make_subplots

fig1 = make_subplots(rows=1, cols=2)

fig1.add_trace(
    go.Scatter(x=prob['07DD001_new'],y=prob['probability'],mode='markers',marker_color='#1F77B4'),
    row = 1, col = 1
)
fig1.add_trace(
    go.Scatter(y=prob['07DD001_new'],x=prob['return-years'],mode='markers',marker_color='#1F77B4'),
    row = 1, col = 2
)
#update axes
fig1.update_xaxes(title_text="Discharge (m³ s⁻¹)", dtick = 1000, row=1, col=1)
fig1.update_xaxes(title_text="Return period (years)", dtick = 5,  row=1, col=2)
fig1.update_yaxes(title_text="Probability", row=1, col=1)
fig1.update_yaxes(title_text="Discharge (m³ s⁻¹)", row=1, col=2)

fig1.update_layout(
#     xaxis_title='Return period (Years)',
#     yaxis_title='Discahrge (m³ s⁻¹)',
    width=800,
    height=400,
    font_family = "Arial",
    font_color = 'black',
    font_size = 12,
    template="simple_white",
    showlegend=False，
    margin=dict(l=20, r=20, t=20, b=20),
#     title='Flow_path, best_WSE_cgvd213 scatter plot',
#     xaxis
#     legend_title="Legend Title",
#     legend = dict(
#     yanchor='top',
#     y=0.85,
#     xanchor='right',
#     x=0.935
#     )
)