Spatial and temporal simulation of groundwater recharge amount and cross-validation with point measurement-based estimations on a tropical basin comprising volcanic aquifers: case study of Lake Tana basin, northwestern Ethiopia

2021 ◽  
Author(s):  
Alemu Yenehun ◽  
Mekete Dessie ◽  
Fenta Nigate ◽  
Ashebir Sewale Belay ◽  
Mulugeta Azeze ◽  
...  
Keyword(s):  
Land Use ◽  
Groundwater Recharge ◽  
Water Table ◽  
Surface Runoff ◽  
Water Infiltration ◽  
Balance Model ◽  
Lake Tana ◽  
Aquifer Systems ◽  
The Mean ◽  
Lake Tana Basin

<p>A physically distributed water balance model called WetSpass is applied to estimate the recharge for the semi-humid Lake Tana basin in northwest Ethiopia. Lake Tana basin, one of the major sub-basins of the Upper Blue Nile River basin, covers 15,077 km<sup>2</sup> of which 3,156<sup></sup>km<sup>2</sup> is the lake water body. The basin is regarded as one of the growth corridors of the country, where huge waterworks infrastructure is being developed. The basin has complex volcanic aquifer systems due to the multi-stage volcanism of the Cenozoic and Quaternary eras comprising many dikes, extended volcanic necks, and centers. Hence, estimating hydrological terms such as groundwater recharge considering the high basin physical heterogeneities is difficult, though highly important. In this study, the WetSpass model is developed, and recharge surface, surface runoff, and evapotranspiration at 90 m grid resolution have been developed. The spatial recharge map is cross-validated with water table fluctuation (WTF) and chloride mass balance (CMB) methods. The mean annual recharge, surface runoff, and evapotranspiration over the whole basin using WetSpass are estimated at 315 mm, 416 mm, and 770 mm, respectively. The mean annual recharge ranges from 0 mm to 1085 mm: 0 mm at water bodies and highest on highly fractured Quaternary basalt. Similarly, a high range of recharge is also noted using WTF and CMB methods showing the strongly heterogeneous nature of the hydro(meteoro)logical characteristics of the area. Generally, the recharge is found higher in the southern and eastern catchments and lower in the northern catchments, primarily due to higher rainfall amounts and highly permeable geological formations in the former parts. A fair general correlation between the recharge by WTF and WetSpass is found. However, WetSpass is more effective in the highland areas where the recharge is controlled by rainfall, while the WTF method is more effective in the storage controlled flat floodplain area. CMB is applied in a less spatially distributed way, and hence, the spatial performance of the method is not well evaluated. However, logged water infiltration in the floodplains, and transpiration from the groundwater in shallow water table areas have disturbed the estimated recharge by the CMB method. The land-use change from 1986-2014 brought relatively small hydrological change, although the land use has changed significantly.</p>

scholarly journals Spatial and temporal simulation of groundwater recharge and cross-validation with point measurements in volcanic aquifers with variable topography

2021 ◽  
Author(s):  
Alemu Yenehun ◽  
Mekete Dessie ◽  
Fenta Nigate ◽  
Ashebir Sewale Belay ◽  
Mulugeta Azeze ◽  
...  
Keyword(s):  
Land Use ◽  
Groundwater Recharge ◽  
Sandy Loam ◽  
Fractured Rock ◽  
Northwest Ethiopia ◽  
Balance Model ◽  
Lake Tana ◽  
Spatial And Temporal Scales ◽  
The Mean ◽  
Lake Tana Basin

Abstract. A physically distributed water balance model called WetSpass is applied to estimate the recharge for the semi-humid Lake Tana basin in northwest Ethiopia. Lake Tana basin is one of the growth corridors of the country, where huge waterworks infrastructure is developing. Estimating groundwater recharge at required spatial and temporal scales is a challenge in groundwater management, sustainability and pollution studies. In this study, the WetSpass model is developed at 90 m grid resolution. The spatial recharge map by WetSpass is cross-validated with water table fluctuation (WTF) and chloride mass balance (CMB) methods. The mean annual recharge, surface runoff, and evapotranspiration over the whole basin using WetSpass are estimated at 315 mm, 416 mm, and 770 mm of rainfall, respectively. The mean annual recharge ranges from 0 mm to 1085 mm (0 % to 57 % of the rainfall): 0 mm at water bodies and highest on flat, sandy loam soil and bush land cover. Similarly, a high range of recharge is also noted using WTF and CMB methods showing the strong heterogeneous nature of the hydro(meteoro)logical characteristics of the area. Generally, the recharge is found higher in southern and eastern catchments and lower in the northern catchments, primarily due to higher rainfall amounts in the former parts. A fair general correlation between the recharge by WTF and WetSpass is found. WetSpass is effective in aquifers where diffuse recharging mechanism is the predominant type and recharge is controlled by rainfall. It is less effective in the storage-controlled flat floodplain alluvial and fractured rock aquifer areas. In these areas, the point estimates by WTF and CMB are effective and can be considered as reliable values. The land use change from 1986 to 2014 brought a relatively small hydrological change in recharge although the land use has changed significantly.

scholarly journals Impacts of land surface model and land use data on WRF model simulations of rainfall and temperature over Lake Tana Basin, Ethiopia

Heliyon ◽  
2019 ◽  
Vol 5 (9) ◽  
pp. e02469 ◽  
Author(s):  
Achenafi Teklay ◽  
Yihun T. Dile ◽  
Dereje H. Asfaw ◽  
Haimanote K. Bayabil ◽  
Kibruyesfa Sisay
Keyword(s):  
Land Use ◽  
Land Surface ◽  
Wrf Model ◽  
Land Surface Model ◽  
Surface Model ◽  
Lake Tana ◽  
Model Simulations ◽  
Lake Tana Basin

scholarly journals Using multiple methods to investigate the effects of land-use changes on groundwater recharge in a semi-arid area

2021 ◽  
Vol 25 (1) ◽  
pp. 89-104
Author(s):  
Shovon Barua ◽  
Ian Cartwright ◽  
P. Evan Dresel ◽  
Edoardo Daly
Keyword(s):  
Land Use ◽  
Groundwater Recharge ◽  
Water Table ◽  
Land Use Changes ◽  
Arid Area ◽  
Land Clearing ◽  
Water Table Fluctuations ◽  
Recharge Rates ◽  
Effects Of Land Use ◽  
Semi Arid

Abstract. Understanding the applicability and uncertainties of methods for documenting recharge rates in semi-arid areas is important for assessing the successive effects of land-use changes and understanding groundwater systems. This study focuses on estimating groundwater recharge rates and understanding the impacts of land-use changes on recharge rates in a semi-arid area in southeast Australia. Two adjacent catchments were cleared ∼180 years ago following European settlement, and a eucalypt plantation forest was subsequently established ∼15 years ago in one of the catchments. Chloride mass balance analysis yields recharge rates of 0.2 to 61.6 mm yr−1 (typically up to 11.2 mm yr−1). The lower of these values probably represents recharge rates prior to land clearing, whereas the higher likely reflects recharge rates following the initial land clearing. The low pre-land-clearing recharge rates are consistent with the presence of old groundwater (residence times up to 24 700 years) and the moderate-to-low hydraulic conductivities (0.31 to 0.002 m d−1) of the aquifers. Recharge rates estimated from tritium activities and water table fluctuations reflect those following the initial land clearing. Recharge rates estimated using water table fluctuations (15 to 500 mm yr−1) are significantly higher than those estimated using tritium renewal rates (0.01 to 89 mm yr−1; typically <14.0 mm yr−1) and approach the long-term average annual rainfall (∼640 mm yr−1). These recharge rates are unrealistic given the estimated evapotranspiration rates of 500 to 600 mm yr−1 and the preservation of old groundwater in the catchments. It is likely that uncertainties in the specific yield results in the water table fluctuation method significantly overestimating recharge rates, and despite the land-use changes, the present-day recharge rates are relatively modest. These results are ultimately important for assessing the impacts of land-use changes and management of groundwater resources in semi-arid regions in Australia and elsewhere.

Estimation of Spatial and Temporal Groundwater Balance Components in Khadir Canal Sub-Division, Chaj Doab, Pakistan

Hydrology ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 178
Author(s):  
Muhammad Aslam ◽  
Ali Salem ◽  
Vijay P. Singh ◽  
Muhammad Arshad
Keyword(s):  
Land Use ◽  
Water Balance ◽  
Groundwater Recharge ◽  
Groundwater Resources ◽  
Balance Model ◽  
Annual Rainfall ◽  
Water Balance Components ◽  
Aquifer Management ◽  
Groundwater Balance ◽  
Semi Arid

Evaluation of the spatial and temporal distribution of water balance components is required for efficient and sustainable management of groundwater resources, especially in semi-arid and data-poor areas. The Khadir canal sub-division, Chaj Doab, Pakistan, is a semi-arid area which has shallow aquifers which are being pumped by a plethora of wells with no effective monitoring. This study employed a monthly water balance model (water and energy transfer among soil, plants, and atmosphere)—WetSpass-M—to determine the groundwater balance components on annual, seasonal, and monthly time scales for a period of the last 20 years (2000–2019) in the Khadir canal sub-division. The spatial distribution of water balance components depends on soil texture, land use, groundwater level, slope, and meteorological conditions. Inputs for the model included data on topography, slope, soil, groundwater depth, slope, land use, and meteorological data (e.g., precipitation, air temperature, potential evapotranspiration, and wind speed) which were prepared using ArcGIS. The long-term average annual rainfall (455.7 mm) is distributed as 231 mm (51%) evapotranspiration, 109.1 mm (24%) surface runoff, and 115.6 mm (25%) groundwater recharge. About 51% of groundwater recharge occurs in summer, 18% in autumn, 14% in winter, and 17% in spring. Results showed that the WetSpass-M model properly simulated the water balance components of the Khadir canal sub-division. The WetSpass-M model’s findings can be used to develop a regional groundwater model for simulation of different aquifer management scenarios in the Khadir area, Pakistan.

scholarly journals Groundwater recharge rates and surface runoff response to land use and land cover changes in semi-arid environments

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
S. O. Owuor ◽  
K. Butterbach-Bahl ◽  
A. C. Guzha ◽  
M. C. Rufino ◽  
D. E. Pelster ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Groundwater Recharge ◽  
Surface Runoff ◽  
Land Cover Changes ◽  
Arid Environments ◽  
Recharge Rates ◽  
Semi Arid

scholarly journals Linking soil moisture balance and source-responsive models to estimate diffuse and preferential components of groundwater recharge

2012 ◽  
Vol 9 (7) ◽  
pp. 8455-8492
Author(s):  
M. O. Cuthbert ◽  
R. Mackay ◽  
J. R. Nimmo
Keyword(s):  
Soil Moisture ◽  
Groundwater Recharge ◽  
Water Table ◽  
Preferential Flow ◽  
Numerical Models ◽  
Balance Model ◽  
Shallow Water Table ◽  
Soil Matrix ◽  
Moisture Balance ◽  
Soil Moisture Balance

Abstract. Results are presented of a detailed study into the vadose zone and shallow water table hydrodynamics of a field site in Shropshire, UK. A conceptual model is developed and tested using a range of numerical models, including a modified soil moisture balance model (SMBM) for estimating groundwater recharge in the presence of both diffuse and preferential flow components. Tensiometry reveals that the loamy sand topsoil wets up via macropore flow and subsequent redistribution of moisture into the soil matrix. Recharge does not occur until near-positive pressures are achieved at the top of the sandy glaciofluvial outwash material that underlies the topsoil, about 1 m above the water table. Once this occurs, very rapid water table rises follow. This threshold behaviour is attributed to the vertical discontinuity in the macropore system due to seasonal ploughing of the topsoil, and a lower permeability plough/iron pan restricting matrix flow between the topsoil and the lower outwash deposits. Although the wetting process in the topsoil is complex, a SMBM is shown to be effective in predicting the initiation of preferential flow from the base of the topsoil into the lower outwash horizon. The rapidity of the response at the water table and a water table rise during the summer period while flow gradients in the unsaturated profile were upward suggest that preferential flow is also occurring within the outwash deposits below the topsoil. A variation of the source-responsive model proposed by Nimmo (2010) is shown to reproduce the observed water table dynamics well in the lower outwash horizon when linked to a SMBM that quantifies the potential recharge from the topsoil. The results reveal new insights into preferential flow processes in cultivated soils and provide a useful and practical approach to accounting for preferential flow in studies of groundwater recharge estimation.

scholarly journals A daily salt balance model for representing stream salinity generation process following land use change

2005 ◽  
Vol 2 (4) ◽  
pp. 1147-1183
Author(s):  
M. A. Bari ◽  
K. R. J. Smettem
Keyword(s):  
Land Use ◽  
Water Balance ◽  
Surface Runoff ◽  
Preferential Flow ◽  
Water Movement ◽  
Water Balance Model ◽  
Salt Flux ◽  
Balance Model ◽  
Generation Process ◽  
Salt Balance

Abstract. We developed a coupled salt and water balance model to represent the stream salinity generation process following land use changes. The conceptual model consists of three main components with five stores: (i) Dry, Wet and Subsurface Stores, (ii) saturated Groundwater Store and (iii) a transient Stream zone Store. The Dry and Wet Stores represent the salt and water movement in the unsaturated zone and also the near-stream dynamic saturated areas, responsible for the generation of salt flux associated with surface runoff and interflow. The unsaturated Subsurface Store represents the salt bulge and the salt fluxes. The Groundwater Store comes into play when the groundwater level is at or above the stream invert and quantifies the salt fluxes to the Stream zone Store. In the stream zone module, we consider a "free mixing" between the salt brought about by surface runoff, interflow and groundwater flow. Salt accumulation on the surface due to evaporation and its flushing by initial winter flow is also incorporated in the Stream zone Store. The salt balance model was calibrated sequentially following successful application of the water balance model. Initial salt stores were estimated from measured salt profile data. We incorporated two lumped parameters to represent the complex chemical processes like diffusion-dilution-dispersion and salt fluxes due to preferential flow. The model has performed very well in simulating stream salinity generation processes observed at Ernies and Lemon experimental catchments in south west of Western Australia. The simulated and observed stream salinity and salt loads compare very well throughout the study period. The model slightly over predicted annual stream salt load by 6.2% and 6.8%, with R2 of 0.95 and 0.96 for Ernies and Lemon catchment, respectively.

scholarly journals Dominant Influencing Factors of Groundwater Recharge Spatial Patterns in Ergene River Catchment, Turkey

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 653 ◽  
Author(s):  
Emmanuel Rukundo ◽  
Ahmet Doğan
Keyword(s):  
Land Use ◽  
Groundwater Recharge ◽  
Principal Component ◽  
Base Flow ◽  
Balance Model ◽  
Flow Index ◽  
Model Calculations ◽  
River Catchment ◽  
Total Runoff ◽  
The Difference

Groundwater is of great significance in sustaining life on planet earth. The reliable estimation of groundwater recharge is the key understanding the groundwater reservoir and forecasting its potential accessibility. The main objective of this study was to assess the groundwater recharge and its controlling factors at the Ergene river catchment. A grid-based water balance model was adopted to determine the spatially distributed long-term groundwater recharge and other water budget components, relying upon the hydro-climatic variables, land-use, soil, geology, and relief of the investigated area. The model calculations were performed for the hydrological reference horizon of 20 years at a spatial resolution of 100 × 100 m. The base flow index (BFI) separation concept was applied to split up the simulated total runoff into groundwater recharge and direct runoff. Subsequently, the statistical methods of Pearson product–moment correlation and principal component analysis (PCA) were combined for identifying the dominant catchment and meteorological factors influencing the recharge. The average groundwater recharge over the investigated area amounts to 95 mm/year. The model validation and statistical analysis indicate that the difference between simulated and observed total runoff and recharge values is generally under 20% and no significant inconsistency was observed. PCA indicated that recharge is controlled, in order of significance, by land-use, soil, and climate variables. The findings of this research highlight the key role of spatial variables in recharge determination. In addition, the generated outputs may contribute to groundwater resource management in the Ergene river catchment.

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