Water Works 29 - 6/9/03

Fun with Maps

If you have followed the fortunes of New Jersey’s “BIG Map” for growth management, you know that the controversy it generated finally compelled the NJDEP to remove the map from its web site, which is all the convincing I need that the map is probably a much better idea than anyone thought it was.

Be forewarned through. Its temporary disappearance could mean all those lively red pixels may be headed for that special graveyard reserved for ideas too sensible for New Jersey; to keep company there with the Whitman administration’s late plan to limit sewer expansion into environmentally sensitive land, among others. You may recall the frantic stampede of state legislators incited by that ill-fated proposal, before they spotted Whitman’s NJDEP scattering in the opposite direction, after which both sides agreed to calm down and work together to ignore it to death.

To keep us occupied during BIG Map’s absence, our attention has been officially directed to the Department of Community Affairs and its State Development and Redevelopment Plan, New Jersey’s nationally acclaimed initiative in land use data collection, analysis and mapping, which has provided the Garden State with exhaustively documented and finely detailed paperweights and wall decorations for more than a decade. While we wait for the NJDEP to incorporate the State Plan into a revised map, you should visit the DCA’s web site, to see what the NJDEP will be working with (i) near you as it attempts to make the old Office of State Planning’s repository of land use data into more than a polite suggestion.

That aside, no one does maps better than what we now call the Office of Smart Growth. Its separate Hunterdon County rendering works almost as well as a topographic plat to show you the Delaware and Raritan watersheds snaking along their common border through the western half of the county, from the heights above Bloomsbury down to Ringoes and the Amwell Valley, with the Lockatong and Capoolong sub-basins rising up to shape a small plateau at Quakertown on the way. All you need to remember is that the tips of all those little blue slivers marking streams always point to higher ground. With only a few local coordinates, you can visualize the lines of elevation and the shape of the larger Hunterdon Plateau yourself.

A cross-section of the top ridgeline of the Hunterdon Plateau, where the upper Lockatong and Capoolong watersheds meet at Quakertown, would resemble a wedge in profile: with a steep slope on its northern, Capoolong face, an almost flat, long slope to the south on its Lockatong face, and a small shelf shaved from its summit. The tracings of the streams you can see on the State Plan map reflect the differences in the topography of the watersheds forming the wedge. Lockatong Creek and its tributaries run in longer, straighter strands toward the Delaware River than Capoolong Creek does in its much steeper descent to the Raritan. The Capoolong repeatedly doubles back on itself, to the extent that its tributaries often flow in a direction opposite the main path of the creek, a distinctly different pattern from the Lockatong’s.

The relative differences in elevations and slopes indicated by those stream tracings are substantial. When you stand at Oak Grove on the southern face of the wedge, at the lowest elevation in the upper Lockatong watershed, you are about 3 miles from its 600-foot summit in Quakertown, but only 100 feet below it. On the Capoolong side there is no way you could possibly stand at the same relative distance and elevation down the watershed from Quakertown. The best you could do would be to hover 300 feet in the air above Capoolong Creek.

Water flowing underground through both watersheds from the top of our wedge mirrors the shape of the terrain on each side. A stratum of water-bearing rock of fairly consistent depth runs beneath the surface contours of the entire formation. It follows the local topography where the land rises and falls as it descends through each drainage basin. The water in that layer of rock creates springs, ponds and tributary streams where some of the water forces its way out to the surface. The rest makes its way down to the foundations of the main creeks of each watershed. That stratum of rock through which water travels from the summits of the watersheds to the creeks is our aquifer.

Now here is the punch line to last week’s tickler. As you remember from Water Works 23, the Capoolong Creek side of Quakertown is uphill from the swale that runs through the village, which means that water flowing north in our aquifer from the summit of the Capoolong watershed actually rises after it passes through the swale, before it heads down the north face of the plateau. At that point water really is flowing uphill.

Which is where will pick things up again when we return.

Ron Gutkowski