diff --git a/scripts/base_network.py b/scripts/base_network.py
index 6cdf8afd..9f7f1e7f 100644
--- a/scripts/base_network.py
+++ b/scripts/base_network.py
@@ -245,7 +245,9 @@ def _add_links_from_tyndp(buses, links, links_tyndp, europe_shape):
 
     links_tyndp.index = "T" + links_tyndp.index.astype(str)
 
-    return buses, links.append(links_tyndp, sort=True)
+    links = pd.concat([links, links_tyndp], sort=True)
+
+    return buses, links
 
 
 def _load_lines_from_eg(buses, eg_lines):
diff --git a/scripts/build_powerplants.py b/scripts/build_powerplants.py
index d4ad4989..764028d1 100755
--- a/scripts/build_powerplants.py
+++ b/scripts/build_powerplants.py
@@ -91,7 +91,7 @@ def add_custom_powerplants(ppl, custom_powerplants, custom_ppl_query=False):
                            dtype={'bus': 'str'})
     if isinstance(custom_ppl_query, str):
         add_ppls.query(custom_ppl_query, inplace=True)
-    return ppl.append(add_ppls, sort=False, ignore_index=True, verify_integrity=True)
+    return pd.concat([ppl, add_ppls], sort=False, ignore_index=True, verify_integrity=True)
 
 
 if __name__ == "__main__":
diff --git a/scripts/build_shapes.py b/scripts/build_shapes.py
index 95867d89..22aed1fe 100644
--- a/scripts/build_shapes.py
+++ b/scripts/build_shapes.py
@@ -169,8 +169,10 @@ def nuts3(country_shapes, nuts3, nuts3pop, nuts3gdp, ch_cantons, ch_popgdp):
     swiss = pd.read_excel(ch_popgdp, skiprows=3, index_col=0)
     swiss.columns = swiss.columns.to_series().map(cantons)
 
-    pop = pop.append(pd.to_numeric(swiss.loc['Residents in 1000', 'CH040':]))
-    gdp = gdp.append(pd.to_numeric(swiss.loc['Gross domestic product per capita in Swiss francs', 'CH040':]))
+    swiss_pop = pd.to_numeric(swiss.loc['Residents in 1000', 'CH040':])
+    pop = pd.concat([pop, swiss_pop])
+    swiss_gdp = pd.to_numeric(swiss.loc['Gross domestic product per capita in Swiss francs', 'CH040':])
+    gdp = pd.concat([gdp, swiss_gdp])
 
     df = df.join(pd.DataFrame(dict(pop=pop, gdp=gdp)))
 
@@ -194,7 +196,7 @@ def nuts3(country_shapes, nuts3, nuts3pop, nuts3gdp, ch_cantons, ch_popgdp):
     manual['geometry'] = manual['country'].map(country_shapes)
     manual = manual.dropna()
 
-    df = df.append(manual, sort=False)
+    df = pd.concat([df, manual], sort=False)
 
     df.loc['ME000', 'pop'] = 650.
 
diff --git a/scripts/simplify_network.py b/scripts/simplify_network.py
index 70f27bf2..287dfe32 100644
--- a/scripts/simplify_network.py
+++ b/scripts/simplify_network.py
@@ -124,7 +124,8 @@ def simplify_network_to_380(n):
     several_trafo_b = trafo_map.isin(trafo_map.index)
     trafo_map.loc[several_trafo_b] = trafo_map.loc[several_trafo_b].map(trafo_map)
     missing_buses_i = n.buses.index.difference(trafo_map.index)
-    trafo_map = trafo_map.append(pd.Series(missing_buses_i, missing_buses_i))
+    missing = pd.Series(missing_buses_i, missing_buses_i)
+    trafo_map = pd.concat([trafo_map, missing])
 
     for c in n.one_port_components|n.branch_components:
         df = n.df(c)