Reservoirs hydrology

Robert Horton, an influential pioneer in the field of hydrology, developed one of the first comprehensive representations of the hydrologic cycle in 1931. His original diagram. Fig. 6-4, illustrates the processes by which water moves between the Earth s hydrologic reservoirs. Hydrologic fluxes can be summed up in four... 

In hydrological studies, the transfer of water between reservoirs is of primary interest. The magnitudes of the main reservoirs and fluxes (volume per time) are given in Figure 7. The oceans hold ca 76% of all the earth s water. Most of the remainder, ie, ca 21%, is contained in pores of sediments and in sedimentary rocks. A Httle more than 1% (or 73% of freshwater) is locked up in ice. The other freshwater reservoir of significant size is groundwater. Lakes, rivers, and the atmosphere hold a surprisingly small fraction of the earth s water. 

Fig. 7. The principal reservoirs in the hydrological cycle R, reservoirs in units of 10 metric tons (10 km ) E, fluxes in units of 10 km /yr T, residence time, yr. R/F = volume /input—output. Fluxes (flows) are approximate. For range of estimates, see Ref. 8.

The major reservoirs of water on Earth are the oceans. The hydrologic cycle is driven primarily by evaporation of water from the oceans, lakes. 

Figure 6-3 shows the hydrologic cycle as seven primary reservoirs interconnected by a number of water fluxes. The role of each reservoir in the hydrologic cycle and its connections with other cycles is briefly summarized below, in order of storage volume. 

The oceans are by far the largest reservoir in the hydrologic cycle, containing more than 25 times as much water as the rest of the reservoirs combined. As another means of comparison, the volume of water in the oceans is four orders of magnitude larger than that in the next most visible reservoir, the world s lakes and rivers. The oceans are also one of the Earth s primary... 

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. 

The dependence of the oxygen content in reservoirs on the hydrological input to the system opens the interesting possibility of using long-term hydrological data to quantify the impact of recent climate change. Since precipitation and river runoff... 

Waldron MC, Cohnan JA, and BreaultRF. 2000. Distribution, hydrologic transport, and cycling of total mercury and methyl mercury in a contaminated river-reservoir-wetland system (Sudbury River, eastern Massachusetts), Can J Fish Aquat Sci 57 1080-1091. 

The Water Cycle. The evaporation of water from land and water surfaces, the transpiration from plants, and the condensation and subsequent precipitation of rain cause a cycle of transportation and redistribution of water, a continuous circulation process known as the hydrologic cycle or water cycle (see Fig. 86). The sun evaporates fresh water from the seas and oceans, leaving impurities and dissolved solids behind when the water vapor cools down, it condenses to form clouds of small droplets that are carried across the surface of the earth as the clouds are moved inland by the wind and are further cooled, larger droplets are formed, and eventually the droplets fall as rain or snow. Some of the rainwater runs into natural underground water reservoirs, but most flows, in streams and rivers, back to the seas and oceans, evaporating as it travels. 

Batalla RJ, Gomez CM, Kondolf GM (2004) Reservoir-induced hydrological changes in the Ebro River basin (NE Spain). J Hydrol 290 117-136... 

As we have indicated in the previous sections, there is little information on sediment transport in the River Ebro, and most of it is concentrated in the lower reaches of the catchment, downstream the reservoir complex of Mequinenza-Riba-roja-Flix (Fig. 1). We present here a summary of the results obtained from direct measurements on suspended and bedload obtained by the UdL group during the period 2002-2004 upstream (i.e. SMS) and downstream (i.e. MEMS) the reservoir complex, together with the data collected downstream from the dams during the period 2005-2008 (in the later case referred only to suspended sediment). A hydrological context is provided for each of the sediment transport data sets. 

Calibration of the hydrological parameters of subcatchment 057, using the previously computed streamflow entering the reservoir during the calibration period as runoff at the outlet of the subcatchment. 

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