splitZmap = svg`<svg viewBox="0 0 ${width} ${height}">
<g id ='hillshade'>
${classedSplitZ.map(
(h) =>
`<path d ='M${[h.a.x, h.a.y]}L${[
h.b.x,
h.b.y
]}' stroke="gray" stroke-opacity="0.5"/>`
)}
</g>
<g id ='water'>
${segment_water.map((s) => {
let color = viridish[Math.floor(Math.random() * viridish.length)];
return s.map(
(w) =>
` <path d ='M${[w.a.x, w.a.y]}L${[
w.b.x,
w.b.y
]}' stroke="${color}" stroke-opacity="0.5"/>`
);
})}
</g>
<g id = 'water_outlines'>
${poly_water
.flat()
.map((p) => `<path d="${path(p)}" stroke="teal" fill="none"/>`)}
</g>
</svg>`