinks based on total sediment load for Magela Creek in the Australian wet–dry tropics have been constructed from detailed measurements of stream suspended sediment (turbidity and suspended sand) and bed load for the 10-year period, 2001–2002 to 2010–2011. This work shows that the sediment trap efficiency of the vegetated wetlands on lower Magela is high at ~89.5%. Sediment fluxes are the lowest in the world because of low soil erosion rates and because upstream floodplains and downstream wetlands trap and store sediment. Bedload yields are less than suspended sediment yields, but the amount of silt and clay is much less than the amount of sand (suspended sand and bedload). All sand is stored upstream of the East Alligator River. Downstream connectivity of sediment movement does not occur. Therefore, sediment moves discontinuously from the upper to the lower catchment.

scholarly journals Suspended sediment and discharge dynamics in a glacierized alpine environment: Identifying crucial areas and time periods on several spatial and temporal scales in the Ötztal, Austria

2022 ◽  
Author(s):  
Lena Katharina Schmidt ◽  
Till Francke ◽  
Erwin Rottler ◽  
Theresa Blume ◽  
Johannes Schöber ◽  
...  
Keyword(s):  
Snow Cover ◽  
Suspended Sediment ◽  
Sediment Dynamics ◽  
Recent Sediment ◽  
Mass Balances ◽  
Temporal Scales ◽  
Spatial And Temporal Scales ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Precipitation Events

Abstract. Climatic changes are expected to fundamentally alter discharge and sediment dynamics in glaciated high alpine areas, e.g. through glacier retreat, prolonged snow-free periods and more frequent intense rainfall events in summer. However, how exactly these hydrological changes will affect sediment dynamics is not yet known. In the present study, we aim to pinpoint areas and processes most relevant to recent sediment and discharge dynamics on different spatial and temporal scales in the Ötztal Alpine Region in Tyrol, Austria. Therefore, we analyze observed discharge and relatively long suspended sediment time series of up to 15 years from three gauges in a nested catchment setup. The catchments range from 100 to almost 800 km2 in size with 10 to 30 % glacier cover and span an elevation range of 930 to 3772 m a.s.l.. The investigation of satellite-based snow cover maps, glacier inventories, mass balances and precipitation data complement the analysis. Our results indicate that mean annual specific discharge and suspended sediment fluxes are highest in the most glaciated sub-catchment and both fluxes correlate significantly with annual glacier mass balances. Furthermore, both discharge and suspended sediment loads show a distinct seasonality with low values during winter and high values during summer. However, the spring onset of sediment transport is almost synchronous at the three gauges, contrary to the spring rise in discharge, which occurs earlier further downstream. A spatio-temporal analysis of snow cover evolution indicates that the spring increase in sediment fluxes at all gauges coincides with the onset of snow melt above 2500 m elevation. Zones above this elevation include glacier tongues and recently deglaciated areas, which seem to be crucial for the sediment dynamics in the catchment. Precipitation events in summer were associated with peak sediment concentrations and fluxes, but on average accounted for only 21 % of the annual sediment yields of the years 2011 to 2020. We conclude that glaciers and the areas above 2500 m elevation play a dominant role for discharge and sediment dynamics in the Ötztal area, while precipitation events play a secondary role. Our study extends the scientific knowledge on current hydro-sedimentological changes in glaciated high alpine areas and provides a baseline for investigations on projected future changes in hydro-sedimentological system dynamics.

scholarly journals Water and sediment fluxes in Mediterranean mountainous regions: comprehensive dataset for hydro-sedimentological analyses and modelling in a mesoscale catchment (River Isábena, NE Spain)

2018 ◽  
Vol 10 (2) ◽  
pp. 1063-1075 ◽  
Author(s):  
Till Francke ◽  
Saskia Foerster ◽  
Arlena Brosinsky ◽  
Erik Sommerer ◽  
Jose A. Lopez-Tarazon ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Meteorological Data ◽  
Sediment Source ◽  
Discharge Data ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Mountainous Regions ◽  
Water And Sediment ◽  
Ne Spain ◽  
River Isábena

Abstract. A comprehensive hydro-sedimentological dataset for the Isábena catchment, northeastern (NE) Spain, for the period 2010–2018 is presented to analyse water and sediment fluxes in a Mediterranean mesoscale catchment. The dataset includes rainfall data from 12 rain gauges distributed within the study area complemented by meteorological data of 12 official meteo-stations. It comprises discharge data derived from water stage measurements as well as suspended sediment concentrations (SSCs) at six gauging stations of the River Isábena and its sub-catchments. Soil spectroscopic data from 351 suspended sediment samples and 152 soil samples were collected to characterize sediment source regions and sediment properties via fingerprinting analyses. The Isábena catchment (445 km2) is located in the southern central Pyrenees ranging from 450 m to 2720 m a.s.l.; together with a pronounced topography, this leads to distinct temperature and precipitation gradients. The River Isábena shows marked discharge variations and high sediment yields causing severe siltation problems in the downstream Barasona Reservoir. The main sediment source is badland areas located on Eocene marls that are well connected to the river network. The dataset features a comprehensive set of variables in a high spatial and temporal resolution suitable for the advanced process understanding of water and sediment fluxes, their origin and connectivity and sediment budgeting and for the evaluation and further development of hydro-sedimentological models in Mediterranean mesoscale mountainous catchments. The dataset is available at http://doi.org/10.5880/fidgeo.2018.011.

scholarly journals Water and sediment fluxes in Mediterranean mountainous regions: Comprehensive dataset for hydro-sedimentological analyses and modelling in a mesoscale catchment (River Isábena, NE Spain)

2017 ◽  
Author(s):  
Till Francke ◽  
Saskia Foerster ◽  
Arlena Brosinsky ◽  
Erik Sommerer ◽  
Jose A. Lopez-Tarazon ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Sediment Source ◽  
Discharge Data ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Mountainous Regions ◽  
Water And Sediment ◽  
Meso Scale ◽  
Ne Spain ◽  
River Isábena

Abstract. A comprehensive hydro-sedimentological dataset for the Isábena catchment, NE Spain, for the period 2010–2016 is presented to analyse water and sediment fluxes in a Mediterranean meso-scale catchment. The dataset includes rainfall data from twelve rain gauges distributed within the study area complemented by meteorological data of twelve official meteo-stations. It comprises discharge data derived from water stage measurements as well as suspended sediment concentrations (SSC) at six gauging stations of the River Isábena and its sub-catchments. Soil spectroscopic data from 351 suspended sediment samples and 152 soil samples were collected to characterize sediment source regions and sediment properties via fingerprinting analyses. The Isábena catchment (445 km2) is located in the Southern Central Pyrenees ranging from 450 m to 2,720 m a.s.l., together with a pronounced topography this leads to distinct temperature and precipitation gradients. The River Isábena shows marked discharge variations and high sediment yields causing severe siltation problems in the downstream Barasona Reservoir. Main sediment source are badland areas located on Eocene marls that are well connected to the river network. The dataset features a wide set of parameters in a high spatial and temporal resolution suitable for advanced process understanding of water and sediment fluxes, their origin and connectivity, sediment budgeting and for evaluating and further developing hydro-sedimentological models in Mediterranean meso-scale mountainous catchments. The dataset is available at http://doi.org/10.5880/fidgeo.2017.003.

scholarly journals The failure of community-based health insurance schemes in Tanzania: opening the black box of the implementation process

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ramadhani Kigume ◽  
Stephen Maluka
Keyword(s):  
Health Insurance ◽  
Community Health ◽  
Rural Areas ◽  
Health Coverage ◽  
Access To Health Services ◽  
Community Based ◽  
Community Based Health Insurance ◽  
Urban Districts ◽  
Health Fund ◽  
The Government

Abstract Background Globally, there is increased advocacy for community-based health insurance (CBHI) schemes. Like other low and middle-income countries (LMICs), Tanzania officially established the Community Health Fund (CHF) in 2001 for rural areas; and Tiba Kwa Kadi (TIKA) for urban population since 2009. This study investigated the implementation of TIKA scheme in urban districts of Tanzania. Methods A descriptive qualitative case study was conducted in four urban districts in Tanzania in 2019. Data were collected using semi-structured interviews, focus group discussions and review of documents. A thematic approach was used to analyse the data. Results While TIKA scheme was important in increasing access to health services for the poor and other disadvantaged groups, it faced many challenges which hindered its performance. The challenges included frequent stock-out of drugs and medical supplies, which frustrated TIKA members and hence contributed to non-renewal of membership. In addition, the scheme was affected by poor collections and management of the revenue collected from TIKA members, limited benefit packages and low awareness of the community. Conclusions Similar to rural-based Community Health Fund, the TIKA scheme faced structural and operational challenges which subsequently resulted into low uptake of the schemes. In order to achieve universal health coverage, the government should consider integrating or merging Community-Based Health Insurance schemes into a single national pool with decentralised arms to win national support while also maintaining local accountability.

Do the Heterogeneous Determinants of Repayment Affect Differently across Borrowers of Diverse Credit Sources in Rural Assam? A Double Hurdle Approach

2021 ◽  
pp. 245513332110316
Author(s):  
Tiken Das ◽  
Pradyut Guha ◽  
Diganta Das
Keyword(s):  
Rural Areas ◽  
Probit Model ◽  
Original Data ◽  
Community Based ◽  
Data Set ◽  
Brahmaputra Valley ◽  
Double Hurdle ◽  
Instrumental Variable Probit ◽  
Instrumental Variable Probit Model

This study made an attempt to answer the question: Do the heterogeneous determinants of repayment affect the borrowers of diverse credit sources differently? The study is based on data collected from 240 households from three districts in the lower Brahmaputra valley of Assam through a carefully designed primary survey. Besides, the study uses the double hurdle approach and the instrumental variable probit model to reduce possible selection bias. It observes better repayment performance among formal borrowers, followed by semiformal borrowers, while occupation wise it is prominent among organised employees. It has been found that in general, the household characteristics, loan characteristics and location-specific characteristics significantly affect repayment performance of borrowers. However, the nature of impact of the factors influencing repayment performance is remarkably different across credit sources. It ignores the role of traditional community-based organisations in rural Assam while analysing the determinants of repayment performance. The study also recommends for ensuring productive opportunities and efficient market linkages in rural areas of Assam. The study is based on an original data set that has specially been collected to examine question that—do the heterogeneous determinants of repayment affect the borrowers of diverse credit sources differently in the lower Brahmaputra valley of Assam—which has not been studied before.

scholarly journals Homeless on Main Street: Using Photovoice to Highlight Older Adults Among the Hidden Homeless

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 728-728
Author(s):  
H Shellae Versey
Keyword(s):  
Older Adults ◽  
Rural Areas ◽  
Meaning Making ◽  
Small Towns ◽  
Photo Elicitation ◽  
Service Agency ◽  
Structured Interviews ◽  
Community Based Interventions ◽  
Community Based ◽  
Formerly Homeless

Abstract Homelessness is a reality for a growing number of Americans living in small towns and rural areas. However, unlike in cities, housing instability may be less visible. Using a photo-elicitation method (i.e., Photovoice), this study explores the meaning of place and obscured visibility to currently and formerly homeless older adults living in a small town in central Connecticut. Participants (N = 27) were recruited from a local service agency, given cameras and asked to photograph areas around town that were meaningful to them. Photographs were developed and followed by in-person, semi-structured interviews with participants in which photos and experiences during the project were discussed. Primary themes included belonging, generativity, social isolation, and place-making as meaning-making. The study culminated in a community photography exhibition in which photographs from the project were displayed in public spaces around town. Implications for community-based interventions to reach homeless groups in rural areas are discussed. Part of a symposium sponsored by the Qualitative Research Interest Group.

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