scholarly journals Conceptual Model Modification and the Millennium Drought of Southeastern Australia

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 669
Author(s):  
Justin Hughes ◽  
Nick Potter ◽  
Lu Zhang ◽  
Robert Bridgart
Keyword(s):  
Objective Function ◽  
Goodness Of Fit ◽  
Predictive Performance ◽  
Annual Rainfall ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Model Modification ◽  
Southeastern Australia ◽  
Evaluation Bias ◽  
Millennium Drought

Long-term droughts observed in southern Australia have changed relationships between annual rainfall and runoff and tested some of the assumptions implicit in rainfall–runoff models used in these areas. Predictive confidence across these periods is when low using the more commonly used rainfall–runoff models. Here we modified the GR4J model to better represent surface water–groundwater connection and its role in runoff generation. The modified model (GR7J) was tested in 137 catchments in south-east Australia. Models were calibrated during “wetter” periods and simulation across drought periods was assessed against observations. GR7J performed better than GR4J in evaluation during drought periods where bias was significantly lower and showed improved fit across the flow duration curve especially at low flows. The largest improvements in predictive performance were for catchments where there were larger changes in the annual rainfall–runoff relationship. The predictive performance of the GR7J model was more sensitive to objective function used than GR4J. The use of an objective function that combined daily and annual error produced a better goodness of fit when measured against 80, 50 and 20 percent excedance flow quantiles and reduced evaluation bias, especially for the GR7J model.

scholarly journals Modelling monthly runoff generation processes following land use changes: groundwater–surface runoff interactions

2004 ◽  
Vol 8 (5) ◽  
pp. 903-922 ◽  
Author(s):  
M. Bari ◽  
K. R. J. Smettem
Keyword(s):  
Land Use ◽  
Water Balance ◽  
Surface Runoff ◽  
Land Use Changes ◽  
Annual Rainfall ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Mean Annual Rainfall ◽  
Monthly Runoff ◽  
Stream Bed

Abstract. A conceptual water balance model is presented to represent changes in monthly water balance following land use changes. Monthly rainfall–runoff, groundwater and soil moisture data from four experimental catchments in Western Australia have been analysed. Two of these catchments, "Ernies" (control, fully forested) and "Lemon" (54% cleared) are in a zone of mean annual rainfall of 725 mm, while "Salmon" (control, fully forested) and "Wights" (100% cleared) are in a zone with mean annual rainfall of 1125 mm. At the Salmon forested control catchment, streamflow comprises surface runoff, base flow and interflow components. In the Wights catchment, cleared of native forest for pasture development, all three components increased, groundwater levels rose significantly and stream zone saturated area increased from 1% to 15% of the catchment area. It took seven years after clearing for the rainfall–runoff generation process to stabilise in 1984. At the Ernies forested control catchment, the permanent groundwater system is 20 m below the stream bed and so does not contribute to streamflow. Following partial clearing of forest in the Lemon catchment, groundwater rose steadily and reached the stream bed by 1987. The streamflow increased in two phases: (i) immediately after clearing due to reduced evapotranspiration, and (ii) through an increase in the groundwater-induced stream zone saturated area after 1987. After analysing all the data available, a conceptual monthly model was created, comprising four inter-connecting stores: (i) an upper zone unsaturated store, (ii) a transient stream zone store, (ii) a lower zone unsaturated store and (iv) a saturated groundwater store. Data such as rooting depth, Leaf Area Index, soil porosity, profile thickness, depth to groundwater, stream length and surface slope were incorporated into the model as a priori defined attributes. The catchment average values for different stores were determined through matching observed and predicted monthly hydrographs. The observed and predicted monthly runoff for all catchments matched well with coefficients of determination (R2) ranging from 0.68 to 0.87. Predictions were relatively poor for: (i) the Ernies catchment (lowest rainfall, forested), and (ii) months with very high flows. Overall, the predicted mean annual streamflow was within ±8% of the observed values. Keywords: monthly streamflow, land use change, conceptual model, data-based approach, groundwater

Driving factors of non-linearity rainfall-runoff relationships at different time scales in small Mediterranean-climate catchments

2020 ◽  
Author(s):  
Josep Fortesa ◽  
Jérôme Latron ◽  
Julián García-Comendador ◽  
Miquel Tomàs-Burguera ◽  
Jaume Company ◽  
...  
Keyword(s):  
Mediterranean Climate ◽  
Annual Rainfall ◽  
Land Uses ◽  
Hydrological Response ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Event Scale ◽  
Annual Variability ◽  
Temporal And Spatial ◽  
Annual Scale

<p>The complexity of Mediterranean fluvial systems is caused by the multiple temporal and spatial heterogeneity in the relationships between the natural and human-induced abiotic and biotic variables. Accordingly, Mediterranean rivers are characterized by a large heterogeneity in hydrological regimes promoting significant temporal and spatial differences in the hydrological response.</p><p>This research investigates the non-linearity in the rainfall-runoff relationship at multiple temporal scales to achieve a better understanding of the hydrological response in representative small Mediterranean-climate catchments (i.e., < 10 km<sup>2</sup>). Rainfall-runoff was evaluated at annual and event scales. At annual scale, data from 43 catchments were collected to assess the influence of lithology on runoff response. At event scale, 203 events from 12 catchments were classified according to (a) seasonal occurrence (autumn, winter, spring or summer), (b) pervious or impervious lithology and (c) main land use (agricultural, agroforestry, forest or shrub). Besides, the inter- and intra-annual variability of the rainfall-runoff and the temporal downscaling (i.e., annual to event scale) was studied in Es Fangar Creek catchment (3.35 km<sup>2</sup>; Mallorca, Spain) during five hydrological years (2012-2017).</p><p>The assessment of rainfall-runoff relationships at annual scale in small Mediterranean-climate catchments showed a strong linearity in the hydrological response due to the importance of the annual rainfall amount. However, lithology effects on runoff generation explained an increase of the scattering in these relationships because pervious and impervious materials triggered larger and lower runoff contribution respectively. Although the significant correlation between rainfall and runoff, Es Fangar Creek dataset illustrated a huge intra-annual variability of the rainfall-runoff relationship as seasonal rainfall and evapotranspiration dynamics controlled the runoff response. These dynamics were observed in the average seasonal runoff coefficients, decreasing from winter to summer. These differences should be considered as a starting point of the non-linearity generation in the rainfall-runoff relationships at event scale.</p><p>At event scale, lineal and non-lineal performances were observed in the rainfall-runoff relationships in small Mediterranean-climate catchments suggesting that different factors conditioned the runoff response. Total rainfall was the most significant driver factor although the interaction between seasonality and the spatial diversity of lithology and land uses at catchment scale also played an important role on runoff generation. Thus, the highest correlations at seasonal scale were observed in those events occurred in winter and spring when the highest water reserves favoured the runoff response. Lithology caused higher dispersion in rainfall-runoff relationships at event scale in the set of small Mediterranean-climate catchments because pervious materials required higher antecedent wetness conditions. Agricultural land uses promoted the highest runoff generation. </p><p>These findings will improve the comprehension of hydrological processes as the temporal downscaling of rainfall-runoff linked to the driven factors with the linearity and non-linearity knowledge is needed for accuracy and precision into hydrological modelling at event scale.</p><p>This work was supported by the research project CGL2017-88200-R “Functional hydrological and sediment connectivity at Mediterranean catchments: global change scenarios –MEDhyCON2” funded by the Spanish Ministry of Science, Innovation and Universities, the Spanish Agency of Research (AEI) and the European Regional Development Funds (ERDF). </p>

scholarly journals Non-stationarity driven by long-term change in catchment storage: possibilities and implications

2015 ◽  
Vol 371 ◽  
pp. 7-12 ◽  
Author(s):  
J. D. Hughes ◽  
J. Vaze
Keyword(s):  
Predictive Performance ◽  
Lessons Learned ◽  
Significant Shift ◽  
Model Structure ◽  
Generation Process ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
The Past ◽  
Term Change

Abstract. "Non-stationarity" with reference to hydrology is a term applied to many situations (Milly et al., 2008). While climate change non-stationarity is often examined, these effects can provide a test for assumptions of runoff generation process impliedin rainfall–runoff (RR) models. Observations from South-western Australia (SWA) over the past 40 years show a decline in rainfall and reductions in runoff. Runoff and rainfall relationships in SWA show a significant shift over the past 40 years suggesting a change in runoff generation and catchment state. This has challenged the nature of assumed runoff generation process in SWA as well as the veracity of conceptual RR model structure. We expand on some of the lessons learned from SWA and discuss the climatic and geomorphic conditions that may make reasonable predictions of runoff very difficult with RR models calibrated in traditional ways. Catchment storage has a significant interaction with runoff generation and we examine the situations where these may change in the longer term. We suggest some strategies in terms of model structure and calibration that may improve predictive performance in such situations.

Watersheds may not recover from drought

Science ◽  
2021 ◽  
Vol 372 (6543) ◽  
pp. 745-749 ◽  
Author(s):  
Tim J. Peterson ◽  
M. Saft ◽  
M. C. Peel ◽  
A. John
Keyword(s):  
Natural Experiment ◽  
Southeastern Australia ◽  
Millennium Drought ◽  
Hydrological Droughts ◽  
Meteorological Droughts

The Millennium Drought (southeastern Australia) provided a natural experiment to challenge the assumption that watershed streamflow always recovers from drought. Seven years after the drought, the runoff (as a fraction of precipitation) had not recovered in 37% of watersheds, and the number of recovered watersheds was not increasing. When recovery did occur, it was not explained by watershed wetness. For those watersheds not recovered, ~80% showed no evidence of recovering soon, suggesting persistence within a low-runoff state. The post-drought precipitation not going to runoff was found to be likely going to increased evapotranspiration per unit of precipitation. These findings show that watersheds can have a finite resilience to disturbances and suggest that hydrological droughts can persist indefinitely after meteorological droughts.

scholarly journals Factors Associated with Acute Community-Acquired Pyelonephritis Caused by Extended-Spectrum β-Lactamase-Producing Escherichia coli

2021 ◽  
Vol 10 (21) ◽  
pp. 5192
Author(s):  
Mónica Romero Nieto ◽  
Sara Maestre Verdú ◽  
Vicente Gil ◽  
Carlos Pérez Barba ◽  
Jose Antonio Quesada Rico ◽  
...  
Keyword(s):  
Roc Curve ◽  
Goodness Of Fit ◽  
Logistic Models ◽  
Predictive Performance ◽  
Demographic Characteristics ◽  
E Coli ◽  
Factors Associated ◽  
Extended Spectrum ◽  
Male Sex ◽  
Tract Infections

This study aimed to identify the factors associated with the presence of extended-spectrum ß-lactamase-(ESBL) in patients with acute community-acquired pyelonephritis (APN) caused by Escherechia coli (E. coli), with a view of optimising empirical antibiotic therapy in this context. We performed a retrospective analysis of patients with community-acquired APN and confirmed E. coli infection, collecting data related to demographic characteristics, comorbidities, and treatment. The associations of these factors with the presence of ESBL were quantified by fitting multivariate logistic models. Goodness-of-fit and predictive performance were measured using the ROC curve. We included 367 patients of which 51 presented with ESBL, of whom 90.1% had uncomplicated APN, 56.1% were women aged ≤55 years, 33.5% had at least one mild comorbidity, and 12% had recently taken antibiotics. The prevalence of ESBL-producing E. coli was 13%. In the multivariate analysis, the factors independently associated with ESBL were male sex (OR 2.296; 95% CI 1.043–5.055), smoking (OR 4.846, 95% CI 2.376–9.882), hypertension (OR 3.342, 95% CI 1.423–7.852), urinary incontinence (OR 2.291, 95% CI 0.689–7.618) and recurrent urinary tract infections (OR 4.673, 95% CI 2.271–9.614). The area under the ROC curve was 0.802 (IC 95% 0.7307–0.8736), meaning our model can correctly classify an individual with ESBL-producing E. coli infection in 80.2% of cases.

scholarly journals Spatio-temporal modeling of surface runoff in ungauged sub-catchments of Subarnarekha river basin using SWAT

MAUSAM ◽  
2021 ◽  
Vol 72 (3) ◽  
pp. 597-606
Author(s):  
CHINMAYA PANDA ◽  
DWARIKA MOHAN DAS ◽  
B. C. SAHOO ◽  
B. PANIGRAHI ◽  
K. K. SINGH
Keyword(s):  
Surface Runoff ◽  
Assessment Tool ◽  
Nutrient Loss ◽  
Coefficient Of Determination ◽  
Annual Rainfall ◽  
Model Parameters ◽  
Runoff Generation ◽  
Temporal Modeling ◽  
Spatio Temporal ◽  
R Factors

In this present study, Soil and Water Assessment Tool (SWAT) embedded with ArcGIS interface has been used to simulate the surface runoff from the un-gauged sub-catchments in the upper catchment of Subarnarekha basin. Model calibration and validation were performed with the help of Sequential Uncertainty Fitting (SUFI-2) in-built in the SWAT-CUP package (SWAT Calibration Uncertainty Programs). The model was calibrated for a period from 1996 to 2008 with 3 years warm up period (1996-1998) and validated for a period of 5 years from 2009 to 2013. The model evaluation was performed by Nash - Sutcliffe coefficient (NSE), Coefficient of determination (R2) and Percentage Bias (PBIAS). The degree of uncertainty was evaluated by P and R factors. Basing upon the R2, NSE and PBIAS values respectively, of the order of 0.90, 0.90 and -12%, during calibration and 0.85, 0.83 and -15% during validation, substantiate performance of the model. All uncertainties of model parameters have been well taken by the P and R factors respectively, of the order of 0.95 and 0.77 during calibration and 0.82 and 0.87 during validation. The runoff generation from 19 sub-catchments of Adityapur catchment varies from 29.2-44.1% of the annual rainfall and average surface runoff simulated for the entire catchment is 545 mm. As the surface runoff generated in most of the sub-catchments amounts to above 30% of rainfall, it is recommended for adequate number of structural interventions at appropriate locations in the catchment to store the rainfall excess for providing irrigation, recharging groundwater and restricting the sediment and nutrient loss.

scholarly journals Probability distributions for explaining hydrological losses in South Australian catchments

2013 ◽  
Vol 10 (4) ◽  
pp. 4597-4626
Author(s):  
S. H. P. W. Gamage ◽  
G. A. Hewa ◽  
S. Beecham
Keyword(s):  
Goodness Of Fit ◽  
Probability Distributions ◽  
Joint Probability ◽  
Accurate Estimation ◽  
Rainfall Runoff ◽  
Design Flood ◽  
Wide Variability ◽  
Multiple Variables ◽  
Two Parameter ◽  
Non Parametric

Abstract. The wide variability of hydrological losses in catchments is due to multiple variables that affect the rainfall-runoff process. Accurate estimation of hydrological losses is required for making vital decisions in design applications that are based on design rainfall models and rainfall-runoff models. Using representative single values of losses, despite their wide variability, is common practice, especially in Australian studies. This practice leads to issues such as over or under estimation of design floods. Probability distributions can be used as a better representation of losses. In particular, using joint probability approaches (JPA), probability distributions can be incorporated into hydrological loss parameters in design models. However, lack of understanding of loss distributions limits the benefit of using JPA. The aim of this paper is to identify a probability distribution function that can successfully describe hydrological losses in South Australian (SA) catchments. This paper describes suitable parametric and non-parametric distributions that can successfully describe observed loss data. The goodness-of-fit of the fitted distributions and quantification of the errors associated with quantile estimation are also discussed a two-parameter Gamma distribution was identified as one that successfully described initial loss (IL) data of the selected catchments. Also, a non-parametric standardised distribution of losses that describes both IL and continuing loss (CL) data were identified. The results obtained for the non-parametric methods were compared with similar studies carried out in other parts of Australia and a remarkable degree of consistency was observed. The results will be helpful in improving design flood applications.

scholarly journals A Novel Objective Function DYNO for Automatic Multi-variable Calibration and Application to Assess Effects of Velocity versus Temperature Data for 3D Lake Models Calibration

2021 ◽  
Author(s):  
Wei Xia ◽  
Taimoor Akhtar ◽  
Christine A. Shoemaker
Keyword(s):  
Objective Function ◽  
Hydrodynamic Model ◽  
Model Calibration ◽  
Goodness Of Fit ◽  
Optimization Method ◽  
Parallel Optimization ◽  
Velocity Versus ◽  
Observation Data ◽  
Multiple Variables ◽  
Optimization Search

Abstract. This study introduced a novel Dynamically Normalized objective function (DYNO) for multi-variable (i.e., temperature and velocity) model calibration problems. DYNO combines the error metrics of multiple variables into a single objective function by dynamically normalizing each variable's error terms using information available during the search. DYNO is proposed to dynamically adjust the weight of the error of each variable hence balancing the calibration to each variable during optimization search. The DYNO is applied to calibrate a tropical hydrodynamic model where temperature and velocity observation data are used for model calibration simultaneously. We also investigated the efficiency of DYNO by comparing the result of using DYNO to results of calibrating to either temperature or velocity observation only. The result indicates that DYNO can balance the calibration in terms of water temperature and velocity and that calibrating to only one variable (e.g., temperature or velocity) cannot guarantee the goodness-of-fit of another variable (e.g., velocity or temperature). Our study suggested that both temperature and velocity measures should be used for hydrodynamic model calibration in real practice. Our example problems were computed with a parallel optimization method PODS but DYNO can also be easily used in serial applications.

scholarly journals Estimation of Rainfall-Runoff Relationship and Correlation of Runoff with Infiltration Capacity and Temperature Over East Singhbhum District of Jharkhand

2019 ◽  
Vol 9 (2) ◽  
pp. 461-466
Keyword(s):  
Land Surface ◽  
Pearson Correlation ◽  
Meteorological Parameter ◽  
Research Work ◽  
Soil Surface ◽  
Graphical Analysis ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Runoff ◽  
Infiltration Capacity

In meteorology, Precipitation is any product of the condensation of atmospheric water vapor that falls under the gravity, the rainfall being the principal form of precipitation in India. Rainfall is the most important meteorological parameter for hydrology, as it controls the other processes such as infiltration, runoff, detention storage, and evapotranspiration. When precipitation falls over a catchment area, these processes have to be satisfied before precipitation water becomes runoff. Infiltration is the vertically downward flow of rainfall into ground/underground through percolation inside the soil surface and depends on soil-type, porosity, and permeability. Runoff is the flow of rainwater over the land surface that happens when there is an excess of precipitation over an area. Runoff is produced when the rainwater exceeds the infiltration capacity of the soil. The most important relationships for any watershed are the relationship between rainfall and runoff. This relationship depends on some factors such as characteristics of rainfall, runoff, and infiltration. Though the abovementioned factors have a major impact on the volume of runoff, a consistent correlation between rainfall-runoff enables us to increase more confidence in sufficient time for the formulation of appropriate decision making for the local authority. The present research work was undertaken to analyze the correlation between annual rainfall and annual runoff for the years 1901-2018 over Jamshedpur of East Singhbhum district, Jharkhand. Further in this study, the correlation between infiltration and annual runoff was analyzed over the same area and the same data period. Correlation between temperature and annual runoff was also found. Through the graphical analysis, it was found that the value of annual rainfall and runoff are strongly correlated.As the value of the Pearson correlation coefficient (r) is almost equal to +1 which is a nearly perfect positive correlation, signifies that both variables move in the same direction. It also signifies that the two variables being compared have a perfect positive relationship; that means these two are strongly related. Through the study, it was also found that the infiltration and runoff are largely correlated. There was practically no correlation found between the values of temperature and runoff over the years.

Effects of Geological Structures on Rainfall-Runoff Processes in Headwater Catchments in a Sedimentary Rock Mountain

2021 ◽  
Author(s):  
Jun Inaoka ◽  
Ken'ichirou Kosugi ◽  
Naoya Masaoka ◽  
Tetsushi Itokazu ◽  
Kimihito Nakamura
Keyword(s):  
Sedimentary Rock ◽  
Flow Direction ◽  
Storm Runoff ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Geological Structures ◽  
Headwater Catchments ◽  
Average Flow ◽  
Bedding Planes ◽  
Hydraulic Anisotropy

<p>To clarify rainfall-runoff responses in mountainous areas is essential for disaster prediction as well as water resource management. Runoff is considered to be affected by many factors including evapotranspiration, rainfall, topography, geology, vegetation, and land use. Among them, topography is said to be the most affectable factor. However, previous studies focused on geologies revealed that though catchments in crystalline mountains have less differences among runoffs, catchments in sedimentary rock mountains show great variation in their runoffs. To explain this difference, the geological structures were expected to be the key of runoffs in sedimentary rock mountains. In other words, particularly in headwater catchments located in sedimentary rock mountains, dips and strikes may significantly affect rainwater discharge. Moreover, the groundwater system can significantly be affected by the hydraulic anisotropy originated from geological stratigraphy. Additionally, in sedimentary rock mountains, previous studies suggested convergence of groundwater flows in the direction of strikes, but the effects of dips and strikes on rainfall-runoff responses were not investigated. Furthermore, none of these previous studies focused on the effects of geological structures on storm runoff responses. Therefore, based on the simultaneous observation of twelve catchments that lie radially from a single, isolated mountain peak, this study aims to clarify the effects of dips and strikes, which characterize sedimentary rock mountains, on water discharge.</p><p>The results obtained were as follows: (1) Even though the topographic wetness index (TWI) distributions of the twelve catchments were similar, there were significant differences in their runoff characteristics; (2) Catchments with average flow direction oriented toward the strike direction (strike-oriented catchments) are characterized by large baseflows; (3) Catchments with average flow direction oriented toward the opposite dip direction (opposite dip-oriented catchments) are steep, and this results in quick storm runoff generation; (4) Catchments with average flow direction oriented toward the dip direction (dip-oriented catchments) are gentle, and this results in delayed storm runoff generation. It was supposed that in strike-oriented catchments, large quantities of groundwater flowing along the bedding planes owing to hydraulic anisotropy, exfiltrate and sustain the large amount of the observed baseflow, i.e., in strike-oriented catchments, runoff is directly controlled by geological structures. On the other hand, in opposite dip-oriented and dip-oriented catchments, runoff is indirectly controlled by geological structures, i.e., geological structures affect slope gradients, which result in differences in storm runoff generation. Thus, this study clearly explains that geological structures significantly affect rainfall-runoff responses in headwater catchments located in sedimentary rock mountains.</p>

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