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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 10:40] – ylecoarer | ||
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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 ' | 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 ' | ||
- | Equation (1) is used to calculate | + | Equation (1) is used to calculate the habitat suitability index $\mathit{HSI_i}$ |
(1a) \[HSI_i=SI_H(H_i)\times SI_V(V_i)\times SI_S(S_i)\] | (1a) \[HSI_i=SI_H(H_i)\times SI_V(V_i)\times SI_S(S_i)\] | ||
(1b) \[HSI_i=(SI_H(H_i)\times SI_V(V_i)\times SI_S(S_i))^\frac{1}{3}\] | (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 | + | (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 | ||
+ | (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, | ||
+ | |||
+ | The weighted useable area WUA of the hydraulic model is obtained from equation (2) and the overall suitability index OSI from equation (3) | ||
(2) \[WUA=\sum_{i=1}^M A_i\times HSI_i\] | (2) \[WUA=\sum_{i=1}^M A_i\times HSI_i\] | ||
(3) \[OSI=\frac{WUA}{\sum_{i=1}^M A_i}\] | (3) \[OSI=\frac{WUA}{\sum_{i=1}^M A_i}\] | ||
- | (4) \[{SI_{i, | ||
- | 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, | 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, | ||
+ | |||
+ | (4) \[{SI_{i, | ||
Let us now check a HSI calculation in any mesh of a hydraulic model. | Let us now check a HSI calculation in any mesh of a hydraulic model. |