scholarly journals Impact of Sedimentation on Water Seepage Capacity in Lake Nakuru, Kenya

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Parfait Iradukunda ◽  
Maurice O. Nyadawa
Keyword(s):  
Hydraulic Conductivity ◽  
Water Balance ◽  
Water Level ◽  
Sediment Sample ◽  
Permeability Coefficient ◽  
Lake Nakuru ◽  
Water Seepage ◽  
Average Ratio ◽  
The Impact ◽  
Maximum Permeability

Accumulation and deposition of sediments in waterbody affect the seepage capacity that could lead to improper water balance and results in the water level rise. This study analysed the influence of sedimentation on seepage capacity in Lake Nakuru and the impact of sediment characteristics to the water seepage and the flow rate formation at the lake bed level. The study was performed by sampling and analysing the sediment cores from two locations in the lake. The sediment hydraulic properties, i.e., moisture and porosity, particle sizes, and hydraulic conductivity, were determined using the oven-drying method, sieve analysis, hydrometer analysis, and falling head tests, respectively. The results showed that the lake sediment sample from location P1 had an average ratio of 39.38% for silty soil, 34.00% for clayey sediment, and 26.63% for fine-sand sediment particles with the maximum permeability coefficient of 3.37 ∗ 10 − 5  cm/s, while the one from location P2 had an average ratio of 63.17% for sand, 20.17% for fine particles, and 16.67% for gravels with the maximum permeability coefficient of 0.010793 cm/s. The hydraulic conductivity of sediment sample from location P1 and P2 increased along the core depth. This could lead to the rise of water level due to the decreases of water movement induced from the sediment cementation in the top layers under the waterbody. Sedimentation affects Lake Nakuru water volume and water balance; hence, there is a need to control the inflow of sediment resulting from anthropogenic activities in the watershed.

scholarly journals Features of the balance structure formation of groundwater withdrawal and its effect on river flow at a subsoil water level drawdown

2019 ◽  
Vol 46 (3) ◽  
pp. 247-258
Author(s):  
S. O. Grinevsky ◽  
V. S. Sporyshev
Keyword(s):  
Water Balance ◽  
Water Level ◽  
River Flow ◽  
Groundwater Withdrawal ◽  
Intermediate Water ◽  
Subsoil Water ◽  
Balance Structure ◽  
The Impact ◽  
Subsoil Water Level ◽  
Infiltration Recharge

The balance structure of the pumpage sourses of riverside water-intakes, developing a subsoil aquifer or intermediate water that hydraulically interacts with it, can show the effect of the processes of water balance adjustment in the unsaturated zone to the accompanying subsoil water level drawdown. In this case, because of the shallow depth to subsoil water, its level drop due to water withdrawal causes a decrease in evapotranspiration and an increase in groundwater infiltration recharge. These processes have their effect on the balance structure of usable water resources as components of natural and involved resources and reduce the impact of groundwater pumping on river flow. Analysis of the operational data of the Sudogda waterintake in Vladimir oblast and geohydrological modeling were used to evaluate variations of the groundwater evaportanspiration losses and infiltration recharge and their role in the water balance structure of reserves of a field and in the impact of groundwater withdrawal on river flow.

scholarly journals Conceptual and numerical modeling approach of the Guarani Aquifer System

2013 ◽  
Vol 17 (1) ◽  
pp. 295-314 ◽  
Author(s):  
L. Rodríguez ◽  
L. Vives ◽  
A. Gomez
Keyword(s):  
Hydraulic Conductivity ◽  
Water Balance ◽  
Water Budget ◽  
Flow System ◽  
Regional Scale ◽  
Early Years ◽  
Scale Model ◽  
Aquifer System ◽  
Guarani Aquifer ◽  
The Impact

Abstract. In large aquifers, relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. Yet, it may be conjectured that regional scale groundwater flow models can help in understanding the flow system functioning and the relative magnitude of water budget components, which are important for aquifer management. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormous volume of water; however, it is not well known, being difficult to assess the impact of exploitation currently used to supply over 25 million inhabitants. This is a sensitive issue because the aquifer is shared by four countries. Moreover, an integrated groundwater model, and therefore a global water balance, were not available. In this work, a transient regional scale model for the entire aquifer based upon five simplified, equally plausible conceptual models represented by different hydraulic conductivity parametrizations is used to analyze the flow system and water balance components. Combining an increasing number of hydraulic conductivity zones and an appropriate set of boundary conditions, the hypothesis of a continuous sedimentary unit yielded errors within the calibration target in a regional sense. The magnitude of the water budget terms resulted very similar for all parametrizations. Recharge and stream/aquifer fluxes were the dominant components representing, on average, 84.2% of total inflows and 61.4% of total outflows, respectively. However, leakage was small compared to stream discharges of main rivers. For instance, the simulated average leakage for the Uruguay River was 8 m3 s−1 while the observed absolute minimum discharge was 382 m3 s−1. Streams located in heavily pumped regions switched from a gaining condition in early years to a losing condition over time. Water is discharged through the aquifer boundaries, except at the eastern boundary. On average, pumping represented 16.2% of inflows while aquifer storage experienced a small overall increment. The model water balance indicates that the current rate of groundwater withdrawals does not exceed the rate of recharge in a regional sense.

scholarly journals Conceptual and numerical modeling of the Guaraní Aquifer System

2012 ◽  
Vol 9 (8) ◽  
pp. 9885-9930
Author(s):  
L. Rodríguez ◽  
L. Vives ◽  
A. Gomez
Keyword(s):  
Hydraulic Conductivity ◽  
Water Balance ◽  
Groundwater Modeling ◽  
Regional Scale ◽  
Early Years ◽  
Scale Model ◽  
Aquifer System ◽  
Aquifer Storage ◽  
Guarani Aquifer ◽  
The Impact

Abstract. In large aquifers relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormous volume of water, however, it is not well known being difficult to assess the impact of exploitation currently used to supply over 25 million inhabitants. This is a sensitive issue because the aquifer is shared by four countries. Moreover, an integrated groundwater model, and therefore, a global water balance were not available. In this work, a transient regional scale model for the entire aquifer based upon five simplified, equally plausible conceptual models represented by different hydraulic conductivity parametrizations, is used to analyze the flow system and water balance components. Combining an increasing number of hydraulic conductivity zones and an appropriate set of boundary conditions, the hypothesis of a continuous sedimentary unit yielded errors within the calibration target in a regional sense. The magnitude of the water budget terms resulted very similar for all parametrizations. Recharge and stream/aquifer fluxes were the dominant components representing, on average, 84.2% of total inflows and 61.4% of total outflows, respectively. However, leakage was small compared to stream discharges of main rivers. For instance, the simulated average leakage for the Uruguay river was 8 m3 s−1 while the observed absolute minimum discharge was 382 m3 s−1. Streams located in heavily pumped regions switched from a gaining condition on early years to a losing condition over time. Water is discharged through the aquifer boundaries, except at the eastern boundary. On average, pumping represented 16.2% of inflows while aquifer storage experienced a small overall increment. The model water balance indicates that the current rate of groundwater withdrawals does not exceed the rate of recharge on a regional sense.

scholarly journals Assessing Stream-Aquifer Connectivity in a Coastal California Watershed

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 416
Author(s):  
Bwalya Malama ◽  
Devin Pritchard-Peterson ◽  
John J. Jasbinsek ◽  
Christopher Surfleet
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Water Level ◽  
Time Series Data ◽  
Series Data ◽  
Low Permeability ◽  
Pumping Tests ◽  
Stream Flows ◽  
The Impact

We report the results of field and laboratory investigations of stream-aquifer interactions in a watershed along the California coast to assess the impact of groundwater pumping for irrigation on stream flows. The methods used include subsurface sediment sampling using direct-push drilling, laboratory permeability and particle size analyses of sediment, piezometer installation and instrumentation, stream discharge and stage monitoring, pumping tests for aquifer characterization, resistivity surveys, and long-term passive monitoring of stream stage and groundwater levels. Spectral analysis of long-term water level data was used to assess correlation between stream and groundwater level time series data. The investigations revealed the presence of a thin low permeability silt-clay aquitard unit between the main aquifer and the stream. This suggested a three layer conceptual model of the subsurface comprising unconfined and confined aquifers separated by an aquitard layer. This was broadly confirmed by resistivity surveys and pumping tests, the latter of which indicated the occurrence of leakage across the aquitard. The aquitard was determined to be 2–3 orders of magnitude less permeable than the aquifer, which is indicative of weak stream-aquifer connectivity and was confirmed by spectral analysis of stream-aquifer water level time series. The results illustrate the importance of site-specific investigations and suggest that even in systems where the stream is not in direct hydraulic contact with the producing aquifer, long-term stream depletion can occur due to leakage across low permeability units. This has implications for management of stream flows, groundwater abstraction, and water resources management during prolonged periods of drought.

scholarly journals Treated wastewater irrigation effects on soil hydraulic conductivity and aggregate stability of loamy soils in Israel

2015 ◽  
Vol 63 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Karsten Schacht ◽  
Bernd Marschner
Keyword(s):  
Hydraulic Conductivity ◽  
Chemical Properties ◽  
Aggregate Stability ◽  
Treated Wastewater ◽  
Soil Aggregate Stability ◽  
Irrigation Effects ◽  
Physical And Chemical ◽  
The Impact

Abstract The use of treated wastewater (TWW) for agricultural irrigation becomes increasingly important in water stressed regions like the Middle East for substituting fresh water (FW) resources. Due to elevated salt concentrations and organic compounds in TWW this practice has potential adverse effects on soil quality, such as the reduction of hydraulic conductivity (HC) and soil aggregate stability (SAS). To assess the impact of TWW irrigation in comparison to FW irrigation on HC, in-situ infiltration measurements using mini disk infiltrometer were deployed in four different long-term experimental orchard test sites in Israel. Topsoil samples (0-10 cm) were collected for analyzing SAS and determination of selected soil chemical and physical characteristics. The mean HC values decreased at all TWW sites by 42.9% up to 50.8% compared to FW sites. The SAS was 11.3% to 32.4% lower at all TWW sites. Soil electrical conductivity (EC) and exchangeable sodium percentage (ESP) were generally higher at TWW sites. These results indicate the use of TWW for irrigation is a viable, but potentially deleterious option, as it influences soil physical and chemical properties.

scholarly journals Predicting the impact of biochar on the saturated hydraulic conductivity of natural and engineered media

2021 ◽  
Vol 295 ◽  
pp. 113143
Author(s):  
Yudi Yan ◽  
Seyyed Ali Akbar Nakhli ◽  
Jing Jin ◽  
Godfrey Mills ◽  
Clinton S. Willson ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Saturated Hydraulic Conductivity ◽  
The Impact

On the benefit of the Canadian Small Lake Model to better represent the impact of small natural lakes on GEM-Hydro streamflow simulations.

2021 ◽  
Author(s):  
Etienne Gaborit ◽  
Murray MacKay ◽  
Camille Garnaud ◽  
Vincent Fortin
Keyword(s):  
Water Balance ◽  
Grid Point ◽  
Hydrologic Model ◽  
Surface Fluxes ◽  
Dew Point ◽  
Multiple Model ◽  
Small Lake ◽  
Surface Component ◽  
Lake Model ◽  
The Impact

<p>This study aims at assessing the impact of a new lake model on streamflow simulations performed with the GEM-Hydro hydrologic model developed at ECCC. GEM-Hydro is at the heart of the National Surface and River Prediction System (NSRPS) which ECCC uses to forecast river flows over most of Canada. The GEM-Hydro model mainly consists of the GEM-Surf component to represent surface processes, and of the Watroute model to represent river and lake routing, in order to perform streamflow simulations and forecasts. The surface component of GEM-Hydro can simulate 5 different types of surfaces.  Currently, the water tile consists of a very simple algorithm which, in terms of water balance, consists of producing runoff fluxes simply equal to precipitation minus evaporation. This runoff over water surfaces is then provided as input, along with runoff and drainage generated over other surface tiles, to the Watroute model. The Watroute version used in GEM-Hydro currently only represents major lakes (area greater than 100km<sup>2</sup>) along the river networks, and does not represent the impact that small lakes can have on streamflow, which mainly consists in slowing down runoff before it reaches the main streams of the network.</p><p>Recently, the Canadian Small Lake Model (CSLM) was implemented in the surface component of GEM-Hydro to represent the energy and water balance over water tiles more accurately. So far, CSLM simulations have been shown promising in terms of evaporation, ice cover, absolute and dew point temperature simulations, compared with the former algorithm used over water. However, the impact of CSLM on the resulting streamflow simulations performed with GEM-Hydro has not been evaluated yet. This study aims first at evaluating the impact of CSLM on streamflow simulations, and secondly at testing different CSLM configurations as well as different coupling strategies with Watroute, with the objective of finding the best set up for the prediction of streamflow in Canada. For example, overland runoff generated by the land tile can be provided to the water tile of the same grid point in different ways, and the outflow computed at the outlet of the water tile can be computed with different parameters. Moreover, different outflow computations have to be taken into account depending on if the water tile of a grid point represents subgrid-scale lakes, or if on the contrary it belongs to a lake spanning over multiple model grid points.</p><p>To do so, different GEM-Hydro open-loop simulations have been performed on the Lake of the Woods watershed, located in Canada, with and without CSLM to represent water tiles. The CSLM configurations leading to the best results are presented here. CSLM simulations are also evaluated in terms of surface fluxes, to ensure that the main purpose of the model, which is to improve surface fluxes to ultimately improve atmospheric forecasts, is preserved, compared to the default configuration of the model. Ideas for further improving the coupling between the GEM-Hydro surface and routing components, in terms of lake processes, are also presented and will be tested in future work.</p>

Quantifying recent lake level changes in Patagonia (Argentina and Chile): Back to the future?

2021 ◽  
Author(s):  
Daniel Ariztegui ◽  
Clément Pollier ◽  
Andrés Bilmes
Keyword(s):  
Water Level ◽  
Lake Level ◽  
Satellite Images ◽  
Meteorological Data ◽  
Tierra Del Fuego ◽  
Water Level Fluctuations ◽  
Lake Levels ◽  
The Past ◽  
Rainfall Variations ◽  
The Impact

<p>Lake levels in hydrologically closed-basins are very sensitive to climatically and/or anthropogenically triggered environmental changes. Their record through time can provide valuable information to forecast changes that can have substantial economical and societal impact.</p><p>Increasing precipitation in eastern Patagonia (Argentina) have been documented following years with strong El Niño (cold) events using historical and meteorological data. Quantifying changes in modern lake levels allow determining the impact of rainfall variations while contributing to anticipate the evolution of lacustrine systems over the next decades with expected fluctuations in ENSO frequencies. Laguna Carrilaufquen Grande is located in the intermontane Maquinchao Basin, Argentina. Its dimension fluctuates greatly, from 20 to 55 km<sup>2</sup> water surface area and an average water depth of 3 m. Several well-preserved gravelly beach ridges witness rainfall variations that can be compared to meteorological data and satellite images covering the last ~50 years. Our results show that in 2016 lake level was the lowest of the past 44 years whereas the maximum lake level was recorded in 1985 (+11.8 m above the current lake level) in a position 1.6 km to the east of the present shoreline. A five-years moving average rainfall record of the area was calculated smoothing the extreme annual events and correlated to the determined lake level fluctuations. The annual variation of lake levels was up to 1.2 m (e.g. 2014) whereas decadal variations related to humid-arid periods for the interval 2002 to 2016 were up to 9.4 m. These data are consistent with those from other monitored lakes and, thus, our approach opens up new perspectives to understand the historical water level fluctuations of lakes with non-available monitoring data.</p><p> </p><p>Laguna de los Cisnes in the Chilean section of the island of Tierra del Fuego, is a closed-lake presently divided into two sections of 2.2 and 11.9 km<sup>2</sup>, respectively. These two water bodies were united in the past forming a single larger lake. The lake level was  ca. 4 m higher than today as shown by clear shorelines and the outcropping of large Ca-rich microbialites. Historical data, aerial photographs and satellite images indicate that the most recent changes in lake level are the result of a massive decrease of water input during the last half of the 20<sup>th</sup> century triggered by an indiscriminate use of the incoming water for agricultural purposes. The spectacular outcropping of living and fossil microbialites is not only interesting from a scientific point of view but has also initiated the development of the site as a local touristic attraction. However, if the use of the incoming water for agriculture in the catchment remains unregulated the lake water level might drop dangerously and eventually the lake might fully desiccate.</p><p>These two examples illustrate how recent changes in lake level can be used to anticipate the near future of lakes. They show that ongoing climate changes along with the growing demand of natural resources have already started to impact lacustrine systems and this is likely to increase in the decades to come.</p>

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