Browsing by Author "Quinn, Ruth"
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Item Open Access An assessment of the microbiological water quality of sand dams in southeastern Kenya(MDPI, 2018-05-01) Quinn, Ruth; Avis, Orlando; Decker, Manon; Parker, Alison; Cairncross, SandySand-storage dams have proven to be a successful water harvesting method and potential solution to water and food security issues in semi-arid regions such as south east Kenya. This paper examines the microbiological quality of water both contained in the sand dam via test holes and abstracted from it through covered wells and scoop holes. In total, the values of thermotolerant coliform (TTC) concentration, turbidity, and pH are presented for 47 covered wells, 36 scoop holes, and 29 test holes, as well as the conductivity values in conductivity in 39 covered wells and 11 scoop holes. The water from test holes and covered wells was microbiologically of better quality than the scoop holes with median TTC levels of 0/100 mL and 159/100 mL respectively. However, the median values of turbidity for both scoop holes (20–30 NTU) and covered wells (5–10 NTU) exceed the World Health Organisation (WHO) guideline values. In addition the conductivity of water from 23% of scoop holes and 26% of covered wells is above the recommended WHO limit. This study also found that sanitary surveys are not a useful indicator of water quality in sand dams; however, they can identify areas in which sanitation and improvement of water sources are needed.Item Open Access Evaporation from bare soil: Lysimeter experiments in sand dams interpreted using conceptual and numerical models(Elsevier, 2018-07-06) Quinn, Ruth; Parker, Alison; Rushton, Kenneth R.Unlike evaporation from open water, the magnitude of evaporation from bare soil decreases as the water table falls. Bare soil evaporation studies have included field and laboratory experiments, mathematical formulations and semi-empirical models. However, there is only limited field information, especially concerning evaporation from bare sand. The semi-empirical approach of the FAO1 Irrigation and Drainage Paper 56, which contains guidelines for computing crop water requirements, can be adapted for bare soil evaporation with a three stage process. The suitability of the FAO 56 approach for bare sand evaporation is investigated by installing lysimeters in sand dams. Sand dams are shallow groundwater storage systems, which are designed on the assumption of reduced evaporation as the water table falls. The field results from the lysimeters are simulated adequately by a water balance model based on FAO 56 with an additional component to represent both the difference between the variable saturation with depth, which occurs in practice, and the assumption in standard water balance models of a sudden change from dry to fully-saturated conditions at the water table. This study demonstrates and quantifies the reduction in bare soil evaporation compared to open water or cropped areas and confirms the validity of the three stage FAO semi-empirical approach.Item Open Access An examination of the hydrological system of a sand dam during the dry season leading to water balances(Elsevier, 2019-06-13) Quinn, Ruth; Rushton, Kenneth R.; Parker, Alison H.To address water scarcity in semi-arid regions, rainfall and runoff need to be captured and stored locally before they are lost to the sea. This can be done using a sand dam which consists of a reinforced wall constructed during the dry season across a seasonal riverbed. However it is unclear whether their main utility is to store water in the sand that is also trapped behind them, or to facilitate aquifer recharge. This paper aims to answer this question by the calculation of a water balance in three sand dams in Kenya to quantify the amount of water transferred between the sand dam and the surrounding aquifer system. The components of the water balance were derived from extensive field monitoring. Water level monitoring in piezometers installed along the length of the sand deposits enabled calculation of the hydraulic gradient and hence the lateral flow between the different reaches of the sand dam. In one sand dam water was gained consistently through the dry season, in one it was lost, and in the third it was lost almost all the time except for the early dry season in the upper part of the trapped sand. In conclusion sand dams should not be treated as isolated water storage structures.Item Open Access Sand dam water quality data(Cranfield University, 2018-08-16 15:11) Parker, Alison; Quinn, RuthWater quality data collected in Kenyan sand dams in June and July 2016.Item Open Access Sand dams for sustainable water management: challenges and future opportunities(Elsevier, 2022-05-26) Castelli, Giulio; Piemontese, Luigi; Quinn, Ruth; Aerts, Jeroen; Elsner, Paul; Ertsen, Maurits; Hussey, Stephen; Leal Filho, Walter; Limones, Natalia; Mpofu, Bongani; Neufeld, Doug Graber; Ngugi, Keziah; Ngwenya, Nobubelo; Parker, Alison; Ryan, Cate; de Trincheria, Josep; Villani, Lorenzo; Eisma, Jessica; Bresci, ElenaSand 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.Item Open Access Wasim (soil water balance model)(Cranfield University, 2019-06-04 12:23) Hess, Tim; Parker, Alison; Quinn, Ruth; Rushton, KenA one-dimensional soil water balance model that partitions daily rainfall into evapotranspiration, surface runoff and drainage. Options allow irrigation to be scheduled according to rules, water table position to be simulated with field under drainage, and soil water salinity to be estimated.The installation package includes a user manual, technical manual and a tutorial with sample data.Item Open Access Water balance data(Cranfield University, 2019-07-02 10:05) Parker, Alison; Quinn, Ruth; Rushton, KenSheet 1 is water level data from two sand dams, measured in piezometers.Sheet 2 is conductivity data collected at a different sand dam.Data is described in the paper "An examination of the hydrological system of a sand dam during the dry season leading to water balances" at https://doi.org/10.1016/j.hydroa.2019.100035.