TaqSim block by block ten blocks, seven kinds, five knobs

Before you play: what a block is, what a rule card is, what to watch

What a block is. A TaqSim model is a chain of boxes, and each box does one thing with water: it brings it in, carries it, splits it, stores it, uses it or takes it out of the story. A box never decides anything by itself; it only moves water. The demo below has ten boxes of seven kinds: a river, a canyon, a headworks, a canal, a reservoir, an outlet splitter, a farm, a turbine and two places where the water leaves. The full Zarafshan model is made of the same kinds, only more of them.

What a rule card is. Every box that has a choice to make carries a small piece of Python that tells it what to do each month: how much to send which way, how much to let out of the valve, how much is lost. That piece of code is the block's rule, and this page shows it verbatim when you click the block. Five of the rules contain a number you can turn; those numbers are the five sliders.

What to watch. Pick a month, or press Play, and watch the width of the arrows: that is how much water each edge carries in that month, in Mm³. The reservoir shows how full it is, the farm whether it got all it needs, the turbine whether water spills past its gate. Click any block for its card: the analogy, the rule, this month's numbers and a one-line balance. At the bottom the whole year adds up: what the river brought equals where it all went. Every number was computed by TaqSim in advance; nothing is simulated in the browser.

October: water on every edge, Mm³

Click a block for its card. Hover an edge or a block.

Tap or focus an edge for its monthly volume · Нажмите на стрелку, чтобы увидеть месячный объём

Arrow width: the water carried along that edge this month. Dashed: nothing flows. Scroll sideways to see the whole system →

The five knobs

Each knob is one number inside one block's rule. The sliders snap to the values TaqSim has run.

What to notice

  1. The canyon delays the river by a month. Step from June to July: the river's peak enters the canyon in July, but the headworks receives June's water. The summer peak arrives at the headworks a month late, and the canyon shows what is still inside.
  2. Two kinds of "spill". A full reservoir overflows, and that water returns to the river through a separate outlet; only controlled release reaches the farm. A turbine gate's spill is different: TaqSim records it and does not follow it; it leaves the books. Set the gate to 300 and watch the year strip.
  3. A rule, not a lack of water. Set the valve maximum to 20 and look at May and June: the reservoir holds over 600 of its 667 Mm³, yet the farm is short by 21.6 and 11.8. The water is there; the rule does not release it. Overflow returns to the river and cannot cover the farm’s shortfall.
  4. A little short even with a big valve. With the valve at 120 the farm is still short by a few Mm³ in most months it needs water: 2.8 in October, 10.0 in September. 15 % is lost between the gate and the plants, and the rule asks for the need at the gate, not at the plants.