Exploring the influence of precipitation extremes and human water use on total water storage (TWS) changes in the Ganges-Brahmaputra-Meghna River Basin

Abstract Gravity Recovery and Climate Experiment (GRACE) observations provide information on Total Water Storage Anomaly (TWSA) which is a key variable for drought monitoring and assessment. The so-called Total Water Storage Deficit Index (TWSDI) based on GRACE data has been widely used for characterizing drought events. Here we show that the commonly used TWSDI approach often exhibits significant inconsistencies with meteorological conditions, primarily upon presence of a trend in observations due to anthropogenic water use. In this study, we propose a modified version of TWSDI (termed, MTWSDI) that decomposes the anthropogenic and climatic-driven components of GRACE observations. We applied our approach for drought monitoring over the Ganges–Brahmaputra in India and Markazi basins in Iran. Results show that the newly developed MTWSDI exhibits consistency with meteorological drought indices in both basins. We also propose a deficit-based method for drought monitoring and recovery assessment using GRACE observations, providing useful information about volume of deficit, and minimum and average time for drought recovery. According to the deficit thresholds, water deficits caused by anthropogenic impacts every year in the Ganges–Brahmaputra basin and Markazi basins is almost equal to an abnormally dry condition and a moderate drought condition, receptively. It indicates that unsustainable human water use have led to a form of perpetual and accelerated anthropogenic drought in these basins. Continuation of this trend would deplete the basin and cause significant socio-economic challenges.

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Assessing Impacts of Climate Extremes and Human Water Use on GRACE Total Water Storage Trends in Major U.S. Aquifers

10.5194/gstm2020-61 ◽

2020 ◽

Author(s):

Bridget Scanlon ◽

Ashraf Rateb ◽

Alexander Sun ◽

Himanshu Save

Keyword(s):

Surface Water ◽

Water Use ◽

Groundwater Level ◽

Water Storage ◽

Climate Extremes ◽

High Plains ◽

Total Water ◽

Groundwater Storage ◽

Grace Data ◽

The U.S

There is considerable concern about water depletion caused by climate extremes (e.g., drought) and human water use in the U.S. and globally. Major U.S. aquifers provide an ideal laboratory to assess water storage changes from GRACE satellites because the aquifers are intensively monitored and modeled. The objective of this study was to assess the relative importance of climate extremes and human water use on GRACE Total Water Storage Anomalies in 14 major U.S. aquifers and to evaluate the reliability of the GRACE data by comparing with groundwater level monitoring (~-23,000 wells) and regional and global models. We quantified total water and groundwater storage anomalies over 2002 &#8211; 2017 from GRACE satellites and compared GRACE data with groundwater level monitoring and regional and global modeling results. &#160; The results show that water storage changes were controlled primarily by climate extremes and amplified or dampened by human water use, primarily irrigation. The results were somewhat surprising, with stable or rising long-term trends in the majority of aquifers with large scale depletion limited to agricultural areas in the semi-arid southwest and southcentral U.S. GRACE total water storage in the California Central Valley and Central/Southern High Plains aquifers was depleted by drought and amplified by groundwater irrigation, totaling ~70 km3 (2002&#8211;2017), about 2&#215; the capacity of Lake Mead, the largest surface reservoir in the U.S. In the Pacific Northwest and Northern High Plains aquifers, lower drought intensities were partially dampened by conjunctive use of surface water and groundwater for irrigation and managed aquifer recharge, increasing water storage by up to 22 km3 in the Northern High Plains over the 15 yr period. GRACE-derived total water storage changes in the remaining aquifers were stable or slightly rising throughout the rest of the U.S. GRACE data compared favorably with composite groundwater level hydrographs for most aquifers except for those with very low signals, indicating that GRACE tracks groundwater storage dynamics. Comparison with regional models was restricted to the limited overlap periods but showed good correspondence for modeled aquifers with the exception of the Mississippi Embayment, where the modeled trend is 4x the GRACE trend. The discrepancy is attributed to uncertainties in model storage parameters and groundwater/surface water interactions. Global hydrologic models (WGHM-2d and PCR-GLOBWB-5.0 overestimated trends in groundwater storage in heavily exploited aquifers in the southwestern and southcentral U.S. Land surface models (CLSM-F2.5 and NOAH-MP) seem to track GRACE TWSAs better than global hydrologic models but underestimated TWS trends in aquifers dominated by irrigation. Intercomparing GRACE, traditional hydrologic monitoring, and modeling data underscore the importance of considering all data sources to constrain water storage changes.&#160; GRACE satellite data have critical implications for many nationally important aquifers, highlighting the importance of conjunctively using surface-water and groundwater and managed aquifer recharge to enhance sustainable development.

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Reviving the Ganges Water Machine: why?

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-8727-2015 ◽

2015 ◽

Vol 12 (9) ◽

pp. 8727-8759 ◽

Cited By ~ 3

Author(s):

U. A. Amarasinghe ◽

L. Mutuwatte ◽

L. Surinaidu ◽

S. Anand ◽

S. K. Jain

Keyword(s):

Water Supply ◽

River Basin ◽

Water Use ◽

Water Demand ◽

Monsoon Season ◽

Subsurface Water ◽

Ganges River ◽

Hot Weather ◽

The Ganges ◽

Ganges River Basin

Abstract. The Ganges River Basin may have a major pending water crisis. Although the basin has abundant surface water and groundwater resources, the seasonal monsoon causes a mismatch between supply and demand as well as flooding. Water availability and flood potential is high during the 3–4 months of the monsoon season. Yet, the highest demands occur during the 8–9 months of the non-monsoon period. Addressing this mismatch requires substantial additional storage for both flood reduction and improvements in water supply. Due to hydrogeological, environmental, and social constraints, expansion of surface storage in the Ganges River Basin is problematic. A range of interventions that focus more on the use of subsurface storage (SSS), and on the acceleration of surface–subsurface water exchange, have long been known as the "Ganges Water Machine". One approach for providing such SSS is through additional pumping prior to the onset of the monsoon season. An important necessary condition for creating such SSS is the degree of unmet water demand. This paper highlights that an unmet water demand ranging from 59 to 119 Bm3 exists under two different irrigation water use scenarios: (i) to increase Rabi and hot weather season irrigation to the entire irrigable area, and (ii) to provide Rabi and hot weather season irrigation to the entire cropped area. This paper shows that SSS can enhance water supply, and provide benefits for irrigation and other water use sectors. In addition, it can buffer the inherent variability in water supply and mitigate extreme flooding, especially in the downstream parts of the basin. It can also increase river flow during low-flow months via baseflow or enable the re-allocation of irrigation canal water. Importantly, SSS can mitigate the negative effects of both flooding and water scarcity in the same year, which often affects the most vulnerable segments of society – women and children, the poor and other disadvantaged social groups.

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Satellite-derived surface and sub-surface water storage in the Ganges–Brahmaputra River Basin

Journal of Hydrology Regional Studies ◽

10.1016/j.ejrh.2015.03.004 ◽

2015 ◽

Vol 4 ◽

pp. 15-35 ◽

Cited By ~ 26

Author(s):

Fabrice Papa ◽

Frédéric Frappart ◽

Yoann Malbeteau ◽

Mohammad Shamsudduha ◽

Venugopal Vuruputur ◽

...

Keyword(s):

Surface Water ◽

River Basin ◽

Water Storage ◽

Brahmaputra River ◽

The Ganges ◽

Surface Water Storage

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Assessment of Water Footprint for Koshi River Basin (KRB), Nepal

10.5194/egusphere-egu2020-4395 ◽

2020 ◽

Author(s):

Raj Deva Singh ◽

Kumar Ghimire ◽

Ashish Pandey

Keyword(s):

River Basin ◽

Water Use ◽

Crop Production ◽

Agricultural Land ◽

Water Footprint ◽

Green Water ◽

Blue Water ◽

Total Water ◽

Green And Blue Water ◽

Koshi River Basin

Nepal is an agrarian country and almost one-third of Gross Domestic Product (GDP) is dependent on agricultural sector. Koshi river basin is the largest basin in the country and serves large share on agricultural production. Like another country, Nepalese agriculture holds largest water use in agriculture. In this context, it is necessary to reduce water use pressure. In this study, water footprint of different crop (rice, maize, wheat, millet, sugarcane, potato and barley) have been estimated for the year 2005 -2014 to get the average water footprint of crop production during study period. CROPWAT model, developed by Food and Agriculture Organization (FAO 2010b).For the computation of the green and blue water footprints, estimated values of ET (the output of CROPWAT model) and yield (derived from statistical data) are utilised. Blue and green water footprint are computed for different districts (16 districts within KRB) / for KRB in different years (10 years from 2005 to 2014) and crops (considered 7 local crops). The water footprint of crops production for any district or basin represents the average of WF production of seven crops in the respective district or basin.The study provides a picture of green and blue water use in crop production in the field and reduction in the water footprint of crop production by selecting suitable crops at different places in the field. The Crop, that has lower water footprint, can be intensified at that location and the crops, having higher water footprint, can be discontinued for production or measure for water saving technique needs to be implemented reducing evapotranspiration. The water footprint of agriculture crop production can be reduced by increasing the yield of the crops. Some measures like use of an improved variety of seed, fertilizer, mechanized farming and soil moisture conservation technology may also be used to increase the crop yields.The crop harvested areas include both rainfed as well as irrigated land. Agricultural land occupies 22% of the study area, out of which 94% areas are rainfed whereas remaining 6% areas are under irrigation. The study shows 98% of total water use in crop production is due to green water use (received from rainfall) and remaining 2 % is due to blue water use received from irrigation (surface and ground water as source). Potato has 22% blue water proportion and contributes 85% share to the total blue water use in the basin. Maize and rice together hold 77% share of total water use in crops production. The average annual water footprint of crop production in KRB is 1248 cubic meter/ton having the variation of 9% during the period of 2005-2014. Sunsari, Dhankuta districts have lower water footprint of crop production. The coefficient of variation of water footprint of millet crop production is lower as compared to those of other crops considered for study whereas sugarcane has a higher variation of water footprint for its production.

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