Chemical composition and spatial variation of bulk precipitation at a coastal plain watershed in South Carolina

Abstract

Bulk precipitation was collected for analysis of ionic constituents at eight rainfall stations over a 4‐year period at a 500‐ha watershed in the Lower Coastal Plain of South Carolina. Mean annual deposition rates of ions in greatest supply, Cl−, SO42− ‐S, Ca2+, and Na+, were respectively 14.2, 7.51, 5.69, and 5.66 kg/ha. Annual deposition rate for total inorganic N (NH4+ −N plus NO3− −N) was about 2.6 kg/ha and for orthophosphate‐P about 0.12 kg/ha. Spatial variation of annual depositions to the eight rainfall stations was smallest for SO42−, NO3−, and Ca2+, with coefficients of variation (CV) less than 10%. Variation of annual inputs to the eight collectors was intermediate for Mg2+, Cl−, H+, and Na+ with CV ranging between 13.9 and 21.5%, whereas the CV for annual inputs of NH4+, PO43−, and K+ exceeded 30%. Sample size estimates for this 500‐ha watershed indicated that 19 collectors should provide estimates of the annual bulk precipitation inputs within 10% of true means for 7 of 10 ions (SO42−, NO3−, Ca2+, Mg2+, Cl−, H+, and Na+) and that more than 35 collectors would be necessary to provide similar confidence intervals for annual inputs of NH4+, PO43−, and K+ (± 10% at P < 0.05). Although estimates of annual bulk precipitation inputs may be quite variable over local areas, control of sampling errors can be gained by increasing the number of collectors.

Hurricane impacts on a pair of coastal forested watersheds: implications of selective hurricane damage to forest structure and streamflow dynamics

“…Whether this accelerated the return to historical conditions is an area for further study. Unfortunately there were also understory mechanical treatments conducted on WS77 in 2001 and growing season fire treatments (for more on fire treatments please refer to Richter et al (1982Richter et al ( , 1983) in 2003, which might also have decreased ET on WS77. The exact timing and mechanisms responsible for the onset of the flop period are therefore somewhat confounded, however, since around 2004 the watersheds have returned to a relative state similar to that of the pre era.…”

“…In November 2001, a small section of WS80 was allowed to drain separately through a small culvert reducing its drainage area to 160 ha. WS77 has experienced several silvicultural treatments carried out over the past 40 years (e.g., Gillham, 1984;Richter et al, 1983Richter et al, , 1982Binstock, 1978;Amatya et al, 2006).…”

“…WS77 and WS80 were calibrated using streamflow data between 1969 and 1976, followed by a series of prescribed burning experiments on WS77 from 1977 through 1981 (Richter et al, 1982(Richter et al, , 1983. Data collection resumed in November 1989, following Hugo, and has continued until the present (Amatya et al, 2003Miwa et al, 2003;Sun et al, 2000;Harder et al, 2007;Dai et al, 2013).…”

“…Continuous flow records from these watersheds were collected from 1964 through 1981 Richter et al, 1982Richter et al, , 1983Binstock, 1978;Young and Klawitter, 1968;Young et al, 1972). WS77 and WS80 were calibrated using streamflow data between 1969 and 1976, followed by a series of prescribed burning experiments on WS77 from 1977 through 1981 (Richter et al, 1982(Richter et al, , 1983.…”

Estimating Natural Recharge by Means of Chloride Mass Balance in a Volcanic Aquifer: Northeastern Gran Canaria (Canary Islands, Spain)

“…It has been applied in many studies worldwide [12][13][14][15]. Knowledge of atmospheric chloride deposition is a prerequisite for applying this method, which is never straightforward given a range of processes that control atmospheric deposition [16][17][18][19] as they fluctuate temporally and are spatially variable, which makes extrapolating point measurements difficult. This has often been recognized as the main source of uncertainty when applying the CMB method [6,15,20,21], along with the right evaluation of the chloride concentration of recharge water [5].…”