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Flood Hydrograph and Baseflow Separation Using the Web- Based Hydrograph Analysis Tool
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Different locations have varying degrees of baseflow contribution to the streamflow based on the regional hydrogeological conditions. These can result in streams gaining (receipt of groundwater flow) and losing (discharge to groundwater system) conditions over time and space. Hence, understanding the local characteristics is imperative for the detailed analysis of baseflow conditions as many of the automated baseflow separation approaches do not distinguish between these physical states. Conceptually, the groundwater–surface water interaction processes are increased during a flood event, with significantly greater volumes both in the river and the surrounding landscape. A flood event causes a fast but temporary increase in stream water level that moves rapidly downstream under the force of gravity. This increase in water level can lead to a change in hydrostatic pressure between the river and the groundwater in the surrounding bank. In a gaining stream, depending on the hydrostatic pressure in the surrounding aquifer, this can stimulate the movement of flow from the stream to the bank. As the flood peak subsides, water moves back to the stream and the hydrostatic pressure in the river reduces. Groundwater discharge from aquifers represents the baseflow contribution to streamflow (Brandes et al., 2005). This occurs when the hydrostatic pressure of groundwater is higher than the stream, when aquifer is regularly recharged, and is made up of materials that support the storage and transmission of flow to the stream (Smakhtin, 2001).
Subsurface Water in the Hydrologie Balance
Published in K. Ferguson Bruce, Stormwater Infiltration, 2017
Urbanization’s deflection of flows away from subsurface paths makes base flows decline. During urbanization of Peach-tree Creek’s watershed, annual low flow decreased for a given amount of prior precipitation, particularly during dry years. Declining base flows are environmentally and economically critical: base flows must be sufficient to absorb pollution from sewage treatment plants and non-point sources, support aquatic life dependent on stream flow, and replenish water-supply reservoirs for municipal use in the seasons when lake levels tend to be lowest and water demands highest. Declining base flows reflect declining soil moisture and ground water levels. If the water is no longer in the watershed, having been shunted away by impervious surfaces during storm events, then there is no possibility of fully restoring base flows through reservoirs or any other kind of surface controls.
Water sources for flowing water fish culture
Published in Richard W. Soderberg, Aquaculture Technology, 2017
Stream flow consists of runoff, channel precipitation, and base flow, minus water losses to consumption, evaporation, and seepage. Base flow is the contribution to stream discharge from groundwater. The amount of precipitation that runs off a particular watershed is referred to as the hydrologic response and is expressed as a percentage. The hydrologic response is calculated from a hydrograph, which measures direct runoff above base flow following a precipitation event and from rain gauges in the watershed, which measure total precipitation. Hydrologic response values may range from 1% to 75% and are related to soil permeability, bedrock porosity, slope, and vegetation. Mountainous areas with shallow soils and impermeable bedrock have high hydrologic responses because a relatively large fraction of the water that falls as precipitation enters streams. Low hydrologic responses occur in areas where most of the precipitation enters the groundwater due to low gradients, permeable soils, and porous bedrock, such as limestone or shale.
Testing a modified environmental flows framework for a Southern Ontario (Canada) river system: assessing hydrological alteration and management recommendations
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2021
David Lembcke, Lance Aspden, Mason Marchildon, Steven Murray, Brian K. Ginn
Baseflow is the component of river flow coming from relatively stable sources such as groundwater, wetlands, or lakes and excludes storm event flows (Metcalfe et al. 2013). As the portion of the flow regime that is sustained between precipitation events, maintaining baseflow is essential to healthy ecological functioning in river systems. Brook trout, a key indicator of ecosystem health in coldwater habitats, are positively correlated to baseflow and baseflow index (BFI, the proportion of the total flow volume that is comprised of baseflow volume), as well as forested land cover (Stranko et al. 2008; Thorn, Chu, and Jones 2016). Although modeled baseflow volume showed an increase at Lover’s Creek, BFI decreased with increasing urban land cover, particularly between May and December (Figure 2(b)). The modeled mean annual pre-settlement BFI was 0.74, compared to BFI = 0.71 for the mid-development scenario, and BFI = 0.62 for the current condition. The decrease in BFI between the pre-settlement and mid-development scenarios was not statistically significant.
Land use dynamics and base and peak flow responses in the Choke mountain range, Upper Blue Nile Basin, Ethiopia
Published in International Journal of River Basin Management, 2021
Agenagnew A. Gessesse, Assefa M. Melesse, Anteneh Z. Abiy
Hydrograph analysis is a useful technique in a variety of water resource investigations (Setegn et al. 2010). Quantifying base flow contributions to stream flow is of great interest in the understanding, identification and quantification of stream flow generation processes. Particularly the base flow supports important ecosystem by providing water supply during critical dry season. Separation of stream flow hydrographs into base flow and surface runoff components is used to estimate the groundwater contribution to stream flow. Base flow represents the response of the river on the watershed supplied by groundwater flow and other types of flow that enter more slowly to the river streams (Liu et al. 2014, Novita and Wahyuningsih 2016). Understanding of the runoff generation processes is also essential for assessing the impacts of land use dynamics on the hydrological response of watershed characteristics (Gonzales et al. 2009, Getachew and Melesse 2012, Kebede et al. 2014).
A review of simulated climate change impacts on groundwater resources in Eastern Canada
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2019
Marie Larocque, Jana Levison, Alexandre Martin, Diane Chaumont
Sulis et al. (2011) and Levison et al. (2014a) clearly identified that changes in local aquifers near surface water bodies could lead to more frequent reversals of the hydraulic gradient between aquifers and surface water bodies. These reversals lead to reductions in baseflow and add pressure on ecological habitats and water users in streams and ponds during droughts and low water periods in summer (e.g., Levison, Larocque, and Ouellet 2014b). The absence of significant decreases in baseflows under climate change conditions in New Brunswick can appear counterintuitive since Rivard et al. (2009) have identified decreasing trends in baseflows in past time series for Atlantic Canada. However, the only climate change impact study reported here (Kurylyk, MacQuarrie, and Voss 2014) concerns a very small watershed which might not be representative of larger scale conditions.