scholarly journals Geostatistical regionalization of low-flow indices: PSBI and Top-Kriging

2010 ◽  
Vol 7 (5) ◽  
pp. 7231-7261 ◽  
Author(s):  
S. Castiglioni ◽  
A. Castellarin ◽  
A. Montanari ◽  
J. O. Skøien ◽  
G. Laaha ◽  
...  
Keyword(s):  
Spatial Interpolation ◽  
Central Italy ◽  
Low Flow ◽  
Flow Index ◽  
Ungauged Basins ◽  
Low Flows ◽  
Index Flood ◽  
Point Data ◽  
Leave One Out ◽  
Continuous Estimation

Abstract. Recent studies highlight that geostatistical interpolation, which has been originally developed for the spatial interpolation of point data, can be effectively applied to the problem of regionalization of hydrometric information. This study compares two innovative geostatistical approaches for the prediction of low-flows in ungauged basins. The first one, named Physiographic-Space Based Interpolation (PSBI), performs the spatial interpolation of the desired streamflow index (e.g., annual streamflow, low-flow index, flood quantile, etc.) in the space of catchment descriptors. The second technique, named Topological kriging or Top-Kriging, predicts the variable of interest along river networks taking both the area and nested nature of catchments into account. PSBI and Top-Kriging are applied for the regionalization of Q355 (i.e., the streamflow that is equalled or exceeded 355 days in a year, on average) over a broad geographical region in central Italy, which contains 51 gauged catchments. Both techniques are cross-validated through a leave-one-out procedure at all available gauges and applied to a subregion to produce a continuous estimation of Q355 along the river network extracted from a 90 m DEM. The results of the study show that Top-Kriging and PSBI present complementary features and have comparable performances (Nash-Sutcliffe efficiencies in cross-validation of 0.89 and 0.83, respectively). Both techniques provide plausible and accurate predictions of Q355 in ungauged basins and represent promising opportunities for regionalization of low-flows.

scholarly journals Smooth regional estimation of low-flow indices: physiographical space based interpolation and top-kriging

2011 ◽  
Vol 15 (3) ◽  
pp. 715-727 ◽  
Author(s):  
S. Castiglioni ◽  
A. Castellarin ◽  
A. Montanari ◽  
J. O. Skøien ◽  
G. Laaha ◽  
...  
Keyword(s):  
Spatial Interpolation ◽  
Central Italy ◽  
Low Flow ◽  
Flow Index ◽  
Ungauged Basins ◽  
Low Flows ◽  
Interpolation Techniques ◽  
Point Data ◽  
Leave One Out ◽  
Low Flow Index

Abstract. Recent studies highlight that spatial interpolation techniques of point data can be effectively applied to the problem of regionalization of hydrometric information. This study compares two innovative interpolation techniques for the prediction of low-flows in ungauged basins. The first one, named Physiographical-Space Based Interpolation (PSBI), performs the spatial interpolation of the desired streamflow index (e.g., annual streamflow, low-flow index, flood quantile, etc.) in the space of catchment descriptors. The second technique, named Topological kriging or Top-kriging, predicts the variable of interest along river networks taking both the area and nested nature of catchments into account. PSBI and Top-kriging are applied for the regionalization of Q355 (i.e., a low-flow index that indicates the streamflow that is equalled or exceeded 355 days in a year, on average) over a broad geographical region in central Italy, which contains 51 gauged catchments. The two techniques are cross-validated through a leave-one-out procedure at all available gauges and applied to a subregion to produce a continuous estimation of Q355 along the river network extracted from a 90m elevation model. The results of the study show that Top-kriging and PSBI present complementary features. Top-kriging outperforms PSBI at larger river branches while PSBI outperforms Top-kriging for headwater catchments. Overall, they have comparable performances (Nash-Sutcliffe efficiencies in cross-validation of 0.89 and 0.83, respectively). Both techniques provide plausible and accurate predictions of Q355 in ungauged basins and represent promising opportunities for regionalization of low-flows.

scholarly journals Hydrological characterization of watersheds in the Blue Nile Basin, Ethiopia

2011 ◽  
Vol 15 (1) ◽  
pp. 11-20 ◽  
Author(s):  
S. G. Gebrehiwot ◽  
U. Ilstedt ◽  
A. I. Gärdenas ◽  
K. Bishop
Keyword(s):  
Land Use ◽  
Soil Type ◽  
Low Flow ◽  
Flow Index ◽  
Nile Basin ◽  
Grazing Land ◽  
Blue Nile ◽  
Low Flows ◽  
Blue Nile Basin ◽  
Low Flow Index

Abstract. Thirty-two watersheds (31–4350 km2), in the Blue Nile Basin, Ethiopia, were hydrologically characterized with data from a study of water and land resources by the US Department of Interior, Bureau of Reclamation (USBR) published in 1964. The USBR document contains data on flow, topography, geology, soil type, and land use for the period 1959 to 1963. The aim of the study was to identify watershed variables best explaining the variation in the hydrological regime, with a special focus on low flows. Moreover, this study aimed to identify variables that may be susceptible to management policies for developing and securing water resources in dry periods. Principal Component Analysis (PCA) and Partial Least Square (PLS) were used to analyze the relationship between five hydrologic response variables (total flow, high flow, low flow, runoff coefficient, low flow index) and 30 potential explanatory watershed variables. The explanatory watershed variables were classified into three groups: land use, climate and topography as well as geology and soil type. Each of the three groups had almost equal influence on the variation in hydrologic variables (R2 values ranging from 0.3 to 0.4). Specific variables from within each of the three groups of explanatory variables were better in explaining the variation. Low flow and low flow index were positively correlated to land use types woodland, dense wet forest and savannah grassland, whereas grazing land and bush land were negatively correlated. We concluded that extra care for preserving low flow should be taken on tuffs/basalts which comprise 52% of the Blue Nile Basin. Land use management plans should recognize that woodland, dense wet forest and savannah grassland can promote higher low flows, while grazing land diminishes low flows.

scholarly journals Análise de Componente do Regime Hidrológico da Bacia do Rio Amazonas em Anos de Eventos Climáticos

2019 ◽  
Vol 12 (3) ◽  
pp. 988
Author(s):  
Rogério Souza Aguiar ◽  
Edson José Paulino da Rocha ◽  
José Augusto de Souza Junior ◽  
Joyse Tatiane Souza dos Santos ◽  
Josiane Sarmento Dos Santos
Keyword(s):  
Flow Rate ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Low Flow ◽  
Amazon River ◽  
Low Flows ◽  
La Nina ◽  
Basin Scale ◽  
Historical Series

As cheias e vazantes do rio Amazonas passaram a ser mais persistentes ao longo dos anos. Este estudo busca analisara influência da variabilidade temporal em escala de bacia hidrográfica sobre o regime do rio Amazonas, a partir das vazões da estação hidrológica da Agência Nacional de Águas – ANA, localizada em Óbidos, no Estado do Pará em uma série histórica de janeiro/1970 a dezembro/2013. Além do tempo, o estudo analisou a intensidade do El Niño e La Niña. Como esperado, o tempo influenciou na vazão média interanual encontrada de 98.723 m3/s para os 44 anos da série analisada. Porém com variabilidade anual do regime do rio Amazonas de intensas proporções temporais, com a vazão variando de ordem de 72.380 m3/s (como em 1997) no regime de vazante até uma ordem de 131.620 m3/s (como em 1974) no regime de cheia. Também foi identificado que fenômenos de El Niño e La Niña modularam eventos climáticos extremos sobre as vazões da Bacia Amazônica em cada ano. A análise interanual mostrou que os anos de baixas vazões, possuíam a característica de persistência de ocorrência em relação às altas vazões. A partir de 1989, houve um aumento em relação à amplitude média da vazão de 87.727 m3/s devido a fortes níveis mínimos registrados. Ao analisar a vazão normalizada percebeu-se que na maioria dos anos de baixa vazão foram também anos do fenômeno El Niño. Constatado esta persistência de baixas vazões, investigaram-se os fatores de armazenamento e disponibilidade do rio Amazonas.   Analysis of Hydrological Regime Componentof the Amazonas River Basin in Years of Climate Events. ABSTRACTThe floods and drains of the Amazon River have become more persistent over the years. This study seeks to analyze the influence of the temporal variability in the basin scale on the Amazon river regime, from the flows of the hydrological station of the National Water Agency - ANA, located in Óbidos, State of Pará, in a historical series from January/1970 to December /2013. Besides time, the study analyzed the intensity of El Niño and La Niña. As expected, time influenced the annual interannual flow rate of 98,723 m3/s for the 44 years of the analyzed series. However, with an annual variability of the Amazon river regime of intense flows, with an increase of 72,380 m3/s (as in 1997) in the effluent regime up to an order of 131,620 m3/s (as in 1974) in the flood regime. It was also identified that El Niño and La Niña phenomena modulated extreme climatic events on the Amazon Basin flows each year. The year-on-year analysis showed that the years of low flows had a persistence of occurrence in relation to high flows. As of 1989, there was an increase in relation to the average flow amplitude of 87,727 m3/s due to the strong minimum levels recorded. Analyzing the normalized flow rate, it was observed that in most of the years of low flow there were also years of the El Niño phenomenon. Considering this persistence of low flows, we investigated the storage and availability factors of the Amazon River.Keywords: Time flows. Ecological Maintenance.Amazonriver. 

scholarly journals Multiple causes of nonstationarity in the Weihe annual low-flow series

2018 ◽  
Vol 22 (2) ◽  
pp. 1525-1542 ◽  
Author(s):  
Bin Xiong ◽  
Lihua Xiong ◽  
Jie Chen ◽  
Chong-Yu Xu ◽  
Lingqi Li
Keyword(s):  
Frequency Analysis ◽  
Driving Forces ◽  
Potential Evapotranspiration ◽  
Aridity Index ◽  
Base Flow ◽  
Low Flow ◽  
Distribution Model ◽  
Flow Index ◽  
Explanatory Variables ◽  
Distribution Parameters

Abstract. Under the background of global climate change and local anthropogenic activities, multiple driving forces have introduced various nonstationary components into low-flow series. This has led to a high demand on low-flow frequency analysis that considers nonstationary conditions for modeling. In this study, through a nonstationary frequency analysis framework with the generalized linear model (GLM) to consider time-varying distribution parameters, the multiple explanatory variables were incorporated to explain the variation in low-flow distribution parameters. These variables are comprised of the three indices of human activities (HAs; i.e., population, POP; irrigation area, IAR; and gross domestic product, GDP) and the eight measuring indices of the climate and catchment conditions (i.e., total precipitation P, mean frequency of precipitation events λ, temperature T, potential evapotranspiration (EP), climate aridity index AIEP, base-flow index (BFI), recession constant K and the recession-related aridity index AIK). This framework was applied to model the annual minimum flow series of both Huaxian and Xianyang gauging stations in the Weihe River, China (also known as the Wei He River). The results from stepwise regression for the optimal explanatory variables show that the variables related to irrigation, recession, temperature and precipitation play an important role in modeling. Specifically, analysis of annual minimum 30-day flow in Huaxian shows that the nonstationary distribution model with any one of all explanatory variables is better than the one without explanatory variables, the nonstationary gamma distribution model with four optimal variables is the best model and AIK is of the highest relative importance among these four variables, followed by IAR, BFI and AIEP. We conclude that the incorporation of multiple indices related to low-flow generation permits tracing various driving forces. The established link in nonstationary analysis will be beneficial to analyze future occurrences of low-flow extremes in similar areas.

Low flow frequency analysis for stream with mixed populations

2015 ◽  
Vol 42 (8) ◽  
pp. 503-509 ◽  
Author(s):  
Mike Hulley ◽  
Colin Clarke ◽  
Ed Watt
Keyword(s):  
Frequency Analysis ◽  
Worked Examples ◽  
Low Flow ◽  
Flow Estimation ◽  
Low Flows ◽  
Record Length ◽  
Mixed Populations ◽  
Flow Frequency ◽  
Recommendations For Assessment

A methodology is developed for the estimation of annual low-flow quantiles for streams with annual low flows occurring in both the summer and winter. Since the low flow generating processes are different in summer and winter, independent seasonal analyses are required. The methodology provides recommendations for assessment of record length, randomness, homogeneity, independence and stationarity, as well as guidelines for distribution selection and fitting for seasonal distributions. The seasonal distributions are then used to develop the combined distribution for annual low flow estimation. Four worked examples of long-term Canadian hydrometric stations are provided.

scholarly journals Contrasting Differences in Responses of Streamflow Regimes between Reforestation and Fruit Tree Planting in a Subtropical Watershed of China

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 212 ◽  
Author(s):  
Zhipeng Xu ◽  
Wenfei Liu ◽  
Xiaohua Wei ◽  
Houbao Fan ◽  
Yizao Ge ◽  
...  
Keyword(s):  
Flow Regime ◽  
Fruit Tree ◽  
High Flow ◽  
Tree Planting ◽  
Low Flow ◽  
Jiangxi Province ◽  
Negative Effects ◽  
Flow Duration ◽  
Low Flows ◽  
High Flows

Fruit tree planting is a common practice for alleviating poverty and restoring degraded environment in developing countries. Yet, its environmental effects are rarely assessed. The Jiujushui watershed (261.4 km2), located in the subtropical Jiangxi Province of China, was selected to assess responses of several flow regime components on both reforestation and fruit tree planting. Three periods of forest changes, including a reference (1961 to 1985), reforestation (1986 to 2000) and fruit tree planting (2001 to 2016) were identified for assessment. Results suggest that the reforestation significantly decreased the average magnitude of high flow by 8.78%, and shortened high flow duration by 2.2 days compared with the reference. In contrast, fruit tree planting significantly increased the average magnitude of high flow by 27.43%. For low flows, reforestation significantly increased the average magnitude by 46.38%, and shortened low flow duration by 8.8 days, while the fruit tree planting had no significant impact on any flow regime components of low flows. We conclude that reforestation had positive impacts on high and low flows, while to our surprise, fruit tree planting had negative effects on high flows, suggesting that large areas of fruit tree planting may potentially become an important driver for some negative hydrological effects in our study area.

scholarly journals Changing Low Flow and Streamflow Drought Seasonality in Central European Headwaters

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3575
Author(s):  
Vojtech Vlach ◽  
Ondrej Ledvinka ◽  
Milada Matouskova
Keyword(s):  
Kendall Test ◽  
R Package ◽  
Low Flow ◽  
Headwater Catchments ◽  
Low Flows ◽  
Seasonality Index ◽  
Apparent Shift ◽  
Summer Minimum ◽  
Increasing Temperature

In the context of the ongoing climate warming in Europe, the seasonality and magnitudes of low flows and streamflow droughts are expected to change in the future. Increasing temperature and evaporation rates, stagnating precipitation amounts and decreasing snow cover will probably further intensify the summer streamflow deficits. This study analyzed the long-term variability and seasonality of low flows and streamflow droughts in fifteen headwater catchments of three regions within Central Europe. To quantify the changes in the low flow regime of selected catchments during the 1968–2019 period, we applied the R package lfstat for computing the seasonality ratio (SR), the seasonality index (SI), mean annual minima, as well as for the detection of streamflow drought events along with deficit volumes. Trend analysis of summer minimum discharges was performed using the Mann–Kendall test. Our results showed a substantial increase in the proportion of summer low flows during the analyzed period, accompanied with an apparent shift in the average date of low flow occurrence towards the start of the year. The most pronounced seasonality shifts were found predominantly in catchments with the mean altitude 800–1000 m.a.s.l. in all study regions. In contrast, the regime of low flows in catchments with terrain above 1000 m.a.s.l. remained nearly stable throughout the 1968–2019 period. Moreover, the analysis of mean summer minimum discharges indicated a much-diversified pattern in behavior of long-term trends than it might have been expected. The findings of this study may help identify the potentially most vulnerable near-natural headwater catchments facing worsening summer water scarcity.

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