Use CSV as it's much quicker and easier than scraping HTML :-)

csv.pl

@@ -0,0 +1,51 @@
+#!/usr/bin/env perl -w
+#
+$|=1 if $ENV{DEBUG};
+use strict;
+use diagnostics;
+use DBI;
+use Text::CSV;
+use Date::Manip;
+
+use LWP::UserAgent;
+my $ua = LWP::UserAgent->new;
+$ua->agent("Munin[river_levels_]");
+
+my @stations = qw(
+1129 1135 1133 1143 1132 1137 1134 1145 1139 1131 1130 1144 9274
+);
+
+my $base = "https://check-for-flooding.service.gov.uk/station-csv/";
+
+my $db = DBI->connect("dbi:SQLite:dbname=rivers.db") or die $DBI::errstr;
+
+my $recordlevel    = $db->prepare("REPLACE INTO levels (stationid, timestamp, level) VALUES (?,?,?)") or die $db->errstr;
+my $getlastrecord  = $db->prepare("SELECT MAX(timestamp) FROM levels WHERE stationid=?")              or die $db->errstr;
+
+sub getlatest($) {
+        my ($id) = @_;
+        $getlastrecord->execute($id);
+        my ($lastrecord) = $getlastrecord->fetchrow();
+	return $lastrecord ? $lastrecord : "0";
+}
+
+
+foreach my $station (@stations) {
+        print STDERR "[$station] Requesting $base$station\n" if $ENV{R_DEBUG};
+        my $req = HTTP::Request->new(GET => $base . $station);
+        my $res = $ua->request($req);
+	my $content = $res->content;
+	my $last = getlatest($station);
+	print "[$station] Last record was $last\n" if $ENV{R_DEBUG};
+	foreach my $line (sort split(/^/m, $content)) {
+		next if $line =~ /Timestamp (UTC)/;
+		chomp($line);
+		my ($ts, $level) = split(/,/, $line);
+		if($ts le $last) {
+			print "[$station] Skipping $level at $ts\n" if $ENV{R_DEBUG};
+		} else {
+			print "[$station] Recording $level at $ts\n" if $ENV{R_DEBUG};
+			$recordlevel->execute($station, $ts, $level);
+		}
+	}
+}