Groundwater inflow, rate

By use of eq 11, this isotopic information, and the average annual precipitation and evaporation rates (0.79 and 0.52 m/year, respectively), the average annual groundwater inflow rate to Sparkling Lake was estimated to be 0.27 m/year (expressed as the volumetric flow rate divided by the surface... 

Groundwater-inflow rates as calculated by the solute and isotope mass-balance methods for several northern Wisconsin lakes are listed in Table I. Dissolved calcium was used as the solute tracer because it is the constituent whose concentration differs the most between groundwater and precipitation, the two input components to be separated by the method. In addition, calcium is nearly conservative in the soft-water, moderately acidic to cir-cum-neutral lakes in northern Wisconsin. Results from the two methods agree relatively well, except for Crystal Lake, where groundwater-flow reversals are frequent. 

In the lakes investigated in northern Wisconsin, groundwater-inflow rates ranged from negligible to nearly 25% of the total inflow (Gj/S inflow terms). 

In the simplest case, groundwater-flow rates for lakes at isotopic steady state (or those with relatively long hydraulic-residence times) can be estimated from data on average annual precipitation rates average annual evaporation rates the isotopic compositions of precipitation, lake water, and inflowing ground-water and relative humidity and lake temperature. 

Advection and Diffusion of Hg from Sediments. In lakes such as Pallette Lake, which receive continuous groundwater inflow and outflow, advection and diffusion of chemical constituents can be important for littoral sediments. To assess the importance of advective and diffusive Hg fluxes, information on background groundwater concentrations, levels of Hg at the sediment-water interface, and flow rates of water must be determined. 

Under any circumstances, to maintain a permanent sahne body of water, surface or groundwater inflow must closely approximate, but not exceed, the rate of evaporation (Figure 2). If maintained... 

Because the chemistry of stream water reflects its source in the soil profile, detailed studies of runoff chemistry from small basins should be very useful in delineating the ways and rates at which various elements are released in weathering. In the Mattole basin, it is apparent that groundwater inflow to the stream at the end of the dry season has a relatively high pH ( 8), relatively high dissolved salts (Spec. Cond. 300), and rather low silica (7-8 mg/liter). Thus, the alkalis and alkaline earths are preferentially removed as compared with silica from rock minerals at or near the water table. In surface soils, however, during storm runoff, quite different conditions prevail. The pH of the water may at first be low (5=t), silica release is relatively rapid (8-12 mg/ liter), and alkalis and alkaline earths are removed rather slowly (Spec. Cond. 70-150). The result is that the rate of silica removal compared... 

A successful and effective groundwater control mainly depends on rehable hydrogeological modeling. In the past few decades, under the guidance of groundwater dynamics especially Thiem equation and Theis equation, some analytical models for estimating water inflow rate have been established, which could be utilized to build the... 

In those studies, the colloid-containing groundwater had been previously equilibrated with the sandy sediment until the humic/fulvic acid concentrations of inflowing and outflowing water were identical. Under these conditions, the actinide dissociation rate from the colloids plays the dominant role in controlling the fraction of mobile colloid-borne actinides. 

In a study of lakes worldwide (4665 samples from 1835 lakes) Cole et al. (1994) found the pH ranged from about 4 to 10 and CO- pressures from about 10" to 10 ° bar. Sources of CO2 in lakes include its inflow in surface waters and groundwaters and respiration and decay related to lake sediments and biota. The overall mean CO2 pressure of 1.049 x 10" (10" ° ) bar in lakes was three times greater than the atmospheric value. This reflects a CO2 production and accumulation rate that exceeds its rates of consumption in the growth of aquatic plants and rate of degassing to the atmosphere. 

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