scholarly journals Global 5-km resolution estimates of secondary evaporation including irrigation through satellite data assimilation

Author(s):  
Albert I. J. M. van Dijk ◽  
Jaap Schellekens ◽  
Marta Yebra ◽  
Hylke E. Beck ◽  
Luigi J. Renzullo ◽  
...  

Abstract. A portion of globally generated surface and groundwater resources evaporates from wetlands, water bodies and irrigated areas. This secondary evaporation of blue water directly affects the remaining water resources available for ecosystems and human use. At the global scale, a lack of detailed water balance studies and direct observations limits our understanding of the magnitude and spatial and temporal distribution of secondary evaporation. Here, we propose a methodology to assimilate satellite-derived information into the landscape hydrological model W3 at an unprecedented 0.05° or c. 5 km resolution globally. The assimilated data are all derived from MODIS observations, including surface water extent, surface albedo, vegetation cover, leaf area index, canopy conductance, and land surface temperature (LST). The information from these products is imparted on the model in a simple but efficient manner, through a combination of direct insertion of surface water extent, evaporation flux adjustment based on LST, and parameter nudging for the other observations. The resulting water balance estimates were evaluated against river basin discharge records and the water balance of closed basins and demonstrably improved water balance estimates compared to ignoring secondary evaporation (e.g., bias improved from +38 mm/d to +2 mm/d). The evaporation estimates derived from assimilation were combined with global mapping of irrigation crops to derive a minimum estimate of irrigation water requirements (I0), representative of optimal irrigation efficiency. Our I0 estimates were lower than published country-level estimates of irrigation water use produced by alternative estimation methods, for reasons that are discussed. We estimate that 16 % of globally generated water resources evaporate before reaching the oceans, enhancing total terrestrial evaporation by 6.1 • 1012 m3 y−1 or 8.8 %. Of this volume, 5 % is evaporated from irrigation areas, 58% from terrestrial water bodies and 37 % from other surfaces. Model-data assimilation at even higher spatial resolutions can achieve a further reduction in uncertainty but will require more accurate and detailed mapping of surface water dynamics and areas equipped for irrigation.

2018 ◽  
Vol 22 (9) ◽  
pp. 4959-4980 ◽  
Author(s):  
Albert I. J. M. van Dijk ◽  
Jaap Schellekens ◽  
Marta Yebra ◽  
Hylke E. Beck ◽  
Luigi J. Renzullo ◽  
...  

Abstract. A portion of globally generated surface and groundwater resources evaporates from wetlands, waterbodies and irrigated areas. This secondary evaporation of “blue” water directly affects the remaining water resources available for ecosystems and human use. At the global scale, a lack of detailed water balance studies and direct observations limits our understanding of the magnitude and spatial and temporal distribution of secondary evaporation. Here, we propose a methodology to assimilate satellite-derived information into the landscape hydrological model W3 at an unprecedented 0.05∘, or ca. 5 km resolution globally. The assimilated data are all derived from MODIS observations, including surface water extent, surface albedo, vegetation cover, leaf area index, canopy conductance and land surface temperature (LST). The information from these products is imparted on the model in a simple but efficient manner, through a combination of direct insertion of the surface water extent, an evaporation flux adjustment based on LST and parameter nudging for the other observations. The resulting water balance estimates were evaluated against river basin discharge records and the water balance of closed basins and demonstrably improved water balance estimates compared to ignoring secondary evaporation (e.g., bias improved from +38 to +2 mm yr−1). The evaporation estimates derived from assimilation were combined with global mapping of irrigation crops to derive a minimum estimate of irrigation water requirements (I0), representative of optimal irrigation efficiency. Our I0 estimates were lower than published country-level estimates of irrigation water use produced by alternative estimation methods, for reasons that are discussed. We estimate that 16 % of globally generated water resources evaporate before reaching the oceans, enhancing total terrestrial evaporation by 6.1×1012 m3 yr−1 or 8.8 %. Of this volume, 5 % is evaporated from irrigation areas, 58 % from terrestrial waterbodies and 37 % from other surfaces. Model-data assimilation at even higher spatial resolutions can achieve a further reduction in uncertainty but will require more accurate and detailed mapping of surface water dynamics and areas equipped for irrigation.


Author(s):  
Yu. O. Mikhailov ◽  
A. M. Shevchenko ◽  
Iu. Yu. Danylenko ◽  
S. M. Liutnytskyi ◽  
I. L. Goncharuk ◽  
...  

 Quantitative and qualitative depletion of water resources in Ukraine because of the increase in climate aridity make the problem of integrated surface and ground water management more urgent. The integrated management is based on the water balance of the territories, which automatically takes into account natural and artificial features of water use. The paper presents the results of a long term research aimed at resolving the problems of scientific support of integrated water resources management in Ukraine in the context of climate change. The plans for integrated water management are developed according to the administrative principle allowing optimization of the structure of water consumption and the assessment of available water resources capacity to meet water demand of the required quality without environmental risk for aquatic ecosystems and population. The surface and ground water in Ukraine have spatially homogeneous hydrochemical spectrum, which characterizes the concentration anions and cations in water and the nature of their change at different water exchange rates. Studies of hydrochemical spectrum have shown that its basic parameters are much higher for groundwater than for surface water. The results of the study on the spatial changes in the chemical composition of surface waters in the Dnipro river basin testify to the distinct homogeneity of their hydrochemical spectrum, which gives the reason to limit in practice observations of changes in the chemical composition of water to local points. As the experimental data are accumulated and the geospatial analysis of hydrochemical spectrum is made, the number of such points can be reduced ten times without significant negative impact on the reliability of the final results. It is possible to draw up a water balance with the use of correlation functions, the observance of which will guarantee the rational water resources use, based on their actual available volume and restrictions on the total water inflow, filtration losses, surface runoff (discharges). The water balance in the graphical representation is described by a linear function, which cuts the average of the sum of expendable elements on the ordinate axis over the entire observation period. The tangent of the slope of the graph represents the coefficient of water supply. The scope of this methodological approach's application is limited only by the availability of raw data. There are sufficient data from precipitation observations, water abstraction from all sources in volumes comparable to precipitation and more. It is also desirable to have observations of groundwater level fluctuations and air moisture deficit. The experimental research confirmed a high positive impact on the water resources formation made by forests, shelterbelts and meadows. In the humid zone it is possible to separate natural landscapes of wetlands and floodplains (60% of the territory), in the southern part - transitional landscapes that replace artificial agrolandscapes (40% of the territory). In arid climate conditions, the types of landscapes differ in the area of irrigated lands and the density of shelterbelts. Agrolandscapes are complex natural-technical systems. In most cases, when investigating their impact on the processes of formation and use of water, it is possible to operate a finite number of interconnected parts (subsystems). The purpose of such separation on subsystems is to obtain typical areas for which spatial structure of agricultural landscapes can be experimentally evaluated and the nature of its relationship with the factors of surface water resources formation can be determined. According to the assessment of water balance of rural territories, their water resources potential is equal to the sum of atmospheric precipitation and the volumes of water entering the balance space due to its withdraw for economic needs from surface and ground water bodies. When drawing up water balance for a hydrological year, water resources do not include precipitation, which is almost completely converted to river flow. The available volume of water for use should include the volume of water, the removal of which from natural or artificial circulation will not lead to negative environmental impacts or increase the cost of economic activity and restoration of fresh water bodies. The volume of water available for use is also limited by its qualitative indicators, which in turn are determined by its chemical composition (spectrum).


2021 ◽  
Author(s):  
Marco Mancini ◽  
Chiara Corbari ◽  
Imen Ben Charfi ◽  
Ahmad Al Bitar ◽  
Drazen Skokovic ◽  
...  

<p>The conflicting use of water is becoming more and more evident, also in regions that are traditionally rich in water. With the world’s population projected to increase to 8.5 billion by 2030, the simultaneous growth in income will imply a substantial increase in demand for both water and food. Climate change impacts will further stress the water availability enhancing also its conflictual use. The agricultural sector is the biggest and least efficient water user, accounts for around 24% of total water use in Europe, peaking at 80% in the southern regions.</p><p>This paper shows the implementation of a system for real-time operative irrigation water management at high spatial and temporal able to monitor the crop water needs reducing the irrigation losses and increasing the water use efficiency, according to different agronomic practices supporting different level of water users from irrigation consortia to single farmers. The system couples together satellite (land surface temperature LST and vegetation information) and ground data, with pixel wise hydrological crop soil water energy balance model. In particular, the SAFY (Simple Algorithm for Yield) crop model has been coupled with the pixel wise energy water balance FEST-EWB model, which assimilate satellite LST for its soil parameters calibration. The essence of this coupled modelling is that the SAFY provides the leaf area index (LAI) evolution in time used by the FEST-EWB for evapotranspiration computation while FEST-EWB model provides soil moisture (SM) to SAFY model for computing crop grow for assigned water content.</p><p>The FEST-EWB-SAFY has been firstly calibrated in specific fields of Chiese (maize crop) and Capitanata (tomatoes) where ground measurements of evapotranspiration, soil moisture and crop yields are available, as well as LAI from Sentinel2-Landsat 7 and 8 data. The FEST-EWB-SAFY model has then been validated also on several fields of the RICA farms database in the two Italian consortia, where the economic data are available plus the crop yield. Finally, the modelled maps of LAI have then been validated over the whole Consortium area (Chiese and Capitanata) against satellite data of LAI from Landsat 7 and 8, and Sentinel-2.</p><p>Optimized irrigation volumes are assessed based on a soil moisture thresholds criterion, allowing to reduce the passages over the field capacity threshold reducing the percolation flux with a saving of irrigation volume without affecting evapotranspiration and so that the crop production. The implemented strategy has shown a significative irrigation water saving, also in this area where a traditional careful use of water is assessed.</p><p>The activity is part of the European project RET-SIF (www.retsif.polimi.it).</p>


2017 ◽  
pp. 209-214
Author(s):  
O.S. Koryagina

The study of the reservoirs is of great scientific interest and is of practical importance for the solution of problems of rational use and protection of water resources. The paper describes the latest reservoir in the cascade of Dnipro Kakhovka Reservoir and its component of water balance. The methods of determining the components of the water balance that were once offered the Kakhovka  hydrometeorological observatory are submitted. Great attention is drawn to the surface flow of water into the reservoir from unexplored rivers, which is determined by the method of analogy. The probable error of this method, in turn, is equal to for monthly values 30-50% and annual – 10-20%. So, there is provided somewhat different a method for determining the surface flow using the curve of security component amount of annual precipitation, maps of the norm runoff and tables SNiP 2.01.14.83. The proposed method simplifies and accelerates the process of calculating the amounts of surface water flow in unexplored rivers to Kakhovka reservoir.


Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1367 ◽  
Author(s):  
Tiago Ramos ◽  
Lucian Simionesei ◽  
Ana Oliveira ◽  
Hanaa Darouich ◽  
Ramiro Neves

Hydrological modeling at the catchment scale requires the upscaling of many input parameters for better characterizing landscape heterogeneity, including soil, land use and climate variability. In this sense, remote sensing is often considered as a practical solution. This study aimed to access the impact of assimilation of leaf area index (LAI) data derived from Landsat 8 imagery on MOHID-Land’s simulations of the soil water balance and maize state variables (LAI, canopy height, aboveground dry biomass and yield). Data assimilation impacts on final model results were first assessed by comparing distinct modeling approaches to measured data. Then, the uncertainty related to assimilated LAI values was quantified on final model results using a Monte Carlo method. While LAI assimilation improved MOHID-Land’s estimates of the soil water balance and simulations of crop state variables during early stages, it was never sufficient to overcome the absence of a local calibrated crop dataset. Final model estimates further showed great uncertainty for LAI assimilated values during earlier crop stages, decreasing then with season reaching its end. Thus, while model simulations can be improved using LAI data assimilation, additional data sources should be considered for complementing crop parameterization.


Author(s):  
Roman Ponomarenko ◽  
Leonid Plyatsuk ◽  
Josef Zat’ko

The article analyzes the water quality of surface water bodies (on the example of rivers of the Dnieper basin) by the method of main components, identifies and interprets the main factors that form long-term variability of water quality of surface water bodies and make different contributions to the total variance. The research was carried out according to the samples of control water intake of the Dnieper River within the Basin Water Resources Management at 12 posts, for the period from 2011 to 2020. The leading factors were identified: plant and animal organisms (12…39 %), leaching of Fe- and Cu-containing minerals (10…29 %). The article shows that in the formation of the chemical composition of the water of the rivers of the studied region is determined by the factor of ion from the rocks on which the formation of the catchment. A factor characterizing the local conditions of river runoff formation has been identified - the process of groundwater discharge, which is manifested in changes in the concentrations of silicon and nitrates. In addition, a negative dependence of changes in the content of silicon ions and nitrates on temperature. The originality of the study is based on an integrated approach, which includes research based on available data in the State Agency of Water Resources of Ukraine, which takes into account the principles of biodiversity conservation, sustainable use of water resources, river management and basins, monitoring and evaluation of their status. In the future, the proposed approach may be the subject of research in the direction of establishing factors that characterize the local conditions of formation of river runoff, including taking into account the man-made load on it.


2020 ◽  
Author(s):  
Cheolhee Jang

<p>The Dynamic Water Resources Asesment Tol (DWAT) acounts for water balance on dynamic (hourly or daily) as wel as static (monthly or yearly) bases. It can be aplied to a smal or a mid-sized basin for water resources planing and management with consideration of surface water as wel as groundwater. The DWAT clasifies a watershed into hydrologicaly homogeneous sub-basins so that runof characteristics resulting from geomorphological factors can be objectively represented, and infiltration, evaporation and groundwater flows can be simulated acording to soil layers. In aditon, as the physical input parameters can be easily extracted by the GIS preprocesing module within the system, it can be aplied to areas in various hydrological, geophysical and climatic conditons, such as tropical, rural, forest or newly developed urban areas. The DWAT has ben developed in Korea Instiute of Civil Enginering and Building Technology (KICT) since 2012 as a part of WMO (World Meteorological Organization) RA (Regional Asociation) II WGHS (Working Group on Hydrological Services) and CHy (Commision for Hydrology) AWG (Advisory Working Group) activites, and it has ben suported by the Han River Flod Control Ofice, Ministry of Environment, Republic of Korea. The first version 1.0 beta of the DWAT was developed in the end of 2017, which contains sub-algorithms such as evapotranspiration, infiltration, watershed runof, groundwater flow, chanel routing and user convenience systems. In the midle of 2018, the second version 1.0 was developed with the aditon of rice pady field, snowmelt and manual/automatic parameter optimization modules. In May 2019, the third version of 1.1 was developed in consideration of the recommendations made by the WMO panel of experts.</p><div> <p><strong>Acknowledgements</strong></p> <p><strong> This research is supported by the Research Program (20200041-001) of Korea Institute of Civil Engineering & Building Technology </strong></p> </div><div> </div>


2021 ◽  
Vol 35 (1) ◽  
pp. 84
Author(s):  
Chafda Larasati ◽  
Aji Wijaya Abadi ◽  
M Galih Prakoso ◽  
Novanna Dwi S ◽  
Venny Vivid F ◽  
...  

Abstrak Sumberdaya air penting untuk pemenuhan kebutuhan semua makhluk hidup termasuk manusia. DAS Bodri menyediakan suplai air permukaan melalui sungai-sungai yang ada dalam DAS, yang dapat dimanfaatkan oleh penduduk sekitar. Seiring berjalannya waktu, DAS Bodri mengalami perubahan penggunaan lahan yang menyebabkan terjadinya peningkatan kebutuhan air dan terjadi ketidakseimbangan antara kebutuhan dan ketersediaan air permukaan. Tujuan dari penelitian ini, yaitu mengetahui keseimbangan antara kebutuhan air di masa yang akan datang dengan ketersediaan air permukaan di DAS Bodri tahun 2040. Perhitungan keseimbangan antara kebutuhan dan ketersediaan air permukaan dilakukan dengan membandingkan antara kebutuhan air total dan ketersediaan air permukaan. Parameter kebutuhan air total terdiri dari kebutuhan air domestik, fasilitas kesehatan, fasilitas pendidikan, fasilitas peribadatan, perkantoran, industri, pertokoan dan pasar, warung makan, peternakan, irigasi, dan tambak. Kebutuhan air di tahun mendatang diketahui melalui proyeksi secara eksponensial dan tetap dari data jumlah dalam perhitungan parameter. Kebutuhan air untuk aktivitas domestik dan nondomestik diestimasikan mencapai 2,44 miliar m3 pada tahun 2040. Hasil analisis neraca air menunjukkan bahwa status neraca air DAS Bodri tahun 2010-2019 mengalami defisiensi. Hal tersebut menunjukkan bahwa potensi sumberdaya air permukaan masih belum mencukupi untuk pemenuhan kebutuhan air di DAS Bodri hingga tahun 2040. Abstract Water resources play an important role in meeting the needs of all living things, including humans. The Bodri watershed provides surface water supply through rivers on the watershed, which the local residents can use and utilize. Over time, the Bodri watershed underwent landuse change, which led to an increase in water demand, resulting in an imbalance between water demand and surface water availability. Calculation of the balance between demand and surface water availability is done by comparing the total water demand and the surface water availability. This study aims to determine the balance between future water demand and surface water availability in the Bodri watershed in 2040. The parameters used to determine total water demand consist of water needs of the following sectors; domestic, health facilities, educational facilities, religious facilities, offices, industry, shops and markets, food stalls, livestock, irrigation, and ponds. In the coming year, water demand is known through projections exponentially and permanently from the amount of data in the calculation of parameters. Water demand for domestic and non-domestic activities is estimated to reach 2.44 billion m3 in 2040. The water balance analysis results show that the status of the Bodri watershed water balance in 2010-2019 is deficient. The potential for surface water resources is still insufficient to meet the water needs in the Bodri watershed until 2040.  


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