Global water dynamics: issues for the 21st century

2002 ◽  
Vol 45 (8) ◽  
pp. 53-64 ◽  
Author(s):  
Slobodan P. Simonovic
Keyword(s):  
Water Balance ◽  
System Dynamics ◽  
Water Use ◽  
Water Availability ◽  
Global Scale ◽  
Water Dynamics ◽  
Novel Approach ◽  
Collapse Behavior ◽  
Global World ◽  
Global Water

The WorldWater system dynamics model has been developed for modeling the global world water balance and capturing the dynamic character of the main variables affecting water availability and use in the future. Despite not being a novel approach, system dynamics offers a new way of addressing complex systems. WorldWater simulations are clearly demonstrating the strong feedback relation between water availability and different aspects of world development. Results of numerous simulations are contradictory to the assumption made by many global modelers that water is not an issue on the global scale. Two major observations can be made from early simulations: (a) the use of clean water for dilution and transport of wastewater, if not dealt with in other ways, imposes a major stress on the global world water balance; and (b) water use by different sectors is demonstrating quite different dynamics than predicted by classical forecasting tools and other water-models. Inherent linkages between water quantity and quality sectors with food, industry, persistent pollution, technology, and non-renewable resources sectors of the model create shoot and collapse behavior in water use dynamics. This paper discusses a number of different water-related scenarios and their implications on the global water balance. In particular, two extreme scenarios (business as usual – named “Chaos”, and unlimited desalination – named “Ocean”) are presented in the paper. Based on the conclusions derived from these two extreme cases a set of more moderate and realistic scenarios (named “Conservation”) is proposed and their consequences on the global water balance are evaluated.

scholarly journals GlobWat – a global water balance model to assess water use in irrigated agriculture

2015 ◽  
Vol 19 (9) ◽  
pp. 3829-3844 ◽  
Author(s):  
J. Hoogeveen ◽  
J.-M. Faurès ◽  
L. Peiser ◽  
J. Burke ◽  
N. van de Giesen
Keyword(s):  
Water Balance ◽  
Water Use ◽  
Open Water ◽  
Water Balance Model ◽  
Green Water ◽  
Balance Model ◽  
Irrigated Agriculture ◽  
High Resolution Data ◽  
Food And Agriculture ◽  
Global Water

Abstract. GlobWat is a freely distributed, global soil water balance model that is used by the Food and Agriculture Organization (FAO) to assess water use in irrigated agriculture, the main factor behind scarcity of freshwater in an increasing number of regions. The model is based on spatially distributed high-resolution data sets that are consistent at global level and calibrated against values for internal renewable water resources, as published in AQUASTAT, the FAO's global information system on water and agriculture. Validation of the model is done against mean annual river basin outflows. The water balance is calculated in two steps: first a "vertical" water balance is calculated that includes evaporation from in situ rainfall ("green" water) and incremental evaporation from irrigated crops. In a second stage, a "horizontal" water balance is calculated to determine discharges from river (sub-)basins, taking into account incremental evaporation from irrigation, open water and wetlands ("blue" water). The paper describes the methodology, input and output data, calibration and validation of the model. The model results are finally compared with other global water balance models to assess levels of accuracy and validity.

scholarly journals Variations of global and continental water balance components as impacted by climate forcing uncertainty and human water use

2016 ◽  
Vol 20 (7) ◽  
pp. 2877-2898 ◽  
Author(s):  
Hannes Müller Schmied ◽  
Linda Adam ◽  
Stephanie Eisner ◽  
Gabriel Fink ◽  
Martina Flörke ◽  
...  
Keyword(s):  
Water Resources ◽  
Water Balance ◽  
Water Use ◽  
Climate Forcing ◽  
Land Area ◽  
Water Balance Components ◽  
Climate Forcings ◽  
The Impact ◽  
Global Water

Abstract. When assessing global water resources with hydrological models, it is essential to know about methodological uncertainties. The values of simulated water balance components may vary due to different spatial and temporal aggregations, reference periods, and applied climate forcings, as well as due to the consideration of human water use, or the lack thereof. We analyzed these variations over the period 1901–2010 by forcing the global hydrological model WaterGAP 2.2 (ISIMIP2a) with five state-of-the-art climate data sets, including a homogenized version of the concatenated WFD/WFDEI data set. Absolute values and temporal variations of global water balance components are strongly affected by the uncertainty in the climate forcing, and no temporal trends of the global water balance components are detected for the four homogeneous climate forcings considered (except for human water abstractions). The calibration of WaterGAP against observed long-term average river discharge Q significantly reduces the impact of climate forcing uncertainty on estimated Q and renewable water resources. For the homogeneous forcings, Q of the calibrated and non-calibrated regions of the globe varies by 1.6 and 18.5 %, respectively, for 1971–2000. On the continental scale, most differences for long-term average precipitation P and Q estimates occur in Africa and, due to snow undercatch of rain gauges, also in the data-rich continents Europe and North America. Variations of Q at the grid-cell scale are large, except in a few grid cells upstream and downstream of calibration stations, with an average variation of 37 and 74 % among the four homogeneous forcings in calibrated and non-calibrated regions, respectively. Considering only the forcings GSWP3 and WFDEI_hom, i.e., excluding the forcing without undercatch correction (PGFv2.1) and the one with a much lower shortwave downward radiation SWD than the others (WFD), Q variations are reduced to 16 and 31 % in calibrated and non-calibrated regions, respectively. These simulation results support the need for extended Q measurements and data sharing for better constraining global water balance assessments. Over the 20th century, the human footprint on natural water resources has become larger. For 11–18% of the global land area, the change of Q between 1941–1970 and 1971–2000 was driven more strongly by change of human water use including dam construction than by change in precipitation, while this was true for only 9–13 % of the land area from 1911–1940 to 1941–1970.

scholarly journals GlobWat – a global water balance model to assess water use in irrigated agriculture

2015 ◽  
Vol 12 (1) ◽  
pp. 801-838 ◽  
Author(s):  
J. Hoogeveen ◽  
J.-M. Faurès ◽  
L. Peiser ◽  
J. Burke ◽  
N. van de Giesen
Keyword(s):  
Water Balance ◽  
Water Use ◽  
Open Water ◽  
Water Balance Model ◽  
Green Water ◽  
Balance Model ◽  
Irrigated Agriculture ◽  
Global Soil ◽  
Spatially Distributed ◽  
Global Water

Abstract. GlobWat is a freely distributed, global soil water balance model that is used by FAO to assess water use in irrigated agriculture; the main factor behind scarcity of freshwater in an increasing number of regions. The model is based on spatially distributed high resolution datasets that are consistent at global level and calibrated against values for Internal Renewable Water Resources, as published in AQUASTAT, FAO's global information system on water and agriculture. Validation of the model is done against mean annual river basin outflows. The water balance is calculated in two steps: first a "vertical" water balance is calculated that includes evaporation from in situ rainfall ("green" water) and incremental evaporation from irrigated crops. In a second stage, a "horizontal" water balance is calculated to determine discharges from river (sub-)basins, taking into account incremental evaporation from irrigation, open water and wetlands ("blue" water). The paper describes methodology, input and output data, calibration and validation of the model. The model results are finally compared with other global water balance models.

scholarly journals A global water scarcity assessment under Shared Socio-economic Pathways – Part 2: Water availability and scarcity

2013 ◽  
Vol 17 (7) ◽  
pp. 2393-2413 ◽  
Author(s):  
N. Hanasaki ◽  
S. Fujimori ◽  
T. Yamamoto ◽  
S. Yoshikawa ◽  
Y. Masaki ◽  
...  
Keyword(s):  
Water Use ◽  
Water Availability ◽  
Water Scarcity ◽  
Climate Models ◽  
Water Cycle ◽  
Electricity Production ◽  
Daily Consumption ◽  
Water Abstraction ◽  
Daily Water ◽  
Global Water

Abstract. A global water scarcity assessment for the 21st century was conducted under the latest socio-economic scenario for global change studies, namely Shared Socio-economic Pathways (SSPs). SSPs depict five global situations with substantially different socio-economic conditions. In the accompanying paper, a water use scenario compatible with the SSPs was developed. This scenario considers not only quantitative socio-economic factors such as population and electricity production but also qualitative ones such as the degree of technological change and overall environmental consciousness. In this paper, water availability and water scarcity were assessed using a global hydrological model called H08. H08 simulates both the natural water cycle and major human activities such as water abstraction and reservoir operation. It simulates water availability and use at daily time intervals at a spatial resolution of 0.5° × 0.5°. A series of global hydrological simulations were conducted under the SSPs, taking into account different climate policy options and the results of climate models. Water scarcity was assessed using an index termed the Cumulative Abstraction to Demand ratio, which is expressed as the accumulation of daily water abstraction from a river divided by the daily consumption-based potential water demand. This index can be used to express whether renewable water resources are available from rivers when required. The results suggested that by 2071–2100 the population living under severely water-stressed conditions for SSP1-5 will reach 2588–2793 × 106 (39–42% of total population), 3966–4298 × 106 (46–50%), 5334–5643 × 106 (52–55%), 3427–3786 × 106 (40–45%), 3164–3379 × 106 (46–49%) respectively, if climate policies are not adopted. Even in SSP1 (the scenario with least change in water use and climate) global water scarcity increases considerably, as compared to the present-day. This is mainly due to the growth in population and economic activity in developing countries, and partly due to hydrological changes induced by global warming.

scholarly journals An integrated model for the assessment of global water resources – Part 2: Applications and assessments

2008 ◽  
Vol 12 (4) ◽  
pp. 1027-1037 ◽  
Author(s):  
N. Hanasaki ◽  
S. Kanae ◽  
T. Oki ◽  
K. Masuda ◽  
K. Motoya ◽  
...  
Keyword(s):  
Water Resources ◽  
Water Use ◽  
Water Availability ◽  
Asian Monsoon ◽  
Environmental Flow ◽  
Water Withdrawal ◽  
Monsoon Region ◽  
Asian Monsoon Region ◽  
Meteorological Forcing ◽  
Global Water

Abstract. To assess global water resources from the perspective of subannual variation in water availability and water use, an integrated water resources model was developed. In a companion report, we presented the global meteorological forcing input used to drive the model and six modules, namely, the land surface hydrology module, the river routing module, the crop growth module, the reservoir operation module, the environmental flow requirement module, and the anthropogenic withdrawal module. Here, we present the results of the model application and global water resources assessments. First, the timing and volume of simulated agriculture water use were examined because agricultural use composes approximately 85% of total consumptive water withdrawal in the world. The estimated crop calendar showed good agreement with earlier reports for wheat, maize, and rice in major countries of production. In major countries, the error in the planting date was ±1 mo, but there were some exceptional cases. The estimated irrigation water withdrawal also showed fair agreement with country statistics, but tended to be underestimated in countries in the Asian monsoon region. The results indicate the validity of the model and the input meteorological forcing because site-specific parameter tuning was not used in the series of simulations. Finally, global water resources were assessed on a subannual basis using a newly devised index. This index located water-stressed regions that were undetected in earlier studies. These regions, which are indicated by a gap in the subannual distribution of water availability and water use, include the Sahel, the Asian monsoon region, and southern Africa. The simulation results show that the reservoir operations of major reservoirs (>1 km3) and the allocation of environmental flow requirements can alter the population under high water stress by approximately −11% to +5% globally. The integrated model is applicable to assessments of various global environmental projections such as climate change.

scholarly journals ANALISIS SISTEM DINAMIK NERACA AIR DI PULAU TIDORE

2018 ◽  
Vol 8 (2) ◽  
Author(s):  
Halima Malaka ◽  
M. Yanuar ◽  
J. Purwanto ◽  
Alinda Zein
Keyword(s):  
Water Balance ◽  
Ground Water ◽  
Water Use ◽  
Water Availability ◽  
Water Demand ◽  
Model Simulation ◽  
Balance Model ◽  
Balance System ◽  
Simulation Scenario ◽  
Availability Index

This research was conducted at Tidore Island, –Tidore City, North Maluku Archipelago Province. Objective of this study were  1) build a water balance model Tidore Island. This Method used in this research is method of survey with water balance analysis. Analysis of the data used is the analysis of dynamic system to determine the balance of the year 2009 - 2032 with software stella version 9.0.2. The result of analysis showed that in 2009 there were water balance 21,189,941.20 m3 / year and in 2032 there was a deficit of 427,678.61 m3 / year. Water availability index (IKA) in 2009 amounted to 1416.10 and in the year 2032 amounted to 82.54 IKA the value, it indicates that in 2032 the availability of groundwater only able to serve 82.54% the water demand. To improve the balance of water needed for water saving and conservation policies at each land use.Saving measures water use and conservation of groundwater done using three policy scenarios, the model simulation results indicate that both scenarios can increase the efficiency of water use and water balance in 2009 to 21,270,444.14 m3 / year with a value of 1490.63 and value IKA in 2032 can be water deficit of 31128.46 m3 / year. While the results of the simulation scenario 3 scenario between saving integrated water use and conservation can improve the water balance in 2009 amounted to 21,350,947.08 m3 / year and the value IKA 1573.44, and in 2032 the value decreased to 117.92 IKA shows the availability of ground water able to serve 117.92% of  water demand  people. Keywords: water balance,system dynamic, water demand, ground water availability

scholarly journals Understanding each other's models: a standard representation of global water models to support improvement, intercomparison, and communication

2021 ◽  
Author(s):  
Camelia-Eliza Telteu ◽  
Hannes Müller Schmied ◽  
Wim Thiery ◽  
Guoyong Leng ◽  
Peter Burek ◽  
...  
Keyword(s):  
Water Use ◽  
Water Cycle ◽  
Evaluation Studies ◽  
Model Development ◽  
Water Storage ◽  
Global Scale ◽  
Comprehensive Overview ◽  
Hydrologic Processes ◽  
Water Models ◽  
Global Water

Abstract. Global water models (GWMs) simulate the terrestrial water cycle, on the global scale, and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modeling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how state-of-the-art GWMs are designed. We analyze water storage compartments, water flows, and human water use sectors included in 16 GWMs that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to further enhance model improvement, intercomparison, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Seven models used six compartments, while three models (JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water used by humans for the irrigation sector. We conclude that even though hydrologic processes are often based on similar equations, in the end, these equations have been adjusted or have used different values for specific parameters or specific variables. Our results highlight that the predictive uncertainty of GWMs can be reduced through improvements of the existing hydrologic processes, implementation of new processes in the models, and high-quality input data.

Integrating Climate and Socio-Economic Scenarios in a Hydrological Model for the Santa River Basin, Peru

2020 ◽  
Author(s):  
Claudia Teutsch ◽  
Faizan Anwar ◽  
Jochen Seidel ◽  
András Bárdossy ◽  
Christian Huggel ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Water Balance ◽  
Water Use ◽  
Water Availability ◽  
Hydrological Model ◽  
Irrigated Agriculture ◽  
Domestic Water ◽  
Study Region ◽  
River Catchment

<p>High mountain regions, like the Andes, face various risks due to climate change. In the Santa River catchment in Peru which includes the glaciated Cordillera Blanca, water availability is threatened by many climatic and non-climatic impacts. The water resources in the catchment heavily rely on seasonal precipitation and during the dry season glacier melt water plays an important role. However, both, precipitation patterns and glacier extent are affected by climate change impacts. Additionally, socio-economic changes put further pressure on water resources and hence on water availability.</p> <p>Within the AguaFuturo Project we established a conceptual integrated water balance model based on a semi-distributed HBV model for the data scarce Santa River catchment. The hydrological model processes are extended by feedback loops for agricultural and domestic water use. The model runs on daily time scale and includes two hydrological response units. One includes the irrigated agricultural areas which are predominately located in the valley of the catchment; the other includes non-irrigated areas and domestic water use.</p> <p>To assess future water balance challenges we downscaled and disaggregated monthly CORDEX scenarios for 2020-2050 using information from the new Peruvian precipitation dataset PISCO (Peruvian Interpolated data of the SENAMHI’s Climatological and hydrological Observations) for simulations of future changes in hydro-climatology. In the model, these climate scenarios are combined with possible socio-economic scenarios which are translated into time series for domestic and agricultural water demand. The socio-economic scenarios are developed by using the Cross-Impact-Balance-Analysis (CIB), a method used for analyzing impact networks. Using CIB, the interrelations between 15 social, economic and policy descriptors were analyzed and as a result a total of 29 possible consistent scenarios were determined. For further analysis and validation of these scenarios a participatory process was included, involving local experts and stakeholders of the study region.</p> <p>The climate and socio-economic scenarios are independent and can be combined randomly. The uncertainties of the climatic and socio-economic scenarios are quantified by Monte Carlo simulations.</p> <p>The output of the model runs is an ensemble of possible future discharges of the Santa River, which can be further analyzed statistically to assess the range of the possible discharges. This evaluation provides an estimate of the probability of water shortages, especially with regard to conflict potential with hydropower production and the large scale irrigated agriculture areas in the adjacent coastal desert which also rely on water from the Santa River.</p>

scholarly journals Soil water dynamics and evapotranspiration of forage cactus clones under rainfed conditions

2015 ◽  
Vol 50 (7) ◽  
pp. 515-525 ◽  
Author(s):  
Thieres George Freire da Silva ◽  
Jorge Torres Araújo Primo ◽  
Magna Soelma Beserra de Moura ◽  
Sérvulo Mercier Siqueira e Silva ◽  
José Edson Florentino de Morais ◽  
...  
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Water Consumption ◽  
Water Availability ◽  
Crop Growth ◽  
Water Dynamics ◽  
Soil Water Balance ◽  
Soil Water Availability ◽  
Soil Water Dynamics ◽  
Area Index

Abstract: The objective of this work was to evaluate soil water dynamics in areas cultivated with forage cactus clones and to determine how environmental conditions and crop growth affect evapotranspiration. The study was conducted in the municipality of Serra Talhada, in the state of Pernambuco, Brazil. Crop growth was monitored through changes in the cladode area index (CAI) and through the soil cover fraction, calculated at the end of the cycle. Real evapotranspiration (ET) of the three evaluated clones was obtained as the residual term in the soil water balance method. No difference was observed between soil water balance components, even though the evaluated clones were of different genus and had different CAI increments. Accumulated ET was of 1,173 mm during the 499 days of the experiment, resulting in daily average of 2.35 mm. The CAI increases the water consumption of the Orelha de Elefante Mexicana clone. In dry conditions, the water consumption of the Miúda clone responds more slowly to variation in soil water availability. The lower evolution of the CAI of the IPA Sertânia clone, during the rainy season, leads to a higher contribution of the evaporation component in ET. The atmospheric demand controls the ET of clones only when there is higher soil water availability; in this condition, the water consumption of the Miúda clone decreases more rapidly with the increase of atmospheric demand.

scholarly journals GRACE-Based Estimates of Terrestrial Freshwater Discharge from Basin to Continental Scales

2009 ◽  
Vol 10 (1) ◽  
pp. 22-40 ◽  
Author(s):  
Tajdarul H. Syed ◽  
James S. Famiglietti ◽  
Don P. Chambers
Keyword(s):  
Water Balance ◽  
Mass Balance ◽  
Global Climate ◽  
Precipitable Water ◽  
Global Scale ◽  
Hydrologic Model ◽  
Freshwater Discharge ◽  
Global Ocean ◽  
Annual Cycles ◽  
Global Water

Abstract In this study, new estimates of monthly freshwater discharge from continents, drainage regions, and global land for the period of 2003–05 are presented. The method uses observed terrestrial water storage change estimates from the Gravity Recovery and Climate Experiment (GRACE) and reanalysis-based atmospheric moisture divergence and precipitable water tendency in a coupled land–atmosphere water mass balance. The estimates of freshwater discharge are analyzed within the context of global climate and compared with previously published estimates. Annual cycles of observed streamflow exhibit stronger correlations with the computed discharge compared to those with precipitation minus evapotranspiration (P − E) in several of the world’s largest river basins. The estimate presented herein of the mean monthly discharge from South America (∼846 km3 month−1) is the highest among the continents and that flowing into the Atlantic Ocean (∼1382 km3 month−1) is the highest among the drainage regions. The volume of global freshwater discharge estimated here is 30 354 ± 1212 km3 yr−1. Monthly variations of global freshwater discharge peak between August and September and reach a minimum in February. Global freshwater discharge is also computed using a global ocean–atmosphere mass balance in order to validate the land–atmosphere water balance estimates and as a measure of global water budget closure. Results show close proximity between the two estimates of global discharge at monthly (RMSE = 329 km3 month−1) and annual time scales (358 km3 yr−1). Results and comparisons to observations indicate that the method shows important potential for global-scale monitoring of combined surface water and submarine groundwater discharge at near-real time, as well as for contributing to contemporary global water balance studies and for constraining global hydrologic model simulations.

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