Showing papers on "Streamflow published in 2000"
TL;DR: In this article, the authors provide a review of the nature and variability of the climate and hydrology in the source region of the Blue Nile-the central Ethiopian Highlands, and provide a time series of annual rainfall constructed from 11 gauges for the period 1900 to 1998.
Abstract: The Upper Blue Nile river basin is the largest in Ethiopia in terms of volume of discharge, second largest in terms of area, and contributes over 50 per cent of the long-term river flow of the Main Nile. This paper provides a review of the nature and variability of the climate and hydrology in the source region of the Blue Nile-the central Ethiopian Highlands. Annual rainfall over the basin decreases from the south-west (>2000 mm) to the north-east (around 1000 mm), with about 70 per cent occurring between June and September. A basin-wide time series of annual rainfall constructed from 11 gauges for the period 1900 to 1998 has a mean of 1421millimetres, minimum in 1913 (1148 mm) and maximum in 1903 (1757 mm). Rainfall over the basin showed a marked decrease between the mid-1960s and the late 1980s and dry years show a degree of association with low values of the Southern Oscillation Index (Sol). The October to February dry season in 1997/98 was the wettest on record and responsible for widespread flooding across Ethiopia and also parts of Somalia and Kenya. Available river flow records, which are sparse and of limited duration, are presented for the Blue Nile and its tributaries upstream of the border with Sudan. Runoff over the basin amounts to 45.9 cubic kilometres (equivalent to 1456 m3s−1) discharge, or 261 millimetre depth (1961–1990), a runoff ratio of 18 per cent. Between 1900 and 1997 annual river flow has ranged from 20.6 cubic kilometres (1913) to 79.0 cubic kilometres (1909), and the lowest decade-mean flow was 37.9 cubic kilometres from 1978 to 1987. Annual river flow, like rainfall, shows a strong association with the SOI
395 citations
TL;DR: In this article, artificial neural networks (ANNs) have been used to model watershed runoff in three basins with different climatic and physiographic characteristics (the Fraser River in Colorado, Raccoon Creek in Iowa, and Little Patuxent River in Maryland).
Abstract: Inspired by the functioning of the brain and biological nervous systems, artificial neural networks (ANNs) have been applied to various hydrologic problems in the last 10 years. In this study, ANN models are compared with traditional conceptual models in predicting watershed runoff as a function of rainfall, snow water equivalent, and temperature. The ANN technique was applied to model watershed runoff in three basins with different climatic and physiographic characteristics—the Fraser River in Colorado, Raccoon Creek in Iowa, and Little Patuxent River in Maryland. In the Fraser River watershed, the ANN technique was applied to model monthly streamflow and was compared to a conceptual water balance (Watbal) model. The ANN technique was used to model the daily rainfall-runoff process and was compared to the Sacramento soil moisture accounting (SAC-SMA) model in the Raccoon River watershed. The daily rainfall-runoff process was also modeled using the ANN technique in the Little Patuxent River basin, and the...
326 citations
TL;DR: In this paper, the authors found that changes in streamflow of the Tigris and the Euphrates Rivers are associated with the North Atlantic Oscillation (NAO), a large-scale mode of natural climate variability which governs the path of Atlantic mid-latitude storm tracks and precipitation in the eastern Mediterranean.
Abstract: Changes in streamflow of the Tigris and the Euphrates Rivers are shown to be associated with the North Atlantic Oscillation (NAO), a large-scale mode of natural climate variability which governs the path of Atlantic mid-latitude storm tracks and precipitation in the eastern Mediterranean. Composite indices of Turkish winter (December‐March, DJFM) temperature and precipitation are developed which capture the interannual‐decadal climate variability for the Tigris‐Euphrates headwater region, a significant source of freshwater for Turkey, Syria and Iraq. These indices are significantly correlated with the NAO, with 27% of the variance in precipitation accounted for by this natural mechanism. As evidenced by the recent widespread drought events of 1984, 1989 and 1990, the Tigris‐Euphrates streamflow also exhibits significant, 940% variability, associated with extrema. Copyright © 2000 Royal Meteorological Society.
323 citations
TL;DR: The Soil and Water Assessment Tool (SWAT) was evaluated and parameter sensitivities were determined while modeling daily streamflows in a small central Kentucky watershed over a two-year period as mentioned in this paper.
Abstract: The Soil and Water Assessment Tool (SWAT) was evaluated and parameter sensitivities were determined while
modeling daily streamflows in a small central Kentucky watershed over a two-year period. Streamflow data from 1996
were used to calibrate the model and streamflow data from 1995 were used for evaluation. The model adequately
predicted the trends in daily streamflow during this period although Nash-Sutcliffe R 2 values were –0.04 and 0.19 for
1995 and 1996, respectively. The model poorly predicted the timing of some peak flow values and recession rates during
the last half of 1995. Excluding daily peak flow values from August to December improved the daily R 2 to 0.15, which was
similar to the 1996 daily R 2 value. The Nash-Sutcliffe R 2 for monthly total flows were 0.58 for 1995 and 0.89 for 1996
which were similar to values found in the literature. Since very little information was available on the sensitivity of the
SWAT model to various inputs, a sensitivity analysis/calibration procedure was designed to evaluate parameters that were
thought to influence stream discharge predictions. These parameters included, drainage area, slope length, channel
length, saturated hydraulic conductivity, and available water capacity. Minimization of the average absolute deviation
between observed and simulated streamflows identified optimum values/ranges for each parameter. Saturated hydraulic
conductivity, alpha baseflow factor, drainage area, channel length, and channel width were the most sensitive parameters
in modeling the karst influenced watershed. The sensitivity analysis process confirmed die trace studies in the karst
watershed that a much larger area contributes to streamflow than can be described by the topographic boundaries.
Overall, the results indicate that the SWAT model can be an effective tool for describing monthly runoff from small
watersheds in central Kentucky that have developed on karst hydrology however calibration data are necessary to
account for solution channels draining into or out of the topographic watershed.
319 citations
TL;DR: In this article, the forecasting power of neural network (NN) and autoregressive moving average (ARMA) models are compared based on 3-year continuous river flow data for two contrasting catchments: the Upper River Wye and the River Ouse.
Abstract: The forecasting power of neural network (NN) and autoregressive moving average (ARMA) models are compared. Modelling experiments were based on a 3-year period of continuous river flow data for two contrasting catchments: the Upper River Wye and the River Ouse. Model performance was assessed using global and storm-specific quantitative evaluation procedures. The NN and ARMA solutions provided similar results, although naive predictions yielded poorer estimates. The annual data were then grouped into a set of distinct hydrological event types using a self-organizing map and two rising event clusters were modelled using the NN technique. These alternative investigations provided encouraging results. Copyright © 2000 John Wiley & Sons, Ltd.
253 citations
TL;DR: In this paper, the potential impacts of climate change on the mid-Atlantic coastal (MAC) region of the United States are assessed. And the authors suggest that policies designed to minimize adverse ecological impacts of human activities on coastal ecosystems in the mid Atlantic, such as decreases in nutrient loading of watersheds, could help mitigate some of the risks associated with future climate variability and change in this region.
Abstract: This paper assesses the potential impacts of climate change on the mid-Atlantic coastal (MAC) region of the United States. In order of increasing uncertainty, it is projected that sea level, tem- perature and streamflow will increase in the MAC region in response to higher levels of atmospheric CO2. A case study for Delaware based on digital elevation models suggests that, by the end of the 21st century, 1.6% of its land area and 21% of its wetlands will be lost to an encroaching sea. Sea-level rise will also result in higher storm surges, causing 100 yr floods to occur 3 or 4 times more frequently by the end of the 21st century. Increased accretion in coastal wetlands, however, which may occur in response to increases in CO2, temperature, and streamflow, could mitigate some of the flooding effect of sea-level rise. Warming alone will result in northward displacements of some mobile estuarine spe- cies and will exacerbate the already low summer oxygen levels in mid-Atlantic estuaries because of increased oxygen demand and decreased oxygen solubility. Streamflow increases could substantially degrade water quality, with significant negative consequences for submerged aquatic vegetation and birds. Though climate change may have some positive impacts on the MAC region, such as increased coastal tourism due to warming and some ecological benefits from less-frequent harsh winters, most impacts are expected to be negative. Policies designed to minimize adverse ecological impacts of human activities on coastal ecosystems in the mid-Atlantic, such as decreases in nutrient loading of watersheds, could help mitigate some of the risks associated with future climate variability and change in this region.
247 citations
TL;DR: In this article, an analysis of the hydrological effects of vegetation changes in the Columbia River basin over the last century was performed using two land cover scenarios, c. 1900, as estimated by the federal Interior Columbia Basin Ecosystem Management Project (ICBEMP).
Abstract: An analysis of the hydrological effects of vegetation changes in the Columbia River basin over the last century was performed using two land cover scenarios. The first was a reconstruction of historical land cover vegetation, c. 1900, as estimated by the federal Interior Columbia Basin Ecosystem Management Project (ICBEMP). The second was current land cover as estimated from remote sensing data for 1990. Simulations were performed using the variable infiltration capacity (VIC) hydrological model, applied at one-quarter degree spatial resolution (approximately 500 km2 grid cell area) using hydrometeorological data for a 10 year period starting in 1979, and the 1900 and current vegetation scenarios. The model represents surface hydrological fluxes and state variables, including snow accumulation and ablation, evapotranspiration, soil moisture and runoff production. Simulated daily hydrographs of naturalized streamflow (reservoir effects removed) were aggregated to monthly totals and compared for nine selected sub-basins. The results show that, hydrologically, the most important vegetation-related change has been a general tendency towards decreased vegetation maturity in the forested areas of the basin. This general trend represents a balance between the effects of logging and fire suppression. In those areas where forest maturity has been reduced as a result of logging, wintertime maximum snow accumulations, and hence snow available for runoff during the spring melt season, have tended to increase, and evapotranspiration has decreased. The reverse has occurred in areas where fire suppression has tended to increase vegetation maturity, although the logging effect appears to dominate for most of the sub-basins evaluated. Predicted streamflow changes were largest in the Mica and Corralin sub-basins in the northern and eastern headwaters region; in the Priest Rapids sub-basin, which drains the east slopes of the Cascade Mountains; and in the Ice Harbor sub-basin, which receives flows primarily from the Salmon and Clearwater Rivers of Idaho and western Montana. For these sub-basins, annual average increases in runoff ranged from 4·2 to 10·7% and decreases in evapotranspiration ranged from 3·1 to 12·1%. In comparison with previous studies of individual, smaller sized watersheds, the modelling approach used in this study provides predictions of hydrological fluxes that are spatially continuous throughout the interior Columbia River basin. It thus provides a broad-scale framework for assessing the vulnerability of watersheds to altered streamflow regimes attributable to changes in land cover that occur over large geographical areas and long time-frames. Copyright © 2000 John Wiley & Sons, Ltd.
230 citations
TL;DR: The Magdalena river discharge and sediment load are strongly coupled to the El Nino-La Nina cycle as discussed by the authors, with high discharge occurring during La Nina phase and low discharge during El-Nino phase Cross-spectral analysis between discharge and the Southern Oscillation Index (SOI) indicates an average recurrence interval of 30 years with a coherence, Y 2 =090, and that the discharge anomaly is in phase with the SOI anomaly.
216 citations
TL;DR: In this article, a two-way interface to WATFLOOD, a distributed hydrologic model developed at the University of Waterloo, was designed to improve the representation of the soil water balance in order to simulate, more properly, exchanges with the atmosphere.
Abstract: Second generation land surface schemes are the subject of much development activity among atmospheric modellers. This work is aimed at, among other things, improving the representation of the soil water balance in order to simulate, more properly, exchanges with the atmosphere and to permit the use of model output to generate streamflow for model validation. The Canadian development program is centred on CLASS, the Canadian Land Surface Scheme, developed at Environment Canada. This paper focuses on the improvement of hydrology in CLASS. This was accomplished by designing a two‐way interface to WATFLOOD, a distributed hydrologic model developed at the University of Waterloo. The two models share many features, which facilitated the coupling procedure. The interface retains the three‐layer vertical moisture budget representation in CLASS but adds three horizontal runoff possibilities. Runoff from the surface water follows Manning's equation for overland flow. Interflow is generated from the near‐su...
136 citations
TL;DR: In this article, the authors analyzed possible changes in streamflow associated with logging in 23 western Washington catchments with drainage areas from 14 to 1600 km2 and found that statistically significant trends in annual streamflow minima are all decreasing and are apparently dominated by a regional climate signal associated with the Pacific Decadal Oscillation, rather than land cover change.
Abstract: Possible changes in streamflow associated with logging were analyzed for 23 western Washington catchments with drainage areas from 14 to 1600 km2. Statistically significant trends in annual streamflow minima, uncorrected for climatic influences, are all decreasing and are apparently dominated by a regional climate signal associated with the Pacific Decadal Oscillation, rather than land cover change. Using paired catchment analysis, the number of statistically significant trends detected for the peak flow series is largely within the range of statistical noise. Only in the case of the annual minima were more trends detected than could be attributed to chance, owing in part to the lower relative variability, hence greater detectability of trends in low flows. Investigation of the effect of return period on peak flow changes shows an apparent increase in flood peaks for treatment relative to control catchments, the mean magnitude of which decreases with increasing return interval up to about the 10-year return period. In large part, owing to the small number of catchment pairs available, this analysis cannot be considered conclusive. An alternative approach to evaluating trends in peak flows based on time series residuals of observed flows from hydrology model predictions detected increasing trends in peak flow series, which were largely absent in the paired catchment analysis. This is attributed both to the ability of the model, which acts as the control, to filter out natural variability and to a larger trend “signal” in the residuals analysis resulting from the ability of the method to fix the vegetation condition in the model control.
135 citations
TL;DR: In this article, the impact of water repellency on overland flow and runoff generation at plot and catchment scales for two types of terrain with differing land management and degree of soil hydrophobicity was assessed using the Water Drop Penetration Time (WDPT) test.
TL;DR: The sensitivity of hydrology and water resources to climate variation and climate change is assessed for the Mid-Atlantic Region (MAR) of the United States in this paper, where projections of future streamflow, groundwater, and water quality are made using models determined from these associa- tions and are applied to 2 transient general circulation model (GCM) scenarios.
Abstract: The sensitivity of hydrology and water resources to climate variation and climate change is assessed for the Mid-Atlantic Region (MAR) of the United States. Observed streamflow, groundwa- ter, and water-quality data are shown to vary in association with climate variation. Projections of future streamflow, groundwater, and water quality are made using models determined from these associa- tions and are applied to 2 transient general circulation model (GCM) scenarios. Regional streamflow increases in one scenario, but decreases in the other; both scenarios result in changes in the seasonal- ity of peak flows. Response of groundwater to climate change depends on the GCM scenario used. Canadian Climate Center (CCC) scenarios suggest recharge will occur earlier in the year, and that sea- sonal fluctuations in groundwater levels will be less extreme. Hadley Center scenarios suggest recharge will occur earlier in the medium term, but later in the long term, with seasonal fluctuations in general being more extreme. Both scenarios show that nutrient loads can be expected to increase in winter and spring because of the expected increase in streamflow. Projected decreases in streamflow and associated nutrient fluxes in July and August could ameliorate problems associated with estuarine stratification and eutrophication in late summer. These projections demonstrate that future hydrology and water resources will be influenced by climate change, but that uncertainty in accurately projecting that influence will continue until model scenarios improve.
TL;DR: In this article, the authors studied the relationship between rainfall and mist in the upper Severn River (Afon Hafren and Afon Hore catchments), Plynlimon, mid-Wales.
Abstract: . Variations in sodium and chloride in atmospheric inputs (rainfall and mist), stream runoff and groundwater stores are documented for the upper Severn River (Afon Hafren and Afon Hore catchments), Plynlimon, mid-Wales. The results show five salient features. Sodium and chloride concentrations are highly variable and highly correlated in rainfall and mist. The sodium-chloride relationship in rainfall has a slope close to the sodium/chloride ratio in sea-water, and an intercept that is not significantly different from zero. This indicates that sea-salt is the dominant source of both sodium and chloride in rainfall, which would be expected given the maritime nature of the metrology. For mist, there is also a straight line with near-zero intercept, but with a slightly higher gradient than the sea-salt ratio, presumably due to small additional sodium inputs from other sources. There is an approximate input-output balance for both sodium and chloride, with the exception of one groundwater well, in which high chemical weathering results in an anomalous high Na/Cl ratio. Thus, atmospheric deposition is the dominant source of both sodium and chloride in groundwater and streamflow. The fluctuations in sodium and chloride concentrations in the streams and groundwaters are strongly damped compared to those in the rain and the mist, reflecting the storage and mixing of waters in the subsurface. On all timescales, from weeks to years, sodium fluctuations are more strongly damped than chloride fluctuations in streamflow. The additional damping of sodium is consistent with ion exchange buffering of sodium in the catchment soils. Sodium and chloride concentrations are linearly correlated in the streams and groundwaters, but the slope is almost universally less than the sea-salt ratio and there is a non-zero intercept. The Na/Cl ratio in streamflow and groundwater is higher than the sea-salt ratio when salinity is low and lower than the sea-salt ratio when salinity is high. This pattern of behaviour is again consistent with ion exchange buffering of sodium in the catchment soils. The core features of this study are two fold. Firstly, sodium and chloride concentrations are highly damped within the streams and groundwaters relative to the atmospheric input. Secondly, streamflow sodium and chloride respond in similar ways across the catchments, except for the added cation exchange damping of the sodium signal. These findings are remarkable given the heterogeneous nature of the catchments and the complexity of the chemical time series signals in the streams. Keywords: Sodium; chloride; rainfall; mist; stream water; groundwater; Plynlimon; Hafren; Hore; Tanllwyth; moorland; Sitka spruce; forest; cation exchange; fractal
TL;DR: In this paper, two and three-component hydrograph separation analyses and correlation analyses were performed for six basins to provide insight into streamflow generation during snowmelt and to assess basin sensitivity to acidic deposition.
Abstract: Alpine/subalpine ecosystems in Rocky Mountain National Park may be sensitive to atmospherically derived acidic deposition. Two- and three-component hydrograph separation analyses and correlation analyses were performed for six basins to provide insight into streamflow generation during snowmelt and to assess basin sensitivity to acidic deposition. Three-component hydrograph separation results for five basins showed that streamflow contained from 42 to 57% direct snowmelt runoff, 37 to 54% subsurface water, and 4 to 13% direct rain runoff for the May through October 1994 study period. Subsurface contributions were 89% of total flow for the sixth basin. The reliability of hydrograph separation model assumptions was explored. Subsurface flow was positively correlated with the amount of surficial material in a basin and was negatively correlated with basin slope. Basins with extensive surficial material and shallow slopes are less susceptible to ecosystem changes due to acidic deposition than basins with less surficial material and steeper slopes. This study was initiated to expand the intensive hydrologic research that has been conducted in Loch Vale basin to a more regional scale.
TL;DR: In this paper, several strategies are proposed to reduce the vulnerability of the Canadian Prairies to future droughts, where surface water is the primary water supply and agriculture is the major water user: (1) Continue implementing small-scalewater resources projects and increase water storage through snowmanagement, (2) increase integration between existing water resources systems, and (3) promote water conservation measures in agriculture practice, water pricing and water metering.
Abstract: Past and the present studies show that the Canadian Prairies havebecome warmer and may have been drier in the last four to five decadesbut the drying trends are scattered and inconclusive.Statistical analysis shows that only the Winter and Fall (insome instances) precipitation is marginally related to ENSO andthe PNA (Pacific North Americ) Index, and streamflow is highlyvariable. With uncertainties on the potential impact of climaticchange and other uncertainties, several strategies are proposedto reduce the vulnerability of the Prairies to future droughts,where surface water is the primary water supply and agricultureis the major water user: (1) Continue implementing small-scalewater resources projects and increase water storage through snowmanagement, (2) increase integration between existing waterresources systems, and (3) promote water conservation measuresin agriculture practice, water pricing and water metering.
01 Jan 2000
TL;DR: In this paper, a water balance was computed using 10 years of data collected at the Upper Sheep Creek Watershed, a 26-ha semi-arid mountainous sub-basin within the Reynolds Creek Experimental Watershed in southwest Idaho, USA.
TL;DR: In this paper, the effects of gridcell size on surface runoff modeling using a distributed hydrologic model were examined in two watersheds in northern Mississippian watersheds using a raster-based hydrological CASC2D model.
Abstract: The effects of grid-cell size on surface runoff modeling using a distributed hydrologic model are examined. The raster-based hydrologic CASC2D model is applied to two watersheds in northern Mississ...
TL;DR: In this paper, sediment rating curves have been calculated and used to estimate the evolution of the sediment load from the Rhone River to Lake Geneva, showing that sediment input has decreased by at least a factor 2.
Abstract: During this century, the characteristics of the Upper Rhone River discharge, flowing into Lake Geneva, have been altered in response to the changes which have occurred in its watershed. Principally, numerous hydroelectric dams have been constructed on the course of the Rhone River tributaries. At present the major reservoirs can hold about 1220106m3 of water, which represents 1/5 of the total annual Rhone River flow. Flow regime characteristics of the river have been modified by the dam operations. Water is released from reservoirs during winter and stored in summer. Large floods have also been reduced in amplitude and frequency. From the available literature data, sediment rating curves have been calculated and used to estimate the evolution of the sediment load from the Rhone River to Lake Geneva. They show that sediment input has decreased by at least a factor 2. This reduction has impacted the occurrence of underflows along the lake bottom, due to the reduction of sediment-laden floods, which in turn may have considerable negative effects on the reoxygenation of Lake Geneva deep waters.
TL;DR: In this article, a statistical analysis of historical streamflow, climate, and population data for 39 urbanizing and 21 nearby rural basins in four regions of the United States was used to estimate the future effects of climate change and urbanization on mean annual streamflow.
Abstract: Estimates of the impacts of climate change on streamflow generally have not included concurrent effects of urbanization. A statistical analysis of historical streamflow, climate, and population data for 39 urbanizing and 21 nearby rural basins in four regions of the United States was used to estimate the future effects of climate change and urbanization on mean annual streamflow. Basins were located generally at lower elevations where streamflow was dominated by rainfall rather than snowmelt. Rural basins showed predicted average changes in mean annual streamflow ranging between +24 and −49% for the specific climate change scenarios tested (precipitation changes −20 to +20%, temperature changes 0°C to +4°C). Urbanization increased mean annual streamflow in rough proportion to average cumulative changes in population density on the basins, equivalent to an average flow increase of 103% with complete watershed urbanization. Urbanization also appeared to reduce the sensitivity of mean annual streamflow to temperature changes compared to mean flow response on rural basins. No significant regional differences in mean flow response to climate change and urbanization were found. Despite the uncertainty in predicting future streamflow with models based upon past records, urbanization appears potentially capable of significantly offsetting flow declines or augmenting flow increases caused by climate change.
TL;DR: In this paper, the effects of forest disturbance on streamflow from small (<10 km 2 ) basins have been well documented; however, implications of such disturbance for stream flow from relatively large rivers in the Canadian boreal forest are unclear.
Abstract: The effects of forest disturbance on streamflow from small (<10 km 2 ) basins have been well documented; however, implications of such disturbance for streamflow from relatively large rivers in the Canadian boreal forest are unclear. Landsat imagery was used to determine changes in the type, amount, and location of forest disturbance in northeastern Ontario between 1985 and 1990. These were compared with streamflow responses from medium- and large-scale basins in the region. Harvesting dominated forest disturbance, and total disturbance as of 1990 ranged from 25% of basin area in the northwest part of the region to 5% in the southeast. There was limited streamflow response to land cover changes, with no definitive changes in water year runoff or peak flow magnitude and timing. This likely re- flects the ability of relatively large basins to buffer the hydrologic impacts of the small degree of recent forest distur - bance, combined with the influence of climatic variability on temporal trends in basin streamflow. However, disturbance was associated with increases in moderate and low flows from medium and large basins, respectively, which occurred largely during summer months.
TL;DR: In this article, a physically based distributed hydrologic model was developed for flood inundation simulation combining newly developed overland and channel network flow simulation models with evapotranspiration, unsaturated zone and saturated zone models.
Abstract: A physically based distributed hydrologic model is developed in this study for flood inundation simulation combining newly developed overland and channel network flow simulation models with evapotranspiration, unsaturated zone and saturated zone models. The overland flow and river flow models are validated individually with test data, and then coupled with other models. The model can take fine resolution spatial data as input preserving spatial heterogeneity of physical characteristics of a river basin. River embankments play an important role in flood prevention. The model can incorporate river embankment data in flood inundation simulation. The model is applied in a river catchment in Japan to simulate a flood event in 1996. Outputs from the model show good agreements with observed flood hydrographs and surveyed flood inundation. Copyright © 2000 John Wiley & Sons, Ltd.
TL;DR: In this paper, a fuzzy multi-objective function (FMOF) was proposed to improve the performance of conventional objective functions, such as the root mean square error (RMSE) and the mean absolute percent error (MPE).
TL;DR: In this paper, the authors investigated stormflow generation on an event basis in a first-order rainforest catchment to establish a causal link between soil physical and precipitation characteristics, hillslope flowpaths and stormflow hydrograph attributes.
Abstract: The Amazon basin covers an area of roughly 7 × 106 km2 and encompasses diverse soil – landscape types with potentially differing hydrological behaviour This study was conducted in the Ultisol landscape of the western Amazon basin in Peru Processes of stormflow generation were investigated on an event basis in a first-order rainforest catchment to establish a causal link between soil physical and precipitation characteristics, hillslope flowpaths and stormflow hydrograph attributes A sharp decrease in soil hydraulic conductivity with depth and high rainfall intensity and frequency favour rapid near-surface flowpaths, mainly in the form of saturation-excess overland flow and return flow The latter results in an almost random occurrence of overland flow, with no obvious topographic control Hillslope flowpaths do not vary much with respect to the hydrograph attributes time of rise, response time, lag time and centroid lag time They have the same response time as streamflow, but a somewhat lower time of rise and significantly shorter lag times The recession constant for hillslope hydrographs is about 10 min, in contrast to the streamflow recession constants of 28, 75 and 149 min Stormflow generation in this Ultisol rainforest catchment differs strongly from that reported for Oxisol rainforest catchments These two soilscapes may define a spectrum of possible catchment hydrological behaviour in the Amazon basin Copyright © 2000 John Wiley & Sons, Ltd
TL;DR: In this paper, a study of the hydrological effects of clearing a catchment covered by native, dry sclerophyl eucalypt forest, and replanting it with a Pinus radiata plantation was undertaken.
TL;DR: In this article, the potential impacts of climate change on water yield in the Upper Wind River Basin were examined in a high-elevation, mountain basin with a snowfall/snowmelt dominated stream-flow hydrograph.
Abstract: The potential impacts of climate change on water yield are examined in the Upper Wind River Basin. This is a high-elevation, mountain basin with a snowfall/snowmelt dominated stream-flow hydrograph. A variety of physiographic conditions are represented in the rangeland, coniferous forests, and high-elevation alpine regions. The Soil Water Assessment Tool (SWAT) is used to model the baseline input time series data and climate change scenarios. Five hydroclimatic variables (temperature, precipitation, CO2, radiation, and humidity) are examined using sensitivity tests of individual and coupled variables with a constant change and coupled variables with a monthly change. Results indicate that the most influential variable on annual water yield is precipitation; and, the most influential variable on the timing of streamflow is temperature. Carbon dioxide, radiation, and humidity each noticeably impact water yield, but less significantly. The coupled variable analyses represent a more realistic climate change regime and reflect the combined response of the basin to each variable; for example, increased temperature offsets the effects of increased precipitation and magnifies the effects of decreased precipitation. This paper shows that the hydrologic response to climate change depends largely on the hydroclimatic variables examined and that each variable has a unique effect (e.g., magnitude, timing) on water yield.
TL;DR: The La Plata and Loiza reservoirs, the principal water supply of the San Juan metropolitan area, was at or below the 10th flow percentile for 27% to 50% of the time between December 1993 and May 1996 as mentioned in this paper.
Abstract: During the period from 1990 to 1997, annual rainfall accumulation averaged 87% of normal at the 12 stations with the longest period of record in Puerto Rico, a Caribbean island with a 1999 population of 3.8 million. Streamflow in rivers supplying the La Plata and Loiza reservoirs, the principal water supply of the San Juan metropolitan area, was at or below the 10th flow percentile for 27% to 50% of the time between December 1993 and May 1996. Diminished reservoir levels in 1994 and 1995 affected more than 1 million people in the San Juan metropolitan area. Water rationing was implemented during this period and significant agricultural losses, valued at $165 million, were recorded in 1994. The public endured a year of mandatory water rationing in which sections of the city had their water-distribution networks shut off for 24 to 36 hours on alternate days. During the winter and spring of 1997–1998, water was rationed to more than 200,000 people in northwestern Puerto Rico because water level in the Guajat...
TL;DR: A hydrological model (SLURP) that was designed for simulating hydrologogical processes taking place in large river basins was used successfully to simulate water level variations over a 28-year period (1969-1996) for a 3-ha prairie wetland in Saskatchewan as mentioned in this paper.
Abstract: A hydrological model (SLURP) that was designed for simulating hydrological processes taking place in large river basins was, with minimal modification, used successfully to simulate water level variations over a 28-year period (1969–1996) for a 3-ha prairie wetland in Saskatchewan.
The model calculates a water balance based on precipitation, snowmelt, evaporation, surface runoff and subsurface flow on a daily time-step. The model was first calibrated for two periods (1969–1973 for cropland and 1987–1990 for grassland), then it was applied to records outside the calibration periods. The model reproduced the wetland water level variations during a 28-year period with good accuracy. The wetland water levels were most sensitive to the infiltration coefficient of surface soil under frozen conditions and to maximum soil moisture storage. The applicability of the model and the calibrated parameters to a smaller wetland, with an area of 0·24 ha, was examined. This simulation indicated that scale effects are important, probably largely in relation to snow redistribution by wind. Copyright © 2000 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors examined how the use and management of water resources and waste-water inputs affect the stream flow and its biological quality in a Mediterranean stream, the Congost (NE Spain), and concluded that in Mediterranean streams, even using biological plants, may be insufficient for the recovery of stream communities due to the lack of natural flow related to the climate and the high demand of the water resources.
TL;DR: In this paper, a parsimonious approach for generating continuous daily stream-flow time-series from observed daily rainfall data in a catchment is described, which is used to convert the daily rainfall information from source rain gauges into a continuous daily hydrograph at the destination river site.
Abstract: The paper describes a parsimonious approach for generating continuous daily stream-flow time-series from observed daily rainfall data in a catchment. The key characteristic in the method is a duration curve. It is used to convert the daily rainfall information from source rain gauges into a continuous daily hydrograph at the destination river site. For each source rain gauge a time-series of rainfall related ‘current precipitation index’ is generated and its duration curve is established. The current precipitation index reflects the current catchment wetness and is defined as a continuous function of precipitation, which accumulates on rainy days and exponentially decays during the periods of no rainfall. The process of rainfall-to-runoff conversion is based on the assumption that daily current precipitation index values at rainfall site(s) in a catchment and the destination site's daily flows correspond to similar probabilities on their respective duration curves. The method is tested in several small catchments in South Africa. The method is designed primarily for application at ungauged sites in data-poor regions where the use of more complex and information consuming techniques of data generation may not be justified. Copyright © 2000 John Wiley & Sons, Ltd.