Water Balance Calculations Research Articles

ЗМІНА ВОДНОГО БАЛАНСУ БАСЕЙНУ РІЧКИ ГОРИНЬ В УМОВАХ ПОТЕПЛІННЯ КЛІМАТУ

Warmer climate caused a large complex of effects that appeared in every link of the global hydrological cycle. In most cases, these changes have a non-linear nature and occur with different intensity in hydrological and meteorological systems. Therefore, it is important to study such processes together, which will allow simultaneous detection of their mutual effects. The water balance method, when all components are calculated in the same dimensions (mm), and then compared with each other, is best suited for solving such a problem. The increase in air temperature by 1,2°C caused significant changes in the overall structure of the Horyn River basin water balance: an increase in the expenditure parts uncertainty for the water balance components for the modern period 1991-2020. The closure error increase occurs mainly due to the cost part and its main component of total evaporation. According to Mali Vykorovychi hydrological gauge notes a decrease in the annual precipitation by 18 mm, river runoff by 21 mm, and an increase in total evaporation by 35 mm in absolute values. In the 1961-1990 according to the calculation of climatic water balance, the moisture accumulation prevailed over its utilization almost in 5 times but now, due to the increase in air temperature, their ratio has almost leveled off. Today river water regime almost moved from the excessively moistened to sufficiently moistened, and there are trends indicating the moisture consumption processes dominance in the basin over its accumulation.

Proposing Adjustments to the Dry Season Inter-Reservoir Operation Rules of the Red River System to Improve Water Use Efficiency of the Reservoirs

The Red-Thai Binh River system is an important water resource to the Northern Delta, serving the development of agriculture, people’s livelihood and other economic sectors through its upstream reservoirs and a system of water abstraction works along the rivers. However, due to the impact of climate change and pressure from socio-economic development, the operation of the reservoir system according to Decision No. 740/QD-TTg was issued on June 17, 2019 by the Prime Minister of Government promulgating the Red-Thai Binh River system inter-reservoir operation rules (Operation rules 740) has some shortcomings that need adjustments for higher water use efficiency, meeting downstream water demand and power generation benefits. Through the results of water balance calculation and analysis of economic benefits from water use scenarios, this research proposed adjustment to the inter-reservoir operation during dry season in the Red River system. The result showed that an average water level of 1.0 - 1.7 m should be maintained at Hanoi during the increased release period.

Analysis of Surface Water Availability to Meet Agricultural Water Demands in Kediri Regency, Indonesia

This study aims to analyze the potential of surface water to meet agricultural water needs in Kediri Regency, Indonesia. Data from government agencies (i.e., Indonesian Bureau of Meteorology, Climatology, and Geophysics and Kediri Agriculture Office) and fieldwork were analyzed to achieve the research objectives. The data obtained consisted of rainfall, temperature, infiltration capacity, soil texture, root depth, and agricultural land area. The potential of surface water resources was calculated by using the Thornthwaite–Mather water balance method. The water balance results were compared with agricultural water demands, which were calculated on the basis of the area of agricultural land and type of crop, particularly paddy fields. Critical and noncritical conditions for surface water resources were classified on the basis of the ratio between the availability of surface water resources and the demand for agricultural water. Results showed that the total surface water potential widely varied by season. The water balance calculation indicated that all subwatersheds (SWs) experienced a water surplus in the rainy season, whereas almost all SWs were deficient in surface water in the dry season, Overall, the surface water in Kediri was critical in the rainy season and more severely critical in the dry season. The results of this study indicated that the high demand for agricultural water can affect the availability of water resources in the tropics. The results are expected to be considered in determining regional planning related to the use and need of water resources and supporting infrastructures.

ОЦЕНКА ВЛИЯНИЯ РЫБХОЗА «КРАСНАЯ СЛОБОДА» НА СТОК РЕКИ МОРОЧЬ

A comprehensive assessment of the impact of the Krasnaya Sloboda fish farm on the hydrological regime of the Moroch River in the calculated areas was carried out. The following methods were used in the work: field research, desk data processing, geographical analysis, statistical analysis, regression analysis, water balance calculations. The analysis of the hydrological regime of the calculated sections of the river used for the needs of the fish farm made it possible to determine the minimum average monthly water consumption of 95% probability of excess and ecological runoff, taking into account the intra-annual distribution of runoff. For the central section of the Krasnaya Sloboda fish farm, the permissible volume of withdrawal of water resources from the Moroch River has been determined.

How does dewfall affect drought assessment in different climate regions in China

Dewfall is an important source of additional precipitation, but it is frequently ignored in water balance calculations. In this study, the dewfall of 523 weather stations in China was calculated. An improved drought index SPI-cor was proposed by substituting the precipitation with the summation of dewfall and precipitation by the SPI calculation method, where dewfall was calculated by the Penman-Monteith equation with the GLDAS-2 data. The temporal and spatial distributions characteristics of dewfall were discussed, and the spatial applicability of SPI and SPI-cor was determined. The results indicated that the dewfall formation is periodic, with more than 60% of the dewfall occurring between April and August. The amount of dewfall is lower than that of precipitation. The dewfall in China has a distribution pattern of high dewfall in the northeast and northwest but low dewfall in the center and south. The proportion of dewfall in precipitation increases from south to north with the exception of northwestern China. Comparing of SPI to SPI-cor, the influence of dewfall in arid, semi-arid, sub-humid and humid areas declines in turn in accordance with the proportion of dewfall in precipitation of the four regions and is opposite to the correlation coefficients of SPI and SPI-cor. Dewfall has an average impact of one drought grade on the assessment of drought as long as it works. With the performance of SPI and SPI-cor at different weather stations, historical drought events, and vegetation response to drought, SPI is better in northeastern China and eastern Inner Mongolia, while SPI-cor is more applicable in central and northwestern China; the difference between SPI and SPI-cor drought grades are not noticeable in southern China. Therefore, adopting SPI and SPI-cor to evaluate drought in different regions can help to make more accurate drought assessment.

Baseflow index on Miu watershed based on a digital graphical method

Baseflow is essential for water resource management in the dry season at the watershed scale. Management strategy water resources play a crucial role, especially those related to estimation efforts water supply, water quality management, water balance calculation, and strategy development of other water resources. This study aims to determine the value of baseflow using the Fixed Interval Method. This study used Hydro Office software with input daily discharge data from 2004 to 2013. The average baseflow value obtained was 5.53 m3/s, the process of calibrating by taking discharge data in the dry season, with no rainfall input. The BFI value obtained an average of 0. 9. This value indicates that the Miu watershed has high storage permeability characteristics. It indicates that the Miu watershed has a relatively stable flow during dry periods. The greater the BFI value, the better the water supply in a watershed.

Storage variability controls seasonal runoff generation in catchments at the threshold between energy and water limitation

AbstractAnnual water balance calculations may elide intra‐annual variability in runoff generation, which could limit understanding of the similarities and differences between water‐ and energy‐limited catchments. This may be especially important in comparisons between catchments close to the threshold between water‐ and energy‐limitation. For this study, we examined runoff generation as a function of catchment storage in four watersheds, with focus on two that exist close to these thresholds, to identify how year‐to‐year variability in storage that results in intra‐annual variations of runoff generation efficiency. Specifically, we focused on one energy‐limited catchment in the humid subtropics and one water‐limited catchment in a Mediterranean climate. We used measured and calculated daily water balance components to calculate variations in the relative magnitude of daily storage. We isolated precipitation events to draw connections between storage and runoff generation at intra‐annual scales and compared our findings to the same metrics in two intensely energy‐limited landscapes. We observed distinct stages in daily storage across water years in watersheds at the threshold, where systems experienced wet‐up, plateau, and dry‐down stages. During the wet‐up, precipitation was partitioned to storage and runoff ratios (RR) were low. In the plateau, storage was filled and precipitation was partitioned to runoff, causing high RRs. During the dry‐down, storage decreased as precipitation was partitioned to evapotranspiration and runoff, causing low RRs. The critical role of evapotranspiration during the growing season resulted in relatively higher RRs during the wet‐up than during the dry‐down for a given storage value. Thus, the same storage amount was partitioned to evapotranspiration or runoff differently throughout the year, depending on the storage stage. Despite their different positions on opposite sides of the threshold, the similarity between the two focus catchments suggests a potential characteristic behaviour of systems at the threshold common to both humid and semi‐arid landscapes.

Characterizing groundwater flow in a former uranium mine (Bertholène, France): Present status and future considerations

Study regionBertholène is a former uranium mine in Aveyron, where tailings and waste rocks are stored in a natural valley. This results in acid mine drainage (AMD) at the outlet of the tailings storage facility (TSF), where there is a dedicated water treatment plant. Study focusA detailed data analysis was conducted using data from 13 piezometers and from long-term monitoring of the local climate. A 3D model was developed using MODFLOW to understand groundwater flows at the catchment scale and identify flow paths from the contamination sources within the TSF. Previous geochemical modeling of TSFs had indicated that AMD was expected to occur for 50–100 years, therefore the site must be managed with a long-term view. As climate change may affect not only the recharge but also the frequency and intensity of extreme events, its impact on water balance and water levels at the site has to be studied for the next 100 years. New Hydrological Insights for the RegionData analysis provides information about the unsaturated conditions within the tailings. Then water balance calculations at the TSF outlet validate the contribution of two different water zones. Modeling using the recharge estimation supports the current functioning of the catchment. The impact study of extreme events shows that the water table should not permanently reach the tailings over the next century.

Modeling leachate generation: practical scenarios for municipal solid waste landfills in Poland

The idea of water balance calculations within the landfill is to determine the distribution of water input and output, and finally the volume of leachate generated. The scope of this data is essential for rational planning of water and wastewater management, and designing leachate drainage network and leachate treatment systems. The aim of this study was to assess the possible amounts of leachate generation regarding ten different scenarios of landfill sealing systems. The calculations were performed using the Hydrologic Evaluation of Landfill Performance (HELP) model. It was revealed that the greatest share among the components of water balance in the landfill has precipitation (on average 509 mm in the 5-year period of simulation), together with evapotranspiration (on average 391 mm in the 5-year period of simulation). The study shows that the minimum amount of leachate (797–803 m3/year) occurs when the best placement quality (=5) is regarded for the geomembrane installed in the bottom of the landfill. The maximum leachate generation (830 m3/year) was found for those scenarios in which only three layers of bottom sealing systems were adopted, with the worst placement quality (=1) assigned to geomembranes. The results of this study confirm that the application of multilayer sealing systems has visible impact on the reduction of leachate generation of around 33 m3/year.

Machine Learning Assisted Reservoir Operation Model for Long‐Term Water Management Simulation

ABSTRACTThis study explores strategies for long‐term reservoir simulations by combining generic rule‐based reservoir management model (RMM) and machine learning (ML) models for two major multipurpose reservoirs — Allatoona Lake and Lake Sidney Lanier in the southeastern United States. First, a standalone RMM is developed to simulate daily release and storage during Water Year 1981–2015. Next, using Long‐Short Term Memory (LSTM) as the ML technique, a standalone LSTM model is trained based on reservoir inflow and meteorological observations to simulate reservoir release and estimate reservoir storage through water balance calculation. Three hybrid modeling strategies are developed, one using RMM output as an additional LSTM input (H1), another using LSTM as the initial release estimate in RMM (H2), and the third combining the first two strategies (H3). The Nash–Sutcliffe efficiency (NSE) for release (NSE‐r), storage (NSE‐s), and their mean (NSE‐avg) are used for model evaluation. Overall, H1 improves NSE‐r to 0.65 and 0.54 for Allatoona and Lanier, respectively, compared to standalone RMM (0.44 and 0.21); however, its storage trajectory did not produce a physically feasible solution, similar to LSTM. H2 and especially H3 show that they can retain the best features from RMM and LSTM, with H3 NSE‐avg being 0.695 and 0.55 for Allatoona and Lanier outperforming RMM (0.615 and 0.29). The findings suggest a robust simulation capacity for large‐scale water management in future studies.

Apply MIKE 11 model to study impacts of climate change on water resources and develop adaptation plan in the Mekong Delta, Vietnam: a case of Can Tho city.

Can Tho city in the Mekong Delta is in the top ten areas affected by climate change. Therefore, assessing climate change impacts, social and economic activities require proposed solutions to respond to climate change. This study aims to (i) apply the MIKE 11 model (Hydrodynamic module and Advection-Dispersion module) to simulate the impacts of climate change scenarios on water resources in Can Tho city; (ii) calculate water balance in Can Tho city; and (iii) suggest climate change adaptation plan for sustainable social-economic activities of the city. The results show that when the rainfall changes due to climate change, the flow rate tends to decrease at high tide and increase at low tide. When the sea level rises due to climate change, the flow rate tends to increase at high tide and decrease at low tide. For 2030, the flow will decrease up to 15.6% and 14.3% at the low tide period for RCP 2.6 and RCP 8.5 compared to the present, respectively. The flow will increase up to 63.5% and 58.9% at the high tide period for RCP 2.6 and RCP 8.5 compared to the present, respectively. The water demand evaluation shows that the water resource reserve in Can Tho city meets water demands in current and future scenarios under climate change. While rainwater and groundwater can provide enough water in the rainy season, the city has to use surface water during the dry season due to a lack of rainwater. Of these, agriculture contributes the most water demands (85%). Eight adaptation measures to climate change for Can Tho city are developed from 2021 to 2050.

Analysis of meteorological water availability and water demand in Semarang Regency

Population growths are increasing the demand for water. This can cause an imbalance of water availability to fulfill domestic water demand. Therefore, it is necessary to analyze the water availability and water demand so that water resources are maintained and can fulfill the community needs in the present and future. This research aims to analyze the water availability and domestic water demand in Semarang Regency. The methods consist of calculating monthly rainfall, calculating water balance using F. J Mock model, calculating the water demand regarding to the water availability, and calculating how much water can be obtained from rain harvesting. The results show the highest annual water availability in Semarang Regency is Pringapus district 48,559,764.55 m3/year, while the the lowest is Kaliwungu district 17,352,024.13 m3/year. The highest domestic water demand are in West Ungaran district, East Ungaran district, and Bergas district, while the lowest are in Bancak and Kaliwungu district. The total water demand is 6% of the total water availability, means there is no water deficit in Semarang Regency. The total volume of rainwater harvested is 120,163,412 m3/year which means the volume of rainwater harvested in one year can fulfill the domestic water demand in Semarang Regency.

Evaluating Reference Crop Evapotranspiration of the Selected Field Crops Grown in Different Agricultural Regions in the Vietnamese Mekong Delta

The water balance in six selected crops (mung beans, tomatoes, maize, cassava, yam, and sweet potatoes) was determined at the field block scale in the Vietnamese Mekong Delta for two agricultural growing areas. A novel approach for the calculation of water balance was employed, which combined the reference crop evapotranspiration (ETo), derived from four methods, namely, Penman-Monteith, Blaney-Criddle, Thornthwaite, and Turc. The equation of Penman-Monteith is generally considered to be the most representative to calculate the ETo value. The reference crop evapotranspiration for some crops was calculated. The daily ETo ranges from 1.8 to 7.5 mm, while a monthly ETo ranges from 3.5 to 5.0 mm. The calculations of the water balances show that irrigation is necessary for crops grown on raised beds crops during the dry season. The results show a promising approach for evaluating the water regime to satisfy crop water requirements.

Hydrogeology of a complex karst catchment in Southern Dalmatia (Croatia) and Western Herzegovina (Bosnia and Herzegovina)

ABSTRACT Our study focuses on a sizeable transboundary karst catchment in Croatia and Bosnia and Herzegovina, extending over 2000 km2. A complex underground conduit system and extreme karst forms heterogeneity are the main characteristics of the area in question. Since determining the boundary of such a large and complex catchment is difficult, we used different kinds of data sets, of which the most relevant are the available geological data, hydrochemical data, hydrological data, and tracing tests data, to divide the regional catchment into six subcatchments. We also examined past archived reports and carried out new hydrological investigations of several major and minor springs. Our research results in a hydrogeological map that can be used as a base for establishing site-specific groundwater protection zones, for water balance calculations and the planning of new research in this area, especially the ones regulating combined cross-border efforts to prevent groundwater contamination and ensure sufficient drinking water.

Water balance calculation capability of hydrological models

Currently, in the world, there are many different hydrological models built and developed to solve problems related to the hydrological cycle. Each model has its specific mathematical foundations to describe physical processes in nature. Therefore, each model has its various characteristics: setting up the model, input data requirements, model calibration and verification, and output results. Water balance is still playing an important role in the effective management and use of water resources for agriculture. Based on the results of the hydrological parameter’s calculation, the water balance of the study basin can be calculated by the user or by the separated module of each model. Each hydrological models have its advantages and disadvantages. However, it is impossible to simulate hydrological processes and water balance completely accurately in nature. Still, simulation results can give us a view of the changing trend of hydrological components and the water balance. Model developers are gradually completing the shortcomings and improving the efficiency and accuracy so that the model can simulate reality with the highest accuracy. This paper sets out to review the fifteen hydrological models currently widely used in the world. Within the frame of the present study, some models are only briefly introduced; the rest are considered in more detail, from more aspects, from specific examples so that readers can decide for themselves which model is suitable for their study area and simulation needs, especially in the identity of the complex and unpredictable impacts of climate change on the agricultural sector.

Hydrological mass balance of boreal watersheds in the Canadian Shield

This study aims at evaluating the hydrological balance of large watersheds of the Canadian Shield in the James Bay area in Northwestern Quebec, Canada. The focus is set on six rivers of the Canadian Shield altogether draining more than 185,000 km2 of the Boreal Shield, Taiga Shield and Hudson Plains ecozones of Canada. River discharge measurements, geochemical data (δ2H, δ18O and electrical conductivity [EC] of water), remote sensing, and GIS models are used jointly to calculate water balances. The approach allows for partitioning the influence of rainwater, snowmelt, surface runoff, evaporation, transpiration, and groundwater discharge to the hydrological balances of watersheds. On an annual basis, the results suggest that runoff from rainwater (30–61 % of total precipitation) and snowmelt (18–40 % of total precipitation) are the main contributions to river discharge, while the contribution of groundwater discharge to rivers represents < 12 % of the total precipitation. Over the study area, this contribution represents 2–5 km3 of water. The stable isotope mass balances allow for estimating watershed-scale evaporation over inflow ratios ranging between 2 and 10 % and suggest that transpiration has an isotopic composition close to summer rainwater. The hydrological balances further suggest that the total pool of water stored in the active portion of watersheds represents 10–20 % of the total annual precipitation, while the exports of groundwater beyond the limits of surface watersheds are negligible. The seasonal trends in the hydrological balances of monitored watersheds were further documented to provide insights into the sensitivity of watersheds as they face climate change. The observations are used to propose recommendations for monitoring of rivers in the Canadian Shield and to identify future research needs.

ASSESSMENT OF THE LAHVA FISH FARM IMPACT ON THE SMERD RIVER RUNOFF

A comprehensive assessment of the fish farm "Lahva" impact on the hydrological regime of the Smerd River was carried out. The following methods were used in the work: field research, desk data processing, geographical analysis, statistical analysis, regression analysis, water balance calculations. The analysis of the hydrological regime of the calculated sections of the river used for the needs of the fish farm made it possible to determine the minimum average monthly water runoff of 95% probability of excess and ecological runoff taking into account the intra-annual runoff distribution. The permissible volume of the water resources withdrawal from the Smerd River for the central section of the fish farm "Lahva" has been determined.

Water Balance Calculation Based on Hydrodynamics in Reservoir Operation

Reservoir operation plays an important role in reservoir management. In reservoir operation, water balance calculation is a very important step. At present, one of the main challenges is that reservoir inflow cannot be calculated accurately due to jacking of the reservoir, which is produced by a downstream reservoir after the original course of the river has changed. Another reason that reservoir capacity cannot be calculated accurately is due to the influence of dynamic storage capacity. In order to overcome these problems, this report shows that the land zone in front of the dam can be used to calculate reservoir capacity, since it can serve as the boundary for a hydrodynamic model, which can then be used to calculate reservoir inflow to improve accuracy. The Three Gorges Dam was selected as a case study. The results show that compared with the measured data, the RMSE (root mean square error) of the proposed model was 8.5%, whereas the RMSE of the traditional model was 25.9%. The contributions and novelty of this paper are: (a) the proposed model combines a hydrodynamic model with a water balance calculation model to make the calculation of inflow more accurate; (b) the land zone in front of the dam can be used to make the calculation of reservoir capacity more accurate; (c) the proposed method provides a new way to calculate water balance, which can be used for short-term reservoir operation. The application results indicate that this study can provide technical support for the fine operation of reservoirs.

Long-Term Evolution of Rainfall and Its Consequences on Water Resources: Application to the Watershed of the Kara River (Northern Togo)

The Kara River watershed (KRW), northern Togo, is facing climate-change impacts that have never been clearly characterized. Six decades of rainfall data (1961–2020) from six measuring stations ideally distributed across the watershed were used in this study. The flow records from two stations situated in contrasting locations on the KRW were also used. Statistical tests were conducted to assess the spatial and temporal variability of the rainfall and to detect tendencies within these meteorological series. The water balance method and calculation of the dry-off coefficient and of the groundwater volume drained by rivers allowed evaluating the impact of climatic evolution on surface flow and on groundwater volumes during the six decades studied. The results showed contrasting spatiotemporal variability of rainfall (and of aquifer recharge) over the watershed with a decreasing tendency upstream and an increasing one downstream. At the same time, the water volume drained by the aquifer to sustain the river’s base flow decreased from −22% to −36% depending on the measuring station. These results constitute a decision-making tool for Togolese water resource managers and are of primary importance for characterizing the fate of water resources worldwide in regions subject to severe droughts.

Historical and future Palmer Drought Severity Index with improved hydrological modeling

With the ongoing climate warming, changes in drought and the adverse effects on water resources, food production and ecosystem functioning have been key research topics of ever-increasing interest. The Palmer Drought Severity Index (PDSI) is among the most widely used indicators for drought monitoring and research. However, the two-layer bucket water balance model embedded in the original PDSI model has been criticized for being over-simplified to accurately quantify the surface water balance and therefore raising uncertainties in the subsequent PDSI estimates (PDSIoriginal). Here we improve the water balance calculations in the PDSI model by using direct hydrological outputs from physically-based, more sophisticated global hydrological models (GHMs) participated in the Inter-Sectoral Impact Model Inter-Comparison Project (ISIMIP). Validation results show that the estimated runoff (Q) and evapotranspiration (ET) from ISIMIP GHMs perform much better than those from the original PDSI two-layer bucket model in capturing the long-term trend and monthly variabilities of Q and ET, especially in cold regions and relatively dry areas, using observed Q (at 2191 catchments) and an independent satellite-based ET product (the Global Land Evaporation Amsterdam Model, GLEAM; over the entire terrestrial environment) as the reference. In addition, the new PDSI estimates with improved hydrological modeling (PDSIISIMIP) exhibit a significantly stronger correlation with observed Q than PDSIoriginal in nearly all studied catchments, suggesting that PDSIISIMIP is superior to PDSIoriginal in capturing hydrological droughts. We further compare the long-term PDSI trends and changes in drought using PDSIoriginal and PDSIISIMIP under both historical climate (1900–2005) and future climate change scenarios (2006–2099). We find that PDSIoriginal and the PDSIoriginal-identified land areas under drought generally show a larger trend than those based on PDSIISIMIP. For future climate change scenarios, the PDSIoriginal-projected increasing trend of land proportion under drought is about two times larger than that assessed with PDSIISIMIP, implying that PDSIoriginal may largely overestimate future drought increases, as commonly done in existing studies. In this light, our approach of directly using hydrological outputs from physically-based, more sophisticated GHMs provide an effective, yet relatively simple approach to reduce uncertainties in PDSI estimates thereby achieving a better prediction of drought changes under warming.