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--- en:manuel_reference:methode_micro:verif_habby [2021/12/01 16:08] – ylecoarer
+++ en:manuel_reference:methode_micro:verif_habby [2021/12/02 10:48] () – ylecoarer
@@ 6: / 6: @@
 Here we will check the implementation of the The Instream Flow Incremental Methodology (IFIM) when using a 2D hydraulic model.
+==== HABBY habitat calculations ====
 The classic case consists of using a set of 3 habitat suitability curves for the variables water height, mean velocity and substrate (H,V,S) for a fish species and for a biological stage.
@@ 11: / 13: @@
 For a given variable, and for discrete values of the latter, the biological model provides suitability index SI given values between 0 and 1, qualifying the 'preference' of the fish, the suitability curve is thus constructed.
-Equation (1) is used to calculate the  according to the user options of the habitat according to the user options  suitability index $\mathit{HSI_i}$ in a mesh of index i and area Ai of a hydraulic model, from the mean values of the variables (H,V,S) of this mesh noted $\mathit{H_i,V_i,S_i}$.
+Equation (1) is used to calculate the habitat suitability index $\mathit{HSI_i}$ according to the user options, in a mesh of index i and area Ai of a hydraulic model, from the mean values of the variables (H,V,S) of this mesh noted $\mathit{H_i,V_i,S_i}$.
 (1a) \[HSI_i=SI_H(H_i)\times SI_V(V_i)\times SI_S(S_i)\]
 (1b) \[HSI_i=(SI_H(H_i)\times SI_V(V_i)\times SI_S(S_i))^\frac{1}{3}\]
-(1c) \[HSI_i=\frac{SI_H(H_i)\times SI_V(V_i)\times SI_S(S_i)}{3}\]
+(1c) \[HSI_i=\frac{SI_H(H_i)+ SI_V(V_i)+ SI_S(S_i)}{3}\]
+In case the user decides to use only two variables for example (H,V), these equations are adapted in HABBY and become :
+(1_a2) \[HSI_i=SI_H(H_i)\times SI_V(V_i)\]
+(1_b2) \[HSI_i=(SI_H(H_i)\times SI_V(V_i))^\frac{1}{2}\]
+(1_c2) \[HSI_i=\frac{SI_H(H_i)+ SI_V(V_i)}{2}\]
+The logics (a) product, (b) geometric mean and (c) mean are respected.
+In the case where the biological model is bivariate (H,V) equation (1) is written :
+(1_biv) \[HSI_i=SI_{H,V}(H_i,V_i)\]
+The  weighted useable area WUA of the hydraulic model is obtained from equation (2) and the overall suitability index OSI from equation (3)
 (2) \[WUA=\sum_{i=1}^M A_i\times HSI_i\]
 (3) \[OSI=\frac{WUA}{\sum_{i=1}^M A_i}\]
-(4) \[{SI_{i,S}(S_{i,1},S_{i,2},..S_{i,K})}=\frac{\sum_{k=1}^K S_{i,k}\times SI_S(S_k)}{100} \]
-The  weighted useable area WUA of the hydraulic model is obtained from equation (2) and the overall suitability index OSI from equation (3)
 Note that in the particular case of a description of the substrate in percentages per $\mathit{S_k}$ classes and a calculation of habitat in % of substrate, the value of $\mathit{SI_S(S_i)}$ in equation (1) must be replaced by the formulation in equation (4). In this equation $\mathit{S_{i,k}}$ represents the % of substrate of class $\mathit{S_k}$ in mesh i, the substrate being described by a number K of particle size classes k ∈ $\mathit{[1,K]_N}$.
-Let us now check a HSI calculation in any mesh of a hydraulic model.
+(4) \[{SI_{i,S}(S_{i,1},S_{i,2},..S_{i,K})}=\frac{\sum_{k=1}^K S_{i,k}\times SI_S(S_k)}{100} \]
+==== Let us now check a HSI calculation in any mesh of a hydraulic model. ====
 After building a .hab file with HABBY, choose a biological model for a stage, use the <hi #9BFFFF>**Create duplicate from selection**</hi> button to get 4 times that model. Then set the calculation options, to have not only the calculation for the 3 habitat variables, but also a calculation per variable.