Water table Watershed

Depending on factors such as watershed slope, depth of water table, antecedent soil moisture, and barriers to precipitation and throughfall infiltration, DOM from the forest floor and organic soil horizon can contribute a large flux of allochthonous DOM to surface waters. Soil solution for DOM analysis is typically collected with zero-tension lysimeters placed at the boundary between organic soil and mineral soil. 

Soil structure, geologic strata, and topography influence the location and movement of variable source areas of surface runoff in a watershed. Eragipans or other layers, such as clay pans of distinct permeability changes, can determine when and where perched water tables occur. Shale or sandstone strata also influence soil moisture content and location of saturated zones. For example, water will perch on less permeable layers in the subsurface profile and become evident as surface flow or springs at specific locations in a watershed. Converging topography in vertical or horizontal planes, slope breaks, and hill slope depressions or spurs, also influence... 

CHANGE IN LAKE VOLUME + 6.49 OUTFLOW FROM LAKE 321.45 EVAPORATION FROM LAKE 21.11 PRECIPITATION ON LAKE 32.07 PRECIPITATION ON WATERSHED 391.65 INFLOW TO LAKE 316.98 CHANGE IN WATER TABLE BRASHER FALLS, NY + 0.70 "EVAPOTRANSPIRATION FROM WATERSHED" 73.97... 

Air-equilibrated precipitation having a pH of 3.9 (due to sulfuric acid, H2SO4) falls on a watershed and ultimately recharges the phreatic aquifer. During the process of percolating to the water table, the water... 

Many hydrologic reservoirs can be further subdivided into smaller reservoirs, each with a characteristic turnover time. For example, water resides in the Pacific Ocean longer than in the Atlantic, and the oceans surface waters cycle much more quickly than the deep ocean. Similarly, groundwater near the surface is much more active than deep reservoirs, which may cycle over thousands or millions of years, and water frozen in the soil as permafrost. Typical range in turnover times for hydrospheric reservoirs on a hillslope scale (10-10 m) are shown in Table 6-4 (estimates from Falkenmark and Chapman, 1989). Depths are estimated as typical volume averaged over the watershed area. 

Hg(0), PHg, RGHg), wet deposition, throughfall, and litterfall, as discussed in the program to determine total ecosystem deposition (see Section 2.2.8). A summary of the measurements of Hg species that should be made in an intensive watershed Hg monitoring program is provided in Table 2.4. We envision that stream water measurements of total and dissolved THg and total and dissolved MeHg would also be made. 

Table 2. Significant differences between median (mg/L) background (BACK) and mineralized(MINER) area in ground and surface water in the Ruby Creek Watershed...

Water Management Challenges in Himalayan Watersheds Table 1 Characteristics of two Middle Mountain watersheds 265... 

Included in the first group of general industrial contaminants are all of the aromatic hydrocarbons (no. 12-31, see Table III], most of the phenolic compounds (no. 32-42), most of the chlorinated species (no. 43-54), and some industrial solvents (no. 85,88,89,95). Almost all of these compounds have been Isolated and identified in urban watersheds (2,25,26) where they appear to arise from automobile emissions, water chlorination, and general urban activities. 

Lower toxaphene concentrations have been found in smaller lakes within the Great Lakes watershed. Muir et al. [77] found toxaphene levels averaging 95 pg L 1 in Lake Nipigon (Table 5). Total toxaphene in Lake Siski-wit (Isle Royale) surface water sampled in May 1998 was 210 pgL-1 [74]. Chlorobornane congeners were not determined in this sample however, the heptachlorobornanes were the predominant homolog group (110 pgL-1) followed by octachlorobornanes (76 pg L 1). 

Suspended solids have the potential to silt out stream channels, rivers, lakes, and reservoirs they inhibit aquatic life and are expensive to remove from water. In some industries (e.g., mining) suspended solids, along with various other pollutants, are regulated by law, which requires that sediment ponds at the base of disturbed watersheds be built with sufficient detention time so that the water released meets certain sediment and water chemistry criteria (Tables 9.1 and 9.2). 

Relatively few large rivers account for a large proportion of the N exported to coastal zones globaUy for ah N forms, based on NEWS model predictions. For example, the 25 rivers with the greatest water discharge globaUy (<0.5% of the rivers with a watershed >2500 km ) account for approximately half of the exported DIN and DON, and about a quarter of the exported PN, globaUy (Table 9.1). Some of... 

In some estuaries and coastal embayments, atmospheric deposition direcdy to the water surface can account for a substantial fraction of N input (as much as 40% of the N inputs from river plus atmospheric inputs Table 9.6). Flowever, the relative importance of atmospheric deposition as an N source varies considerably among coastal systems and depends on a number of factors, including the nature of watershed N sources and the relative sizes of the contributing watershed and receiving estuary (Vahgura et ai, 2001). 

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