Impact Of Groundwater Pumping Research Articles

Estimation of Streamflow Depletion Caused by Groundwater Withdrawal in the Bokhacheon Watershed in South Korea Using the Modified SWAT Model

Understanding the effects of groundwater withdrawal on streamflow depletion is important for effectively managing water resources. The Soil and Water Assessment Tool (SWAT) model has a groundwater module to calculate the groundwater budget and groundwater discharge. However, the water pumped from the aquifer is not considered in the SWAT module that estimates groundwater discharge. Therefore, this module was modified to consider the impact of groundwater pumping on the changes in groundwater discharge in the Bokhacheon watershed, South Korea. The model’s water transfer module was improved to allow water from the aquifer to be transferred to destination locations, such as residential, industrial, and agricultural lands. Using the modified SWAT, streamflow responses to groundwater extraction were simulated for 2011–2019. The groundwater withdrawal induced decreases of 14.6 and 24.2% in low and drought flows, respectively, at the watershed’s outlet. The groundwater withdrawals decreased groundwater flow and total water yield by 23.5% and 9.8%, respectively, and increased surface flow, lateral flow, percolation, soil water, and evapotranspiration owing to the increased soil moisture resulting from the partial re-infiltration of the groundwater pumped for agricultural irrigation. The modified SWAT can effectively estimate streamflow depletion resulting from groundwater pumping without extensive hydrogeological input data and computational time.

Assessing Stream-Aquifer Connectivity in a Coastal California Watershed

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.

GROUNDWATER FLOW MODELING IN THE WATES COASTAL AQUIFER, KULON PROGO DISTRICT, YOGYAKARTA SPECIAL PROVINCE, INDONESIA

Due to overcapacity, the current airport of Yogyakarta is going to be replaced with a new one,which is located in Wates coastal area, Kulon Progo District, Yogyakarta Special Province, Indonesia. One ofthe consequences of the development of the new airport is groundwater abstraction due to the airport’s needsand related supporting activities. An excessive withdrawal of groundwater in the new airport will potentiallychange the system and the pattern of groundwater flow. Therefore, groundwater modeling should be done topredict the impact of groundwater abstraction in this area. MODFLOW code is used to simulate thegroundwater flow and the impact of groundwater pumping in the Wates coastal aquifer. The model iscalibrated using water level data from 40 wells in the research area. The results show that the calculatedvalues are fit to the measured data, which indicates that the model is reliable. The effects of groundwaterpumping on water table and seawater intrusion are investigated using a calibrated model. The results showthat the pumping scenario from the airport area causes the groundwater level to drop 0.75 m and seawaterintrusion inland to increase around 100 m.

Evaluation of Bias Associated with Capture Maps Derived from Nonlinear Groundwater Flow Models.

The impact of groundwater withdrawal on surface water is a concern of water users and water managers, particularly in the arid western United States. Capture maps are useful tools to spatially assess the impact of groundwater pumping on water sources (e.g., streamflow depletion) and are being used more frequently for conjunctive management of surface water and groundwater. Capture maps have been derived using linear groundwater flow models and rely on the principle of superposition to demonstrate the effects of pumping in various locations on resources of interest. However, nonlinear models are often necessary to simulate head-dependent boundary conditions and unconfined aquifers. Capture maps developed using nonlinear models with the principle of superposition may over- or underestimate capture magnitude and spatial extent. This paper presents new methods for generating capture difference maps, which assess spatial effects of model nonlinearity on capture fraction sensitivity to pumping rate, and for calculating the bias associated with capture maps. The sensitivity of capture map bias to selected parameters related to model design and conceptualization for the arid western United States is explored. This study finds that the simulation of stream continuity, pumping rates, stream incision, well proximity to capture sources, aquifer hydraulic conductivity, and groundwater evapotranspiration extinction depth substantially affect capture map bias. Capture difference maps demonstrate that regions with large capture fraction differences are indicative of greater potential capture map bias. Understanding both spatial and temporal bias in capture maps derived from nonlinear groundwater flow models improves their utility and defensibility as conjunctive-use management tools.

Tools to Estimate Groundwater Levels in the Presence of Changes of Precipitation and Pumping

Central Wisconsin has the greatest density of high capacity wells in the state, most of which are used for agricultural irrigation. Irrigated agriculture has been growing steadily in the region since the 1950’s, when irrigation systems and high capacity wells became inexpensive and easy to install. Recent low lake and river levels have increased concerns that unregulated groundwater pumping for irrigation will undermine the availability of groundwater to support surface waters and domestic uses. Some research has quantified the magnitude of groundwater level declines due to irrigation pumping, but no studies have identified its relation to climatic precipitation changes. Changes in precipitation can appear to exacerbate or mask the effect of groundwater pumping. In this study, four groundwater monitoring wells and five climate stations were examined for shifts in groundwater levels and precipitation changes. Through statistical analysis, significant precipitation increases were identified in the southern part of the study area which averaged 2.7 mm per year, but no significant change was determined for the northern portion. Bivariate analysis identified water level declines within the region in the years 1974, 1992 and 1999 for irrigated land covers. Multiple regression analysis explained, predicted and quantified the interaction between precipitation and pumping. Wells located in areas with many high capacity wells showed a decline in water levels of up to 1.28 meters. In the southern portion of the study area where increases in precipitation occurred, this decline was thought to be masked. Results for one region (Plover) agreed with a previously published calibrated groundwater model, which demonstrates that this statistical method may be used to separate the impact of groundwater pumping from changing precipitation, even where observation well data are not widely available.

Modeling Water Resources and River-Aquifer Interaction in the Júcar River Basin, Spain

The paper presents how to solve some practical problems of water planning in a medium/large river basin, such as: the water resources assessment and its spatial-temporal variability over the long-short term, the impact of human activities on the water cycle, due to groundwater pumping and water returns into aquifers, the river-aquifer interactions and the aquifer depletion. It is based on the use of a new monthly conceptual distributed water balance model -PATRICAL- that includes the surface water (SW), groundwater (GW) behavior and the river-aquifer interaction. The model is applied to the Jucar River Basin District (RBD) in Spain (43,000 km2), with more than 250 aquifers, including catchments with humid climates (Jucar RBD northern), semiarid and arid catchments (southern). The model has a small number of parameters and obtains a satisfactory performance in SW and GW behavior. It has been calibrated/validated using monthly streamflows and two additional elements not generally used in models for large river basins, GW levels and river-aquifer interactions. In the hydrological time series of the Jucar RBD headers a statistical change point in the year 1979/80 is detected. It is due to changes in precipitation patterns and represents a 40 % of reduction in streamflows in relation with the previous period. The impact of GW pumping in all aquifers is determined, the ‘Mancha Oriental’ aquifer produces a significant reduction in streamflows of the Jucar river –around 200–250 hm3/year. The GW level in the ‘Villena-Benejama’ aquifer -Vinalopo Valley- has declined more than 200 m in last 30 years.

Influence of groundwater pumping and rainfall spatio-temporal variation on streamflow

Summary Groundwater pumping and surface water management structures, i.e. dams and water flow diversions, have been raising serious concerns about the declines in groundwater levels and streamflow in different watersheds throughout the world. Small island watersheds with complex land use, and strong spatio-temporal climate and edaphic variability (e.g. Hawaiian watersheds) offer an ideal environment to help improve our understanding of groundwater–surface water interaction and the hydrological processes it involves. In this study, we investigate the spatio-temporal relationships between streamflow, rainfall, and groundwater using long-term (>40 years) data records from a small Hawaiian watershed. A suite of Mann–Kendall tests were used to evaluate trends and shifts in time series data. The impact of groundwater pumping in the valley on streamflow was also investigated; multiple linear regression analysis was used to quantify the effect of pumping on streamflow. Stream base flow and total flow have declined significantly since 1960, while rainfall showed no statistically significant trends since the 1960s. Groundwater pumping has significantly increased since 1960, and our findings indicate it is a significant contributing factor to streamflow decline. Watershed yield experienced two successive downward shifts: first around 1971–1972 and then again around 1991–1992. The first downward shift appears to be related to the pumping of groundwater from the mid-valley area which began in 1968. The second downward shift is the result of pumping in the upper valley, which began in 1991. Regression models and double mass curve analyses indicate that pumping may have captured significant amounts of groundwater that otherwise would have comprised stream base flow. Streamflow has been reduced by 19–22% since 1971 and as much as 36% since 1991.

Pumping‐Induced Drawdown and Stream Depletion in a Leaky Aquifer System

The impact of ground water pumping on nearby streams is often estimated using analytic models of the interconnected stream-aquifer system. A common assumption of these models is that the pumped aquifer is underlain by an impermeable formation. A new semianalytic solution for drawdown and stream depletion has been developed that does not require this assumption. This solution shows that pumping-induced flow (leakage) through an underlying aquitard can be an important recharge mechanism in many stream-aquifer systems. The relative importance of this source of recharge increases with the distance between the pumping well and the stream. The distance at which leakage becomes the primary component of the pumping-induced recharge depends on the specific properties of the aquifer, aquitard, and streambed. Even when the aquitard is orders of magnitude less transmissive than the aquifer, leakage can be an important recharge mechanism because of the large surface area over which it occurs. Failure to consider aquitard leakage can lead to large overestimations of both the drawdown produced by pumping and the contribution of stream depletion to the pumping-induced recharge. The ramifications for water resources management and water rights adjudication can be significant. A hypothetical example helps illustrate these points and demonstrates that more attention should be given to estimating the properties of aquitards underlying stream-aquifer systems. The solution presented here should serve as a relatively simple but versatile tool for practical assessments of pumping-induced stream-aquifer interactions. However, this solution should not be used for such assessments without site-specific data that indicate pumping has induced leakage through the aquitard.