Streamflow-base flow ratio in a lowland area of North-Eastern Romania

Soluble reactive phosphorus (SP) present in groundwater (GW) is generally considered insignificant, and therefore of little consequence to the quality of waters receiving base-flow discharges. In this study we investigated whether: (i) significant quantities of SP were present in GW (GW-SP); (ii) potential existed for GW-SP to be exported to streams via base-flow discharge; and (iii) the exports are a health risk to ecosystems receiving base-flow discharges. Investigations were carried out at two sites in the Tully River Catchment (TRC) during three consecutive rainy seasons, and 24 wells in the Johnstone River Catchment (JRC) were also monitored during one rainy season, in the north-eastern wet tropics of Australia. In the TRC, the GW-SP varied temporally, within and between rainy seasons, from 2 to 158 μg P/L at Site 1 and from 3 to 31 μg P/L at Site 2. The temporal variations in GW-SP were driven by fluctuating water-table at Site 2, but no such trend was observed at Site 1. The SP in drain-water (DW-SP) varied temporally from 0.6 to 110 μg P/L at Site 1, compared with 2–83 μg P/L at Site 2. The positive association between DW-SP and GW-SP at Site 2 indicated an export of SP from GW to a drain via base-flow discharge. In the JRC, the GW-SP in the 24 wells varied temporally from 0 to 300 μg P/L with the means across the wells ranging from 5 to 190 μg P/L, with the variations driven by fluctuating water-tables. More than 50% of the GW-SP or DW-SP concentrations in TRC were significantly higher than the P trigger values, 2–5 μg P/L, proposed to sustain the health of aquatic ecosystems in this region; a similar result was observed in the JRC. Speciation analysis via filtering (i.e. P passing through a 0.45-μm filter) for selected GW samples indicated substantial quantities of soluble organic P in some wells, ranging from 5 to 89% (mean 38%) of the total soluble P (SP plus soluble organic P). Because the soluble organic P was not included in GW-SP determinations, the hazard/risk mentioned above is an underestimate. The GW-SP exported during rainy seasons, from both catchments, ranged from 0.16 to 0.43 kg P/ha. Our findings indicate there were significant quantities of SP and soluble organic P in GW, it was exported to streams, and there is a health risk to receiving surface water bodies.

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Comparison of different base flow separation methods in a lowland catchment

Hydrology and Earth System Sciences ◽

10.5194/hess-13-2055-2009 ◽

2009 ◽

Vol 13 (11) ◽

pp. 2055-2068 ◽

Cited By ~ 89

Author(s):

A. L. Gonzales ◽

J. Nonner ◽

J. Heijkers ◽

S. Uhlenbrook

Keyword(s):

Flow Separation ◽

Base Flow ◽

Water Levels ◽

Runoff Generation ◽

Flow Process ◽

Groundwater Levels ◽

Groundwater Assessment ◽

Base Flow Separation ◽

Lowland Area ◽

The Impact

Abstract. Assessment of water resources available in different storages and moving along different pathways in a catchment is important for its optimal use and protection, and also for the prediction of floods and low flows. Moreover, understanding of the runoff generation processes is essential for assessing the impacts of climate and land use changes on the hydrological response of a catchment. Many methods for base flow separation exist, but hardly one focuses on the specific behaviour of temperate lowland areas. This paper presents the results of a base flow separation study carried out in a lowland area in the Netherlands. In this study, field observations of precipitation, groundwater and surface water levels and discharges, together with tracer analysis are used to understand the runoff generation processes in the catchment. Several tracer and non-tracer based base flow separation methods were applied to the discharge time series, and their results are compared. The results show that groundwater levels react fast to precipitation events in this lowland area with shallow groundwater tables. Moreover, a good correlation was found between groundwater levels and discharges suggesting that most of the measured discharge also during floods comes from groundwater storage. It was estimated using tracer hydrological approaches that approximately 90% of the total discharge is groundwater displaced by event water mainly infiltrating in the northern part of the catchment, and only the remaining 10% is surface runoff. The impact of remote recharge causing displacement of near channel groundwater during floods could also be motivated with hydraulic approximations. The results show further that when base flow separation is meant to identify groundwater contributions to stream flow, process based methods (e.g. the rating curve method; Kliner and Knezek, 1974) are more reliable than other simple non-tracer based methods. Also, the recursive filtering method (proposed by Eckhardt, 2005) can be calibrated well using the results of tracer investigation giving good results. Consequently, non-tracer based base flow separation methods that can be validated for some events may provide a powerful tool for groundwater assessment or model calibration/validation in lowland areas.

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Comparison of different base flow separation methods in a lowland catchment

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-3483-2009 ◽

2009 ◽

Vol 6 (2) ◽

pp. 3483-3515 ◽

Cited By ~ 7

Author(s):

A. L. Gonzales ◽

J. Nonner ◽

J. Heijkers ◽

S. Uhlenbrook

Keyword(s):

Flow Separation ◽

Base Flow ◽

Water Levels ◽

Runoff Generation ◽

Flow Process ◽

Groundwater Levels ◽

Groundwater Assessment ◽

Base Flow Separation ◽

Lowland Area ◽

The Impact

Abstract. Assessment of water resources kept in different storages and moving along different pathways in a catchment is important for its optimal use and protection, and also for the prediction of floods and low flows. Moreover, understanding of the runoff generation processes is essential for assessing the impacts of climate and land use changes on the hydrological response of a catchment. Many methods for base flow separation exist, but hardly one focuses on the specific behaviour of temperate lowland areas. This paper presents the results of a base flow separation study carried out in a lowland area in the Netherlands. In this research, field observations of precipitation, groundwater and surface water levels and discharges, together with tracer analysis are used to understand the runoff generation processes in the catchment. Several tracer and non-tracer based base flow separation methods were applied to the discharge time series, and their results are compared. The results show that groundwater levels react fast to precipitation events in this lowland area with shallow groundwater tables. Moreover, a good correlation was found between groundwater levels and discharges meaning that most of the measured discharge also during floods comes from the groundwater storage. It was determined using tracer hydrological approaches that approximately 90% of the total discharge is groundwater displaced by event water infiltrating in the northern part of the catchment, and only the remaining 10% is surface runoff. The impact of remote recharge causing displacement of near channel groundwater during floods could also be motivated with hydraulic approximations. The results show further that when base flow separation is meant to separate groundwater contributions to stream flow, process based methods (e.g. rating curve method; Kliner and Knezek, 1974) are more reliable than other simple non-tracer based methods. Also, the recursive filtering method (proposed by Eckhardt, 2005) can be calibrated well using the results of tracer investigation, and this resulted in good results. Consequently, simple non-tracer based base flow separation methods that could be validated for some events may provide a powerful tool for groundwater assessment or model calibration/validation in lowland areas.

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Assessment of Runoff and Drainage Conditions in a North Banat Sub-Catchment, North-Eastern Serbia

Journal of Environmental Geography ◽

10.2478/jengeo-2019-0008 ◽

2019 ◽

Vol 12 (3-4) ◽

pp. 13-19

Author(s):

Milica Vranešević ◽

Andrea Salvai ◽

Atila Bezdan ◽

Radoš Zemunac

Keyword(s):

Drainage Basin ◽

Drainage System ◽

Runoff Coefficient ◽

Empirical Formulas ◽

Southeastern Part ◽

Current State ◽

North Eastern ◽

Lowland Area ◽

Regional Character ◽

Different Parts

Abstract The lowland area of the southeastern part of the Carpathian Basin is exposed to extreme hydrological conditions. The monitoring and analysis of the excess inland water are necessary in order to understand the scope and direction of the development of this type of flooding. When solving the problem of the drainage of an area and dimensioning drainage systems, one of the most important steps is to calculate the rate of runoff. Before calculating the rate of runoff, it is necessary to perform various analysis such as: hydrological, hydrogeological, pedological and land use analysis. The use of empirical formulas by different authors is one of the methods for determining the rate of runoff. These formulas can be of regional character, while some are applicable in different parts of the world. In this paper, the runoff coefficient and rate of runoff were calculated as indicators of the efficiency of the area drainage, employing the formulas by Nemet and Turazzo. The emphasis was put on the usage of modern tools and databases of soil characteristics while using a “traditional” method to determine rate of runoff. The obtained results demonstrate that the rate of runoff which reflects the current state of the drainage basin is very similar to the rate of runoff used for dimensioning of drainage system. The problem of retaining smaller amounts of water that remains even after the anticipated drainage deadlines can be solved with the regular maintenance of amelioration canals and additional ameliorative measures.

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Effect of Segment Endwall Boundary Layer Suction on Compressor 3D Corner Separation

Volume 2A: Turbomachinery ◽

10.1115/gt2015-42024 ◽

2015 ◽

Author(s):

Ping-Ping Chen ◽

Wei-Yang Qiao ◽

Karsten Liesner ◽

Robert Meyer

Keyword(s):

Boundary Layer ◽

High Speed ◽

Flow Behavior ◽

Pressure Ratio ◽

Base Flow ◽

Flow Ratio ◽

Compressor Cascade ◽

Corner Separation ◽

Boundary Layer Suction ◽

Suction Flow

Due to the strong secondary flow behavior in the compressor endwall/blade suction-side corner region, a large three-dimensional corner separation will usually be formed with large amounts of compressor aerodynamic loss. In this paper, a linear high-speed compressor cascade, with five NACA 65-K48 stator profiles, is numerically simulated to understand the state of this phenomenon. Based on the experiment, the base flow is validated for the numerical result. Active control of 3D corner separation was investigated by using segment endwall boundary layer suction, which is located along the pressure-side leg of leading-edge horse-shoe vortex during its development in the frontal part of the blade passage. The influence of suction flow ratio was investigated in an effort to quantify the improvements of compressor cascade performance. The results show the optimal suction flow ratio is not the largest, but a critical value, which is 0.83% of inflow mass flow rate. Taking all performance parameters’ changes into consideration, the best is with 1% suction flow ratio. The total-pressure loss is eventually reduced by 11.2% with the optimal suction flow ratio compared to the design condition, and an increase of 9.84% is obtained for the static-pressure ratio.

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