Uchan-su (river)

{{Infobox river

| name = Uchan-su (Vodopadnaya)

| image = Uchan-su.JPG

| image_size =

| image_caption = Uchan-su river in Yalta, Crimea

| mapframe = yes

| mapframe-zoom = 11

| source1_location = Ai-Petri

| mouth_location =

| subdivision_type1 = Country

| subdivision_name1 = Ukraine

| length =

| source1_elevation =

| mouth_elevation =

| discharge1_avg =

| basin_size = Black Sea

| extra =

}}

Uchan-su ({{langx|uk|Учан-Су}}, {{langx|ru|Учан-Су}}, {{langx|crh|Uçan Suv}}) or Vodopadnaya ({{lang|ru|Водопадная}}), is a river that flows in the South Coast of Crimea. The name translates from the Crimean Tatar language for 'swift water' .

The river runs into the Black Sea in the center city of Yalta. It begins at the foot of Ai-Petri, flows upstream the gorge and then at a distance of {{convert|2|km|abbr=on}} from the source forms the Uchan-su waterfall, located at an altitude of {{convert|390|m|sp=us}} and consists of several levels (the height of the waterfall is {{convert|98|m|sp=us}}).

The river water is used extensively for water supply and irrigation.