scholarly journals Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model

2016 ◽  
Author(s):  
N. Tangdamrongsub ◽  
S. C. Steele-Dunne ◽  
B. C. Gunter ◽  
P. G. Ditmar ◽  
E. H. Sutanudjaja ◽  
...  
Keyword(s):  
Water Resources ◽  
Hydrological Model ◽  
Hexi Corridor ◽  
Accurate Estimation ◽  
Groundwater Depletion ◽  
Correlated Errors ◽  
Grace Data ◽  
The Impact ◽  
Semi Arid

Abstract. An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of Terrestrial Water Storage (TWS) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an Ensemble Kalman Filter (EnKF) approach. The region considered was the Hexi Corridor of Northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. In this study, EnKF 3D scheme, which accounts for the GRACE spatially-correlated errors, was used. The correlated errors were propagated from the full error variance-covariance matrices provided as a part of the GRACE data product. The impact of the GRACE Data Assimilation (DA) scheme was evaluated in terms of the TWS, as well as individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWS but also for the groundwater component, which had annual amplitude, phase, and long-term trend estimates closer to the GRACE observations. This study also assessed the benefits of taking into account correlations of errors in GRACE-based estimates. The assessment was carried out by comparing the EnKF results, with and without taking into account error correlations, with the in situ groundwater data from 5 well sites and the in situ streamflow data from two river gauges. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. No significant benefits of GRACE DA were observed in terms of streamflow estimates, which reflect a limited spatial and temporal resolution of GRACE observations. Results from the 9-year long GRACE DA study were used to assess the status of water resources over the Hexi Corridor. Areally-averaged values revealed that TWS, soil moisture, and groundwater storages over the region decreased with an average rate of approximately 0.2, 0.1, and 0.1 cm/yr in terms of equivalent water heights, respectively. A substantial decline in TWS (approximately −0.4 cm/yr) was seen over the Shiyang River Basin in particular, and the reduction mostly occurred in the groundwater layer. An investigation of the relationship between water resources and agriculture suggested that groundwater consumption required to maintain the growing period in this specific basin was likely the cause of the groundwater depletion.

scholarly journals Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model

2017 ◽  
Vol 21 (4) ◽  
pp. 2053-2074 ◽  
Author(s):  
Natthachet Tangdamrongsub ◽  
Susan C. Steele-Dunne ◽  
Brian C. Gunter ◽  
Pavel G. Ditmar ◽  
Edwin H. Sutanudjaja ◽  
...  
Keyword(s):  
Water Resources ◽  
Hydrological Model ◽  
Hexi Corridor ◽  
Accurate Estimation ◽  
Groundwater Depletion ◽  
Time Interval ◽  
Grace Data ◽  
The Impact ◽  
Semi Arid

Abstract. An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of terrestrial water storage variation (TWSV) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an ensemble Kalman filter (EnKF) approach. The region considered was the Hexi Corridor in northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. The impact of the GRACE data assimilation (DA) scheme was evaluated in terms of the TWSV, as well as the variation of individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWSV but also for the groundwater component. In this study, spatially correlated errors in GRACE data were taken into account, utilizing the full error variance–covariance matrices provided as a part of the GRACE data product. The benefits of this approach were demonstrated by comparing the EnKF results obtained with and without taking into account error correlations. The results were validated against in situ groundwater data from five well sites. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. In contrast, a validation against in situ streamflow data from two river gauges showed no significant benefits of GRACE DA. This is likely due to the limited spatial and temporal resolution of GRACE observations. Finally, results of the GRACE DA study were used to assess the status of water resources over the Hexi Corridor over the considered 9-year time interval. Areally averaged values revealed that TWS, soil moisture, and groundwater storages over the region decreased with an average rate of approximately 0.2, 0.1, and 0.1 cm yr−1 in terms of equivalent water heights, respectively. A particularly rapid decline in TWS (approximately −0.4 cm yr−1) was seen over the Shiyang River basin located in the southeastern part of Hexi Corridor. The reduction mostly occurred in the groundwater layer. An investigation of the relationship between water resources and agricultural activities suggested that groundwater consumption required to maintain crop yield in the growing season for this specific basin was likely the cause of the groundwater depletion.

scholarly journals Climate-dependent propagation of precipitation uncertainty into the water cycle

2020 ◽  
Author(s):  
Ali Fallah ◽  
Sungmin O ◽  
Rene Orth
Keyword(s):  
Hydrological Model ◽  
Water Cycle ◽  
State Of The Art ◽  
Rain Gauge ◽  
Multiple Sources ◽  
Current State ◽  
Wide Range ◽  
The Impact ◽  
Conceptual Hydrological Model

Abstract. Precipitation is a crucial variable for hydro-meteorological applications. Unfortunately, rain gauge measurements are sparse and unevenly distributed, which substantially hampers the use of in-situ precipitation data in many regions of the world. The increasing availability of high-resolution gridded precipitation products presents a valuable alternative, especially over gauge-sparse regions. Nevertheless, uncertainties and corresponding differences across products can limit the applicability of these data. This study examines the usefulness of current state-of-the-art precipitation datasets in hydrological modelling. For this purpose, we force a conceptual hydrological model with multiple precipitation datasets in > 200 European catchments. We consider a wide range of precipitation products, which are generated via (1) interpolation of gauge measurements (E-OBS and GPCC V.2018), (2) combination of multiple sources (MSWEP V2) and (3) data assimilation into reanalysis models (ERA-Interim, ERA5, and CFSR). For each catchment, runoff and evapotranspiration simulations are obtained by forcing the model with the various precipitation products. Evaluation is done at the monthly time scale during the period of 1984–2007. We find that simulated runoff values are highly dependent on the accuracy of precipitation inputs, and thus show significant differences between the simulations. By contrast, simulated evapotranspiration is generally much less influenced. The results are further analysed with respect to different hydro-climatic regimes. We find that the impact of precipitation uncertainty on simulated runoff increases towards wetter regions, while the opposite is observed in the case of evapotranspiration. Finally, we perform an indirect performance evaluation of the precipitation datasets by comparing the runoff simulations with streamflow observations. Thereby, E-OBS yields the best agreement, while furthermore ERA5, GPCC V.2018 and MSWEP V2 show good performance. In summary, our findings highlight a climate-dependent propagation of precipitation uncertainty through the water cycle; while runoff is strongly impacted in comparatively wet regions such as Central Europe, there are increasing implications on evapotranspiration towards drier regions.

The assessment of surface water resources for the semi-arid Yongding River Basin from 1956 to 2000 and the impact of land use change

2010 ◽  
Vol 24 (9) ◽  
pp. 1123-1132 ◽  
Author(s):  
Lei Wang ◽  
Zhongjing Wang ◽  
Toshio Koike ◽  
Hang Yin ◽  
Dawen Yang ◽  
...  
Keyword(s):  
Land Use ◽  
Surface Water ◽  
Water Resources ◽  
Land Use Change ◽  
River Basin ◽  
Surface Water Resources ◽  
The Impact ◽  
Semi Arid ◽  
Yongding River

Comparison of GRACE Level-3 Data with Super Conducting Gravimeters in Europe By Means of Signal Decomposition Analysis

2020 ◽  
Author(s):  
Miguel Angel Izquierdo Perez ◽  
Christian Voigt ◽  
Elmas Sinem Ince ◽  
Frank Flechtner
Keyword(s):  
Decomposition Analysis ◽  
Decomposition Methods ◽  
Component Analysis ◽  
In Situ Measurements ◽  
Alternative Methods ◽  
Earth Tides ◽  
Grace Data ◽  
The Individual ◽  
The Impact

<p>With the launch of the Gravity Recovery and Climate Experiment (GRACE) mission in 2002 and continued with GRACE Follow-on (GRACE-FO) since 2018, it is nowadays possible to monitor important mass variations in the Earth system. Nevertheless, validating these observations is a challenging task due to the lack of alternative methods to obtain directly comparable in-situ measurements. The most appropriate approach for this endeavor consists of comparing the GRACE derived Total Water Storage (TWS) residuals against Superconducting Gravimeter (SG) residuals, which provide long term stability.</p> <p>The in-situ data used for this project are the gravity residuals obtained after removing the effects of solid Earth tides and ocean tidal loading, atmospheric loading, instrumental drift, polar motion and length‐of‐day induced gravity changes, from nine SG stations between January 2010 and March 2017. Such residuals were then compared with GRACE retrieved TWS residuals obtained from the Gravity Information System (GravIS) portal (gravis.gfz-potsdam.de).</p> <p>In this project, three decomposition methods were used for the comparisons: Principal Component Analysis (PCA), Spatiotemporal Independent Component Analysis (stICA) and Multivariate Singular Spectral Analysis (MSSA). The main aim was to assess the impact of the GRACE data corrections applied by GravIS to the coefficient C20, the coefficients of degree/order one, and the Glacial Isostatic Adjustment (GIA) effect. Moreover, the Gaussian, DDK and VDK filtering techniques were evaluated as well.</p> <p>The tested methods proved to cope with the residual hydrological effects on SG measurements up to an extend that allows an objective evaluation of the data. The results obtained from this analysis indicate that the most optimal solution is achieved by correcting the C20 and degree/order 1 coefficients. The most effective filters are DDK1, VDK2 and Gaussian with a 500 km bandwidth, in that order. Furthermore, the GIA correction demonstrates to be relevant for northern locations like Onsala.</p> <p>Concerning the decomposition methods, MSSA demonstrates to be a powerful tool, synthesizing the most important common trends among the in-situ measurements of different stations, and displaying the local differences of the signals. The common signals extracted from PCA represent a good overview of the trends from the data but is not detailed at the individual locations. Finally, the stICA decomposition is not able to extract these common signals when the input data is significantly different across the individual variables for SG data. This is explained by the Blind Source Separation (BSS) nature of the methodology, which intends to identify differences among the signals, and is not useful in this case where the signals are affected by the local hydrology.</p> <p>The importance of this study lies in the versatility that the successfully tested methods show for the purpose of GRACE data comparison. Furthermore, the methodology applied in this project can be extended to analyze the current GRACE-FO mission as well other gravimetric satellite missions in the future.</p>

scholarly journals Groundwater Depletion in an Urban Environment under Semiarid Climate and Persistent Drought–City of Marrakesh (Morocco)

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3253
Author(s):  
Mohammed Analy ◽  
Nour-Eddine Laftouhi
Keyword(s):  
Water Table ◽  
Groundwater Resources ◽  
Shallow Aquifer ◽  
Arid Climate ◽  
Groundwater Depletion ◽  
Hydrodynamic Behaviour ◽  
General Decline ◽  
Persistent Drought ◽  
The Impact ◽  
Semi Arid

The quantitative monitoring of the shallow aquifer in Marrakesh and its surrounding area shows that the water table has been lowered gradually over the last 40 years, and attaining an acute decline in the early 2000s. This declining trend—if confirmed in the future—may lead to a water shortage, or even to a total aquifer depletion, which would be devastating for a region where economic activity and drinking water supply rely partly on groundwater resources. Two factors account for this situation: the hot semi-arid climate characterized by high temperatures and low precipitation, causing an inadequate groundwater recharge (deficit between rainwater supply and the potential evapotranspiration), and the over-pumping of groundwater from wells for intensive agricultural uses and some leisure activities (golf courses, waterparks and pools, for example). The objective of this study is to assess the hydrodynamic behaviour of the shallow aquifer in this context of persistent drought and semi-arid climate under intense use conditions. Based on earlier research studies and hydrological data recently collected from the field, a spatiotemporal analysis using a geographic information system has been conducted, allowing researchers to monitor the evolution of groundwater resources under the impact of intense exploitation. This study shows a general decline of groundwater level in the city of Marrakesh between 1962–2019. However, by dividing this period into three periods (1962–1985, 1986–2001 and 2002–2019), it is obvious that the main groundwater fall occurred during the two last decades, a period marked by highest recorded temperatures and decreased precipitation levels. This water table decline impacted 85% of the study area and is estimated at 0.9 m/year. The area most affected by the drawdown of the water table experienced a decline reaching 37 m between 2002 and 2019 (more than 2 m a year).

scholarly journals Modeling the Near-Surface Energies and Water Vapor Fluxes Behavior in Response to Summer Canopy Density across Yanqi Endorheic Basin, Northwestern China

2021 ◽  
Vol 13 (18) ◽  
pp. 3764
Author(s):  
Patient Mindje Kayumba ◽  
Gonghuan Fang ◽  
Yaning Chen ◽  
Richard Mind’je ◽  
Yanan Hu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Resources ◽  
Surface Energy ◽  
Northwestern China ◽  
Energy Fluxes ◽  
Evaporative Fraction ◽  
Near Surface ◽  
Available Energy ◽  
Semi Arid

The Yanqi basin is the main irrigated and active agroecosystem in semi-arid Xinjiang, northwestern China, which further seeks responses to the profound local water-related drawbacks in relation to the unceasing landscape desiccation and scant precipitation. Yet, it comes as an astonishment that a few reported near-surface items and water vapor fluxes as so far required for water resources decision support, particularly in a scarce observation data region. As a contributive effort, here we adjusted the sensible heat flux (H) calibration mechanism of Surface Energy Balance Algorithm for Land (SEBAL) to high-resolution satellite dataset coupled with in-situ observation, through a wise guided “anchor” pixel assortment from surface reflectance-α, Leaf area index-LAI, vegetation index-NDVI, and surface temperature (Pcold, Phot) to model the robustness of energy fluxes and Evapotranspiration-ETa over the basin. Results reasonably reflected ETa which returned low RMSE (0.6 mm d−1), MAE (0.48 mm d−1) compared to in-situ recordings, indicating the competence of SEBAL to predict vapor fluxes in this region. The adjustment unveiled the estimates of the land-use contribution to evapotranspiration with an average ranging from 3 to 4.69 mm d−1, reaching a maximum of 5.5 mm d−1. Furthermore, findings showed a high striking energy dissipation (LE/Rn) across grasslands and wetlands. The vegetated surfaces with a great evaporative fraction were associated with the highest LE/Rn (70–90%), and water bodies varying between 20% and 60%, while the desert ecosystem dissipated the least energy with a low evaporative fraction. Still, besides high portrayed evaporation in water, grasslands and wetlands varied interchangeably in accounting for the highest ETa followed by cropland. Finally, a substantial nexus between available energy (Rn-G) and ETa informed the available energy, influenced by NDVI to be the primary driver of these oases’ transpiration. This study provides essentials of near-surface energy fluxes and the likelihood of ETa with considerable baseline inferences for Yanqi that may be beneficial for long-term investigations that will attend in agrometeorological services and sustainable management of water resources in semi-arid regions.

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