<?xml version="1.0" encoding="UTF-8"?>
<toolchain saga-version="2.1.3">
	<group>ta_hydrology</group>
	<identifier>twi</identifier>
	<name>Topographic Wetness Index (One Step)</name>
	<author>O.Conrad (c) 2014</author>
	<description>
		Calculates the Topographic Wetness Index (TWI) based on the supplied Digital Elevation Model (DEM). Slopes (Beta), Specific Catchment Areas (SCA), and a depressionless DEM for SCA calculation are derived internally.

		TWI = ln(SCA / tan(Beta))
	</description>
	<menu>Topographic Indices</menu>
	<reference>
		<authors>Beven, K.J., Kirkby, M.J.</authors>
		<year>1979</year>
		<title>A physically-based variable contributing area model of basin hydrology</title>
		<where>Hydrology Science Bulletin 24(1), p.43-69.</where>
	</reference>
	<reference>
		<authors>Moore, I.D., Grayson, R.B., Ladson, A.R.</authors>
		<year>1991</year>
		<title>Digital terrain modelling: a review of hydrogical, geomorphological, and biological applications</title>
		<where>Hydrological Processes, Vol.5, No.1.</where>
	</reference>
	<parameters>
	<option varname="GRID_SYSTEM" type="grid_system">
		<name>Grid System</name>
	</option>
	<input varname="DEM" type="grid" parent="GRID_SYSTEM">
		<name>Elevation</name>
	</input>
	<output varname="TWI" type="grid" parent="GRID_SYSTEM">
		<name>Topographic Wetness Index</name>
	</output>
	<option varname="FLOW_METHOD" type="choice">
		<name>Flow Distribution</name>
		<choices>Deterministic 8|Rho 8|Braunschweiger Reliefmodell|Deterministic Infinity|Multiple Flow Direction|Multiple Triangular Flow Direction|Multiple Maximum Downslope Gradient Based Flow Direction|</choices>
		<value>4</value>
	</option>
	</parameters>
		<tools>
		<tool library="ta_preprocessor" tool="2" name="Sink Removal">
			<input id="DEM">DEM</input>
			<output id="DEM_PREPROC">DEM_PREPROC</output>
		</tool>
		<tool library="ta_hydrology" tool="0" name="Catchment Area (Top-Down)">
			<input id="ELEVATION">DEM_PREPROC</input>
			<output id="FLOW">FLOW</output>
			<option id="METHOD" varname="true">FLOW_METHOD</option>
		</tool>
		<tool library="ta_hydrology" tool="19" name="Flow Width and Specific Catchment Area">
			<input id="DEM">DEM_PREPROC</input>
			<input id="TCA">FLOW</input>
			<output id="SCA">SCA</output>
			<option id="METHOD">2</option>
		</tool>
		<tool library="ta_morphometry" tool="0" name="Slope, Aspect, Curvature">
			<input id="ELEVATION">DEM_PREPROC</input>
			<output id="SLOPE">SLOPE</output>
			<option id="METHOD">6</option>
		</tool>
		<tool library="ta_hydrology" tool="20" name="Topographic Wetness Index (TWI)">
			<input id="SLOPE">SLOPE</input>
			<input id="AREA">SCA</input>
			<output id="TWI">TWI</output>
			<option id="CONV">0</option>
			<option id="METHOD">0</option>
		</tool>
	</tools>
</toolchain>
