Model, SQL: Fix solver parameters loading.

src/Model/River.py

@@ -251,12 +251,10 @@ class River(Graph, SQLSubModel):
         )
 
         # Parameters
-        for solver in new._parameters:
-            data["solver"] = solver
-            new._parameters[solver] = SolverParametersList(
-                execute,
-                data
-            )
+        new._parameters = SolverParametersList._sql_load(
+            execute,
+            data
+        )
 
         return new