Water Resources Studies Research Articles

Development and evaluation of a physically-based lake level model for water resource management: A case study for Lake Buchanan, Texas

Abstract Study region Lake Buchanan, a major reservoir for the City of Austin area, the Texas Hydrologic Region 12, USA. Numerical climate models are increasingly being used by climate scientists to inform water management. However, successful transitions from climate models (O(10–100 km)) to water resources studies (O(100 m–1 km)) still need improved data structures and modeling strategies to resolve spatial scale mismatch. In this study, we introduce a mechanistic lake-level modeling framework that consists of a state-of-the-art land surface model – Noah-MP, a vector-based river routing scheme – RAPID, and a lake mass-balance model. By conducting a case study for Lake Buchanan, we demonstrate the capability of the framework in predicting lake levels at seasonal lead times. The experiments take into account different runoff resolutions, model initialization months, and multiple lead times. Uncertainty analyses and sensitivity tests are also conducted to guide future research. New hydrological insights Different from traditional grid-based solutions, the framework is directly coupled on the vector-based NHDPlus dataset, which defines accurate hydrologic features such as rivers, dams, lakes and reservoirs. The resulting hybrid framework therefore allows for more flexibility in resolving “scaling-issues” between large-scale climate models and fine-scale applications. The presented hindcast results also provide insight into the influences of baseline LSM resolutions, initialization months, and lead times, which would ultimately help improve lake-level forecast skills.

Using an ensemble smoother to evaluate parameter uncertainty of an integrated hydrological model of Yanqi basin

Model uncertainty needs to be quantified to provide objective assessments of the reliability of model predictions and of the risk associated with management decisions that rely on these predictions. This is particularly true in water resource studies that depend on model-based assessments of alternative management strategies. In recent decades, Bayesian data assimilation methods have been widely used in hydrology to assess uncertain model parameters and predictions. In this case study, a particular data assimilation algorithm, the Ensemble Smoother with Multiple Data Assimilation (ESMDA) (Emerick and Reynolds, 2012), is used to derive posterior samples of uncertain model parameters and forecasts for a distributed hydrological model of Yanqi basin, China. This model is constructed using MIKESHE/MIKE11software, which provides for coupling between surface and subsurface processes (DHI, 2011a; DHI, 2011b; DHI, 2011c ; DHI, 2011d). The random samples in the posterior parameter ensemble are obtained by using measurements to update 50 prior parameter samples generated with a Latin Hypercube Sampling (LHS) procedure. The posterior forecast samples are obtained from model runs that use the corresponding posterior parameter samples. Two iterative sample update methods are considered: one based on an a perturbed observation Kalman filter update and one based on a square root Kalman filter update. These alternatives give nearly the same results and converge in only two iterations. The uncertain parameters considered include hydraulic conductivities, drainage and river leakage factors, van Genuchten soil property parameters, and dispersion coefficients. The results show that the uncertainty in many of the parameters is reduced during the smoother updating process, reflecting information obtained from the observations. Some of the parameters are insensitive and do not benefit from measurement information. The correlation coefficients among certain parameters increase in each iteration, although they generally stay below 0.50.

Assessing the performance of a semi‐distributed hydrological model under various watershed discretization schemes

AbstractPhysically based distributed and semi‐distributed hydrological models have become some of the primary tools for water resources studies and management over the past decades owing to increased computational capabilities and advances in data measurements. Representation of the existing heterogeneity in nature still remains one of the main challenges in these models and is accomplished primarily via watershed discretization, subdividing watersheds into hydrologically similar land parcels. Discretization decisions in distributed modelling studies are often ad hoc and determined with little or no quantitative analysis to support these decisions. In this work, we present a quantitative methodology for assessing alternative watershed discretization schemes in terms of their corresponding model performance in ungauged basins. The effect of the computational time spent for calibrating each scheme (calibration budget) is considered as part of the assessment. Here, these schemes differ in how they represent landscape attributes and range from a simple lumped scheme to more complex ones by adding spatial land cover and then soil information. The methodology is demonstrated using the Modélisation Environmentale–Surface et Hydrologie (MESH) model as applied to the Nottawasaga River basin in Ontario, Canada. Results reveal that model performance in ungauged basins depends upon the location of the validation sub‐basin (i.e. upstream or downstream) with respect to the calibration sub‐basins. Also, using a more complex scheme did not necessarily lead to improved performance in validation, when constrained by calibration budget. Therefore, the calibration budget also should be considered as a factor in the assessment process. This methodology was also implemented using a shorter sub‐period for calibration, which leads to substantial computational saving. Results of the sub‐period test were promising and consistent particularly when sufficient budget is spent to calibrate the model. Other strategies utilized for reducing the computational burden of the proposed analyses are also discussed in this study. Copyright © 2015 John Wiley & Sons, Ltd.

Comments on Uncertainty in Groundwater Governance in the Volcanic Canary Islands, Spain

The uncertainty associated with natural magnitudes and processes is conspicuous in water resources and groundwater evaluation. This uncertainty has an essential component and a part that can be reduced to some extent by increasing knowledge, improving monitoring coverage, continuous elaboration of data and accuracy and addressing the related economic and social aspects involved. Reducing uncertainty has a cost that may not be justified by the improvement that is obtainable, but that has to be known to make the right decisions. With this idea, this paper contributes general comments on the evaluation of groundwater resources in the semiarid Canary Islands and on some of the main sources of uncertainty, but a full treatment is not attempted, nor how to reduce it. Although the point of view is local, these comments may help to address similar situations on other islands where similar problems appear. A consequence of physical and hydrological uncertainty is that different hydrogeological and water resource studies and evaluations may yield different results. Understanding and coarsely evaluating uncertainty helps in reducing administrative instability, poor decisions that may harm groundwater property rights, the rise of complaints and the sub-optimal use of the scarce water resources available in semiarid areas. Transparency and honesty are needed, but especially a clear understanding of what numbers mean and the uncertainty around them, to act soundly and avoid conflicting and damaging rigid attitudes. However, the different situations could condition that what may be good in a place, may not always be the case in other places.

Strategies to reduce water stress in Euro-Mediterranean river basins

A portfolio of water management strategies now exists to contribute to reach water demand and supply targets. Among them, integrated water resource management has a large potential for reducing water disagreement in water scarcity regions. Many of the strategies are based on well tested choices and technical know-how, with proven benefits for users and environment. This paper considers water management practices that may contribute to reduce disagreement in water scarcity areas, evaluating the management alternatives in the Mediterranean basins of Europe, a region that exemplifies other water scarcity regions in the world. First, we use a model to compute water availability taking into account water management, temporal heterogeneity, spatial heterogeneity and policy options, and then apply this model across 396 river basins. Second, we use a wedge approach to illustrate policy choices for selected river basins: Thrace (Greece), Guadalquivir, Ebro, Tagus and Duero (Spain), Po (Italy) and Rhone (France). At the wide geographical level, the results show the multi-determinant complexities of climate change impacts and adaptation measures and the geographic nature of water resources and vulnerability metrics. At the local level, the results show that optimisation of water management is the dominating strategy for defining adaptation pathways. Results also show great sensitivity to ecological flow provision, suggesting that better attention should be paid to defining methods to estimate minimum ecological flows in water scarcity regions. For all scales, average water resource vulnerability computed by traditional vulnerability indicators may not be the most appropriate measure to inform climate change adaptation policy. This has large implications to applied water resource studies aiming to derive policy choices, and it is especially interesting in basins facing water scarcity. Our research aims to contribute to shape realistic water management options at the regional level and therefore provide information to climate change, agricultural and water policies.

Isotopic study of water resources in a semi-arid region, western Iraq

Hydrochemistry and stable isotopic technique were used in studying the water resources interaction in a semi-arid area, western Iraq. Throughout Iraq, 28 groundwater samples, 7 surface water samples from the study area, and 18 rainwater samples were analyzed for 2H and 18O stable isotopes and hydrochemical analysis. In this study, the temperature, altitude and continental effects on the isotopic composition of rain water in Iraq were studied. The results show that isotopes content in rainwater, in the current study, increases with increasing temperature and a good correlation exists between increasing latitude with decreasing δ 18O values. Rainwater isotopes show evidence of temperature effect and continental effect associated with altitude effect. Generally, due to variation in temperature and altitude throughout Iraq, the values of isotopic composition of rainwater range from (−7.25 ‰) to (−2.79 ‰), and from (−45 ‰) to (−9.7 ‰) for δ18O and δD, respectively. The similarity of isotopic composition of water of the Euphrates River and Haditha reservoir with that of groundwater taken from neighbor wells gives indication that intermixing between them is exist, while the groundwater of the wells far from the surface water resources is mostly affected by rainwater.

Monitoring implementation of desertification combating plan using geomatics – A case study, districts Dhar and Jhabua, Madhya Pradesh

The world’s drylands are subject to desertification as a result of extended droughts, climate change, and human activities. Development in drylands depends on addressing degradation of the ecosystem, mainstreaming sustainable natural resources management, and building upon the existing adaptive capacities of communities and institutions. In this regard, recent scientific results aimed to promote sustainable development through action plans for combating desertification. In India, under the Integrated Mission for Sustainable Development (IMSD) programme, remote sensing based integrated land and water resource studies were carried out with an objective to generate locale specific action plans for sustainable development of a region. A specific study was carried out, in districts of Jhabua and Dhar, in Madhya Pradesh using Composite Land Development Sites (CLDS) approach for forest and wasteland development and soil and water conservation. Various treatments were suggested and implemented in 1995. The present study was carried out with an objective to monitor the positive impacts of combating plan implementation through visual interpretation and NDVI analysis of temporal images of LISS III data, since 1991 to 2013. The study reveals that there is substantial increase in the area of irrigated agricultural land with increase in number of check dams along with the stream channels.

Collection and Application of Outcrop Measurements in Glacial Materials for Geo-Engineering and Hydrogeology along the Vermilion River, East-Central Illinois

Outcrop mapping by close-range photogrammetry was undertaken at three remote sites as part of a study of water resources to improve characterization of glacial sedimentary assemblages and to evaluate the utility of terrestrial remote sensing to supplement routine geologic mapping. Two features were measured from georeferenced stereomodels, clast pavements, and buried channel deposits over a 2-year period along a segment of the Middle Fork of the Vermilion River. Cobble-size clasts, spaced less than 3.28 ft (1 m) apart, form clusters approximately 6.56 to 9.84 ft (2 to 3 m) in length. These clasts compose a semi-continuous pavement between two tills deposited during the Wisconsin Episode. Five of the 26 clusters measured occur within the Tiskilwa Formation. Deposits of coarse- and fine-grained sediments, informally assigned to the Glasford Formation lithostratigraphic unit, fill buried channels that provide an important source of groundwater in east-central Illinois for areas that do not receive water from the Mahomet aquifer. Measurements of buried channels included width, maximum sediment thickness, area, and perimeter. Widths equated to more than half of the outcrop length. Aspect ratios (width: thickness) of the channels are consistent with deltaic distributary systems formed in front of retreating ice margins, and systems having varying interconnectivity. Differences in area: perimeter of the buried channels provide a measure of shape that may partially account for the variation in yields from water wells in this area. Consequently, we postulate that yield could be improved through lateral drilling within the channel or by connecting adjacent channels.

Temporal stability of surface soil moisture of different vegetation types in the Loess Plateau of China

The temporal stability of soil moisture (TSSM) was widely applied to optimize the soil moisture sampling scheme on a catchment or even larger spatial scale over wet and dry observational periods. However, the integration of the TSSM feature with specific hydrological response at a small plot scale has not been sufficiently researched. This study analyzed the temporal stability of surface soil moisture (0–10cm) characteristics and corresponding influencing factors of different vegetation types under two typical soil moisture changing processes including wet-to-dry (WTD) and dry-to-wet (DTW), and determined the representative points. A total of 16 microplots (60×60cm each) that were composed of three vegetation types containing Andropogon, Artemisia scoparia and Spiraea pubescens and bare land cover were selected. And the soil moisture in the central point (CP) and four ambient points (APs) of each microplot were measured during the WTD and DTW processes. The results showed that, 1) from DTW to WTD processes, the distribution of the soil water content in different vegetation types indicated a significant difference. Compared with the soil moisture in the AP or CP area of other vegetation types, the soil water content in tall shrub types (S. pubescens) was the lowest. 2) The autocorrelation coefficient indicated that both in the AP and CP areas, the soil moisture of the low shrub types (A. scoparia) had a higher temporal stability than that of other vegetation types. However, the soil water content in bare land had the highest temporal fluctuation from the DTW to WTD processes. Additionally, in the CP area, the TSSM of all the vegetation types tended to decrease during the WTD process. 3) Based on the TSSM analysis system that was derived from the principle of probability and statistics, the soil moisture in the low shrub types (A. scoparia) most likely provides the best representativeness of the spatial average soil water content of heterogeneous vegetation types. The determination of the representative soil moisture point via the hydrological-trait sampling method could be supplementary and significant for a TSSM study of the available soil water resources in an arid and semi-arid ecosystem.

Study of water resources for crop utilization in China from the perspective of Virtual Water

Study of water resources for crop utilization in China from the perspective of Virtual Water

General strategies for the development of surface water resources in the province of Najaf

Dry, including the study area, Najaf Governorate, due to the importance these resources play in achieving economic development, so drawing any development policy, whether in the civil, agricultural or industrial aspect, must be accompanied by a study of available water resources and a study of current and future requirements. This aspect may lead to the faltering of development plans if it does not lead to their failure.

Assessment of Water Resources Carrying Capacity for Sustainable Development Based on a System Dynamics Model: A Case Study of Tieling City, China

Studies of water resources carrying capacity (WRCC) can provide helpful information about how the socio-economic system is both supported and restrained by the water resources system. As such, there is a need to develop better quantitative assessment methods to determine the potential maximum socio-economic growth within a catchment subjected to a given amount of water resource. An improved WRCC assessment method based on a system dynamics model (WRCC-SDM) is proposed in this paper. WRCC-SDM is built on synthesis simulations of coupling effects and feedback mechanisms within the society-economy-water compound system. The results can integrally represent system behaviors and states, and the evaluation of WRCC is achieved using this model. Moreover, an integrated indicator (Population-GDP-GDP per capita) is proposed to express the threshold value of WRCC. Based on the natural water resources supply capacity and associated socio-economic development potential, the concepts of critical WRCC and extreme WRCC are put forward. Critical WRCC represents the socio-economic scale that will cause total water demand to reach the maximum natural water resources supply capacity, while extreme WRCC reflects the socio-economic scale when the GDP growth rate constrained by limited water resources is zero. The methodology was applied to assess the water resources situation in Tieling City, China under different scenarios. The results indicate that: (1) Given the constraints represented by water resources, projected GDP growth tends to follow an S-curve growth pattern; and (2) Rapid population growth may lead to earlier and more severe water resources constraints.

Sensitivity and tolerance of Riparian arthropod communities to altered water resources along a drying river.

BackgroundRivers around the world are drying with increasing frequency, but little is known about effects on terrestrial animal communities. Previous research along the San Pedro River in southeastern AZ, USA, suggests that changes in the availability of water resources associated with river drying lead to changes in predator abundance, community composition, diversity, and abundance of particular taxa of arthropods, but these observations have not yet been tested manipulatively.Methods and ResultsIn this study, we constructed artificial pools in the stream bed adjacent to a drying section of the San Pedro River and maintained them as the river dried. We compared pitfall trapped arthropods near artificial pools to adjacent control sites where surface waters temporarily dried. Assemblage composition changed differentially at multiple taxonomic levels, resulting in different assemblages at pools than at control sites, with multiple taxa and richness of carabid beetle genera increasing at pools but not at controls that dried. On the other hand, predator biomass, particularly wolf spiders, and diversity of orders and families were consistently higher at control sites that dried. These results suggest an important role for colonization dynamics of pools, as well as the ability of certain taxa, particularly burrowing wolf spiders, to withstand periods of temporary drying.ConclusionsOverall, we found some agreement between this manipulative study of water resources and a previous analysis of river drying that showed shifts in composition, changes in diversity, and declines in abundance of certain taxa (e.g. carabid beetles). However, colonization dynamics of pools, as well as compensatory strategies of predatory wolf spiders seem to have led to patterns that do not match previous research, with control sites maintaining high diversity, despite drying. Tolerance of river drying by some species may allow persistence of substantial diversity in the face of short-term drying. The long-term effects of drying remain to be investigated.

Lake Fluctuation Effectively Regulates Wetland Evapotranspiration: A Case Study of the Largest Freshwater Lake in China

Lakes and wetlands provide valuable water resources. Wetland evapotranspiration (ET) is a key hydrologic component; however, the effects of lake fluctuation on wetland ET remain unclear. The Poyang Lake is the largest freshwater lake in China and experiences a dramatic fluctuation in water level and inundated area. This study used remote sensing data to estimate the wetland ET for Poyang Lake and to illustrate the distribution of wetland ET and its response to lake fluctuations. Our results showed that wetland ET was related to lake fluctuation both spatially and temporally. Within the same year, the difference between annual water evaporation (Ewater) and wetland ET (ETwetland) was primarily attributed to lake fluctuation through its effects on inundated area and exposure days. A 1% increase in inundated area would result in a 7.87 ± 1.13 mm a−1 reduction in annual Ewater-to-ETwetland differences, and a 10-day elongation of exposure could lead to an 11.1 ± 1.6 mm a−1 increase in annual Ewater-to-ETwetland differences, on average. Inter-annually, the Ewater-to-ETwetland differences were attributed to the combined effects of atmospheric and environmental variables and lake fluctuation. The lake fluctuation contributed 73% to the inter-annual ET difference, followed by relative humidity (19%), net radiation (5%), and wind speed (4%). Overall, lake fluctuation effectively regulates wetland ET, and its effect should receive careful consideration in hydrological and water resources studies under the current changing climate.

Effects of land use, topography and socio-economic factors on river water quality in a mountainous watershed with intensive agricultural production in East china.

Understanding the primary effects of anthropogenic activities and natural factors on river water quality is important in the study and efficient management of water resources. In this study, analysis of Variance (ANOVA), Principal component analysis (PCA), Pearson correlations, Multiple regression analysis (MRA) and Redundancy analysis (RDA) were applied as an integrated approach in a GIS environment to explore the temporal and spatial variations in river water quality and to estimate the influence of watershed land use, topography and socio-economic factors on river water quality based on 3 years of water quality monitoring data for the Cao-E River system. The statistical analysis revealed that TN, pH and temperature were generally higher in the rainy season, whereas BOD5, DO and turbidity were higher in the dry season. Spatial variations in river water quality were related to numerous anthropogenic and natural factors. Urban land use was found to be the most important explanatory variable for BOD5, CODMn, TN, DN, NH4 +-N, NO3 −-N, DO, pH and TP. The animal husbandry output per capita was an important predictor of TP and turbidity, and the gross domestic product per capita largely determined spatial variations in EC. The remaining unexplained variance was related to other factors, such as topography. Our results suggested that pollution control of animal waste discharge in rural settlements, agricultural runoff in cropland, industrial production pollution and domestic pollution in urban and industrial areas were important within the Cao-E River basin. Moreover, the percentage of the total overall river water quality variance explained by an individual variable and/or all environmental variables (according to RDA) can assist in quantitatively identifying the primary factors that control pollution at the watershed scale.

A STUDY ON GEOGRAPHICAL CHARACTERISTICS OF THE KRISHNA WESTERN DELTA USING GIS AND REMOTE SENSING TECHNIQUES

Water is a prime natural resource, basic human need and a precious national asset. Though water is considered as a renewable resource it is not unlimited, and as such, can no longer be taken for granted and has to be treated as a valuable resource. Since water is a critical resource for development of other resources, the assessment of water resources available and demand of water for various purposes is of utmost importance without which it is difficult to prepare any developmental plan. Rainfall is the main source of water which is unevenly distributed spatially and temporally. The ever increasing demand of water due to high industrialization, enormous population growth, agricultural expansion and urbanization has already created serious problems. As water demand increases, issues on water availability and demand become critical. This makes the management of water resources, such as assessing, managing and planning of water resources for sustainable use, a complex task. Remote Sensing with its advantages of spatial, spectral and temporal availability of data covering large and inaccessible areas with in short time has become a very handy tool in assessing, monitoring and conserving land use/ land cover classification around the world. Remote Sensing integrated with Geographical Information System has been efficiently used in generating input parameters of hydrological models. The GIS and RS technology have opened new paths in water resources studies. In the present investigation, an attempt has been made to delineate the Krishna Western Delta In Andhra Pradesh, India for the assessment of spatial distribution of runoff. The GIS layers namely, Topomap, contours and Digital Elevation Model (DEM) were prepared including watershed boundary. The Digital Elevation Model (DEM) of the study area was generated in ArcGIS using Contours and Stream layers. The Georeferenced soil map has been clipped to the boundary of the Krishna Western Delta and the areas corresponding to each variety of soil is calculated in ArcGIS.

The Study of Available Water Resources in Northern Shaanxi

In order to alleviate the contradictions about water resources shortage and socio-economic development in Northern Shaanxi, the water resources and their availability were studied. Through use the method of surface water resources deducte river ecological basic flow and flood discharge, calculated the surface available water resources and total available water resources of Northern Shaanxi, summarized their distribution characteristics. Study result showed that the available water resources of Northern Shaanxi is low, only 1.6 billion m3, available rate is 40%, water resources and their availability principally distribute in Yulin.

Predictive modeling of groundwater nitrate pollution using Random Forest and multisource variables related to intrinsic and specific vulnerability: A case study in an agricultural setting (Southern Spain)

Watershed management decisions need robust methods, which allow an accurate predictive modeling of pollutant occurrences. Random Forest (RF) is a powerful machine learning data driven method that is rarely used in water resources studies, and thus has not been evaluated thoroughly in this field, when compared to more conventional pattern recognition techniques key advantages of RF include: its non-parametric nature; high predictive accuracy; and capability to determine variable importance. This last characteristic can be used to better understand the individual role and the combined effect of explanatory variables in both protecting and exposing groundwater from and to a pollutant.In this paper, the performance of the RF regression for predictive modeling of nitrate pollution is explored, based on intrinsic and specific vulnerability assessment of the Vega de Granada aquifer. The applicability of this new machine learning technique is demonstrated in an agriculture-dominated area where nitrate concentrations in groundwater can exceed the trigger value of 50mg/L, at many locations. A comprehensive GIS database of twenty-four parameters related to intrinsic hydrogeologic proprieties, driving forces, remotely sensed variables and physical–chemical variables measured in “situ”, were used as inputs to build different predictive models of nitrate pollution. RF measures of importance were also used to define the most significant predictors of nitrate pollution in groundwater, allowing the establishment of the pollution sources (pressures).The potential of RF for generating a vulnerability map to nitrate pollution is assessed considering multiple criteria related to variations in the algorithm parameters and the accuracy of the maps. The performance of the RF is also evaluated in comparison to the logistic regression (LR) method using different efficiency measures to ensure their generalization ability. Prediction results show the ability of RF to build accurate models with strong predictive capabilities.

水文・水資源学における学際的大型研究の重要性

水文・水資源学における学際的大型研究の重要性

Hydrogeochemical Study of Surface Water Resources of Orlu, Southeastern Nigeria

Hydrogeochemical assessment of surface water Resources of Orlu and its environs was carried out in order to evaluate the chemical composition and quality profile with respect to the environmental setting of the study area. A total of six samples were collected, from different rivers and streams traversing different communities in the area, and analyzed for major cations and anions as well as trace elements like Fe, Mn, Zn, Pb and As. The major cation concentrations determined were in the order of Ca2+> Na+> K+> Mg2+ with mean values of 4.14, 3.78, 1.60 and 1.19 mg/L respectively and that of the major anion concentration of the surface water is of the order HCO32-> Cl-> SO42-> NO3- with mean values of 19.83, 11.67, 3.45 and 0.24 mg/L respectively. Two major water groups were identified based on characterization on the Piper Trilinear diagram. They include Ca-(Mg)-Na-HCO3 and Ca-Mg-(SO4)-HCO3. This reflects diverse effects of bedrock lithologies, base exchange processes, precipitation and weathering. The pollution index (PI) value of 9.10 (which is greater than the critical value of unity) shows that the surface water bodies in the area are slightly polluted by the trace elements and as such not fit for domestic use as those parameters exceeded the maximum permissible level set by the Nigerian Industrial Standard (2007) and the World Health Organization (2006) Standard. Finally the electrical conductivity (EC) values of 13.0 to 97.0 µs/cm and total dissolved solids (TDS) values of 8.0 to 66.0 mg/L, alongside the estimated sodium absorption ratio (SAR) of 1.74 revealed a fresh water grade that is fairly suitable for agricultural purposes. Key words: Hydrogeochemistry, pollution index, water facies, water quality.