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.

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 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

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 Analysis of Rainfall Trends and Its Relationship with SST Signals in the Lake Tana Basin, Ethiopia

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Tesfay Mekonnen Weldegerima ◽  
Tadesse Terefe Zeleke ◽  
Belay Simane Birhanu ◽  
Benjamin Frederick Zaitchik ◽  
Zewdu Alamineh Fetene
Keyword(s):  
Human Life ◽  
Kendall Test ◽  
Annual Rainfall ◽  
Lake Tana ◽  
Spatial And Temporal Scales ◽  
Rainfall Trends ◽  
Rate Of Increase ◽  
Debre Tabor ◽  
Seasonal Analysis ◽  
Lake Tana Basin

The impacts of climate change and climate variability on human life have led the scientific community to monitor the behavior of weather and climate variables at different spatial and temporal scales. This paper explores seasonal and annual trends of rainfall in the Lake Tana basin (LTB) and their teleconnections with global sea surface temperatures (SSTs) over the period between 1979 and 2015. The nonparametric Mann–Kendall test and Sen’s slope estimate are applied to the rainfall data collected from the National Meteorology Agency (NMA) of Ethiopia for detecting and estimating rainfall trends. Additionally, Pearson’s correlation coefficient method is used to determine the effect of SST variations on rainfall. The assessment of rainfall trends indicates that the amount of annual rainfall in the Lake Tana basin is increasing, but the rate of increase is not statistically significant. Seasonal analysis reveals that the smallest amount of rainfall occurs in the Bega season, and this season is getting drier with time. However, the analysis indicates that the other two seasons (Belg and Kiremt) are becoming wetter. The rainfall in Kiremt is increasing significantly (significant at the p=0.05 level) in Debre Tabor station with a rate of 10.20 mm/year. Besides, 78.1% of the total annual rainfall in the basin occurs during this rainy (Kiremt) season, whereas Bega and Belg contribute some 9.4% and 12.5%, respectively. Furthermore, the correlation analysis of rainfall and SSTs indicates that rainfall of the LTB is highly affected by the variations of SSTs.

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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