Open AccessArticle
Climate Change and Its Impacts on Water Resources in the Bandama Basin, Côte D’ivoire
Hydrology 2017, 4(1), 18; doi:10.3390/hydrology4010018 -
Abstract
This study aims to assess future trends in monthly rainfall and temperature and its impacts on surface and groundwater resources in the Bandama basin. The Bandama river is one of the four major rivers of Côte d’Ivoire. Historical data from 14 meteorological and
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This study aims to assess future trends in monthly rainfall and temperature and its impacts on surface and groundwater resources in the Bandama basin. The Bandama river is one of the four major rivers of Côte d’Ivoire. Historical data from 14 meteorological and three hydrological stations were used. Simulation results for future climate from HadGEM2-ES model under representative concentration pathway (RCP) 4.5 and RCP 8.5 scenarios indicate that the annual temperature may increase from 1.2 °C to 3 °C. These increases will be greater in the north than in the south of the basin. The monthly rainfall may decrease from December to April in the future. During this period, it is projected to decrease by 3% to 42% at all horizons under RCP 4.5 and by 5% to 47% under RCP 8.5. These variations will have cause an increase in surface and groundwater resources during the three periods (2006–2035; 2041–2060; 2066–2085) under the RCP 4.5 scenario. On the other side, these water resources may decrease for all horizons under RCP 8.5 in the Bandama basin. Full article
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Open AccessArticle
Hydrological Modelling Using a Rainfall Simulator over an Experimental Hillslope Plot
Hydrology 2017, 4(1), 17; doi:10.3390/hydrology4010017 -
Abstract
Hydrological processes are complex to compute in hilly areas when compared to plain areas. The governing processes behind runoff generation on hillslopes are subsurface storm flow, saturation excess flow, overland flow, return flow and pipe storage. The simulations of the above processes in
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Hydrological processes are complex to compute in hilly areas when compared to plain areas. The governing processes behind runoff generation on hillslopes are subsurface storm flow, saturation excess flow, overland flow, return flow and pipe storage. The simulations of the above processes in the soil matrix require detailed hillslope hydrological modelling. In the present study, a hillslope experimental plot has been designed to study the runoff generation processes on the plot scale. The setup is designed keeping in view the natural hillslope conditions prevailing in the Northwestern Himalayas, India where high intensity rainfall events occur frequently. A rainfall simulator was installed over the experimental hillslope plot to generate rainfall with an intensity of 100 mm/h, which represents the dominating rainfall intensity range in the region. Soil moisture sensors were also installed at variable depths from 100 to 1000 mm at different locations of the plot to observe the soil moisture regime. From the experimental observations it was found that once the soil is saturated, it remains at field capacity for the next 24–36 h. Such antecedent moisture conditions are most favorable for the generation of rapid stormflow from hillslopes. A dye infiltration test was performed on the undisturbed soil column to observe the macropore fraction variability over the vegetated hillslopes. The estimated macropore fractions are used as essential input for the hillslope hydrological model. The main objective of the present study was to develop and test a method for estimating runoff responses from natural rainfall over hillslopes of the Northwestern Himalayas using a portable rainfall simulator. Using the experimental data and the developed conceptual model, the overland flow and the subsurface flow through a macropore-dominated area have been estimated/analyzed. The surface and subsurface runoff estimated using the developed hillslope hydrological model compared well with the observed surface runoff for a rainfall intensity of 100 mm/h. The surface runoff hydrograph was very well predicted by the model, with correlation coefficient (R2) and Nash–Sutcliffe efficiency coefficient (E) as 0.95 and 0.91, respectively. The observed soil/macropore storage component was estimated with the help of water balance equation and compared with the model predicted macropore storage. The error in computing the soil/macropore storage was estimated as 0.38 mm i.e., 13%. Full article
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Open AccessArticle
Hydrological Modeling and Runoff Mitigation in an Ungauged Basin of Central Vietnam Using SWAT Model
Hydrology 2017, 4(1), 16; doi:10.3390/hydrology4010016 -
Abstract
The A-Luoi district in Thua Thien Hue province of Vietnam is under extreme pressure from natural and anthropogenic factors. The area is ungauged and suffering from data scarcity. To evaluate the water resources availability and water management, we used Soil and Water Assessment
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The A-Luoi district in Thua Thien Hue province of Vietnam is under extreme pressure from natural and anthropogenic factors. The area is ungauged and suffering from data scarcity. To evaluate the water resources availability and water management, we used Soil and Water Assessment Tools (SWAT). A multi-approach technique was used to calibrate the hydrological model. The model was calibrated in three time scales: daily, monthly and yearly by river discharge, actual evapotranspiration (ETa) and crop yield, respectively. The model was calibrated with Nash-Sutcliffe and R2 coefficients greater than 0.7, in daily and monthly scales, respectively. In the yearly scale, the crop yield inside the model was calibrated and validated with Root Mean Square Error (RMSE) less than 2.4 ton/ha. The water resource components were mapped temporally and spatially. The outcomes showed that the highest mean monthly surface runoff, 323 to 369 mm, between September and November, resulted in extreme soil erosion and sedimentation. The monthly average of actual evapotranspiration was the highest in May and lowest in December. Furthermore, installing “Best Management Practices” (BMPs) reduced surface runoff in agricultural lands. However, using event-based hydrological and hydraulic models in the prediction and simulation of flooding events is recommended in further studies. Full article
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Open AccessFeature PaperArticle
Catchment Hydrology during Winter and Spring and the Link to Soil Erosion: A Case Study in Norway
Hydrology 2017, 4(1), 15; doi:10.3390/hydrology4010015 -
Abstract
In the Nordic countries, soil erosion rates in winter and early spring can exceed those at other times of the year. In particular, snowmelt, combined with rain and soil frost, leads to severe soil erosion, even, e.g., in low risk areas in Norway.
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In the Nordic countries, soil erosion rates in winter and early spring can exceed those at other times of the year. In particular, snowmelt, combined with rain and soil frost, leads to severe soil erosion, even, e.g., in low risk areas in Norway. In southern Norway, previous attempts to predict soil erosion during winter and spring have not been very accurate owing to a lack of catchment-based data, resulting in a poor understanding of hydrological processes during winter. Therefore, a field study was carried out over three consecutive winters (2013, 2014 and 2015) to gather relevant data. In parallel, the development of the snow cover, soil temperature and ice content during these three winters was simulated with the Simultaneous Heat and Water (SHAW) model for two different soils (sand, clay). The field observations carried out in winter revealed high complexity and diversity in the hydrological processes occurring in the catchment. Major soil erosion was caused by a small rain event on frozen ground before snow cover was established, while snowmelt played no significant role in terms of soil erosion in the study period. Four factors that determine the extent of runoff and erosion were of particular importance: (1) soil water content at freezing; (2) whether soil is frozen or unfrozen at a particular moment; (3) the state of the snow pack; and (4) tillage practices prior to winter. SHAW performed well in this application and proved that it is a valuable tool for investigating and simulating snow cover development, soil temperature and extent of freezing in soil profiles. Full article
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Open AccessArticle
Change in Future Rainfall Characteristics in the Mekrou Catchment (Benin), from an Ensemble of 3 RCMs (MPI-REMO, DMI-HIRHAM5 and SMHI-RCA4)
Hydrology 2017, 4(1), 14; doi:10.3390/hydrology4010014 -
Abstract
This study analyzes the impact of climate change on several characteristics of rainfall in the Mekrou catchment for the twenty-first century. To this end, a multi-model ensemble based on regional climate model experiments considering two Representative Concentration Pathways (RCP4.5 and RCP8.5) is used.
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This study analyzes the impact of climate change on several characteristics of rainfall in the Mekrou catchment for the twenty-first century. To this end, a multi-model ensemble based on regional climate model experiments considering two Representative Concentration Pathways (RCP4.5 and RCP8.5) is used. The results indicate a wider range of precipitation uncertainty (roughly between −10% and 10%), a decrease in the number of wet days (about 10%), an increase (about 10%) of the total intensity of precipitation for very wet days, and changes in the length of the dry spell period, as well as the onset and end of the rainy season. The maximum rainfall amounts of consecutive 24 h, 48 h and 72 h will experience increases of about 50% of the reference period. This change in rate compared to the reference period may cause an exacerbation of extreme events (droughts and floods) in the Mekrou basin, especially at the end of the century and under the RCP8.5 scenario. To cope with the challenges posed by the projected climate change for the Mekrou watershed, strong governmental policies are needed to help design response options. Full article
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Open AccessArticle
Evaluating Global Reanalysis Datasets as Input for Hydrological Modelling in the Sudano-Sahel Region
Hydrology 2017, 4(1), 13; doi:10.3390/hydrology4010013 -
Abstract
This paper investigates the potential of using global reanalysis datasets as input for hydrological modelling in the data-scarce Sudano-Sahel region. To achieve this, we used two global atmospheric reanalyses (Climate Forecasting System Reanalysis and European Center for Medium-Range Weather Forecasts (ECMWF) ERA-Interim) datasets
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This paper investigates the potential of using global reanalysis datasets as input for hydrological modelling in the data-scarce Sudano-Sahel region. To achieve this, we used two global atmospheric reanalyses (Climate Forecasting System Reanalysis and European Center for Medium-Range Weather Forecasts (ECMWF) ERA-Interim) datasets and one global meteorological forcing dataset WATCH Forcing Data methodology applied to ERA-Interim (WFDEI). These datasets were used to drive the Soil and Water Assessment Tool (SWAT) in the Logone catchment in the Lake Chad basin. Model performance indicators after calibration showed that, at daily and monthly time steps, only WFDEI produced Nash Sutcliff Efficiency (NSE) and Coefficient of Determination (R2) values above 0.50. Despite a general underperformance compared to WFDEI, CFSR performed better than the ERA-Interim. Model uncertainty analysis after calibration showed that more than 60% of all daily and monthly observed streamflow values at all hydrometric stations were bracketed within the 95 percent prediction uncertainty (95PPU) range for all datasets. Results from this study also show significant differences in simulated actual evapotranspiration estimates from the datasets. Overall results showed that biased corrected WFDEI outperformed the two reanalysis datasets; meanwhile CFSR performed better than the ERA-Interim. We conclude that, in the absence of gauged hydro-meteorological data, WFDEI and CFSR could be used for hydrological modelling in data-scarce areas such as the Sudano-Sahel region. Full article
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Open AccessArticle
Radioactive Seepage through Groundwater Flow from the Uranium Mines, Namibia
Hydrology 2017, 4(1), 11; doi:10.3390/hydrology4010011 -
Abstract
The study focused on the seepage of uranium from unlined tailing dams into the alluvial aquifer in the Gawib River floodplain in Namibia where the region solely relies on groundwater for its economic activities as a result of arid climatic condition. The study
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The study focused on the seepage of uranium from unlined tailing dams into the alluvial aquifer in the Gawib River floodplain in Namibia where the region solely relies on groundwater for its economic activities as a result of arid climatic condition. The study reviewed previous works besides water sample collection and analyses for major ions, metals and environmental isotopes in addition to field tests on physico-chemical parameters (pH, Electrical Conductivity, Redox and T). Estimation of seepage velocity (true velocity of groundwater flow) has been conducted in order to understand the extent of radioactive plume transport. The hydrochemistry, stable isotopes and tritium results show that there is uranium contamination from the unlined uranium tailings in the Gawib shallow aquifer system which suggests high permeability of the alluvial aquifer facilitating groundwater flow in the arid region. The radioactive contaminants could spread into the deeper aquifer system through the major structures such as joints and faults. The contamination plume could also spread downstream into the Swakop River unless serious interventions are employed. There is also a very high risk of the plume to reach the Atlantic Ocean through seasonal flash floods that occurs in the area. Full article
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Open AccessArticle
Estimating the Effect of Urban Growth on Annual Runoff Volume Using GIS in the Erbil Sub-Basin of the Kurdistan Region of Iraq
Hydrology 2017, 4(1), 12; doi:10.3390/hydrology4010012 -
Abstract
The growth and spread of impervious surfaces within urbanizing catchment areas pose signiificant threats to the quality of natural and built-up environments. Impervious surfaces prevent water infiltration into the soil, resulting in increased runoff generation. The Erbil Sub-basin was selected because the impervious
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The growth and spread of impervious surfaces within urbanizing catchment areas pose signiificant threats to the quality of natural and built-up environments. Impervious surfaces prevent water infiltration into the soil, resulting in increased runoff generation. The Erbil Sub-basin was selected because the impervious cover is increasing rapidly and is affecting the hydrological condition of the watershed. The overall aim of this study is to examine the impact of urban growth and other changes in land use on runoff response during the study period of 1984 to 2014. The study describes long-term hydrologic responses within the rapidly developing catchment area of Erbil city, in the Kurdistan Region of Iraq. Data from six rainfall stations in and around the Erbil Sub-basin were used. A Digital Elevation Model (DEM) was also used to extract the distribution of the drainage network. Historical levels of urban growth and the corresponding impervious areas, as well as land use/land cover changes were mapped from 1984 to 2014 using a temporal satellite image (Landsat) to determine land use/land cover changes. Land use/land cover was combined with a hydrological model (SCS-CN) to estimate the volume of runoff from the watershed. The study indicates that the urbanization of the watershed has increased the impervious land cover by 71% for the period from 1984 to 2004 and by 51% from 2004 to 2014. The volume of runoff was 85% higher in 2014 as compared to 1984 due to the increase in the impervious surface area; this is attributed to urban growth. The study also points out that the slope of the watershed in the Erbil sub-basin should be taken into account in surface runoff estimation as the upstream part of the watershed has a high gradient and the land is almost barren with very little vegetation cover; this causes an increase in the velocity of the flow and increases the risk of flooding in Erbil city. Full article
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Open AccessArticle
Highlighting the Role of Groundwater in Lake– Aquifer Interaction to Reduce Vulnerability and Enhance Resilience to Climate Change
Hydrology 2017, 4(1), 10; doi:10.3390/hydrology4010010 -
Abstract
method is presented to analyze the interaction between groundwater and Lake Linlithgow (Australia) as a case study. A simplistic approach based on a “node” representing the groundwater component is employed in a spreadsheet of water balance modeling to analyze and highlight the effect
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method is presented to analyze the interaction between groundwater and Lake Linlithgow (Australia) as a case study. A simplistic approach based on a “node” representing the groundwater component is employed in a spreadsheet of water balance modeling to analyze and highlight the effect of groundwater on the lake level over time. A comparison is made between the simulated and observed lake levels over a period of time by switching the groundwater “node “on and off. A bucket model is assumed to represent the lake behaviour. Although this study demonstrates the understanding of Lake Linlithgow’s groundwater system, the current model reflects the contemporary understanding of the local groundwater system, illustrates how to go about modeling in data-scarce environments, and provides a means to assess focal areas for future data collection and model improvements. Results show that this approach is convenient for getting first‐hand information on the effect of groundwater on wetland or lake levels through lake water budget computation via a node representing the groundwater component. The method can be used anywhere and the applicability of such a method is useful to put in place relevant adaptation mechanisms for future water resources management, reducing vulnerability and enhancing resilience to climate change within the lake basin. Full article
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Open AccessArticle
Application of HEC-HMS in a Cold Region Watershed and Use of RADARSAT-2 Soil Moisture in Initializing the Model
Hydrology 2017, 4(1), 9; doi:10.3390/hydrology4010009 -
Abstract
This paper presents an assessment of the applicability of using RADARSAT-2-derived soil moisture data in the Hydrologic Modelling System developed by the Hydrologic Engineering Center (HEC-HMS) for flood forecasting with a case study in the Sturgeon Creek watershed in Manitoba, Canada. Spring flooding
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This paper presents an assessment of the applicability of using RADARSAT-2-derived soil moisture data in the Hydrologic Modelling System developed by the Hydrologic Engineering Center (HEC-HMS) for flood forecasting with a case study in the Sturgeon Creek watershed in Manitoba, Canada. Spring flooding in Manitoba is generally influenced by both winter precipitation and soil moisture conditions in the fall of the previous year. As a result, the soil moisture accounting (SMA) and the temperature index algorithms are employed in the simulation. Results from event and continuous simulations of HEC-HMS show that the model is suitable for flood forecasting in Manitoba. Soil moisture data from the Manitoba Agriculture field survey and RADARSAT-2 satellite were used to set the initial soil moisture for the event simulations. The results confirm the benefit of using satellite data in capturing peak flows in a snowmelt event. A sensitivity analysis of SMA parameters, such as soil storage, maximum infiltration, soil percolation, maximum canopy storage and tension storage, was performed and ranked to determine which parameters have a significant impact on the performance of the model. The results show that the soil moisture storage was the most sensitive parameter. The sensitivity analysis of initial soil moisture in a snowmelt event shows that cumulative flow and peak flow are highly influenced by the initial soil moisture setting of the model. Therefore, there is a potential to utilize RADARSAT-2-derived soil moisture for hydrological modelling in other snow-dominated Manitoba watersheds. Full article
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Open AccessArticle
Exact and Approximate Solutions of Fractional Partial Differential Equations for Water Movement in Soils
Hydrology 2017, 4(1), 8; doi:10.3390/hydrology4010008 -
Abstract
This paper presents solutions of the fractional partial differential equation (fPDE) for analysing water movement in soils. The fPDE explains processes equivalent to the concept of symmetrical fractional derivatives (SFDs) which have two components: the forward fractional derivative (FFD) and backward fractional derivative
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This paper presents solutions of the fractional partial differential equation (fPDE) for analysing water movement in soils. The fPDE explains processes equivalent to the concept of symmetrical fractional derivatives (SFDs) which have two components: the forward fractional derivative (FFD) and backward fractional derivative (BFD) of water movement in soils with the BFD representing the micro-scale backwater effect in porous media. The distributed-order time-space fPDE represents water movement in both swelling and non-swelling soils with mobile and immobile zones with the backwater effect operating at two time scales in large and small pores. The concept of flux-concentration relation is now updated to account for the relative fractional flux of water movement in soils. Full article
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Open AccessArticle
A Multi-Faceted Debris-Flood Hazard Assessment for Cougar Creek, Alberta, Canada
Hydrology 2017, 4(1), 7; doi:10.3390/hydrology4010007 -
Abstract
A destructive debris flood occurred between 19 and 21 June 2013 on Cougar Creek, located in Canmore, Alberta. Cougar Creek fan is likely the most densely developed alluvial fan in Canada. While no lives were lost, the event resulted in approximately $40 M
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A destructive debris flood occurred between 19 and 21 June 2013 on Cougar Creek, located in Canmore, Alberta. Cougar Creek fan is likely the most densely developed alluvial fan in Canada. While no lives were lost, the event resulted in approximately $40 M of damage and closed both the Trans-Canada Highway (Highway 1) and the Canadian Pacific Railway line for a period of several days. The debris flood triggered a comprehensive hazard assessment which is the focus of this paper. Debris-flood frequencies and magnitudes are determined by combining several quantitative methods including photogrammetry, dendrochronology, radiometric dating, test pit logging, empirical relationships between rainfall volumes and sediment volumes, and landslide dam outburst flood modeling. The data analysis suggests that three distinct process types act in the watershed. The most frequent process is normal or “clearwater” floods. Less frequent but more damaging are debris floods during which excessive amounts of bedload are transported on the fan, typically associated with rapid and extensive bank erosion and channel infilling and widening. The third and most destructive process is interpreted to be landslide dam outbreak floods. This event type is estimated to occur at return periods exceeding 300 years. Using a cumulative magnitude frequency technique, the data for conventional debris floods were plotted up to the 100–300s year return period. A peak-over-threshold approach was used for landslide dam outbreak floods occurring at return periods exceeding 300 years, as not all such events were identified during test trenching. Hydrographs for 6 return period classes were approximated by using the estimated peak discharges and fitting the hydrograph shape to integrate to the debris flood volumes as determined from the frequency-magnitude relationship. The fan volume was calculated and compared with the integrated frequency-magnitude curve to check of the validity of the latter. A reasonable match was accomplished, verifying the overall relationship. The findings from this work were later used as input to a risk assessment seeking to quantify risk to loss of life and economic losses. The risk assessment then formed the basis for design of debris-flood mitigation structures. Full article
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Open AccessArticle
Revisiting Cent-Fonts Fluviokarst Hydrological Properties with Conservative Temperature Approximation
Hydrology 2017, 4(1), 6; doi:10.3390/hydrology4010006 -
Abstract
We assess the errors produced by considering temperature as a conservative tracer in fluviokarst studies. Heat transfer that occurs between karstic Conduit System (CS) and Porous Fractured Matrix (PFM) is the reason why one should be careful in making this assumption without caution.
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We assess the errors produced by considering temperature as a conservative tracer in fluviokarst studies. Heat transfer that occurs between karstic Conduit System (CS) and Porous Fractured Matrix (PFM) is the reason why one should be careful in making this assumption without caution. We consider the karstic aquifer as an Open Thermodynamic System (OTS), which boundaries are permeable to thermal energy and water. The first principle of thermodynamics allows considering the enthalpy balance between the input and output flows. Combined with a continuity equation this leads to a two-equation system involving flows and temperatures. Steady conditions are approached during the recession period or during particular phases of pumping test experiments. After a theoretical study of the error induced by the conservative assumption in karst, we have applied the method to revisit the data collected during a complete campaign of pumping test. The method, restricted to selected data allowed retrieving values of base flow, mixing of flow, intrusions of streams, and aquifer answer to drawdown. The applicability of the method has been assessed in terms of propagation of the temporal fluctuations trough the solving but also in terms of conservative assumption itself. Our results allow retrieving the main hydrological properties of the karst as observed on field (timed volumetric samplings, geochemical analyses, step pumping test and allogenic intrusion of streams). This consistency argues in favor of the applicability of the conservative temperature method to investigating fluviokarst systems under controlled conditions. Full article
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Open AccessArticle
Spatial and Temporal Variability of Potential Evaporation across North American Forests
Hydrology 2017, 4(1), 5; doi:10.3390/hydrology4010005 -
Abstract
Given the widespread ecological implications that would accompany any significant change in evaporative demand of the atmosphere, this study investigated spatial and temporal variation in several accepted expressions of potential evaporation (PE). The study focussed on forest regions of North America, with 1
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Given the widespread ecological implications that would accompany any significant change in evaporative demand of the atmosphere, this study investigated spatial and temporal variation in several accepted expressions of potential evaporation (PE). The study focussed on forest regions of North America, with 1 km-resolution spatial coverage and a monthly time step, from 1951–2014. We considered Penman’s model (EPen), the Priestley–Taylor model (EPT), ‘reference’ rates based on the Penman–Monteith model for grasslands (ERG), and reference rates for forests that are moderately coupled (ERFu) and well coupled (ERFc) to the atmosphere. To give context to the models, we also considered a statistical fit (EPanFit) to measurements of pan evaporation (EPan). We documented how each model compared with EPan, differences in attribution of variance in PE to specific driving factors, mean spatial patterns, and time trends from 1951–2014. The models did not agree strongly on the sensitivity to underlying drivers, zonal variation of PE, or on the magnitude of trends from 1951–2014. Sensitivity to vapour pressure deficit (Da) differed among models, being absent from EPT and strongest in ERFc. Time trends in reference rates derived from the Penman–Monteith equation were highly sensitive to how aerodynamic conductance was set. To the extent that EPanFit accurately reflects the sensitivity of PE to Da over land surfaces, future trends in PE based on the Priestley–Taylor model may underestimate increasing evaporative demand, while reference rates for forests, that assume strong canopy-atmosphere coupling in the Penman–Monteith model, may overestimate increasing evaporative demand. The resulting historical database, covering the spectrum of different models of PE applied in modern studies, can serve to further investigate biosphere-hydroclimate relationships across North America. Full article
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Open AccessEditorial
Acknowledgement to Reviewers of Hydrology in 2016
Hydrology 2017, 4(1), 4; doi:10.3390/hydrology4010004 -
Abstract The editors of Hydrology would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article
Open AccessArticle
Influence of Crust Formation on Soil Porosity under Tillage Systems and Simulated Rainfall
Hydrology 2017, 4(1), 3; doi:10.3390/hydrology4010003 -
Abstract
Surface crusts, formed by raindrop impact, degrade the soil surface structure causing changes in porosity. An experiment was conducted with the objective of evaluating the influence of the formation of a crusting layer on the porosity (percentage of area, shape and size) of
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Surface crusts, formed by raindrop impact, degrade the soil surface structure causing changes in porosity. An experiment was conducted with the objective of evaluating the influence of the formation of a crusting layer on the porosity (percentage of area, shape and size) of a Haplic Acrisol under three tillage systems, and simulated rainfall. The tillage systems were: conventional tillage (CT), reduced tillage (RT) and no-tillage (NT). Each tillage system was submitted to different levels of simulated rainfall (0, 27, 54 and 80 mm) at an intensity of 80 mm·h−1. Undisturbed soil samples were collected and resin impregnated for image analysis in two layers: layer 1 (0–1 cm) and layer 2 (1–2 cm). Image analysis was used to obtain the pore area percentage, pore shape and size. The degradation of the soil surface and change in porosity, caused by rainfall, occurred differently in the tillage systems. In the CT and RT systems, the most pronounced pore changes caused by rainfall occurred in layer 1, but in the NT system, this change occurred in layer 2. The rainfall caused change of pore area percentage in the CT and RT systems, with reduction of complex and an increase of rounded pores. The NT system showed greater occurrence of the rounded pores (vesicles), originated by processes of wetting below the residue cover, and by alternating periods of wetting and drying. In this study, the changes in porosity were attributed to two main factors: (1) to the effect of the raindrop directly on the soil surface (for CT and RT tillage systems) and (2) water transfer processes in the soil surface (for NT systems). Full article
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Open AccessArticle
Land Use and Land Cover Changes under Climate Uncertainty: Modelling the Impacts on Hydropower Production in Western Africa
Hydrology 2017, 4(1), 2; doi:10.3390/hydrology4010002 -
Abstract
The Bui hydropower plant plays a vital role in the socio-economic development of Ghana. This paper attempt to explore the combined effects of climate-land use land cover change on power production using the (WEAP) model: Water Evaluation and Planning system. The historical analysis
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The Bui hydropower plant plays a vital role in the socio-economic development of Ghana. This paper attempt to explore the combined effects of climate-land use land cover change on power production using the (WEAP) model: Water Evaluation and Planning system. The historical analysis of rainfall and stream flow variability showed that the annual coefficient of variation of rainfall and stream flow are, respectively, 8.6% and 60.85%. The stream flow varied greatly than the rainfall, due to land use land cover changes (LULC). In fact, the LULC analysis revealed important changes in vegetative areas and water bodies. The WEAP model evaluation showed that combined effects of LULC and climate change reduce water availability for all of demand sectors, including hydropower generation at the Bui hydropower plant. However, it was projected that Bui power production will increase by 40.7% and 24.93%, respectively, under wet and adaptation conditions, and decrease by 46% and 2.5%, respectively, under dry and current conditions. The wet condition is defined as an increase in rainfall by 14%, the dry condition as the decrease in rainfall by 15%; current account is business as usual, and the adaptation is as the efficient use of water for the period 2012–2040. Full article
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Open AccessArticle
Provision of Desalinated Irrigation Water by the Desalination of Groundwater within a Saline Aquifer
Hydrology 2017, 4(1), 1; doi:10.3390/hydrology4010001 -
Abstract
Irrigated land accounts for 70% of global water usage and 30% of global agricultural production. Forty percent of this water is derived from groundwater. Approximately 20%–30% of the groundwater sources are saline and 20%–50% of global irrigation water is salinized. Salinization reduces crop
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Irrigated land accounts for 70% of global water usage and 30% of global agricultural production. Forty percent of this water is derived from groundwater. Approximately 20%–30% of the groundwater sources are saline and 20%–50% of global irrigation water is salinized. Salinization reduces crop yields and the number of crop varieties which can be grown on an arable holding. Structured ZVI (zero valent iron, Fe0 pellets desalinate water by storing the removed ions as halite (NaCl) within their porosity. This allows an “Aquifer Treatment Zone” to be created within an aquifer, (penetrated by a number of wells (containing ZVI pellets)). This zone is used to supply partially desalinated water directly from a saline aquifer. A modeled reconfigured aquifer producing a continuous flow (e.g., 20 m3/day, 7300 m3/a) of partially desalinated irrigation water is used to illustrate the impact of porosity, permeability, aquifer heterogeneity, abstraction rate, Aquifer Treatment Zone size, aquifer thickness, optional reinjection, leakage and flow by-pass on the product water salinity. This desalination approach has no operating costs (other than abstraction costs (and ZVI regeneration)) and may potentially be able to deliver a continuous flow of partially desalinated water (30%–80% NaCl reduction) for $0.05–0.5/m3. Full article
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Open AccessArticle
Hydrodynamic Modeling of Nokoué Lake in Benin
Hydrology 2016, 3(4), 44; doi:10.3390/hydrology3040044 -
Abstract
Nokoué Lake is a complex ecosystem, the understanding of which requires control of physical processes that have occurred. For this, the Surface Water Modeling System (SMS) hydrodynamic model was calibrated and validated on the water depth data. The results of these simulations show
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Nokoué Lake is a complex ecosystem, the understanding of which requires control of physical processes that have occurred. For this, the Surface Water Modeling System (SMS) hydrodynamic model was calibrated and validated on the water depth data. The results of these simulations show a good match between the simulated and observed data for bottom roughness and turbulent exchange coefficients, of 0.02 m−1/3·s and 20 m2/s respectively. Once the ability of the model to simulate the hydrodynamics of the lake is testified, the model is used to simulate water surface elevation, exchanged flows and velocities. The simulation shows that the tidal amplitude is maximum at the inlet of the channel and decreases gradually from the inlet towards the lagoon’s main body. The propagation of the tidal wave is characterized by the dephasing and the flattening of the amplitude tide, which increases as we move away from the channel. This dephasing is characterized by a high and low tides delay of about 1 or 4 h and also depends on the tide amplitude and location. The velocities inside the lake are very low and do not exceed 0.03 m/s. The highest are obtained at the entrance of the channel. In a flood period, in contrast with the low-water period, incoming flows are higher than outflows, reinforced by the amplitude of the tide. An average renewal time of the lake has been estimated and corresponds during a flood period to 30 days for an average amplitude tide and 26.3 days on a high amplitude tide. In a low water period it is 40.2 days for an average amplitude tide and 30 days for a high amplitude tide. From the results obtained, several measures must be taken into account for the rational management of the lake water resources. These include a dam construction at the lake upstream, to control the river flows, and the dredging of the channel to facilitate exchanges with the sea. Full article
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Open AccessArticle
Rainfall Variability across the Agneby Watershed at the Agboville Outlet in Côte d’Ivoire, West Africa
Hydrology 2016, 3(4), 43; doi:10.3390/hydrology3040043 -
Abstract
This study analyzes, at local and regional scales, the rainfall variability across the Agneby watershed at the Agboville outlet over the period 1950–2013. Daily rainfall data from 14 rain gauges are used. The methods used are based, firstly, on the rainfall index which
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This study analyzes, at local and regional scales, the rainfall variability across the Agneby watershed at the Agboville outlet over the period 1950–2013. Daily rainfall data from 14 rain gauges are used. The methods used are based, firstly, on the rainfall index which aims to characterize the inter-annual and decadal variability of rainfall and, secondly, on the moving average to determine the dynamics of the mean seasonal cycle of the precipitations. Furthermore, the Pettitt test and the Hubert segmentation are applied to detect change-point in the rainfall series. At the basin scale, analysis of rainfall signals composites has shown that the rainfall deficit was more pronounced after the leap of monsoon. Dry years were characterized by an early monsoon demise which is remarkable after 1968. Moreover, the years after 1969 presented a shift of the peaks in precipitation for about 12 days. These peaks were reached early. The rainfall signal showed that the rainfall deficit for the period after 1968, relatively to the period before, was 10% in June against 36% in October for the average rainfall in the Agneby basin. At the local scale, the deficit of the peaks depends on the location. These rainfall deficits were 23% against 36.3% in June for the Agboville and Bongouanou rain gauges, respectively. Full article
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