Darcy's Law — Groundwater Flow

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  <!-- Tank left -->
  <rect x="40"  y="40"  width="80" height="200" fill="#bae6fd" stroke="#0f172a"/>
  <text class="lab" x="50" y="34">h₁</text>
  <!-- Porous medium -->
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  <text class="lab" x="200" y="180">porous medium · K, L</text>
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  <text class="lab" x="410" y="94">h₂</text>
  <!-- Flow arrow -->
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  <text class="lab" x="240" y="160" fill="#dc2626">q (flow per area)</text>
  <!-- Equations -->
  <text class="lab" x="40" y="270">q = −K · dh/dL    ·    Q = q · A    ·    K = hydraulic conductivity</text>
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