The CRCH Package routes a fraction of the diffuse areal recharge (assigned in the traditional MODFLOW RCH Package) into nodes of conduit pipes. This functionality may be useful in scenarios where rainfall runs directly into karst features, such as sinkholes or swallets. If activated for CFPM1 or CFPM3 simulations, the CRCH Package can route a fraction or all of the diffuse areal recharge into a specified conduit node. The routed direct recharge will be subtracted from the diffuse recharge for MODFLOW water-budget calculations. Note the RCH Package must be active when the CRCH Package is active. This file is only used for CFP Modes 1 and 3.
IFLAG_CRCH—is an integer value that activates or deactivates the reading of CRCH data.
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If IFLAG_CRCH is not equal to -1, then NODE_NUMBERS and P_CRCH values are read for the total number of nodes (NNODES) in the simulation. Each node must be listed with NODE_NUMBERS and P_CRCH values.
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If IFLAG_CRCH equals -1, NODE_NUMBERS and P_CRCH from the last stress period are used for the current stress period.
P_CRCH is a real number equal to a fraction of diffuse areal recharge (entered in the MODFLOW-2005 RCH Package) partitioned directly into the conduit node NODE_NUMBERS. If the user, for example, wants the direct conduit recharge to equal the diffuse recharge rate assigned for the model cell in which the pipe is located, the user would enter a value of 1.0 for P_CRCH. In this case, the diffuse areal recharge for the model cell would equal zero in MODFLOW water-budget calculations.