Salinity Problems Associated with Reuse Water Irrigation on Southwestern Golf Coursesby Jenny B. Chapman, Desert Research Inst, Las Vegas, United States,
Richard H. French, Desert Research Inst, Las Vegas, United States,
Abstract: One of the most severe of the potential reuse water quality problems is salinity. While many water supplies in the southwest have relatively high total dissolved solids (TDS) concentrations, treated wastewater has an even higher TDS than the original supply due to evaporative losses and ions added by water softeners; thus, degradation of vegetation and soil caused by water salinity is a concern. At a golf course, it is important to minimize additional increases in the TDS prior to irrigation use. If open ponds are used to store reuse water, then relatively deep ponds will slow the rate of evaporative salinity increase, and may also limit algal populations by reducing light penetration and temperature. An optimum pond depth in terms of salinity can be calculated given an evaporation rate and the TDS of the incoming water. The optimum depth for a pond in southern Nevada supplied by reuse water with a TDS of approximately 1100 mg/L is calculated to be 8 to 10 ft. Deeper ponds produce increasingly smaller improvements in salinity and shallower ponds produce progressingly greater increases in salinity. The irrigation process itself can provide an effective mechanism for slowing the rate of salinity buildup because irrigation pumping provides an exit for dissolved salts from the ponds. A pond with no discharge other than evaporation would experience its greatest increase in salinity during the summer, while the same pond used for irrigation can actually have a reduction in its salinity at this time because of the large volumes of water removed for irrigation. If the water in the ponds is not routinely used for irrigation, the only exit for salts is leakage through the bottom of the pond, so that the ponds become salt sinks with ever increasing values of TDS. In such situations, periodic flushing could be used for salinity control. Whether used for irrigation or not, lining the ponds to prevent the irrigation leaching fraction from returning to the ponds as groundwater will aid in salinity control.
Subject Headings: Salt water | Irrigation | Ponds | Water supply | Irrigation water | Salinity | Evaporation | Dissolved solids | Nevada | North America | United States
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