diff --git a/src/View/InitialConditionsTemperature/Table.py b/src/View/InitialConditionsTemperature/Table.py
index 8fda2b25..bbe38581 100644
--- a/src/View/InitialConditionsTemperature/Table.py
+++ b/src/View/InitialConditionsTemperature/Table.py
@@ -30,7 +30,7 @@ from PyQt5.QtWidgets import (
     QDialogButtonBox, QPushButton, QLineEdit,
     QFileDialog, QTableView, QAbstractItemView,
     QUndoStack, QShortcut, QAction, QItemDelegate,
-    QComboBox,
+    QComboBox, QMessageBox,
 )
 
 from View.Tools.PamhyrTable import PamhyrTableModel
@@ -212,15 +212,28 @@ class InitialConditionTableModel(PamhyrTableModel):
 
         row = index.row()
         column = index.column()
+        column_name = self._headers[column]
 
         try:
+            new_value = (
+                self._river.edge(value).id
+                if column_name == "reach"
+                else value
+            )
+            if (column_name in ("reach", "rk")
+                    and self._overlaps_existing_rk(
+                        row, column_name, new_value
+                    )):
+                QMessageBox.warning(
+                    self._table_view,
+                    self._trad["msg_rk_overlap_title"],
+                    self._trad["msg_rk_overlap_text"]
+                )
+                return False
+
             self._undo.push(
                 SetCommandSpec(
-                    self._data, self._lst, row, self._headers[column],
-                    (self._river.edge(value).id
-                     if self._headers[column] == "reach"
-                     else value
-                    )
+                    self._data, self._lst, row, column_name, new_value
                 )
             )
         except Exception as e:
@@ -230,6 +243,25 @@ class InitialConditionTableModel(PamhyrTableModel):
         self.dataChanged.emit(index, index)
         return True
 
+    def _overlaps_existing_rk(self, row, column, value):
+        current = self._lst[row]
+        reach = value if column == "reach" else current.reach
+        rk = value if column == "rk" else current.start_rk
+        if reach in (None, -1) or rk is None:
+            return False
+
+        rk = float(rk)
+        return any(
+            other is not current
+            and not other.is_deleted()
+            and other.reach == reach
+            and other.start_rk is not None
+            and other.end_rk is not None
+            and min(other.start_rk, other.end_rk) <= rk
+            <= max(other.start_rk, other.end_rk)
+            for other in self._data._data
+        )
+
     def add(self, row, parent=QModelIndex()):
         self.beginInsertRows(parent, row, row - 1)
 
diff --git a/src/View/InitialConditionsTemperature/translate.py b/src/View/InitialConditionsTemperature/translate.py
index d8517008..b856b7cd 100644
--- a/src/View/InitialConditionsTemperature/translate.py
+++ b/src/View/InitialConditionsTemperature/translate.py
@@ -32,6 +32,16 @@ class IcTemperatureTranslate(MainTranslate):
 
         self._dict["rk"] = self._dict["unit_rk"]
 
+        self._dict["msg_rk_overlap_title"] = _translate(
+            "InitialConditionTemperature",
+            "Chainage already used"
+        )
+        self._dict["msg_rk_overlap_text"] = _translate(
+            "InitialConditionTemperature",
+            "An initial temperature condition is already defined at this "
+            "chainage on the selected reach."
+        )
+
         self._sub_dict["table_headers"] = {
             "name": self._dict["name"],
             "temperature": self._dict["unit_temperature"],