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Description:
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This research evaluates and improves capabilities incorporated in the Water Rights Analysis Package (WRAP ) modeling system for tracking salt loads , particularly for applications dealing with natural salt pollution problems that are prevalent in several major river basins in Texas and neighboring states . WRAP is the river /reservoir system simulation model incorporated in the Water Availability Modeling (WAM ) System applied by agencies and consulting firms in Texas in planning and water right regulatory activities . A salinity simulation component of WRAP called WRAP -SALT was developed recently at Texas A &M University . WRAP -SALT was based on the premise of complete mixing within the monthly computational time step . However , salt concentrations actually have time variation throughout a reservoir . This thesis research investigates more realistic salinity routing methods . Historical gauged data provide a basis for calibration of routing parameters . The timing of the inflow load to determine outflow concentration is calculated by lag parameters with the monthly time steps . Complete mixing occurs during the lag months . Two options are incorporated into WRAP -SALT for setting the lag parameter . With the first option , the model -user sets a constant that is applied during every month of the simulation . This option requires calibration studies to determine the lag . With the alternative option , a variable lag is computed within the model in each month based on the concept of retention time , which is a representation of the time required for a monthly volume of water and its salt load to flow through a reservoir . When the lag is activated , the accuracy between observed and computed mean monthly salinity concentrations through the reservoir is generally improved . The basin -wide simulation was performed for the Brazos River Basin for conditions with and without salt control dams proposed by the Corps of Engineers . The proposed salt control impoundments improve water quality throughout the basin . |