Your search found 4 records
1 Jensen, K. H.. 1998. Impact of geological heterogeneity on groundwater protection. In Stockholm International Water Institute, Proceedings, Stockholm Water Symposium, Stockholm, August 10-13, 1998: Water - The key to socio-economic development and quality of life. Stockholm, Sweden: SIWI. pp.201-208.
Groundwater management ; Geology ; Water pollution ; Aquifers ; Soil water ; Hydraulics ; Experiments / Denmark
(Location: IWMI-HQ Call no: 333.91 G000 STO Record No: H023918)
2 Vithanage, Meththika; Engesgaard, P.; Villholth, Karen G.; Jensen, K. H.. 2011. The effects of the 2004 tsunami on a coastal aquifer in Sri Lanka. Ground Water, 50(5):704-714. [doi: https://doi.org/10.1111/j.1745-6584.2011.00893.x]
Tsunamis ; Coastal area ; Aquifers ; Groundwater ; Water table ; Models ; Salt water intrusion ; Hydraulic conductivity / Sri Lanka
(Location: IWMI HQ Call no: e-copy only Record No: H045001)
(1.27 MB)
On December 26, 2004, the earthquake off the southern coast of Sumatra in the Indian Ocean generated far-reaching tsunami waves, resulting in severe disruption of the coastal aquifers in many countries of the region. The objective of this study was to examine the impact of the tsunami on groundwater in coastal areas. Field investigations on the east coast of Sri Lanka were carried out along a transect located perpendicular to the coastline on a 2.4 km wide sand stretch bounded by the sea and a lagoon. Measurements of groundwater table elevation and electrical conductivity (EC) of the groundwater were carried out monthly from October 2005 to August 2007. The aquifer system and tsunami saltwater intrusion were modeled using the variable-density flow and solute transport code HST3D to understand the tsunami plume behavior and estimate the aquifer recovery time. EC values reduced as a result of the monsoonal rainfall following the tsunami with a decline in reduction rate during the dry season. The upper part of the saturated zone (down to 2.5 m) returned to freshwater conditions (EC < 1000 µS/cm) 1 to 1.5 years after the tsunami, according to field observations. On the basis of model simulations, it may take more than 15 years for the entire aquifer (down to 28 m) to recover completely, although the top 6 m of the aquifer may become fresh in about 5 years.
3 Shu, Y.; Villholth, K. G.; Jensen, K. H.; Stisen, S.; Lei, Y. 2012. Integrated hydrological modeling of the North China Plain: options for sustainable groundwater use in the alluvial plain of Mt. Taihang. Journal of Hydrology, 464-465:79-93. [doi: https://doi.org/10.1016/j.jhydrol.2012.06.048]
Water management ; Water balance ; Groundwater management ; Aquifers ; Pumping ; Hydrology ; Models ; Plains ; Evapotranspiration ; Cropping patterns ; Precipitation ; Calibration / China / North China Plain / Mount Taihang
(Location: IWMI HQ Call no: e-copy only Record No: H045583)
(2.62 MB)
The integrated hydrological model MIKE SHE was applied to a part of the North China Plain to examine the dynamics of the hydrological system and to assess water management options to restore depleted groundwater resources. The model simulates the spatio-temporal distribution of recharge to and the associated dynamics of the alluvial aquifers based on climatic conditions, land use, soil characteristics, irrigation and coupled unsaturated-saturated zone processes. The model was auto-calibrated for the period 1996–2002 against daily observations of groundwater head from wells distributed across the 7230 km2 region and actual evapotranspiration measured at an agricultural station located within the model area. The model simulations compared well with observations and acceptable values were obtained for both root mean square error and correlation coef cient. The calibrated model was subsequently used for scenario analysis of the effect of different cropping rotations, irrigation intensity, and other water management options, like the implementation of the South to North Water Transfer (SNWT) project. The model analysis veri ed that groundwater tables in the region are subject to steep declines (up to 1 m/yr) due to decades of intensive exploitation of the groundwater resources for crop irrigation, primarily the widespread crop rotation of irrigated winter wheat and mostly rainfed summer maize. The SNWT project mitigates water stress in Shijiazhuang city and areas adjacent to wastewater canals but cannot solely reverse declining water tables across the region. Combining the SNWT project and implementing region-wide crop and irrigation system changes, including de cit irrigation, wastewater irrigation, and alternating winter fallow, provides a feasible means to stabilize groundwater levels in the area.
4 Sorensen, J. P. R.; Davies, J.; Ebrahim, Girma Y.; Lindle, J.; Marchant, B. P.; Ascott, M. J.; Bloomfield, J. P.; Cuthbert, M. O.; Holland, M.; Jensen, K. H.; Shamsudduha, M.; Villholth, Karen G.; MacDonald, A. M.; Taylor, R. G. 2021. The influence of groundwater abstraction on interpreting climate controls and extreme recharge events from well hydrographs in semi-arid South Africa. Hydrogeology Journal, 29(8):2773-2787. [doi: https://doi.org/10.1007/s10040-021-02391-3]
Groundwater extraction ; Groundwater recharge ; Well hydrographs ; Semiarid climate ; Catchment areas ; Groundwater table ; Rain ; River flow ; Stream flow ; Extreme weather events ; El Nino-Southern Oscillation ; Hydrogeology ; Boreholes ; Spatial distribution ; Land use / South Africa / Limpopo / Mogalakwena Catchment / Sand River Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H050671)
https://link.springer.com/content/pdf/10.1007/s10040-021-02391-3.pdf
https://vlibrary.iwmi.org/pdf/H050671.pdf
https://vlibrary.iwmi.org/pdf/H050671.pdf
(6.26 MB) (6.26 MB)
There is a scarcity of long-term groundwater hydrographs from sub-Saharan Africa to investigate groundwater sustainability, processes and controls. This paper presents an analysis of 21 hydrographs from semi-arid South Africa. Hydrographs from 1980 to 2000 were converted to standardised groundwater level indices and rationalised into four types (C1–C4) using hierarchical cluster analysis. Mean hydrographs for each type were cross-correlated with standardised precipitation and streamflow indices. Relationships with the El Nino– Southern Oscillation (ENSO) were also investigated. The four hydrograph types show a transition of autocorrelation over increasing timescales and increasingly subdued responses to rainfall. Type C1 strongly relates to rainfall, responding in most years, whereas C4 notably responds to only a single extreme event in 2000 and has limited relationship with rainfall. Types C2, C3 and C4 have stronger statistical relationships with standardised streamflow than standardised rainfall. C3 and C4 changes are significantly (p < 0.05) correlated to the mean wet season ENSO anomaly, indicating a tendency for substantial or minimal recharge to occur during extreme negative and positive ENSO years, respectively. The range of different hydrograph types, sometimes within only a few kilometres of each other, appears to be a result of abstraction interference and cannot be confidently attributed to variations in climate or hydrogeological setting. It is possible that high groundwater abstraction near C3/C4 sites masks frequent small-scale recharge events observed at C1/C2 sites, resulting in extreme events associated with negative ENSO years being more visible in the time series.
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