Sand Dam Research Articles

El impacto de incluir el coeficiente sísmico vertical kv en el análisis de estabilidad pseudoestático de tranques de relaves construidos con arenas mediante el método constructivo aguas abajo

In Chile, the limit equilibrium analysis under pseudostatic conditions is compulsory according to the Supreme Decree 248 (DS248, 2007), which establishes a minimum factor of safety (FoS) of 1.2 for stability analysis. In Chilean geotechnical practice, it is usually considered just the horizontal seismic coefficient (kh) for the analyses. However, there is a constant discussion about the necessity of applying both horizontal and vertical seismic coefficient (kv) into the analyses. In addition, there is uncertainty about what kv/kh should be considered and the effect that the sense of application (upward or downward) could have on the FoS. This paper presents an analysis of the effect of considering different |kv|/kh from 0 to 1 on both analysis directions for generic downstream tailings sand dam. Based on this, different dam heights, beach lengths and seepage conditions are also analysed. The obtained results show that when both kh and kv are applied, the FoS increase if kv acts downward and decrease when it acts upward. In addition, the effect for |kv|/kh ≤ 0.5 is almost neglectable, especially for kh ≤ 0.15. Furthermore, although a short beach length significantly impacts the FoS, the influence of applying both kh and kv seems to be independent of the beach length

Large‐scale siting of sand dams: A participatory approach and application in Angolan drylands

AbstractSand dams are simple and effective structures built across ephemeral riverbeds in arid/ semiarid regions to harvest water within sand pores and increase water availability and quality for rural communities. The complex morphological, hydrological, social, and economic conditions that make sand dams a beneficial tool for water resilience are largely influenced by the siting phase. Proper location of a sand dam can reduce communities' travel time to water points, reduce water conflicts, and increase food security through expansion of irrigated agriculture. On the other hand, a misplacement of sand dams can, at worst, increase disparities in water access and increase local conflicts. To approach a viable siting of sand dams, most projects are developed and delivered with the community through a bottom‐up approach. However, in the case of large‐scale projects, remote sensing and biophysical analysis are the dominant approach, leaving the socio‐economic component at the margins of the siting strategy and eventually affecting the benefits to local communities. In this paper, we propose a large‐scale participatory methodology to sand dams siting, which draws on mixed‐methods connecting the conventional top‐down biophysical analysis with bottom‐up participatory research. We first describe the generic approach developed for sand dams siting in Namibe, a semi‐arid region of Southwest of Angola, then we draw on our case to propose a generic approach to large‐scale participatory siting beyond Namibe.

A Comparative Study of the Physiochemical and Bacteriological Parameters of Potable Water from Different Sources in Kitui County, Kenya

Developing nations are experiencing an ever-increasing demand for safe water due to climate change and the ever-increasing human population. Various strategies including construction of shallow wells, boreholes and sand dams along the river are done to make water available to various households. However, availability of water sources near are faced with challenges of pollution from a variety of sources. The aim of this study was to determine the levels of selected bacteriological and physico-chemical parameters in three potable water sources namely Kiembeni borehole, Mwitasyano River and Kalundu Dam in Kitui County. The quality of this water was compared to the standards for potable water prescribed by Kenya Bureau of Standards (KEBS). Representative sampling was conducted during the wet season (October 2019) and the dry season (August 2020) in the three sampling sites. The samples were analyzed for physico-chemical parameters: pH, color, turbidity, alkalinity, conductivity, iron, calcium, magnesium, hardness, chloride, fluoride, sulphates, ammonia, total dissolved solids and bacteriological parameters: total and fecal coliform. The analysis was performed at the Kenya Water Institute (KEWI) laboratory using standard procedures. The values obtained for the different water sources in the wet season and dry season were pooled and mean values calculated to determine the overall quality of drinking water. The results indicated that all the water sources had fecal coliform levels unsuitable for drinking water. Most of the values obtained for pH, color, alkalinity, conductivity, calcium, fluoride and sulphates in all sources of water were within the recommended potable water standards by KEBS. However, turbidity, iron and total coliform obtained values for borehole water samples were not within the recommended KEBS standards. The river and dam water samples were within the recommended standards for magnesium, hardness, chloride, ammonia and total dissolved solids. Although results indicate that some of the physico-chemical parameters were in conformance with the recommended standards, the overall bacteriological parameters render the water unsuitable for drinking. Thus, public health intervention programmes should be focused on addressing various sources of water pollution including regular disinfection of water. Keywords: Water quality, Physico-chemical, Kitui County, Assessment DOI: 10.7176/JEES/12-11-05 Publication date: November 30 th 2022

Analysis of Water Supply Capacity of a Sand Dam

A sand dam is an old technology used to trap sand materials and store water in dry riverbeds. Besides the volume of sand stored, the water storage and supply capacity of the sand dam depends principally on material properties including hydraulic conductivity (K) and the specific yield (Sy). In this study, the water supply capacity of a sand dam, applied in South Korea with a modified scheme, was analyzed. Imported sand materials were placed in three layers, and perforated drain pipes were installed to abstract the water to a collection tank. Using a Modular Finite-Difference Groundwater Flow (MODFLOW) model, the drain pipe discharge related to aquifer properties and supply capacity of a sand dam was evaluated. Using the model, the productivity of the sand storage with several cases of inflow conditions was assessed. For the period from 9 March 2020 to 16 May 2022, the results of calculation of water supply for the installation and operation of new sand dam are as follows. Regarding the actual inflow condition, compared to the average water supply of the existing water intake source, the sand dam installation increased water supply by 61.6%, and the sand dam installation showed an effect of improving the water supply by 36.0% for the minimum water supply. The calculated water supply for the condition where the inflow was reduced by 50% showed an effect of improving water supply by over 70% on average due to the installation of the sand dam. The findings would be a benchmark for future expansions of the scheme in related places, and management and maintenance of the system.

Conjunctive Operation of Sand Dam and Groundwater Well for Reliable Water Supply during Drought Conditions

Some mountainous regions without water service facilities are among the areas most vulnerable to drought. In these locations, it is particularly essential to establish practical alternatives to cope with the increase in the intensity and duration of droughts caused by climate change. This study proposes a methodology for the conjunctive use of a sand dam and groundwater well under various drought conditions. The method has been applied to a small mountainous area in South Korea. Owing to the scarcity of observational data, it is crucial to properly estimate the hydrological components necessary for judging the feasibility and reliability of conjunctive operations. The step-by-step procedures for performing the tasks are presented in this study. For the inflow of the sand dam, which is a portion of the basin runoff, two different approaches were employed and compared: the Kajiyama formula and a simple two-parameter monthly water balance model (TPM). Water budget analysis allowed for the determination of whether the current and increased water demand could be met under various drought conditions. Preliminary analysis revealed that a sand dam alone could not reliably meet the demand for 10-year or more severe drought conditions. Various water allocation scenarios between surface water (i.e., sand dam) and groundwater were tested. Conjunctive use of a sand dam and groundwater well turned out to increase the reliability of the water supply. As water demand increases and droughts become more severe, the role of groundwater increases. With appropriate resource allocation, 100% water supply reliability could be achieved, even for one year-lasting 50-year drought. We demonstrated how a system could be flexibly operated to meet the target demands monthly, given the system reliability level.

Geoinformation analysis of the satellite imagery data in order to assess the changes in radiohydrological conditions over the study territories

The article considers the relevance of the application of a set of terrestrial hydrological, radioecological and modern remote sensing methods in the process of monitoring studies of areas that are difficult to access, waterlogged, largely radionuclide contaminated. The example of the Ukrainian part of the left-bank Pripyat drainage system within the Chornobyl Exclusion Zone shows that remotely obtained data together with the materials integrated into the geographic information systems of the terrestrial measurements provide the adequate monitoring information on the spatio-temporal changes in the hydrological and radioecological situation in general. Among the research methods, the simulation, the methods of hydrometric, balancing, remote sensing studies of water bodies were most used. The main purpose of the research is to perform the retrospective and current analyses of the hydrological situation based on archival and recent satellite images, assess the effectiveness of the water protection complex on the left bank of the Pripyat River, especially after the introduction of hydrotechnical measures to improve its radioecological status. In the research process the LANDSAT, SPOT, IRS, WorldView images were used. In particular, a significant sensitivity of the "surface water – dry land" system to the changes in the environment of this area was established and the mapping of objects of open water surface was performed as well as its spatial and temporal variability was followed. When comparing the results of calculations of the radionuclides carry-over by water (in particular, 90Sr) before and after the implementation of appropriate measures at the water protection complex the notable negative consequences of its implementation and operation during a period from 1986 to 2001 were revealed. It was found that the diverted one-time 90Sr carry-over due to the construction of a "new" left-bank dam (according to the 1999 flood scenario) is "compensated" by 40% through the increase of its carry-over prolonged in time as a result of operation of the polder pumping station (PPS) and the inundation of the contaminated areas, which is caused by the complicated conditions for the discharge of surface and underground runoff caused by the "new" and "old" dams. The ecological advisability and validity of hydraulic measures (clearing of canals, reconstruction of culverts) and the recommended form of the operational complex (without the use of PPS, with natural filtration discharge of the body of the "new" sand dam in the Pripyat River) are confirmed by the results of thematic interpretation of the multiband images. Thus, within the complex, minor flooding and waterlogging of the inter-dam section, as well as areas to the north-east from the "old" dam are established. Prospects for the further research of various hydrological processes and radioecological situation on the left bank of the Pripyat River are seen in the use of high resolution remote surveys, which would be performed over the short periods of time. The informative result in good quality can be obtained on the basis of the use of unmanned aerial vehicles technology.

Sand dams for sustainable water management: Challenges and future opportunities

Sand dams are impermeable water harvesting structures built to collect and store water within the volume of sediments transported by ephemeral rivers. The artificial sandy aquifer created by the sand dam reduces evaporation losses relative to surface water storage in traditional dams. Recent years have seen a renaissance of studies on sand dams as an effective water scarcity adaptation strategy for drylands. However, many aspects of their functioning and effectiveness are still unclear. Literature reviews have pointed to a range of research gaps that need further scientific attention, such as river corridors and network dynamics, watershed-scale impacts, and interaction with social dynamics. However, the scattered and partially incomplete information across the different reviews would benefit from an integrated framework for directing future research efforts. This paper is a collaborative effort of different research groups active on sand dams and stems from the need to channel future research efforts on this topic in a thorough and coherent way. We synthesize the pivotal research gaps of a) unclear definition of “functioning” sand dams, b) lack of methodologies for watershed-scale analysis, c) neglect of social aspects in sand dam research, and d) underreported impacts of sand dams. We then propose framing future research to better target the synthesized gaps, including using the social-ecological systems framework to better capture the interconnected social and biophysical research gaps on sand dams, fully utilizing the potential of remote sensing in large-scale studies and collecting sand dam cases across the world to create an extensive database to advance evidence-based research on sand dams.

Evaluation of Water Supply Capacity of a Small Forested Basin Water Supply Facilities Using SWAT Model and Flow Recession Curve

This study develops a system for calculating the number of days of availability at upstream water intake sources for drought response in the Mullo stream basin in Gangwon-do, a multistage sand dam construction project's candidate site, in response to Korea's lack of water supply and demand calculation system for upstream intake sources. The Soil and Water Assessment Tool (SWAT) model calculated the upstream water supply capacity, and the automatic water level gauges measured the flow rate at three points in the target area: the stream, intake weir, and water tank. The SWAT parameter test and correction result using the daily flow rate measurements showed a coefficient of determination of 0.74, which was used to calculate the streamflow over 10 years. Based on daily streamflow data, 53 rainfall reduction events were identified, deriving a curve equation for the number of days of availability following the flow rate during drought seasons. This study's results can be used to compare data before and after constructing the sand dam. In addition, the results can be considered primary data for priority selection and efficiency analysis when expanding and distributing structural drought measures, such as sand dams, through national reviews.

The multiple uses of water derived from managed aquifer recharge systems in Kenya and India

Abstract‘Multiple-use services’ (MUS) takes into account the fact that households use water for both domestic and for productive uses. This paper is the first to determine how managed aquifer recharge (MAR) systems are a form of MUS. Two cases were studied in India and in Kenya. In the Kenyan case, sand dams are the form of MAR, and in India check dams and infiltration ponds of various scales are used. Through observations, interviews, and water quality data, it is possible to describe how the communities access the water from these infrastructures in multiple ways for different uses, according to their water needs and the characteristics of the different access points. MAR involves harvesting rainwater and retaining run-off water into the dry season thus increasing the amount of available water and enabling diversification of water uses. It should therefore be considered as an option by water managers aiming to develop water resources meeting both the domestic and productive needs of communities.

Sand Dams for Sustainable Water Management: Challenges and Future Opportunities

Sand Dams for Sustainable Water Management: Challenges and Future Opportunities

Study on Sedimentary Characteristics of Chang 9 Member of Triassic in Ordos Basin

The Triassic Yanchang Formation in the Ordos Basin is one of the main exploration targets. Based on the detailed exploration of the outcrop at the southern margin of the Ordos Basin, combined with previous results, a systematic analysis of lithology, rock assemblage, sedimentary facies characteristics and temporal evolution is carried out. The results show that the Changchang 9 oil-bearing group on the southern margin of the Ordos Basin can be divided into 9 lithofacies types, and three types of sedimentary facies, meandering river, meandering river delta, and braided river delta are developed. The meandering river facies develops riverbed retention deposits, beaches, and There are four types of microfacies in natural dikes and rupture fans. There are five types of microfacies in meandering river deltas: underwater distributary channels, underwater natural dikes, divert bays, estuary dams, and remote sand dams. Braided river deltas develop underwater distributary channels, There are two kinds of microfacies between distributary channels; the Chang 9 oil-bearing group has a coarse-fine-coarse compound rhythm in the vertical direction; meandering river sand bodies and delta front sand bodies are the main places for oil and gas migration and accumulation.

Effect of Upstream Dam Geometry on Peak Discharge During Overtopping Breach in Noncohesive Homogeneous Embankment Dams; Implications for Tailings Dams

AbstractTailings dams differ from conventional water‐retaining dams in design, materials retained behind the dam and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams were constructed with upstream slope angles varying between 10.0° and 30.0° and brought to failure by V notch overtopping. Slope angle was observed to define the height of flow over the erosional breach crest hydraulic control structure that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. A semiellipse was observed to be an excellent approximation of the geometry of the breach throughout the rising limb of the hydrograph to peak outflow. This observation permitted the use of the Ramanujan approximation for perimeter of an ellipse to define a mathematical relationship between breach width and arc length. A simplified method to predict the rising limb of the outflow hydrograph was then proposed based on the assumption of linear growth of breach width coupled with a semielliptical breach geometry. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.

Augmenting freshwater availability in mountain headwater streams: Assessing the sustainability under baseline and future climate change scenarios

Mountain headwater streams are important freshwater sources, but they are mostly intermittent and highly susceptible to climate change. This paper examines the sustainability of augmented freshwater availability in mountain headwater streams for water supply under baseline and future climate change scenarios using an integrated modeling approach. The climate change data in the 2040s (2030–2059), under Representative Concentration Pathway 4.5 and 8.5 scenarios, were downscaled for the impact assessment. In the region, climate change raises the average precipitation by 5–7% and the temperature by 13–15% in the 2040s. SWAT–MODFLOW model, integrating Soil and Water Assessment Tool (SWAT2012) and finite-difference Modular Groundwater Flow (MODFLOW) models in a single package, was used to assess the water balance. Results show that extracting a minimum of 16.2 m3/day from the sand storage and 30 m3/day from the aquifer was possible without affecting the groundwater table and water yield. The average annual catchment recharge was 6% of the precipitation under the baseline simulation. Climate change is projected to reduce the average water yield and groundwater recharge by 26% and 19%, respectively. However, the water supply-demand is significantly small compared to the exploitable rate of water in the area. This study was based on limited data, and therefore the findings need to be interpreted with caution, though the model output was validated using satellite products. Construction of a series of sand dams is suggested to maximize the benefit under the potential climate change and water supply-demand increase.

Assessing the Impact of Land Cover, Soil, and Climate on the Storage Potential of Dryland Sand Dams

Sand dams, a water-harvesting structure employed by rural communities in drylands have an inconsistent record of effectiveness. While many sand dams are highly functioning, improper siting, siltation, seepage, and high rates of evaporation from shallow sand reservoirs inhibit the water storage capacity of some sand dams. This study examines large-scale drivers of sand dam storage potential through analysis of an integrated surface and subsurface flow model. Multiple simulations were run, and comparative simulation analyses consider the effect of geomorphological factors, intraseasonal rainfall variability, and future climate conditions on sand dam performance criteria. The analyses revealed that a watershed highly cultivated with low water crops actually reduces evapotranspiration below that of natural vegetation and supports higher groundwater recharge. Additionally, intraseasonal variation and volume of rainfall impact sand dam performance less than the prevailing pattern and duration of dry and rainy seasons. Sand dams constructed in watersheds with sandier soils may experience greater connectivity with the stream margins and thus provide additional groundwater recharge. Lastly, climate change may improve some conditions desirable for sand dam performance, such as extending the duration of the rainy season and reducing overall evapotranspiration. However, the interactions between the expected climate change conditions and other geomorphological factors may result in a net decline in sand dam performance. The results of this study may help identify watersheds that are likely to support a sand dam with high potential for capturing and storing water throughout the dry season.

Discussion on marine facies and beach bar—lagoon system of Xujiahe Formation in Sichuan Basin

The oil and gas exploration of Xujiahe formation in Sichuan Basin has achieved good results. Natural gas reserves have been submitted by Yingshan structure, Tongjiang-nanjiang-bazhong structure, Guang’an and Hechuan, in this paper, we focus on the sedimentary characteristics of the upper triassic xujiahe formation in northeastern Sichuan Basin which is considered to be the interactive of the Delta and Lake deposit systems. It is believed that the Xujiahe formation in Sichuan Basin belongs to the Gulf environment. In the northeastern part of the basin, it is the combination of Beach bar-lagoon sedimentary deposit includes sand bars, all kinds of sand beaches, estuaries and tidal channels of lagoon or estuaries confined by sand bars, and the terraforming lagoon plain and its range of ancient sand dams.

Water Storage in Dry Riverbeds of Arid and Semi-Arid Regions: Overview, Challenges, and Prospects of Sand Dam Technology

Augmenting water availability using water-harvesting structures is of importance in arid and semi-arid regions (ASARs). This paper provides an overview and examines challenges and prospects of the sand dam application in dry riverbeds of ASARs. The technology filters and protects water from contamination and evaporation with low to no maintenance cost. Sand dams improve the socio-economy of the community and help to cope with drought and climate change. However, success depends on the site selection, design, and construction. The ideal site for a sand dam is at a transition between mountains and plains, with no bend, intermediate slope, and impermeable riverbed in a catchment with a slope greater than 2°. The spillway dimensioning considers the flow velocity, sediment properties, and storage target, and the construction is in multi-stages. Recently, the failure of several sand dams because of incorrect siting, evaporation loss, and one-stage construction were reported. Revision of practitioners’ manuals by considering catchment scale hydrological and hydrogeological characteristics, spillway height, and sediment transport are recommended. Research shows that protected wells have better water quality than open wells and scoop holes. Therefore, the community should avoid open defecation, pit latrines, tethering of animals, and applying pesticides near the sand dam.

Sand Dams as a Potential Solution to Rural Water Security in Drylands: Existing Research and Future Opportunities

Sand dams, a rainwater harvesting technique, are small dams constructed across ephemeral streams. During the rainy season, water is stored in the sand that accumulates behind the dam. Sand dams provide communities in drylands with water during the dry season via scoop holes, pools, and shallow wells. Whilst many studies portray sand dams as a positive solution to the growing threat of dryland water insecurity, others highlight their challenges, including poor water quality, evaporation and leakage from some dams, and the contested failure rate and ability of dams to provide water year-round. This article reviews the peer-reviewed and gray literature on sand dams discovered through Scopus and Google Scholar searches, reference lists, and personal contacts. Findings from the collected literature were reviewed and categorized into sand dam hydrology, health and well-being impacts, economic cost and benefits, and water quality topics. In most numerical simulations, sand dams supply water to the local community throughout much of the dry season and exhibit a long-term positive impact on groundwater. Accounts of water storage and loss based on field measurements, conversely, often show that most water is lost due to evapotranspiration and seepage from the sand reservoir rather than community use. Furthermore, the positive impact on local groundwater storage, while variable, is likely seasonal. Sand dams are relatively affordable to build; construction estimates range from 6,000 to 8,500 EUR. However, existing literature suggests that sand dams are likely not a cost-efficient means of supplying water. Nevertheless, successful sand dams can significantly increase water availability and use, whilst reducing traveling time for water collection, subsequently providing a host of secondary benefits from improved hygiene, economic opportunity, and education. Positive impacts, however, are not equally shared and depend on variables, such as abstraction method, catchment, and household location. Furthermore, their water quality is variable, with high microbiological levels detected especially in scoop holes. Whilst sand dams can increase water security and resilience, they may not be an inclusive solution for all. More research is needed to assess the long-term sustainability of sand dams while accounting for the uncertainty of a changing climate.

Assessment of water presence and use at sand dams in Kenya

Levels of water access provided by sand dams were assessed by measuring water presence and use in a representative sample of 97 dams in Kenya. Most dams were filled with sediment capable of holding water, with a 25% median reduction of water capacity due to siltation when using a high estimate for sediment specific yield. Multiple sediment cores taken from each dam indicated the presence of water in over half of sediment cores from 57% of dams. Although there is individual variation, generally dams in the region were therefore capable of accumulating water. Analysis of Landsat satellite images indicated that this did not translate into an average increase in vegetative greening and moisture indices at dam sites compared to controls sites. Observational data on activities at dams indicated variable levels of water use; only 43% of dams had active water harvesting present, and only 39% of dams had current agricultural activities adjacent to the sand dam site. Cross-sectional comparison of data did not indicate consistently higher levels of water harvesting or agricultural use at dams with more water. Results point towards a high level of community understanding of sand dam benefits, but a lower rate of actually realizing those benefits.

A data-driven approach to assessing the impact of water harvesting structures on regional water storage in East Africa

Abstract A small-scale water harvesting structure known as a sand dam has gained popularity across East Africa due to the efforts of non-governmental organizations. A sand dam is a subsurface water reservoir that stores water between sand grains. Stored thus, the water is filtered and protected from evaporation. This study uses remotely sensed data to investigate the impact of these structures on water storage and vegetative growth. The relationship between sand dams and water storage was modeled using a binary sand dam factor, climate data from the Famine Early Warning Systems Network Land Data Assimilation System (FLDAS), and water storage data measured by the Gravity Recovery and Climate Experiment (GRACE) twin satellites. The analysis revealed that GRACE largely fails to detect a statistically significant impact of sand dams on regional water storage. However, analysis of the Normalized Difference Vegetation Index (NDVI) indicated that sand dams have a significant impact on regional vegetation. Vegetative growth is correlated with groundwater levels, indicating that sand dams have a positive impact on water storage albeit on a smaller scale than GRACE can regularly detect. Significantly, this study shows that NDVI data can be used effectively to study small-scale, regional changes in vegetation and water storage.

The conditions and methods of biological diversity preservation and restoration on post-technogenic lands

Oil production, as well as the transportation of oil and gas through pipeline systems, cause the destruction and man-made transformation of the natural ecosystems of Northern Eurasia, an increase in the area of disturbed lands, and a reduction in the habitats of specially protected plant species. In this regard, the most significant measures for biological diversity are the identification of conditions for the growth of populations of rare plants in man-made biotopes and the development of methods for their conservation and restoration. 12 species (Carex sylvatica, Dactylorhiza baltica, D. fuchsii, D. incarnata, D. maculata, Fragaria moschata, Glyceria lithuanica, Listera ovata, Neottia nidus-avis, Ophioglossum vulgatum, Platanthera bifolia, Veratrum lobelianum) from the Red Book of the Yaroslavl region and 1 species (Dactylorhiza baltica) from the Red Book of the Leningrad region were recorded in the protected area of oil pipelines. Moreover,Dactylorhiza balticais listed in the Red Book of the Russian Federation. ForDactylorhiza fuchsii, D. incarnata, D. maculata, Fragaria moschata, at the risk of complete destruction of their biotopes, methods of their transplantation, repatriation and rehabilitation have been developed and transferred to the appropriate Department of the Yaroslavl region. For the restoration of biotopes on bulk sand dams of an oil field in Western Siberia, an experimental study of the wild speciesLeymus arenarieusas a fixative of technogenic sands showed good results.