Land Use

(These parameters apply to the Soil Moisture method. For the Simplified Coefficient Method, see Simplified Coefficient Method, Land Use; for the MABIA Method, see MABIA, Land Use; for the Plant Growth Method, see Plant Growth Model Method, Land Use.)

Area

Land area for land cover class within branch or basin catchment.  Note: You can use WEAP's Automatic Catchment Delineation to help you calculate catchment area.

Kc

The crop coefficient, relative to the reference crop, for a land class type.

Root Zone Water Capacity

The effective water holding capacity of the top layer of soil, represented in mm (top "bucket").

Deep Water Capacity

Effective water holding capacity of lower, deep soil layer (bottom "bucket"), represented in mm. This is given as a single value for the catchment and does not vary by land class type. This is ignored if the demand site has a return flow link to a groundwater node.

Deep Conductivity

Conductivity rate (length/time) of the deep layer (bottom "bucket") at full saturation (when relative storage z2 = 1.0), which controls transmission of baseflow. This is given as a single value for the catchment and does not vary by land class type. Baseflow will increase as this parameter increases. This is ignored if the demand site has a return flow link to a groundwater node.

Runoff Resistance Factor

Used to control surface runoff response. Related to factors such as leaf area index and land slope. Runoff will tend to decrease with higher values (range 0 to 1000). This parameter can vary among the land class types.

Root Zone Conductivity

Root zone (top "bucket") conductivity rate at full saturation (when relative storage z1 = 1.0), which will be partitioned, according to Preferred Flow Direction, between interflow and flow to the lower soil layer. This rate can vary among the land class types.

Preferred Flow Direction

Preferred Flow Direction: 1.0 = 100% horizontal, 0 = 100% vertical flow. Used to partition the flow out of the root zone layer (top "bucket") between interflow and flow to the lower soil layer (bottom "bucket") or groundwater. This value can vary among the land class types.

Initial Z1

Initial value of Z1 at the beginning of a simulation. Z1 is the relative storage given as a percentage of the total effective storage of the root zone water capacity.

Initial Z2

Initial value of Z2 at the beginning of a simulation. Z2 is the relative storage given as a percentage of the total effective storage of the lower soil bucket (deep water capacity). This parameter is ignored if the demand site has a runoff/infiltration link to a groundwater node. This rate cannot vary among the land class types.

Conceptual diagram and equations incorporated in the Two-bucket model

See also: Soil Moisture Method Calculation Algorithm

Entered on: Data View, Branch: Catchments, Category: Land Use, Tabs: Area, Initial Z1, Initial Z2, Runoff Resistance Factor, Kc, Root Zone Conductivity, Preferred Flow Direction, Soil Water Capacity, Deep Water Capacity, Deep Conductivity.