diff --git a/GUI/CSPGshiftSLxshore.m b/GUI/CSPGshiftSLxshore.m
new file mode 100644
index 0000000..51982e4
--- /dev/null
+++ b/GUI/CSPGshiftSLxshore.m
@@ -0,0 +1,18 @@
+function new_sl = CSPGshiftSLxshore(sl,SLtransects,xshore_shift,sl_elevation)
+
+new_sl =NaN(length(SLtransects.x),3); %new shoreline based on forecast
+
+
+for j = 1:length(SLtransects.x)
+    [x_int,~] = polyxpoly(sl.xyz(:,1),sl.xyz(:,2),SLtransects.x(:,j),SLtransects.y(:,j));
+    alpha = polyfit(SLtransects.x(:,j),SLtransects.y(:,j),1);
+    xnew = x_int+xshore_shift/sqrt(1+alpha(1)^2);
+    ynew = polyval(alpha,xnew);
+    if ~isempty(xnew) %Catch in case shoreline does not intersect with that transect
+        new_sl(j,:) = [xnew ynew sl_elevation]; %Elevation defined in function 
+    end
+end
+
+%Remove any NaNs
+I = find(isnan(new_sl(:,1)));
+new_sl(I,:) = [];