Water Resources Simulation Research Articles

Relationships between Precipitation and Elevation in the Southeastern Tibetan Plateau during the Active Phase of the Indian Monsoon

The precipitation gradient (PG) is a crucial parameter for watershed hydrological models. Analysis of daily precipitation and elevation data from 30 stations in the southeastern Tibetan Plateau (SETP) during the active phase of the Indian monsoon reveals distinct patterns. Below 3000 m, precipitation generally decreases with increasing altitude. Between 3000 and 4000 m, precipitation patterns are more complex; in western regions, precipitation increases with elevation, whereas in eastern regions, it decreases. Above 4000 m, up to the highest observation point of 4841 m, precipitation continues to decrease with elevation, with a more pronounced decline beyond a critical height. In the SETP, PGs for LYR and NYR are positive, at 11.3 ± 2.7 mm/100 m and 17.3 ± 3.8 mm/100 m, respectively. Conversely, PLZB exhibits a negative PG of −22.3 ± 4.2 mm/100 m. The Yarlung Zangbo River (YLZBR) water vapor channel plays a significant role in these PGs, with the direction and flux of water vapor potentially influencing both the direction and magnitude of the PG. Additional factors such as precipitation intensity, the number of precipitation days, precipitation frequency, and station selection also significantly impact the PG. Notable correlations between elevation and variables such as the number of precipitation days, non-precipitation days, and precipitation intensity. The precipitation intensity gradients (PIGs) are 0.06 ± 0.02 mm/d/100 m, 0.11 ± 0.04 mm/d/100 m, and −0.18 ± 0.04 mm/d/100 m for the three catchments, respectively. Future research should incorporate remote sensing data and expand site networks, particularly in regions above 5000 m, to enhance the accuracy of precipitation–elevation relationship assessments, providing more reliable data for water resource simulation and disaster warning.

Evaluating changes in flood frequency due to climate change in the Western Cape, South Africa

This study assesses the impact of climate change on flood frequency across seven sites in the Western Cape province of South Africa. The calibrated Water Resources Simulation Model (WRSM)/Pitman hydrological model was run using precipitation inputs from two representative concentration pathways (RCP) scenarios (RCP 4.5 and 8.5) using a combination of eight global circulatory models (GCM) for the two periods (2030–2060 and 2070–2100). GCMs were statistically downscaled using the delta change (DC), linear scaling (LS) and quantile delta mapping (QDM) approaches. Average daily discharge was estimated from each downscaled daily precipitation dataset using the Pitman/WRSM model with the Fuller and Sangal estimation methods used to calculate daily instantaneous peak flows. Flood frequency curves (FFC) were generated using the annual maximum series (AMS) for the GCM ensemble mean and individual GCMs for the return periods between 2 and 100 years. FFCs generated based on LS and QDM downscaling methods were aligned for the GCM ensemble mean in terms of the direction of FFCs. Further analysis was conducted using outputs based on the QDM approach, given its suitability in projecting peak flows. Under this method, both Fuller and Sangal FFCs exhibited a decreasing trend across the Jonkershoek and Little Berg River sites; however, estimated quantiles for low-probability events were higher under the Fuller method. This study noted the variation in FFCs from individual GCMs compared to the FFC representing the GCM ensemble mean. Further research on climate change flood frequency analysis (FFA) in South Africa should incorporate other advanced downscaling and instantaneous peak flow estimation (IPF) methods.

Climatic Modeling of Seawater Intrusion in Coastal Aquifers: Understanding the Climate Change Impacts

The study examines the impacts of climate change and sea level rise on coastal aquifers, focusing on the influence of the components of the water cycle on seawater intrusion, and the evolution of the phenomenon in the future. The simulation of coastal water resources was performed using an integrated modeling system (IMS), designed for agricultural coastal watersheds, which consists of inter-connected models of surface hydrology (UTHBAL), groundwater hydrology (MODFLOW), and seawater intrusion (SEAWAT). Climatic models for the adverse impact scenario (RCP8.5) and the medium impact scenario (RCP4.5) of climate change were used. Transient boundary head conditions were set to the coastal boundary, to dynamically represent the rise in sea level due to climate change. The response of groundwater in the coastal Almyros Basin, located in central Greece, was simulated from 1991 to 2100. The findings indicate that seawater intrusion will be advanced in the future, in both climate change scenarios. The models show varying patterns in groundwater recharge, with varying uncertainty projected into the future, and sensitivity to time in the fluctuation of the components of the water cycle.

Assessing Climate Change Impacts on Yield of “Dual‐Priority” Water Rights in Carryover Systems at Catchment Scale

AbstractFuture water availability is threatened by changes in both climate and water demand. Water rights with differing priorities are an important foundation of demand‐side tools (e.g., buyback, water pricing, and water market) to improve water use efficiency and reduce water scarcity, especially in highly regulated river systems. This paper assesses the impact of climate change on water yields from carryover storage with dual‐priority (high/low) water rights allocation systems using a simple and rapid analytical method. The method characterizes reservoir inflows using readily available flow characteristics (annual mean and Cv). We evaluate this method against a water resource simulation model in the Goulburn River basin, Australia. In general, our analytical “dual‐priority” Gould‐Dincer model reproduces water allocation estimates from the simulation model. We further demonstrate this method across 12 Australian catchments to investigate the climate change impact on “dual‐priority” water rights yield at the catchment scale. The hydrological projections show decreasing mean annual runoff and increasing annual runoff variability, except for some catchments in northern Australia. Water yield for high‐priority water rights (HPWRs) and low‐priority water rights (LPWRs) decreases for most catchments except for some catchments in northern Australia. South Dandalup in the 2070s (RCP8.5) shows the largest percentage decrease in HPWR and LPWR yield (about −53.53% and −56.81%, respectively). Our results show that changes in mean annual inflow have a more significant influence on water yield of HPWR and LPWR than Cv. Overall, the simple method provides a rapid assessment of water yields with “dual‐priority” water rights which is applicable across multiple sites at regional or even global scale.

Predictive simulation and optimal allocation of surface water resources in reservoir basins under climate change

Predicting and allocating surface water resources are becoming increasingly important tasks for addressing the risk of water shortages and challenges of climate change, especially in reservoir basins. However, surface water resource management includes many systematic uncertainties and complexities that are difficult to address. Thus, advanced models must be developed to support predictive simulations and optimal allocations of surface water resources, which are urgently required to ensure regional water supply security and sustainable socioeconomic development. In this study, a soil and water assessment tool-based interval linear multi-objective programming (SWAT-ILMP) model was developed and integrated with climate change scenarios, SWAT, interval parameter programming, and multi-objective programming. The developed model was applied to the Xinfengjiang Reservoir basin in South China and was able to identify optimal allocation schemes for water resources under different climate change scenarios. In the forecast year 2025, the optimal water quantity for power generation would be the highest and account for ∼60% of all water resources, the optimal water quantity for water supply would account for ∼35%, while the optimal surplus water released from the reservoir would be the lowest at ≤5%. In addition, climate change and reservoir initial storage would greatly affect the surplus water quantity but not the power generation or water supply quantity. In general, the SWAT-ILMP model is applicable and effective for water resource prediction and management systems. The results from different scenarios can provide multiple alternatives to support rational water resource allocation in the study area.

Comprehensive evaluation and scenario simulation of water resources carrying capacity: A case study in Xiong’an New Area, China

Water resources play a pivotal role in sustaining and shaping urban development. To assess the suitability of a site for urban construction, a water-resource–carrying capacity (WRCC) assessment is typically conducted. Here, we expand on the concept of the WRCC and construct an evaluation system based on the water quantity, quality, watershed and flow (WQQSF). Using this WQQSF evaluation system, we investigated the suitability of water resources for the development of the Xiong’an New Area (XNA) in China. Specifically, we evaluated the WRCC of XNA from 2010 to 2020 and identified the main obstacle factors. By building a system dynamics (SD) model, we analyzed projected changes in the carrying capacity of XNA from 2021 to 2035. The main findings were as follows:(1) the average WQQSF-index was 0.32 from 2010 to 2017, which corresponds to the overload condition, and rises to 0.41 from 2018 to 2020, which corresponds to the critical overload condition. (2) From the perspective of obstacle factors, the water quantity factor has a large influence on the water resources bearing condition of XNA accounting for about 40 %. (3) Considering that XNA is a water-scarce area, we should first ensure the balance between the supply and demand of water resources, and secondly, choose the optimal scenario for the carrying capacity. Among the five scenarios based on uncertainty, the S3 scenario not only meets the balance of water resources supply and demand but also has the best-carrying index, which is 0.7, showing a weak carrying condition. To ensure the sustainable development of WRCC in XNA, water conservation and strict control of population size should be adhered to in the future while increasing water recharge through multiple channels. This study provides a decision basis for the management, rational development, and allocation of WRCC in XNA.

Delivering the latest global water resource simulation results to the public

Increasing demands from governments and businesses for accurate and actionable information regarding water security have led to the development of various interactive websites that provide water risk indicators. However, these websites often lack adequate descriptions of the sources and limitations of their datasets and failure to take any uncertainty associated with water risk indicators into account can have serious consequences. Furthermore, websites that only provide data for specific time points, such as mid-century and end-of-century, may be less useful. To address these limitations, we present the H08 Water Risk Tool, a scientifically rigorous platform designed to assess historical and future water resources.The H08 Water Risk Tool incorporates advanced hydrological simulations that utilize the latest modeling techniques, input data, and parameter calibration methods. Our validation indicates that the temporal variation and spatial distribution characteristics of the historical water risk indicators produced by the H08 Water Risk Tool agree with previous observations. This platform provides the public with high-quality water risk indicators, as well as the tools necessary to interpret these indicators. To ensure complete transparency, the H08 Water Risk Tool uses open-source tools and provides detailed information on its methodology and assumptions.Despite the ongoing Water Action Decade initiative launched by the United Nations, avoiding a global water crisis will require considerable work. The H08 Water Risk Tool will be a defining asset providing comprehensive and realistic assessments of water scarcity, both current and future, as well as helping to prioritize adjustments to climate change.

Compilation simulation of surface water and groundwater resources using the SWAT-MODFLOW model for a karstic basin in Iran

Compilation simulation of surface water and groundwater resources using the SWAT-MODFLOW model for a karstic basin in Iran

Simulation and Evaluation of Water Resources Management Scenarios Under Climate Change for Adaptive Management of Coastal Agricultural Watersheds

The main objective of this paper is to analyze the impact of climate change on water resources management and groundwater quantity and quality in the coastal agricultural Almyros Basin, in Greece. Intensive groundwater abstractions for irrigation and nitrogen fertilization for crop production maximization, have caused a large water deficit, nitrate pollution, as well as seawater intrusion in the Almyros aquifer system. Multi-model climate projections for Representative Concentration Pathways (RCPs 4.5 and 8.5) from the Med-CORDEX database for precipitation and temperature have been used to evaluate the impacts of climate change on the study area. The multi-model climate projections have been bias-corrected with Delta, Delta change of Mean and Variance, Quantile Delta Change, Quantile Empirical Mapping, and Quantile Gamma Mapping methods, and statistically tested to find the best GCM/RCM multi-model ensemble. Simulation of coastal water resources has been performed using an Integrated Modelling System (IMS) that contains connected models of surface hydrology (UTHBAL), groundwater hydrology (MODFLOW), nitrate leaching/crop growth (REPIC), nitrate pollution (MT3DMS), and seawater intrusion (SEAWAT). The results indicate that the best climate multi-model ensemble consists of three (3) climate models for both RCP4.5 and RCP8.5 using the Quantile Empirical Mapping bias-correction method. The IMS was applied for historical and future periods with observed and simulated meteorological inputs (e.g. precipitation and temperature) and various irrigation and agronomic scenarios and water storage works development (i.e. reservoirs). The results indicate that at least deficit irrigation and deficit irrigation along with rain-fed cultivation schemes, combined with or without the development and operation of reservoirs, should be applied to overcome the degradation of groundwater quality and quantity in the study basin. Based on the findings of this work, the water resources management should be adaptive to tackle the water resources problems of the Almyros Basin.

Simulation of water resources carrying capacity of the Hangbu River Basin based on system dynamics model and TOPSIS method

Water resources play a key role in development. The research on water resources carrying capacity (WRCC) is helpful to judge the development status and provide suggestions for regional policy-making. In this study, the System Dynamics (SD) model and the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method are combined to calculate the change of WRCC of the Hangbu River basin from 2015 to 2035 under four development scenarios. The results show that WRCC of each scenario decreases first and then increases. The scenario that prioritizes water resources is the best for the Hangbu River Basin, under which the WRCC will increase to 0.631 in 2035, achieving a good level. This is different from other WRCC studies. Through analysis, the research method and the development level and focus of the study area may be the reasons for this difference. In addition, some suggestions were provided such as focusing on improving the efficiency of irrigation water use and looking at the long-term development of the region.

Hydrological Drought-Indexed Insurance for Irrigated Agriculture in a Highly Regulated System

Water scarcity is an increasingly recurring problem for irrigated agriculture in Mediterranean regions. It is, therefore, necessary to establish technical and financial measures to enable irrigators to deal with this problem. This study presents a new index-based drought insurance scheme in an irrigation district in the Jucar river basin in Spain, a highly regulated water system. Three insurance scheme options were evaluated and, the values of the fair risk premiums, the maximum compensation, and the deductible franchise were established. These insurance schemes were designed in agreement with the preexisting drought system operating rules to reduce moral hazard and adverse selection. Risk-reducing and effective evaluation methods were used to determine the insurance coverage’s viability for irrigators: standard deviation gross margin, minimum gross margin, and RMSL. The proposed insurances were also evaluated using synthetic hydrological time series generated with a stochastic ARMA model through a basin-wide water resource simulation model developed in the DSS Shell AQUATOOL. Financial indicators, such as the basis risk and claim ratio were applied to analyze the economic feasibility for insurance companies. The results show that a suitable and efficient option is an early-bird contract combined with a trigger of emergency or alert state in a multi-year contract. This type of specialized insurance helps to fill the existing gap in traditional insurance schemes for irrigated crops and offered additional coverage to farmers under drought and water scarcity conditions.

Sustainable water resource planning at the basin scale with simultaneous goals of agricultural development and wetland conservation

Abstract Reducing the quantity of water in recent years has increased the competition between development projects and the environment. Wetlands are increasingly under pressure due to human activities. The most serious threats to wetlands are excessive agriculture and the diversion of water for irrigation. In recent years, due to water shortage and drought, wetland dryness in Iran has caused many problems, including the dust crisis. Therefore, planning at the basin scale is necessary to achieve sustainable development, which emphasizes the employment of mathematical models. In this study, using a reliability-based simulation–optimization approach, development planning in the Karkheh basin with the following two objectives is investigated: (1) total area under cultivation of agricultural development sectors and (2) supply reliability of the environmental flow requirement. The Water Evaluation and Planning (WEAP) model is used for the simulation of water resources and the multi-objective particle swarm optimization (MOPSO) algorithm is employed for optimization. The results show that in addition to significantly improving the supply reliability of the wetland requirement (from 55 to 79%), the design of agricultural development projects has been optimized. The reliability-based model has prevented unsustainable developments in the basin. Also, the average supply reliability of agricultural demands has increased from 51% (in previous studies) to 72%.

Delivering the Latest Global Water Resource Simulation Results to the Public

Delivering the Latest Global Water Resource Simulation Results to the Public

Modeling streamflow driven by climate change in data-scarce mountainous basins

The impacts of climate change on the water environment have aroused widespread concern. With global warming, mountainous basins are facing serious water supply situations. However, there are limited meteorological stations on mountains, which thus creates a challenge in terms of accurate simulation of streamflow and water resources. To solve this problem, this study developed a method to model streamflow in data-scarce mountainous basins. Selecting the two head waters originating in the Tienshan mountains, Aksu and Kaidu Rivers, we firstly reconstructed precipitation and temperature dynamics based on Earth system data products, and then integrated the radial basis function artificial neural network and complete ensemble empirical mode decomposition with adaptive noise to model streamflow. Comparison with the observed streamflow according to hydrological stations indicated that the proposed approach was highly accurate. The modeling results showed that the El-Niño Southern Oscillation, temperature, precipitation, and the North Atlantic Oscillation are the main factors driving streamflow, and the streamflow decreased in both the Aksu River and Kaidu River between 2000 and 2017.

Cryosphere Water Resources Simulation and Service Function Evaluation in the Shiyang River Basin of Northwest China

Water is the most critical factor that restricts the economic and social development of arid regions. It is urgent to understand the impact on cryospheric changes of water resources in arid regions in western China under the background of global warming. A cryospheric basin hydrological model (CBHM) was used to simulate the runoff, especially for glaciers and snowmelt water supply, in the Shiyang River Basin (SRB). A cryosphere water resources service function model was proposed to evaluate the value of cryosphere water resources. The annual average temperature increased significantly (p > 0.05) from 1961 to 2016. The runoff of glacier and snowmelt water in the SRB decreased significantly. This reduction undoubtedly greatly weakens the runoff regulation function. The calculation and value evaluation of the amount of water resources in the cryosphere of Shiyang River Basin is helpful to the government for adjusting water structure to realize sustainable development.

Intercomparison of ten ISI-MIP models in simulating discharges along the Lancang-Mekong River basin

Water resources are of strategic importance for socioeconomic development. Many hydrological models (HMs) and land surface models (LSMs) have been developed for water resources assessment. However, systematic evaluation of discharge simulation from multiple models is still lacking in the Lancang-Mekong River basin. Here, we evaluated the performances of ten HMs and LSMs by evaluating their simulated discharge against observations at the basin scale. The selected models were within the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP2a) framework driven by Global Soil Wetness Project 3 (GSWP3) climate forcing data. Five discharge percentile series were used to evaluate the model performances for low, mean, and high flows. The intercomparison according to four statistical criteria revealed considerable differences exist in model performances for different discharge percentiles, indicating a large uncertainty caused by the choice of models with different degree of physical complexity and sensitivity to the quality of the input data. The models generally performed better for high flow than for low flow. Furthermore, the models generally performed better in downstream than in upstream, with the exception of close to the estuary, where complex processes involving interactions between freshwater and saline water are present. It is not surprising that the two calibrated model (WaterGAP2 and WAYS) are superior over the other models. This systematic intercomparison provides insights into the model behaviours and accuracies in discharges predicting with varying intensities, which can aid in quantifying uncertainties in water resources simulation at the basin scale.

Water replenishment for ecological flow with E-WAS framework: a case study of the Longgang River Basin, Shenzhen, China

Abstract. With rapid urbanization, there will be more conflict between human systems and the riverine ecological system, and therefore, ecological operations, practices and research must involve the ecological water replenishment of entire river basins with new modeling tools. In this study, we establish an ecological flow-oriented water resource allocation and simulation framework (E-WAS). Virtual reservoirs and ecological units are added to the water resources network. With new water balance equations for virtual reservoirs and ecological units, the E-WAS can simulate the ecological replenishment process in a river basin and can provide a recommended water replenishment scheme that considers optimization principles. The E-WAS was applied in the Longgang River Basin, Shenzhen, China. 17 ecological units and 45 water supply nodes are considered in the model. A water replenishment scheme that used water from 31 reservoirs and reclaimed water from 7 water sewage plants was selected. This scheme significantly increased the satisfactory degree of ecological water demand and efficiently supported the formulation of a control scheme for the water environment of a basin. The E-WAS framework is similar to model plug-ins but helps to avoid the large workload that is required for model redevelopment and can expand the functions of models quickly.

Simulation and prediction of surface water quality using stochastic models

In recent years, surface water quality has decreased due to the increasing demand for water and increasing the use of fertilizers, pesticides and the discharge of domestic and municipal wastewater to surface water. The purpose of this research is a comparison of the efficiency of different time-series models in modeling and prediction of monthly water quality performance in Harmaleh area of Khuzestan in the southwest of Iran. Water quality parameters including Ca, HCO3, SO4, Ec, pH, Mg, Cl, Na, and TDS for the period of 2001 to 2014 were evaluated. Five time-series models (AR, MA, ARMA, ARIMA, and SARIMA) with 12 different structures were assessed by R software. First, the data were normalized using Kolmogorov–Smirnov test. Also, the adequacy of data was tested by Hurst’s coefficient. The Hurst coefficient was > 0.5 for all investigated parameters, which indicated suitable length of the time series for the modeling. As the components of trend, jump, and seasonality are usually specific, modeling of them is not required, but modeling of stochastic components is of importance in water resources simulation and management. Therefore, using the R software, deterministic parts of the time series (e.g., trend, jump, and seasonality) were eliminated and non-deterministic component (e.g., randomness) was simulated (from 2011 to 2014), and finally, the data were predicted (from 2015 to 2018) based on the optimized models. The optimized models were selected based on auto-correlation function (ACF) and partial auto-correlation function (PACF) as well as the use of Akaike information criteria (AIC) and coefficient of determination. Results showed that in 66% of data ARMA [with the same rate of ARMA (1, 2), ARMA (2, 1), and ARMA (2, 2)], in 22% of data AR (1), and in 11% of data ARIMA (1, 1, 2) models presented the highest efficiency in monthly water quality simulation. Finally, each quality parameter was also predicted for the next 4 years (2015–2018) based on the selected optimized models. Results indicated that the values of SO4 and pH, respectively, showed the highest and lowest correlation with the related observations with a coefficient of determination of 0.54 and 0.19. Overall, modeling of water quality using stochastic models could save time and costs, especially when time series of parameters are long and adequate.

Research on Numerical Simulation and Theoretical Method of Water Resources Carrying Capacity

In this paper, 11 indexes were selected from three aspects: water resources environment, economy and society to construct the evaluation index system, and the main component analysis method was used to comprehensively evaluate the carrying capacity of water resources in Henan province for the past three years. The research results show that: 1. During the current period, the carrying capacity of water resources in Henan Province has been steadily increasing. The cities with good carrying capacity of water resources are: Zhengzhou, Luoyang, Xinxiang and Nanyang; Cities with better water resources capacity include Kaifeng, Pingdingshan, Anyang, Jiaozuo and Xinyang; The remaining cities have general water resources carrying capacity;The contribution of each subsystem to the integrated carrying capacity of water resources is increasing year by year, among which the contribution of water resources environmental subsystem and economic subsystem is the largest and the contribution of social subsystem is relatively stable.The conclusion shows that the development level of Waterscape tourism industry in Zhengzhou, Luoyang, Kaifeng, Jiaozuo and other areas is higher, while the Waterscape tourism industry in Luohe, Xuchang, Zhoukou and other areas is lower. The development level of Waterscape tourism industry in Henan Province from the view of the overall spatial pattern is higher. The water resources management and utilization level of henan is relatively high.

Testing the WEAP Hydrologic Model for Awash Basin, Ethiopia “Soil Moisture Module with Watershed Demand Approach”

The research is financed by the Egyptian Government through the Nile Sector bilateral cooperation project Abstract Currently, there are several hydrological simulation models in use worldwide. Prior to adoption of a model to a specific basin, its feasibility and practicality should be tested. This study highlights on the application of Water Evaluation and Planning system (WEAP) model for hydrologic simulation of Awash river basin in Ethiopia. A monthly time step hydrologic model was developed using the soil moisture rainfall-runoff method incorporated in WEAP with an aim to check the suitability of the model for Awash river basin. For this purpose five selected flow gauge stations located at the upper, middle and lower Awash basin were used as control stations. The model is configured taking into account the effects of development and hence the water abstractions, storage, loss rate, etc. are estimated using the data provided through various kinds of research and survey in Ethiopia. Standard methods are also used to prepare the hydro-metrological and landuse input data for each sub-catchment. Based on data availability, the time period 1986-2005 was selected for the hydrologic simulation. The observed data were split for calibration (1986–1995) and validation (1996–2005) purposes. Initially, the model was set up using the default model parameters. Then, manual calibration is performed to reproduce the observed streamflow. The model-simulated values are compared with those obtained from observations using standard statistical tests on monthly and monthly average basis. From the performance test results, it is observed that the coefficient of determination (R 2 ) and the Index of Agreement (IA) show a good fit. Furthermore, the Nash-Sutcliffe Efficiency (NSE) and the Percent Bias (PBIAS) calibration and validation results show good performance for Upper Awash stations and satisfactory results for the middle and lower Awash control stations. As a conclusion, the main modelling constraints were discussed and possible solutions were also suggested in order to improve the performance of water resources simulation models for the Awash basin. Keywords : Awash Basin, Hydrologic Simulation, Calibration, Validation, Model Performance, WEAP DOI: 10.7176/CER/12-3-07 Publication date: March 31 st 2020