scholarly journals Understanding process controls on groundwater recharge variability across Africa through recharge landscapes

2021 ◽  
Author(s):  
Charles West ◽  
Rafael Rosolem ◽  
Alan MacDonald ◽  
Mark Cuthbert ◽  
Thorsten Wagener
Keyword(s):  
Water Supply ◽  
Groundwater Recharge ◽  
Mean Annual Precipitation ◽  
Clear Understanding ◽  
Land Area ◽  
Recharge Rates ◽  
Landscape Units ◽  
Process Controls ◽  
Global Datasets

Groundwater is critical in supporting current and future reliable water supply throughout Africa. Although continental maps of groundwater storage and recharge have been developed, we currently lack a clear understanding on how the controls on groundwater recharge vary across the entire continent. Reviewing the existing literature, we synthesize information on reported groundwater recharge controls in Africa. We find that 15 out of 22 of these controls can be characterised using global datasets. We develop 11 descriptors of climatic, topographic, vegetation, soil and geologic properties using global datasets, to characterise groundwater recharge controls in Africa. These descriptors cluster Africa into 15 Recharge Landscape Units for which we expect recharge controls to be similar. Over 80% of the continents land area is organized by just nine of these units. We also find that aggregating the Units by similarity into four broader Recharge Landscapes (Desert, Dryland, Wet tropical and Wet tropical forest) provides a suitable level of landscape organisation to explain differences in ground-based long-term mean annual recharge and recharge ratio estimates. Furthermore, wetter Recharge Landscapes are more efficient in converting rainfall to recharge than drier Recharge Landscapes as well as having higher annual recharge rates. In Dryland Recharge Landscapes, we found that annual recharge rates largely varied according to mean annual precipitation, whereas recharge ratio estimates increase with increasing monthly variability in P-PET. However, we were unable to explain why ground-based estimates of recharge signatures vary across other Recharge Landscapes, in which there are fewer ground-based recharge estimates, using global datasets alone. Even in dryland regions, there is still considerable unexplained variability in the estimates of annual recharge and recharge ratio, stressing the limitations of global datasets for investigating ground-based information.

scholarly journals Long-term groundwater recharge rates across India by in situ measurements

2018 ◽  
Author(s):  
Soumendra N. Bhanja ◽  
Abhijit Mukherjee ◽  
Rangarajan Ramaswamy ◽  
Bridget R. Scanlon ◽  
Pragnaditya Malakar ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
River Basins ◽  
Base Flow ◽  
Groundwater Abstraction ◽  
Pumping Wells ◽  
Anthropogenic Discharge ◽  
Stressed Region ◽  
Recharge Rates ◽  
Using Data

Abstract. Groundwater recharge sustains groundwater discharge, including natural discharge through springs and base flow to surface water as well as anthropogenic discharge through pumping wells. Here, for the first time, we compute long-term (1996–2015) groundwater recharge rates using data retrieved from several groundwater level monitoring locations across India (3.3 million km2 area), the most groundwater-stressed region globally. Spatial variations in groundwater recharge rates (basin-wide mean: 17 to 960 mm/yr) were estimated in the 22 major river basins across India. The extensive plains of the Indus–Ganges–Brahmaputra (IGB) river basins are subjected to prevalence of comparatively higher recharge. This is mainly attributed to occurrence of coarse sediments, higher rainfall, and intensive irrigation-linked groundwater abstraction inducing recharge by increasing available groundwater storage and return flows. Lower recharge rates (

scholarly journals Reliability of recharge rates estimated from groundwater age with a simplified analytical approach

2020 ◽  
Author(s):  
Yanhui Dong ◽  
Yueqing Xie ◽  
Jun Zhang ◽  
Andy Love ◽  
Xin Dai
Keyword(s):  
Groundwater Recharge ◽  
Analytical Approach ◽  
Groundwater Age ◽  
Sampling Point ◽  
Flux Boundary Condition ◽  
Point Of Entry ◽  
Flux Boundary Conditions ◽  
The Mean ◽  
Recharge Rates

Groundwater age is often used to estimate groundwater recharge through a simplified analytical approach. This estimated recharge is thought to be representative of the mean recharge between the point of entry and the sampling point. However, given the complexity in actual recharge, whether the mean recharge is reasonable is still unclear. This study examined the validity of the method to estimate long-term average groundwater recharge and the possibility of obtaining reasonable spatial recharge pattern. We first validated our model in producing reasonable age distributions using a constant flux boundary condition. We then generated different flow fields and age patterns by using various spatially-varying flux boundary conditions with different magnitudes and wavelengths. Groundwater recharge was estimated and analyzed afterwards using the method at the spatial scale. We illustrated the main findings with a field example in the end. Our results suggest that we can estimate long-term average groundwater recharge with 10% error in many parts of an aquifer. The size of these areas decreases with the increase in both the amplitude and the wavelength. The chance of obtaining a reasonable groundwater recharge is higher if an age sample is collected from the middle of an aquifer and at downstream areas. Our study also indicates that the method can also be used to estimate local groundwater recharge if age samples are collected close to the water table. However, care must be taken to determine groundwater age regardless of conditions.

scholarly journals Recharge Estimation Using CMB and Environmental Isotopes in the Verlorenvlei Estuarine System, South Africa and Implications for Groundwater Sustainability in a Semi-Arid Agricultural Region

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1362
Author(s):  
Andrew Watson ◽  
Anya Eilers ◽  
Jodie A. Miller
Keyword(s):  
South Africa ◽  
Groundwater Recharge ◽  
Low Flow ◽  
Mean Annual Precipitation ◽  
Severe Drought ◽  
Estuarine System ◽  
Groundwater Mixing ◽  
Dry Spell ◽  
Recharge Rates ◽  
Semi Arid

Groundwater recharge remains one of the most difficult hydrogeological variables to measure accurately, especially for semi-arid environments where the recharge flux is much smaller than in humid conditions. In this study, groundwater recharge was estimated using chloride mass balance (CMB) in the Verlorenvlei catchment, South Africa where the effects of recent severe drought conditions in an already semi-arid environment have impacted both agricultural activity as well as the RAMSAR-listed Verlorenvlei estuarine system. Chloride, 18O and 2H tracers were used to improve understanding of the groundwater flow patterns and allowed the fresh parts of the groundwater system, defined by Ca2+-HCO3− groundwater types, to be separated from those where additional salts were being introduced through groundwater mixing, and thus characterized as Na+-Cl− groundwater types. Recharge rates calculated from CMB in the fresh parts of the system were between 4.2–5.6% and 11.4–15.1% of mean annual precipitation for the headwater valley and mountains of the Krom Antonies and are largely consistent with previous studies. However, much lower recharge rates in the valleys where agriculture is dominant contrasts with previous results, which were higher, since groundwater-mixing zones were not recognised. Although the chloride concentration in precipitation is based on only one year of data between 2015 and 2016, where 2015 had on average 28% less precipitation than 2016, the results provide a snapshot of how the system will respond to increasing drought frequency in the future. The results suggest that low rates of groundwater recharge under dry spell conditions will impact on low flow generations which are required to sustain the Verlorenvlei estuarine lake system. Overall, the study highlights the importance of combining hydrochemical tracers such as bulk chloride and stable isotopes with numerical modelling in data-scarce catchments to fully understand the nature of hydrological resilience.

scholarly journals SPATIAL-TEMPORAL VARIATION OF GROUNDWATER RECHARGE FROM PRECIPITATION IN THE STONY ATHI SUB-CATCHMENT, KENYA

2020 ◽  
Vol 3 (1) ◽  
pp. 21
Author(s):  
Morris W. Mathenge ◽  
Dr. Gladys M. Gathuru ◽  
Dr. Esther L. Kitur
Keyword(s):  
Temporal Variation ◽  
Groundwater Recharge ◽  
Sandy Loam ◽  
Annual Rainfall ◽  
Mean Annual Precipitation ◽  
Spatial Average ◽  
Unique Contribution ◽  
Physically Based ◽  
Spatially Distributed

Purpose: Groundwater recharge is an important process for sustainable groundwater development and its quantification is a prerequisite for efficient management of groundwater resources. The purpose of this study was to evaluate the scale and spatial-temporal variation of groundwater recharge from precipitation in the semi-arid Stony Athi sub-catchment. Methodology: A descriptive case study approach was used for the evaluation. WetSpass-M, a GIS physically based, spatially distributed watershed model was applied. The model integrates biophysical and climatic characteristics of a watershed to simulate the long term mean groundwater recharge. Grid maps of the sub-catchment characteristics were prepared from primary and secondary data using ArcMap. The model was applied for four periods, namely, 1984, 1995, 2005 and 2017. Besides the average groundwater recharge, other outputs of the model include surface run-off and actual evapotranspiration. The study was carried out between January and December 2018. Findings: Land cover in the Stony Athi sub-catchment is comprised of built-up area, agricultural land, grassland, shrub-land, mixed forest and bare land. Topography ranges from 1493 m to 2,082 m above sea level with a slope of between 0% and 30%. Soil types include sandy loam, loam, sandy clay loam, sandy loam and clay. The mean annual precipitation is about 634 mm while the potential evapotranspiration is about 1,490 mm. Annual temperature averages 19.0°C with a mean maximum of 25°C and a mean minimum of 12.7°C. The results of the simulation indicated that the long-term temporal and spatial average annual rainfall of 634 mm is distributed as 88 mm (14%) recharge, 77 mm (12%) surface runoff while 475 mm (75%) is lost through evapotranspiration.   Unique contribution to theory, practice and policy: This study demonstrate the importance of physically-based spatially-distributed hydrological models in estimating the water balance. The study provides a theoretical basis for scientific, rational resource allocation and utilization as well as creating awareness of the need to enhance groundwater governance. Results from this study can be used as an input for building an integrated groundwater modelling and for evaluation of potential sites for managed artificial recharge through harvesting runoff to improve groundwater storage.  

scholarly journals Long-term groundwater recharge rates across India by in situ measurements

2019 ◽  
Vol 23 (2) ◽  
pp. 711-722 ◽  
Author(s):  
Soumendra N. Bhanja ◽  
Abhijit Mukherjee ◽  
R. Rangarajan ◽  
Bridget R. Scanlon ◽  
Pragnaditya Malakar ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
River Basins ◽  
Base Flow ◽  
Groundwater Abstraction ◽  
Fractured Aquifers ◽  
Anthropogenic Discharge ◽  
Stressed Region ◽  
Recharge Rates ◽  
Using Data

Abstract. Groundwater recharge sustains groundwater discharge, including natural discharge through springs and the base flow to surface water as well as anthropogenic discharge through pumping wells. Here, for the first time, we compute long-term (1996–2015) groundwater recharge rates using data retrieved from several groundwater-level monitoring locations across India (3.3 million km2 area), the most groundwater-stressed region globally. Spatial variations in groundwater recharge rates (basin-wide mean: 17 to 960 mm yr−1) were estimated in the 22 major river basins across India. The extensive plains of the Indus–Ganges–Brahmaputra (IGB) river basins are subjected to prevalence of comparatively higher recharge. This is mainly attributed to occurrence of coarse sediments, higher rainfall, and intensive irrigation-linked groundwater-abstraction inducing recharge by increasing available groundwater storage and return flows. Lower recharge rates (<200 mm yr−1) in most of the central and southern study areas occur in cratonic, crystalline fractured aquifers. Estimated recharge rates have been compared favorably with field-scale recharge estimates (n=52) based on tracer (tritium) injection tests. Results show that precipitation rates do not significantly influence groundwater recharge in most of the river basins across India, indicating human influence in prevailing recharge rates. The spatial variability in recharge rates could provide critical input for policymakers to develop more sustainable groundwater management in India.

scholarly journals Effect of Climate Variability and Change in Groundwater in Europe

1990 ◽  
Vol 21 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Richard Thomsen
Keyword(s):  
Climate Variability ◽  
Water Supply ◽  
Groundwater Recharge ◽  
Historical Data ◽  
Public Water Supply ◽  
Climate Variability And Change ◽  
Winter Rainfall ◽  
The Past ◽  
Current Value ◽  
Recharge Rates

Public water supply in Europe relies very heavily on groundwater. Recharge of groundwater takes place mainly in the winter months. An analysis of winter rainfall data shows that current recharge rates are abnormally high, and that during several periods in the past the rate has been less than half the current value. A return to such low values could have catastrophic consequences, but even more modest drops would be serious. Useful predictions must be based on climatic models and the full use of climatic, paleohydrological and historical data.

scholarly journals Supplementary material to "Long-term groundwater recharge rates across India by in situ measurements"

2018 ◽  
Author(s):  
Soumendra N. Bhanja ◽  
Abhijit Mukherjee ◽  
Rangarajan Ramaswamy ◽  
Bridget R. Scanlon ◽  
Pragnaditya Malakar ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
In Situ Measurements ◽  
Supplementary Material ◽  
Recharge Rates

Investigating artificial groundwater recharge to ensure the water supply to the city of Graz

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
Wilhelm Tischendorf ◽  
Hans Kupfersberger ◽  
Christian Schilling ◽  
Oliver Gabriel
Keyword(s):  
Water Supply ◽  
Groundwater Recharge ◽  
Water Demand ◽  
Bulk Water ◽  
Retention Rates ◽  
Subsurface Water ◽  
Artificial Groundwater Recharge ◽  
Advantages And Disadvantages ◽  
Water Recharge ◽  
Water Supply Company

Being Austria's fourth largest water-supply company, the Grazer Stadtwerke AG., has ensured the successful water-supply of the Styrian capital with 250.000 inhabitants for many years. The average daily water demand of the area amounts to about 50,000 m3. Approximately 30 % of the total demand is covered by the bulk water supply from the Zentral Wasser Versorgung Hochschwab Süd. The waterworks Friesach and Andritz, which cover the additional 70 % of the water demand, operate by means of artificial groundwater recharge plants where horizontal filter wells serve as drawing shafts. The groundwater recharge systems serve to increase the productivity of the aquifer and to reduce the share of the infiltration from the Mur River. Protection areas have been identified to ensure that the water quality of the aquifer stay at optimal levels. The protection areas are divided into zones indicating various restrictions for usage and planning. Two respective streams serve as the source for the water recharge plants. Different infiltration systems are utilised. Each of the various artificial groundwater recharge systems displays specific advantages and disadvantages in terms of operation as well as maintenance. In order to secure a sustainable drinking water supply the recharge capacity will be increased. Within an experimental setting different mixtures of top soils are investigated with respect to infiltration and retention rates and compared to the characteristics of the existing basins. It can be shown that the current operating sand basin with more than 90% grains in the range between 0.063 and 6.3 mm represents the best combination of infiltration and retention rates. In future experiments the performance of alternative grain size distributions as well as planting the top soil will be tested. Additionally, in order to optimize the additional groundwater recharge structures the composition of the subsurface water regarding its origin is statistically analyzed.

scholarly journals Development and Verification of the Available Number of Water Intake Days in Ungauged Local Water Source Using the SWAT Model and Flow Recession Curves

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1511
Author(s):  
Jung-Ryel Choi ◽  
Il-Moon Chung ◽  
Se-Jin Jeung ◽  
Kyung-Su Choo ◽  
Cheong-Hyeon Oh ◽  
...  
Keyword(s):  
Water Supply ◽  
Water Intake ◽  
Water Resource Management ◽  
Assessment Tool ◽  
Swat Model ◽  
High Water ◽  
Coefficient Of Determination ◽  
Severe Drought ◽  
Regional Government

Climate change significantly affects water supply availability due to changes in the magnitude and seasonality of runoff and severe drought events. In the case of Korea, despite high water supply ratio, more populations have continued to suffer from restricted regional water supplies. Though Korea enacted the Long-Term Comprehensive Water Resources Plan, a field survey revealed that the regional government organizations limitedly utilized their drought-related data. These limitations present a need for a system that provides a more intuitive drought review, enabling a more prompt response. Thus, this study presents a rating curve for the available number of water intake days per flow, and reviews and calibrates the Soil and Water Assessment Tool (SWAT) model mediators, and found that the coefficient of determination, Nash–Sutcliffe efficiency (NSE), and percent bias (PBIAS) from 2007 to 2011 were at 0.92, 0.84, and 7.2%, respectively, which were “very good” levels. The flow recession curve was proposed after calculating the daily long-term flow and extracted the flow recession trends during days without precipitation. In addition, the SWAT model’s flow data enables the quantitative evaluations of the number of available water intake days without precipitation because of the high hit rate when comparing the available number of water intake days with the limited water supply period near the study watershed. Thus, this study can improve drought response and water resource management plans.

Sign in / Sign up

Export Citation Format

Share Document