Variability Of Water Balance Components Research Articles

Current Changes in the Major Water Balance Components of the Pechora and Kolyma Deltas under Warming Climate

Long-term variations of water balance components are compared for the deltas of the Pechora and Koluma rivers, flowing in the occurrence area of discontinuous and continuous permafrost rocks. Trends in the variations in the major components of water balance equation (river water flow, precipitation, and losses or increment of runoff in the delta) are considered for the conditions of climate warming (the late XX–early XXI centuries). A distinct increase, most pronounced in 2008–2018, was recorded in the major components of water balance.

Modeling the spatial and temporal availability of water resources potential over Abbay river basin, Ethiopia

Study regionAbbay River Basin, Ethiopia. Study focusThis research focused on assessing the spatio-temporal availability and variability of water resources potential using physically based hydrological model. The availability and spatial variability of water balance components were modeled for each subbasins of Abbay River basin. New hydrological insights for the regionMulti statistical performance criteria proved that ArcSWAT model has the capacity to reproduce flows that agree with the measured flows at daily time scale simulation and found as applicable over Abbay River basin. The Calibration and Validation were done at different subbasins. The result revealed that the performance of the model well improved as the basin was partitioned into subbasins. For reproduction of the measured flow at different flow segments, the model performed very good especially for high and peak flows segments. The rainfall distribution revealed that the basin is characterized by high spatial and temporal variation of rainfall. Three fourth of the annual rainfall was contributed from June to September. The water balance components analysis proved that Evapotranspiration is high over the basin which covers more than half (55.20 %) of the annual rainfall. Water yield (WYLD_Qmm) covers only 21.73 % of the annual rainfall. This research can be used as basis to give emphasis on water resources potential modeling in the future considering climate and land use changes.

Modelling the recent variations of water balance components and water availability within the Senegal River basin: using WEAP21 model

Modelling the recent variations of water balance components and water availability within the Senegal River basin: using WEAP21 model

Trends and variability of water balance components over a tropical savanna and Eucalyptus forest in Australia

Abstract In this paper, the long-term dynamics of water balance components in two different contrasting ecosystems in Australia were simulated with an ecohydrological model (WAter Vegetation Energy and Solute modelling (WAVES)) over the period 1950–2015. The selected two ecosystems are woodland savanna in Daly River and eucalyptus forest in Tumbarumba. The WAVES model was first manually calibrated and validated against soil water content measured by cosmic-ray probe and evapotranspiration measured with eddy flux techniques. The calibrated model was then used to simulate long-term water balance components with observed climate data at two sites. Analyzing the trends and variabilities of potential evapotranspiration and precipitation is used to interpret the climate change impacts on ecosystem water balance. The results showed that the WAVES model can accurately simulate soil water content and evapotranspiration at two study sites. Over the period of 1950–2015, annual evapotranspiration at both sites showed decreasing trends (−1.988 mm year−1 in Daly and −0.381 mm year−1 in Tumbarumba), whereas annual runoff in Daly increased significantly (5.870 mm year−1) and decreased in Tumbarumba (–0.886 mm year−1). It can be concluded that the annual runoff trends are consistent with the rainfall trends, whereas trends in annual evapotranspiration are influenced by both rainfall and potential evapotranspiration. The results can provide evidence for controlling the impacting factors for different ecosystems under climate change.

Signatures of Hydrologic Function Across the Critical Zone Observatory Network

AbstractDespite a multitude of small catchment studies, we lack a deep understanding of how variations in critical zone architecture lead to variations in hydrologic states and fluxes. This study characterizes hydrologic dynamics of 15 catchments of the U.S. Critical Zone Observatory (CZO) network where we hypothesized that our understanding of subsurface structure would illuminate patterns of hydrologic partitioning. The CZOs collect data sets that characterize the physical, chemical, and biological architecture of the subsurface, while also monitoring hydrologic fluxes such as streamflow, precipitation, and evapotranspiration. For the first time, we collate time series of hydrologic variables across the CZO network and begin the process of examining hydrologic signatures across sites. We find that catchments with low baseflow indices and high runoff sensitivity to storage receive most of their precipitation as rain and contain clay‐rich regolith profiles, prominent argillic horizons, and/or anthropogenic modifications. In contrast, sites with high baseflow indices and low runoff sensitivity to storage receive the majority of precipitation as snow and have more permeable regolith profiles. The seasonal variability of water balance components is a key control on the dynamic range of hydraulically connected water in the critical zone. These findings lead us to posit that water balance partitioning and streamflow hydraulics are linked through the coevolution of critical zone architecture but that much work remains to parse these controls out quantitatively.

Simulation of monthly streamflow using the SWAT model of the Ib River watershed, India

The objective of the study is simulating the streamflow and predicting water balance components using Soil and Water Assessment Tool (SWAT) model for Ib River watershed in Mahanadi River basin. Tropical Rainfall Measuring Mission (TRMM) daily rainfall and monthly streamflow data were used to develop the model from 1993 to 2011. The calibration showed better response than validation in which the determination of coefficient, Nash–Sutcliffe efficiency and percent of bias were 0.77; 0.75 and −19.1, respectively. The temporal and spatial variability of water balance components over study area were determined. This study shows that almost 26–50% of the rainfall was lost by evapotranspiration. The spatial variability of surface runoff was higher on the southern region, groundwater was lower due to the dominance of tile drainage, and lateral flow was higher on southern region. This study will enhance the understanding of hydrological components behaviour on the sparse rain network.

Modeling the impact of agricultural crops on the spatial and seasonal variability of water balance components in the Lake Tana basin, Ethiopia

AbstractThe Lake Tana basin hosts more than three million people and it is well known for its water resource potential by the Ethiopian government. The major economic activity in the region is agriculture, but the effect of agricultural crops on water resources is poorly understood. Understanding the crop water interaction is important to design proper water management plans. Therefore, the primary objective of this research is to investigate the effect of different agricultural crops on the spatial and seasonal variability of water balance components of Gilgelabay, Gumara, and Ribb catchment areas of Lake Tana basin, Ethiopia. To this end, the hydrologic model SWAT (Soil and Water Assessment Tool) was used to simulate the water fluxes between 1980 and 2014. The water balance components, which were mapped for each hydrologic response unit, indicated the spatial variations of water fluxes in the study. Cereal crops like teff and millet had significant effect in enhancing groundwater recharge, whereas leguminous crops like peas had significant impact in increasing runoff generation. Moreover, the model outputs showed that the total streamflow is dominated by baseflow and about 13%, 9%, and 7% of the annual rainfall goes to the deep aquifer system of Gilgelabay, Gumara, and Ribb catchment areas, respectively.

Quantifying the space – time variability of water balance components in an agricultural basin using a process-based hydrologic model and the Budyko framework

Process-based distributed hydrologic models (PBHMs), which link watershed characteristics with process representations, are useful tools to evaluate distributed and ensemble hydrologic responses of a basin to climate inputs. However, complexities associated with parameter interactions and their spatial heterogeneity may introduce high uncertainty in the parameterization of a PBHM. The Budyko curve framework offers an effective approach for evaluating the variability in the water balance components from a PBHM and can be used to explore the link between model performance with parameter heterogeneities and the Budyko curve characteristics. In this work a PBHM was calibrated using a multi-site calibration strategy, which was built upon a step-wise calibration algorithm combined with multiple calibration targets including river discharges, evapotranspiration and ground water heads, to reduce compensation errors caused by component interactions. This strategy was used for the Kalamazoo River watershed in Michigan, USA, with obvious physiographic and land surface heterogeneities. The Budyko framework characterized the water balance variability at the sub-watershed scale; two empirical methods were used to evaluate the calibrated PBHM parameters using Budyko-estimated values and to assess the physical relevance of the parameters. The relative infiltration capacity is found to play an important role in affecting the spatial variability of the annual water balance of this watershed. This work brings out the importance of optimizing calibration strategies by linking catchment heterogeneities with processes reasoning in order to understand the underlying hydrologic controls.

A comparative study of available water in the major river basins of the world

Numerous large river basins of the world have few and irregular observations of the components of the terrestrial hydrological cycle with the exception of stream gauges at a few locations and at the outlet along with sparsely distributed rain gauges. Using observations from satellite sensors and output from global land surface models, it is possible to study these under-observed river basins. With populations greater than a billion people, some of these rivers (e.g., the Ganga-Brahmaputra, the Yangtze, the Nile and the Mekong) are the economic engines of the countries they transect, yet thorough assessment of their flow dynamics and variability in regard to water resource management is still lacking. In this paper, we use soil moisture (0–2 m) and surface runoff from the NASA Global Land Data Assimilation System (GLDAS), evapotranspiration, and Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and rainfall from the Tropical Rainfall Measuring Mission (TRMM) and total water storage anomaly from the Gravity Recovery and Climate Experiment (GRACE) to examine variability of individual water balance components. To this end, understanding the inter-annual and intra-seasonal variability and the spatial variability of the water balance components in the major river basins of the world will help to plan for improved management of water resources for the future.

Runoff Simulation by SWAT Model Using High-Resolution Gridded Precipitation in the Upper Heihe River Basin, Northeastern Tibetan Plateau

The scarcity and uneven distribution of precipitation stations in the inland river basins of the Northeastern Tibetan Plateau restrict the application of the distributed hydrological model and spatial analysis of water balance component characteristics. This study used the upper Heihe River Basin as a case study, and daily gridded precipitation data with 3 km resolution based on the spatial interpolation of gauged stations and a regional climate model were used to construct a soil and water assessment tool (SWAT) model. The aim was to validate the precision of high-resolution gridded precipitation for hydrological simulation in data-scarce regions; a scale transformation method was proposed by building virtual stations and calculating the lapse rate to overcome the defects of the SWAT model using traditional precipitation station data. The gridded precipitation was upscaled from the grid to the sub-basin scale to accurately represent sub-basin precipitation input data. A satisfactory runoff simulation was achieved, and the spatial variability of water balance components was analysed. Results show that the precipitation lapse rate ranges from 40 mm/km to 235 mm/km and decreases from the southeastern to the northwestern areas. The SWAT model achieves monthly runoff simulation compared with gauged runoff from 2000 to 2014; the determination coefficients are higher than 0.71, the Nash–Sutcliffe efficiencies are higher than 0.76, and the percentage bias is controlled within ±15%. Meadow and sparse vegetation are the major water yield landscapes, and the elevation band from 3500 m to 4500 m is the major water yield area. Precipitation and evapotranspiration present a slightly increasing trend, whereas water yield and soil water content present a slightly decreasing trend. This finding indicates that the high-resolution gridded precipitation data fully depict its spatial heterogeneity, and scale transformation significantly promotes the application of the distributed hydrological model in inland river basins. The spatial variability of water balance components can be quantified to provide references for the integrated assessment and management of basin water resources in data-scarce regions.

Integrating Topography and Soil Properties for Spatial Soil Moisture Storage Modeling

The understanding of the temporal and spatial dynamics of soil moisture and hydraulic property of soil is crucial to the study of hydrological and ecological processes. The purpose of this study was to derive equations that describe spatial soil water storage deficit based on topography and soil properties. This storage deficit together with the topographical index can be used to conclude the spatial distribution curve of storage capacity in a (sub-) basin for developing hydrological model. The established model was able to match spatial and temporal variations of water balance components (i.e., soil moisture content (SMC), evapotranspiration, and runoff) over the Ziluoshan basin. Explicit expression of the soil moisture storage capacity (SMSC) in the model reduced parameters, which provides a method for hydrological simulation in ungauged basins.

Spatial‑temporal variability of water balance components in the North area of the Zailiisky Alatau Range

Analysis of changes in WB components (precipitation, evaporation, glacier runoff, dynamical water resources) on the Northern slope of the Zailiisky Alatau was performed for the 1946–2005 time divided into two periods: 1946–1975 and 1976–2005. The territory under investigation included basins of the following rivers: Bolshaya Almatinka, Malaya Almatinka, Talgar, Turgen, Issyk, Chemolgan, Kaskelen, Kargalinka, Prohodnaya, and Uzunkargaly. Their total area down to the closing gauge points amounts to 2644 km2. Summarized glacier areas in these basins and annual runoff were equal, respectively, to: 306.6 km2 and 39.05 km3in 1946–1975, and 253.0 km2 and 38.35 km3 in 1975–2005. In 1946–2005, typical features of regional glaciation dynamics were increasing area of the moraine cover on glaciers and reducing area of bare ice that results in decreasing of the glacial runoff volume, all other factors being the same. The method to calculate the WB components consists of the following constituents: model of seasonal runoff from melted snow and ice in the areas of accumulation and ablation of glaciers; complex of formulas to calculate precipitation, air temperature and humidity, intensity of ice melting under the moraine, bare ice and evaporation within the height intervals corresponding to the main types of surfaces on the glaciers. On the basis of our method, we could reconstruct for the 1876–2015 period long‑term series of data on a runoff, separately annual values and sums for the vegetation periods. They can be used for regional scientific and applied analyses of the river stream discharges. The data on runoff in the Malaya Almatinka River basin and observational data on the meteorological station Almaty (Hydrometeorological Observatory) had been quantitatively substantiated as the representative information for modeling and calculation of water resources on the Northern slope of the Zailiisky Alatau Range.

Effects of Crop Growth on Hydrological Processes in River Basins and on Regional Climate in China

The regional climate model RegCM3 incorporating the crop model CERES, called the RegCM3_CERES model, was used to study the effects of crop growth and development on regional climate and hydrological processes over seven river basins in China. A 20-year numerical simulation showed that incorporating the crop growth and development processes improved the simulation of precipitation over the Haihe River Basin, Songhuajiang River Basin and Pearl River Basin. When compared with the RegCM3 control run, RegCM3_CERES reduced the negative biases of monthly mean temperature over most of the seven basins in summer, especially the Haihe River Basin and Huaihe River Basin. The simulated maximum monthly evapotranspiration for summer (JJA) was around 100 mm in the basins of the Yangtze, Haihe, Huaihe and Pearl Rivers. The seasonal and annual variations of water balance components (runoff, evapotranspiration and total precipitation) over all seven basins indicate that changes of evapotranspiration agree well with total precipitation. Compared to the RegCM3, RegCM3_CERES simulations indicate reduced local water recycling rate over most of the seven basins due to lower evapotranspiration and greater water flux into these basins and an increased precipitation in the Heihe River Basin and Yellow River Basin, but reduced precipitation in the other five basins. Furthermore, a lower summer leaf area index (1.20 m2 m–2), greater root soil moisture (0.01 m3 m–3), lower latent heat flux (1.34 W m–2), and greater sensible heat flux (2.04 W m–2) are simulated for the Yangtze River Basin. CitationQin, P.-H., F. Chen, and Z.-H. Xie, 2013: Effects of crop growth on hydrological processes in river basins and on regional climate in China. Adv. Clim. Change Res., 4(3), doi: 10.3724/SP.J.1248.2013.173.

Temporal and spatial variation of the main water balance components in the three rivers source region, China from 1960 to 2000

The three rivers source region (TRSR) is the most sensitive region of global climate change in China. The temporal and spatial variations of main water balance components (precipitation, snowmelt, actual evaporation, runoff, etc.) during the period from 1960 to 2000 in the TRSR were analyzed by hydrologic simulation and statistical detection. The results showed that: when compared with the components in 1960s, (1) the variation of precipitation from 1970s to 1990s was not significant in the whole TRSR though it increased slightly in the Yellow River Source Region (YeSR) and Yangtze River Source Region (YaSR), but decreased slightly in the Lancang River Source Region (LcSR); (2) the snowmelt increased in most regions of TRSR except the downstream of YeSR and YaSR, but the trend was statistically significant only in the YeSR; (3) the actual evaporation increased continually in the whole TRSR, but the trends were significant in the middle stream of the YeSR and YaSR, and the YeSR was the greatest; (4) Although the runoff depth decreased gradually in the TRSR, the trends were significant only in the middle stream of the YeSR and YaSR and the YeSR was the greatest. Inevitably, the discharge decreased in the TRSR but the trend was not statistically significant. Climate change (i.e., the slightly decreasing of precipitation and the increasing of air temperature) was the most important factor to affect the variations of water balance components. The most sensitive region to climate change was YeSR, followed by YaSR, and the least one was LcSR. This study was expected to provide the foundation and a reference to analyze the water resources evolution and test the climate change impacts in TRSR as well as the whole China.

Agrohydrological efficiency of spring wheat sowing based on the fallow predecessor in forest-steppe and steppe zones

Presented is the quantitative estimation of agrohydrological efficiency of spring wheat sowing based on the fallow predecessor. The research is based on the numerical experiment using the model of the water regime formation of the agricultural field. Investigated are the spatial and temporal variability of water balance components of agricultural fields, as well as the water supply when sowing the spring wheat using the nonfallow and fallow predecessors.

Modelling and observation of hedgerow transpiration effect on water balance components at the hillslope scale in Brittany

AbstractVegetation has a major influence on the water and energy balance of the earth's surface. In the last century, human activities have modified land use, inducing a consequent change in albedo and potential evapotranspiration. Linear vegetation structures (hedgerows, shelterbelts, open woodland, etc) were particularly abundant but have declined considerably over the past several decades. In this context, it is important to quantify their effect on water and energy balance both on a global scale (climate change and weather prediction) and on a local scale (soil column, hillslope and watershed). The main objective of this study was to quantify the effect of hedgerows on the water cycle by evaluating spatial and temporal variations of water balance components of a hillslope crossed by a hedgerow. Water flow simulation was performed using Hydrus‐2D to emphasize the importance of transpiration in the water balance and to evaluate water extraction from groundwater. Model validation was performed by comparing simulated and observed soil matrix potentials and groundwater levels. Hedgerow transpiration was calculated from sap flow measurements of four trees. Water balance components calculated with a one‐dimensional water balance equation were compared with simulations. Simulation runs with and without tree root uptake underlined the effect of hedgerow transpiration, increasing capillary rise and decreasing drainage. Results demonstrated that the spatial and temporal variability of water balance components was related to the hedgerow presence as well as to the meteorological context. The relations between transpiration, groundwater proximity and soil‐water availability determined the way in which water balance components were affected. Increased capillary rise and decreased drainage near hedges were related to the high transpiration of trees identified in this study. Transpiration reached twice the potential evapotranspiration when groundwater level and precipitation amounts were high. Water balance analysis showed that transpiration was a substantial component, representing 40% of total water output. These results may offer support for improving hydrological models by including the effect of land use and land cover on hydrological processes. Copyright © 2012 John Wiley & Sons, Ltd.

Hydrological observation and modelling relationship for the determination of water budget in Lusatian post-mining landscape

The hydrological observation network in a small, sparsely vegetated watershed within the post-mining landscape includes measurements of meteorological quantities (precipitation, temperature, global radiation, humidity, wind speed), of water level in a swale by pressure transducers, and of soil water by TDR-probes, tensiometers and a seepage gravity lysimeter. The field observations resulted in a modelling concept, where modules for actual evapotranspiration, soil water movement and surface runoff were specified and coupled with each other. The results of measurements and modelling for a 2 years observation period revealed a predominant relation of the distribution of hydraulic properties on hummocks and erosion channels, formed by runoff and erosion. On hummocks both processes are intensified by the water repellency of the tertiary sandy overburden, which seems to be related to wetting–drying-cycles of the dump substrate. During periods of hydrophobic conditions, surface runoff is increased from the hummocks and most groundwater recharge occurs within the erosion channels. Under consideration of the wetting–drying-cycles, the components of the water balance were obtained from daily precipitation values by a simplified storage approach version of the model in acceptable quality compared to the results of the detailed model version. In this version surface runoff occurs only under water repellent substrate conditions. To analyse the variability of water balance components for a real fluctuation of weather conditions, a 30-year meteorological record was considered. The precipitation in the investigated catchment (corrected for errors of wind, for wetting of the collector and for loss of evaporation from the collector) of 628 mm per year is divided into the evapotranspiration of 325 mm per year, groundwater recharge of 303 mm per year for 30-year average climatic conditions.

A distributed monthly hydrological model for integrating spatial variations of basin topography and rainfall

AbstractHydrological models at a monthly time‐scale are important tools for hydrological analysis, such as in impact assessment of climate change and regional water resources planning. Traditionally, monthly models adopt a conceptual, lumped‐parameter approach and cannot account for spatial variations of basin characteristics and climatic inputs. A large requirement for data often severely limits the utility of physically based, distributed‐parameter models. Based on the variable‐source‐area concept, we considered basin topography and rainfall to be two major factors whose spatial variations play a dominant role in runoff generation and developed a monthly model that is able to account for their influences in the spatial and temporal dynamics of water balance. As a hybrid of the Xinanjiang model and TOPMODEL, the new model is constructed by innovatively making use of the highly acclaimed simulation techniques in the two existing models. A major contribution of this model development study is to adopt the technique of implicit representation of soil moisture characteristics in the Xinanjiang model and use the TOPMODEL concept to integrate terrain variations into runoff simulation. Specifically, the TOPMODEL topographic index ln(a/tanβ) is converted into an index of relative difficulty in runoff generation (IRDG) and then the cumulative frequency distribution of IRDG is used to substitute the parabolic curve, which represents the spatial variation of soil storage capacity in the Xinanjiang model. Digital elevation model data play a key role in the modelling procedures on a geographical information system platform, including basin segmentation, estimation of rainfall for each sub‐basin and computation of terrain characteristics. Other monthly data for model calibration and validation are rainfall, pan evaporation and runoff. The new model has only three parameters to be estimated, i.e. watershed‐average field capacity WM, pan coefficient η and runoff generation coefficient α. Sensitivity analysis demonstrates that runoff is least sensitive to WM and, therefore, it can be determined by a prior estimation based on the climate and soil properties of the study basin. The other two parameters can be determined using optimization methods. Model testing was carried out in a number of nested sub‐basins of two watersheds (Yuanjiang River and Dongjiang River) in the humid region in central and southern China. Simulation results show that the model is capable of describing spatial and temporal variations of water balance components, including soil moisture content, evapotranspiration and runoff, over the watershed. With a minimal requirement for input data and parameterization, this terrain‐based distributed model is a valuable contribution to the ever‐advancing technology of hydrological modelling. Copyright © 2006 John Wiley & Sons, Ltd.

Variability of water balance components in a coffee crop in Brazil

Establishing field water balances is difficult and costly, the variability of their components being the major problem to obtain reliable results. This component variability is presented herein for a coffee crop grown in the Southern Hemisphere, on a tropical soil with 10% slope. It was observed that: rainfall has to be measured with an appropriate number of replicates; irrigation can introduce great variability into calculations; evapotranspiration, calculated as a remainder of the water balance equation, has exceedingly high coefficients of variation; the soil water storage component is the major contributor in error propagation calculations to estimate evapotranspiration; and that runoff can be satisfactorily controlled on the 10% slope through crop management practices.