scholarly journals Lithological and Tectonic Control on Groundwater Contribution to Stream Discharge During Low-Flow Conditions

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 821 ◽  
Author(s):  
Stefanie Wirth ◽  
Claire Carlier ◽  
Fabien Cochand ◽  
Daniel Hunkeler ◽  
Philip Brunner
Keyword(s):  
Water Resources ◽  
Stream Flow ◽  
Low Flow ◽  
Limited Information ◽  
Flow Conditions ◽  
Stream Discharge ◽  
Low Flows ◽  
Dry Spells ◽  
Deep Boreholes ◽  
Groundwater Contribution

Knowing how stream discharge in an ungauged catchment reacts to dry spells is a major challenge for managing water resources. The role of geology on these dynamics is poorly understood. For the Swiss Molasse basin, we therefore explored how the geology influences the groundwater contribution to stream flow during low-flow conditions. Using existing data from geological reports and maps as well as from deep boreholes, we constructed a basin-wide overview of the hydrogeological quality of the bedrock and investigated five catchments in 3D. We found that catchments with the most permeable sedimentary bedrock are least sensitive to low flows (marine sandstone, K = 10−4 to 10−5 m/s, Peff = 5–10%). In contrast, if bedrock K is low (K < 10−6 m/s), the presence of a productive Quaternary volume becomes decisive for groundwater contribution to stream flow. Limitations exist due to a restricted database for K and Peff values of the Molasse and limited information on continuation of lithologies with depth. This emphasizes the need for more hydrogeologically relevant data for the future management of water resources. Our results highlighting what lithotypes favor groundwater contribution to stream flow are valid also in other regions for the assessment of a catchment’s sensitivity to low flows.

ANALYSIS OF LOW-FLOW CONDITIONS IN A HETEROGENEOUS KARST CATCHMENT AS A BASIS FOR FUTURE PLANNING OF WATER RESOURCE MANAGEMENT

2020 ◽  
Author(s):  
Klaudija Sapač ◽  
◽  
Simon Rusjan ◽  
Nejc Bezak ◽  
Mojca Šraj ◽  
...  
Keyword(s):  
Water Resources ◽  
Water Use ◽  
Water Resource Management ◽  
Flow Characteristics ◽  
Low Flow ◽  
Flow Conditions ◽  
Discharge Data ◽  
River Catchment ◽  
Low Flows ◽  
Recession Curves

Understanding and prediction of low-flow conditions are fundamental for efficient water resources planning and management as well as for identification of water-related environmental problems. This is problematic especially in view of water use in economic sectors (e.g., tourism) where water-use peaks usually coincide with low-flow conditions in the summer time. In our study, we evaluated various low-flow characteristics at 11 water stations in the non-homogenous Ljubljanica river catchment in Slovenia. Approximately 90% of the catchment is covered by karst with a diverse subsurface, consisting of numerous karst caves. The streams in the remaining part of the catchment have mainly torrential characteristics. Based on daily discharge data we calculated and analyzed values of 5 low-flow indices. In addition, by analyzing hydrograph recession curves, recession constants were determined to assess the catchment’s responsiveness to the absence of precipitation. By using various calculation criteria, we analyzed the influence of individual criteria on the values of low-flow recession constants. Recession curves are widely used in different fields of hydrology, for example in hydrological models, baseflow studies, for low-flow forecasting, and in assessing groundwater storages which are crucial in view of assessing water availability for planning water resources management. Moreover, in the study we also investigated the possible impact of projected climate change (scenario RCP4.5) on low-flow conditions in two sub-catchments of the Ljubljanica river catchment. For the evaluation we used the lumped conceptual hydrological model implemented in the R package airGR. For periods 2011-2040, 2041-2070, and 2071-2100 low-flow conditions were evaluated based on flow duration curves compared with the 1981-2010 period. The lowest discharges at all water stations in the Ljubljanica river catchment occur mostly during the summer months. Our results for the future show that we can expect a decrease of the lowest low-flows in the first two 30-year periods, while in the last one low-flows could increase by approx. 15%. However, the uncertainty/variability of the results is very high and as such should be taken into account when interpreting and using the results. This study demonstrates that evaluation of several low-flow characteristics is needed for a comprehensive and holistic overview of low-flow dynamics. In non-homogeneous catchments with a high karstic influence, the hydrogeological conditions of rivers should also be taken into account in order to adequately interpret the results of low-flow analyses. This proved to be important even in case of neighboring water stations.

Non-stationarity of low flows and their relevance to river modelling during drought periods

2017 ◽  
Vol 68 (12) ◽  
pp. 2306 ◽  
Author(s):  
David W. Rassam ◽  
Daniel Pagendam ◽  
Mat Gilfedder ◽  
Lu Zhang
Keyword(s):  
Regression Analysis ◽  
River Flow ◽  
Low Flow ◽  
Flow Conditions ◽  
Low Flows ◽  
River Modelling ◽  
Quantile Regression Analysis ◽  
River Models ◽  
Groundwater Contribution ◽  
Ltb Metric

Changes in groundwater storage lead to a reduction in groundwater contribution to river flow and present as non-stationarity, especially during low-flow conditions. Conventional river models typically ignore this non-stationarity, and, hence, their predictions of declines in low flows during drought periods are likely to be compromised. The present study assesses non-stationarity and highlights its implications for river modelling. A quantile regression analysis showed non-stationarity of low flows in the Namoi catchment (Australia), with statistically significant downward trends in the 10th percentile of log-transformed baseflow (10-LTB). This highlighted the usefulness of the 10-LTB metric to identify non-stationarity and, hence, alert modellers to the importance of adopting models that explicitly account for groundwater processes when modelling such river systems.

scholarly journals Supplemental irrigation potential and impact on downstream flow of Karkheh River Basin of Iran

2012 ◽  
Vol 9 (12) ◽  
pp. 13519-13536 ◽  
Author(s):  
B. Hessari ◽  
A. Bruggeman ◽  
A. Akhoond-Ali ◽  
T. Oweis ◽  
F. Abbasi
Keyword(s):  
Water Resources ◽  
River Basin ◽  
Stream Flow ◽  
Water Productivity ◽  
Environmental Flow ◽  
Flow Conditions ◽  
Supplemental Irrigation ◽  
Irrigation Potential ◽  
Downstream Flow ◽  
Karkheh River Basin

Abstract. Supplemental irrigation of rainfed winter crops improves and stabilizes crop yield and water productivity. Although yield increases by supplemental irrigation are well established at the field level, its potential extent and impact on water resources at the basin level are less researched. This work presents a GIS-based methodology for identifying areas that are potentially suitable for supplemental irrigation and a computer routine for allocating stream flow for supplemental irrigation in different subbasins. A case study is presented for the 42 908 km2 upper Karkheh River Basin (KRB) in Iran, which has 15 840 km2 of rainfed crop areas. Rainfed crop areas within 1 km from the streams, with slope classes 0–5%, 0–8%, 0–12% and 0–20%, were assumed to be suitable for supplemental irrigation. Four stream flow conditions (normal, normal with environmental flow requirements, drought and drought with environmental flow) were considered for the allocation of water resources. Thirty-seven percent (5801 km2) of the rainfed croplands had slopes less than 5%. Sixty-one percent (3559 km2) of this land was suitable for supplemental irrigation, but only 22% (1278 km2) could be served with irrigation in both fall (75 mm) and spring (100 mm), under normal flow conditions. If irrigation would be allocated to all suitable land with slopes up to 20%, 2057 km2 could be irrigated. This would reduce the average annual outflow of the upper KRB by 9%. If environmental flow requirements are considered, a maximum (0–20% slopes) of 1444 km2 could receive supplemental irrigation. Under drought conditions a maximum of 1013 km2 could be irrigated, while the outflow would again be reduced by 9%. Thus, the withdrawal of steam flow for supplemental irrigation has relatively little effect on the outflow of the upper KRB. However, if the main policy goal would be to improve rainfed areas throughout the upper KRB, options for storing surface water need to be developed.

scholarly journals Analysis of groundwater regime on the basis of stream flow hydrograph

2012 ◽  
Vol 10 (3) ◽  
pp. 301-314 ◽  
Author(s):  
Vesna Djukic ◽  
Vladislava Mihailovic
Keyword(s):  
Water Resources ◽  
Simulation Model ◽  
Stream Flow ◽  
Local Minimum ◽  
Base Flow ◽  
Low Flow ◽  
Retention Basin ◽  
Groundwater Regime ◽  
Flow Changes

During the drought the flow in streams is reduced and is dominated by base flow. Baseflows are characteristic of low flow periods and provide information on available water resources in the basin during the drought, particularly on the aquifer and retention basin characteristics. This paper deals with the possibility of analysis and simulation of baseflow, and the determination of the pattern of its changes based on the total registered streamflow hydrograph at the catchment outlet. The basis for modeling the base flow changes in the time were base flow values obtained from the streamflow hydrograph by application of the graphical local minimum method. Applying the simulation model developed in this study, simulations of base flow hydrographs were performed for three characteristic years (1970, 1985, and 1990). It was shown that discrepancies between values of the base flows obtained through application of the local minimum method and the model are within the limits of tolerance.

Phosphorus and nitrogen loads in waters associated with the River Murray near Albury-Wodonga, and their effects on photoplankton populations

1982 ◽  
Vol 33 (2) ◽  
pp. 223 ◽  
Author(s):  
KF Walker ◽  
TJ Hillman
Keyword(s):  
Stream Flow ◽  
Algal Blooms ◽  
Low Flow ◽  
Light Penetration ◽  
Flow Conditions ◽  
Nutrient Inputs ◽  
Low Light ◽  
Nitrogen Loads ◽  
Nutrient Assimilation ◽  
Enrichment Experiments

This is part of a survey carried out to assess the likely impact on the River Murray of urban development at Albury-Wodonga. The study area included two impoundments, Lake Hume and Lake Mulwala, the tributary Mitta Mitta, Kiewa and Ovens Rivers, and the River Murray. Phosphorus and nitrogen loads were examined over 4 years, incorporating a high flow period, 1974-75, and a low flow period, 1976-77. Loads varied directly with stream flow, although loadings to the two impoundments were generally high and above levels considered indicative of eutrophy elsewhere. Phytoplankton biomasses did not reflect this situation, howeyer, and averaged below 2000 mm3 m-3 Phytoplankton growth, and hence nutrient assimilation, probably were restricted by low light penetration resulting from high turbidities. This is supported by preliminary laboratory experiments involving nutrient enrichments over a range of turbidities. Under low flow conditions, nutrient inputs to the impoundments were reduced and underwater light penetration increased, due to settling of abiogenic suspended material. Nutrient enrichment experiments in Lake Mulwala supported the proposition that availability of nutrients, particularly phosphorus, could limit phytoplankton biomass under those conditions. The results generally indicate that pro rata inputs from Albury-Wodonga need to be reduced as the urban population grows, if the risk of nuisance algal blooms during low flow periods is to be minimized.

Effects of increasing salinity on freshwater ecosystems in Australia

2003 ◽  
Vol 51 (6) ◽  
pp. 655 ◽  
Author(s):  
D. L Nielsen ◽  
M. A. Brock ◽  
G. N. Rees ◽  
D. S. Baldwin
Keyword(s):  
Physical Environment ◽  
Aquatic Ecosystems ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Limited Information ◽  
Flow Conditions ◽  
Saline Groundwater ◽  
Natural Flow ◽  
And Function ◽  
Natural Component

Salt is a natural component of the Australian landscape to which a number of biota inhabiting rivers and wetlands are adapted. Under natural flow conditions periods of low flow have resulted in the concentration of salts in wetlands and riverine pools. The organisms of these systems survive these salinities by tolerance or avoidance. Freshwater ecosystems in Australia are now becoming increasingly threatened by salinity because of rising saline groundwater and modification of the water regime reducing the frequency of high-flow (flushing) events, resulting in an accumulation of salt. Available data suggest that aquatic biota will be adversely affected as salinity exceeds 1000 mg L–1 (1500 EC) but there is limited information on how increasing salinity will affect the various life stages of the biota. Salinisation can lead to changes in the physical environment that will affect ecosystem processes. However, we know little about how salinity interacts with the way nutrients and carbon are processed within an ecosystem. This paper updates the knowledge base on how salinity affects the physical and biotic components of aquatic ecosystems and explores the needs for information on how structure and function of aquatic ecosystems change with increasing salinity.

scholarly journals Assessment of observed and simulated low flow indices for a highly managed river basin

2018 ◽  
Vol 49 (6) ◽  
pp. 1831-1846 ◽  
Author(s):  
Hagen Koch ◽  
Stefan Liersch ◽  
José Roberto Gonçalves de Azevedo ◽  
Ana Lígia Chaves Silva ◽  
Fred Fokko Hattermann
Keyword(s):  
Water Management ◽  
Land Use ◽  
Water Resources ◽  
River Basin ◽  
Low Flow ◽  
Natural Phenomena ◽  
Resources Management ◽  
Spatial And Temporal Scales ◽  
Natural Processes ◽  
Low Flows

Abstract Droughts and resulting low flows are a threat for society, economy, and ecosystems. Droughts are natural phenomena, but anthropogenic water use can increase the pressure on water resources. To analyze the effects of changing land-use or water management and climate variability/change on water resources, models integrating the most important hydrological processes are needed. These models must account for natural processes and water resources management at different spatial and temporal scales, e.g., reservoir operation, water withdrawals. Low flow indices are analyzed for observed and simulated flows for the highly managed São Francisco river basin in Brazil, showing that during wet, normal, and moderately dry years, the existing reservoir system is able to augment low flows while during strong droughts the system reaches its limits. This effect is also represented in the simulations using the eco-hydrological model SWIM, which was adapted to account for region-specific characteristics of land-use and water management. While good to very good performance was achieved for calibration and validation for most gauges, for some gauges at tributaries only insufficient quantitative criteria are reached. The reasons for the deviation between observations and simulation results are discussed. Overall, the model is able to represent natural discharges and observed, managed discharges.

The effects of drought on the river systems

1978 ◽  
Vol 363 (1712) ◽  
pp. 69-96 ◽  
Keyword(s):  
Water Resources ◽  
Low Flow ◽  
River Systems ◽  
River Flows ◽  
England And Wales ◽  
Low Flows ◽  
River Thames ◽  
Effects Of Drought

The drought of 1975–76 had a significant effect on the river systems of England and Wales and will be used in water resources design for many years. It is therefore important to recognize that for the river flows it was not uniformly severe. Further, for many purposes, the duration of the low flow is at least as important as its severity. As an example, for the river Thames at Teddington it was only for periods of one and two months that the flow in 1976 was lower than that in 1921. The paper reviews the conditions which give rise to low flows in rivers, compares a representative set of low flow records, comments on criteria which were used to reduce the effect of the drought on the quantity and quality of river flows and suggests methods by which the management of rivers in time of drought might be improved.

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