Merge pull request #214 from iggroup/swmm_roughness_translation_corre…

…ction

Swmm roughness translation correction

swmm_views/04_vw_swmm_conduits.sql

@@ -19,7 +19,7 @@ SELECT
 		WHEN re.coefficient_of_friction IS NOT NULL THEN (1 / re.coefficient_of_friction::double precision)
 		WHEN re.coefficient_of_friction IS NULL AND re.wall_roughness IS NOT NULL THEN 
 			CASE
-				WHEN re.clear_height IS NOT NULL THEN (1 / (4 * SQRT(9.81) * POWER((32 / re.clear_height::double precision / 1000),(1 / 6::double precision))*LOG(((3.71 * re.clear_height::double precision / 1000) / (re.wall_roughness / 1000)))))::numeric(7,4)
+				WHEN re.clear_height IS NOT NULL THEN 1./((4. * SQRT(9.81) * POWER((32. / (re.clear_height::double precision / 1000.)),(1. / 6.::double precision)))*LOG(((3.71 * (re.clear_height::double precision / 1000.)) / (re.wall_roughness / 1000.))))::numeric(7,4)
 				WHEN re.clear_height IS NULL AND re.swmm_default_coefficient_of_friction IS NOT NULL THEN (1 / re.swmm_default_coefficient_of_friction::double precision)
 				ELSE 0.01
 			END
@@ -37,10 +37,10 @@ SELECT
 	concat_ws(';',
 	ws.identifier,
 	CASE
-		WHEN re.coefficient_of_friction IS NOT NULL THEN '1 / K_Strickler is used as roughness'
+		WHEN re.coefficient_of_friction IS NOT NULL THEN '1 / K_Strickler, 1/re.coefficient_of_friction is used as roughness'
 		WHEN re.coefficient_of_friction IS NULL AND re.wall_roughness IS NOT NULL THEN
 			CASE
-				WHEN re.clear_height IS NOT NULL THEN 'The approximation of 1 / K_Strickler is computed using K_Colebrook to determined the roughness as roughness'
+				WHEN re.clear_height IS NOT NULL THEN 'The approximation of 1 / K_Strickler is computed from re.wall_roughness using an approximation formula.'
 				WHEN re.clear_height IS NULL AND re.swmm_default_coefficient_of_friction IS NOT NULL THEN 'The default value stored in reach.swmm_default_coefficient_of_friction is used'
 				ELSE 'Default value 0.01 is used as roughness'
 			END