[Tex/LaTex] How to draw a Sankey Diagram using TikZ

Question

This question led to a new package:
sankey

I would like to draw something similar to this (not exactly):

using TikZ. Ideally I would be able to set the width by variables and rejoin two flows into one again. Is there a good way to do this?

Since this will be my first TikZ diagram I am looking for pointers how to generally approach this problem, not for a complete solution, so that I can read the documentation effectively.
How would I branch of a (variable) portion of a rectangle? How would I rejoin such portions into one again?

partial solution:

\documentclass{article}
\usepackage{tikz}
\begin{document}
    \begin{tikzpicture}[scale=.5]
    \draw[very thick] (1,0) -- (4,-1) -- (7,0) -- (7,-4) to [out=-90,in=180] (8,-5) -- (23,-5) -- (24,-6.5) --  (23,-8) -- (20,-8) to [out=180,in=0] (15,-10) -- (15,-10) (14,-10) -- (10,-10) to [out=0, in=90] (14,-14) -- (14,-8) to [out=90,in=0] (13,-7) -- (11,-7);
    \draw[very thick] (15,-7) to [out=0,in=180] (20,-6) -- (11,-6) -- (13,-6) to [out=0,in=90] (15,-8) to (15,-20) -- (13.5,-21) -- (12,-20) to (12,-14) to [out=90,in=0] (11,-13) -- (5,-13) to [out=180,in=-90] (1,-9) to (1,0);
    \draw[very thick] (4,-4) to [out=-90, in=180] (8,-8) -- (14,-8) (15,-8) -- (16,-8) to [out=0,in=180] (20,-7) to [out=180, in=0] (15,-9) (14,-9) -- (6,-9) to [out=180,in=-90] (4,-7) -- (4,-4);
    \draw[very thick] (2,-6) to (2,-7) to [out=-90,in=180] (6,-11) -- (10,-11) to [out=0,in=90] (13,-14) -- (13,-14) to [out=90,in=0] (11,-12) -- (5,-12) to [out=180,in=-90] (2,-9) -- (2,-7);
    \end{tikzpicture}
\end{document}

Gives:

but this is all hardcoded. I would ideally want to have the width of the flows variable (without needing to recalculate all the points by hand)

Syntax-wise I could imagine something like this:

\stream[width=x,direction=down] (initial_amount)
\redirect[initialamount,x\%][from=rightedge][to=right] (choide_A)
\redirect[choiceA,y\%][from=middle,rejoinrest=true][to=down] (choice_C)
\redirect[initial_amount,g\%][from=right][to=right] (choice_D) %i.e. that what's left of it after redirecting choice_A
\redirect[choid_D,h\%][from=left][to=down] (choice_E) %left in the sense that it the left side turned by 90 degrees

\join[initial_amount][choice_D][choice_C]
\join[choice_A][choice_E]

Points I'm thinking about

• streams have a flow direction, but tikz should be allowed to shift it (a right turn followed by a left turn or vice versa) for example when joining streams.
• layering should probably be so that first == lowest layer and whatever comes after should just pile on it
• straight portions, or shifting are adaptable in length/shift amount to whatever the spacing needs.

Update:

The following has a portion branching off to the right (\def'd by \choiceA)

\documentclass{article}
\usepackage{tikz}
\begin{document}
    \def\startstreamx{1}
    \def\startstreamy{1}
    \def\initialwidth{6}
    \def\initialheight{4}
    \def\choiceA{.9}
    \begin{tikzpicture}[scale=.5]
    \draw[very thick] (\startstreamx,-\startstreamy-\initialheight) -- (\startstreamx,-\startstreamy) --    (\startstreamx+\initialwidth,-\startstreamy) -- (\startstreamx+\initialwidth,-\startstreamy-\initialheight);
    \draw[very thick] (\startstreamx+\initialwidth,-\startstreamy-\initialheight) to [out=-90, in=180] (\startstreamx+\initialwidth+1,-\startstreamy-\initialheight-1);
    \draw[very thick] (\startstreamx+\initialwidth-\choiceA*\initialwidth,-\startstreamy-\initialheight) to [out=-90, in=180] (\startstreamx+\initialwidth+1,-\startstreamy-\initialheight-1-\choiceA*\initialwidth);
    \draw[very thick] (\startstreamx,-\startstreamy-\initialheight) to (\startstreamx,-\startstreamy-\initialheight-1-\choiceA*\initialwidth);
    \draw[very thick] (\startstreamx+\initialwidth-\choiceA*\initialwidth,-\startstreamy-\initialheight) to (\startstreamx+\initialwidth-\choiceA*\initialwidth,-\startstreamy-\initialheight-1-\choiceA*\initialwidth);
    \end{tikzpicture}
\end{document}

one could add now another such code snippet with the inital x and y and width values set to the end of the remaining (downwards) stream and again branch something off to the right.

Answer 1

Edit

Since release 3.0 of TikZ/PGF, the arguments of atan2 are swapped.

New Version (TikZ/PGF 3.0)

Here is a first attempt with my new environment sankeydiagram.

Its optional argument is useful to fix some global parameters:

• sankey tot quantity is a number and represents the total quantity of the global flow (default value: 100 for 100%).

• sankey tot length is the width of the global flow (default value: 100pt).

• sankey min radius is the minimum radius of each turn (default value: 30pt).

• sankey fill is the style used to fill the flows.

• sankey draw is the style used to draw the flows.

• sankey debug (a flag) is useful to debug a diagram during its construction (default value: false).

The sankeydiagram environment defines some useful commands to construct a sankey diagram:

• \sankeynode{prop}{angle}{name}{pos} makes a sankey node (a flow) of prop capacity (in quantity units), named name. Its orientation and position are given by angle and pos.

• \sankeynodestart and \sankeynodeend are similar to \sankeynode (same arguments) but make respectively and flow starting and a flow ending.

• \sankeyadvance{name}{distance} moves forward the sankey node named name.

• \sankeyturn{name}{angle} turns the sankey node named name.

• \sankeyfork{name}{list of forks} forks the sankey node named name. The list of forks is a list of pairs: quantity/name (the sum of quantities must be equal to the quantity of sankey node to fork).

Here is the results (first without sankey debug then with sankey debug).

And, now, the code:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{etoolbox}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfdeclarelayer{sankeydebug}
\pgfsetlayers{background,main,foreground,sankeydebug}

\newif\ifsankeydebug

\newenvironment{sankeydiagram}[1][]{

  \def\sankeyflow##1##2{% sn, en
    \path[sankey fill]
    let
    \p1=(##1.north east),\p2=(##1.south east),
    \n1={atan2(\y1-\y2,\x1-\x2)-90},
    \p3=(##2.north west),\p4=(##2.south west),
    \n2={atan2(\y3-\y4,\x3-\x4)+90}
    in
    (\p1) to[out=\n1,in=\n2] (\p3) --
    (\p4) to[in=\n1,out=\n2] (\p2) -- cycle;
    \draw[sankey draw]
    let
    \p1=(##1.north east),\p2=(##1.south east),
    \n1={atan2(\y1-\y2,\x1-\x2)-90},
    \p3=(##2.north west),\p4=(##2.south west),
    \n2={atan2(\y3-\y4,\x3-\x4)+90}
    in
    (\p1) to[out=\n1,in=\n2] (\p3)
    (\p4) to[in=\n1,out=\n2] (\p2);
  }


  \tikzset{
    sankey tot length/.store in=\sankeytotallen,
    sankey tot quantity/.store in=\sankeytotalqty,
    sankey min radius/.store in=\sankeyminradius,
    sankey arrow length/.store in=\sankeyarrowlen,
    sankey debug/.is if=sankeydebug,
    sankey debug=false,
    sankey flow/.style={
      to path={
        \pgfextra{
          \pgfinterruptpath
          \edef\sankeystart{\tikztostart}
          \edef\sankeytarget{\tikztotarget}
          \sankeyflow{\sankeystart}{\sankeytarget}
          \endpgfinterruptpath
        }
      },
    },
    sankey node/.style={
      inner sep=0,minimum height={sankeyqtytolen(##1)},
      minimum width=0,draw=none,line width=0pt,
    },
    % sankey angle
    sankey angle/.store in=\sankeyangle,
    % sankey default styles
    sankey fill/.style={line width=0pt,fill,white},
    sankey draw/.style={draw=black,line width=.4pt},
  }

  \newcommand\sankeynode[4]{%prop,orientation,name,pos
    \node[sankey node=##1,rotate=##2] (##3) at (##4) {};
    \ifsankeydebug
    \begin{pgfonlayer}{sankeydebug}
      \draw[red,|-|] (##3.north west) -- (##3.south west);
      \pgfmathsetmacro{\len}{sankeyqtytolen(##1)/3}
      \draw[red] (##3.west)
      -- ($(##3.west)!\len pt!90:(##3.south west)$)
      node[font=\tiny,text=black] {##3};
    \end{pgfonlayer}
    \fi
  }

  \newcommand\sankeynodestart[4]{%prop,orientation,name,pos
    \sankeynode{##1}{##2}{##3}{##4}
    \begin{scope}[shift={(##3)},rotate=##2]
      \path[sankey fill]
      (##3.north west) -- ++(-\sankeyarrowlen,0)
      -- ([xshift=-\sankeyarrowlen/6]##3.west)
      -- ([xshift=-\sankeyarrowlen]##3.south west)
      -- (##3.south west) -- cycle;
      \path[sankey draw]
      (##3.north west) -- ++(-\sankeyarrowlen,0)
      -- ([xshift=-\sankeyarrowlen/6]##3.west)
      -- ([xshift=-\sankeyarrowlen]##3.south west)
      -- (##3.south west);
    \end{scope}
  }

  \newcommand\sankeynodeend[4]{%prop,orientation,name,pos
    \sankeynode{##1}{##2}{##3}{##4}
    \begin{scope}[shift={(##3)},rotate=##2]
      \path[sankey fill]
      (##3.north east)
      -- ([xshift=\sankeyarrowlen]##3.east)
      -- (##3.south west) -- cycle;
      \path[sankey draw]
      (##3.north east)
      -- ([xshift=\sankeyarrowlen]##3.east)
      -- (##3.south west);
    \end{scope}
  }

  \newcommand\sankeyadvance[3][]{%newname,name,distance
    \edef\name{##2}
    \ifstrempty{##1}{
      \def\newname{##2}
      \edef\name{##2-old}
      \path [late options={name=##2,alias=\name}];
    }{
      \def\newname{##1}
    }
    \path
    let
    % sankey node angle
    \p1=(##2.north east),
    \p2=(##2.south east),
    \n1={atan2(\y1-\y2,\x1-\x2)-90},
    % sankey prop
    \p3=($(\p1)-(\p2)$),
    \n2={sankeylentoqty(veclen(\x3,\y3))},
    % next position
    \p4=($(##2.east)!##3!-90:(##2.north east)$)
    in
    \pgfextra{
      \pgfmathsetmacro{\prop}{\n2}
      \pgfinterruptpath
      \sankeynode{\prop}{\n1}{\newname}{\p4}
      \path (\name) to[sankey flow] (\newname);
      \endpgfinterruptpath
    };
  }

  \newcommand\sankeyturn[3][]{%newname,name,angle
    \edef\name{##2}
    \ifstrempty{##1}{
      \def\newname{##2}
      \edef\name{##2-old}
      \path [late options={name=##2,alias=\name}];
    }{
      \def\newname{##1}
    }
    \ifnumgreater{##3}{0}{
      \typeout{turn acw: ##3}
      \path
      let
      % sankey node angle
      \p1=(##2.north east),
      \p2=(##2.south east),
      \p3=($(\p1)!-\sankeyminradius!(\p2)$),
      \n1={atan2(\y1-\y2,\x1-\x2)-90},
      % sankey prop
      \p4=($(\p1)-(\p2)$),
      \n2={sankeylentoqty(veclen(\x4,\y4))},
      \p5=(##2.east),
      \p6=($(\p3)!1!##3:(\p5)$)
      in
      \pgfextra{
        \pgfmathsetmacro{\prop}{\n2}
        \pgfinterruptpath
        % \fill[red] (\p3) circle (2pt);
        % \fill[blue](\p6) circle (2pt);
        \sankeynode{\prop}{\n1+##3}{\newname}{\p6}
        \path (\name) to[sankey flow] (\newname);
        \endpgfinterruptpath
      };
    }{
      \typeout{turn acw: ##3}
      \path
      let
      % sankey node angle
      \p1=(##2.south east),
      \p2=(##2.north east),
      \p3=($(\p1)!-\sankeyminradius!(\p2)$),
      \n1={atan2(\y1-\y2,\x1-\x2)+90},
      % sankey prop
      \p4=($(\p1)-(\p2)$),
      \n2={sankeylentoqty(veclen(\x4,\y4))},
      \p5=(##2.east),
      \p6=($(\p3)!1!##3:(\p5)$)
      in
      \pgfextra{
        \pgfmathsetmacro{\prop}{\n2}
        \pgfinterruptpath
        % \fill[red] (\p3) circle (2pt);
        % \fill[blue](\p6) circle (2pt);
        \sankeynode{\prop}{\n1+##3}{\newname}{\p6}
        \path (\name) to[sankey flow] (\newname);
        \endpgfinterruptpath
      };
    }
  }

  \newcommand\sankeyfork[2]{%name,list of forks
    \def\name{##1}
    \def\listofforks{##2}
    \xdef\sankeytot{0}
    \path 
    let
    % sankey node angle
    \p1=(\name.north east),
    \p2=(\name.south east),
    \n1={atan2(\y1-\y2,\x1-\x2)-90},
    % sankey prop
    \p4=($(\p1)-(\p2)$),
    \n2={sankeylentoqty(veclen(\x4,\y4))}
    in
    \pgfextra{
      \pgfmathsetmacro{\iprop}{\n2}
    }
    \foreach \prop/\name[count=\c] in \listofforks {
      let
      \p{start \name}=($(\p1)!\sankeytot/\iprop!(\p2)$),
      \n{nexttot}={\sankeytot+\prop},
      \p{end \name}=($(\p1)!\n{nexttot}/\iprop!(\p2)$),
      \p{mid \name}=($(\p{start \name})!.5!(\p{end \name})$)
      in
      \pgfextra{
        \xdef\sankeytot{\n{nexttot}}
        \pgfinterruptpath
        \sankeynode{\prop}{\n1}{\name}{\p{mid \name}}
        \endpgfinterruptpath
      }
    }
    \pgfextra{
      \pgfmathsetmacro{\diff}{abs(\iprop-\sankeytot)}
      \pgfmathtruncatemacro{\finish}{\diff<0.01?1:0}
      \ifnumequal{\finish}{1}{}{
        \message{*** Warning: bad sankey fork (maybe)...}
        \message{\iprop-\sankeytot}
      }
    };
  }

  \tikzset{
    % default values,
    declare function={
      sankeyqtytolen(\qty)=\qty/\sankeytotalqty*\sankeytotallen;
      sankeylentoqty(\len)=\len/\sankeytotallen*\sankeytotalqty;
    },
    sankey tot length=100pt,
    sankey tot quantity=100,
    sankey min radius=30pt,%
    sankey arrow length=10pt,%
    % user values
    #1}
}{
}



\begin{document}
\begin{tikzpicture}[x=1pt,y=1pt]

  \begin{sankeydiagram}[
    sankey tot length=90pt,%
    sankey tot quantity=6,%
    sankey min radius=15pt,%
    sankey fill/.style={
      draw,line width=0pt,
      fill,
      lime!50,
    },
    sankey draw/.style={
      draw=black,
      line width=1pt,
      line cap=round,
      line join=round,
    },
    sankey debug,
    ]
    \sankeynodestart{6}{-90}{p0}{0,100};
    \sankeyadvance{p0}{50pt}

    \sankeyfork{p0}{3/p1,3/p2}

    \sankeyturn{p1}{90}
    \sankeyadvance{p1}{20pt}

    \sankeyadvance{p2}{60pt}

    \sankeyfork{p2}{2/p3,1/p4}

    \sankeyturn{p3}{90}
    \sankeyadvance{p3}{50pt}

    \sankeyfork{p3}{1/p5,1/p6}

    \sankeyadvance{p5}{70pt}

    \sankeyfork{p1}{1/p7,1/p8,1/p9}
    \sankeyadvance{p7}{50pt}
    \sankeyadvance{p9}{50pt}

    \sankeyadvance{p4}{40pt}
    \sankeyturn{p4}{90}
    \sankeyadvance{p4}{65pt}

    \sankeyadvance{p7}{40pt}

    \sankeynode{3}{0}{p11}{[shift={(50pt,-15pt)}]p7}
    \sankeyfork{p11}{1/p7a,1/p9a,1/p5a}
    \path (p7) to[sankey flow] (p7a);
    \path (p9) to[sankey flow] (p9a);
    \path (p5) to[sankey flow] (p5a);
    \sankeyadvance{p11}{30pt}
    \sankeynodeend{3}{0}{p11}{p11}

    {
      \tikzset{
        sankey fill/.append style={
          line width=0pt,
          lime!50!green!50,
        }
      }
      \sankeyturn{p8}{-90}
      \sankeyadvance{p8}{40pt}

      \sankeyturn{p6}{-90}
      \sankeyturn{p4}{-90}

      \sankeynode{3}{-90}{p10}{[shift={(-15pt,-60pt)}]p8}
      \sankeyfork{p10}{1/p8a,1/p6a,1/p4a}
      \path (p4) to[sankey flow] (p4a);
      \path (p6) to[sankey flow] (p6a);
      \path (p8) to[sankey flow] (p8a);
      \sankeyadvance{p10}{30pt}
      \sankeynodeend{3}{-90}{p10}{p10}
    }



  \end{sankeydiagram}
\end{tikzpicture}
\end{document}

Here is another example with the same preamble (it's the same sankey diagram as your first example but with adjusted value: Industrie=86.1 . Without adjustment, there are bad sums...) :

Then the code (without preamble):

\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}

  \begin{sankeydiagram}[
    sankey tot length=5cm,%
    sankey tot quantity=524.3,%
    sankey min radius=3mm,%
    sankey fill/.style={
      draw,line width=0pt,
      fill,
      cyan!50!blue!50!black,
    },
    sankey draw/.style={
      draw=none,
      line width=1pt,
      line cap=round,
      line join=round,
    },
    %sankey debug,
    ]

    \sankeynodestart{7.2}{-90}{B}{-.5,0}
    \coordinate[below=1mm of B.center] (B label);
    \sankeyadvance{B}{5mm}
    \sankeynodestart{137.3}{-90}{GI}{1,0}
    \coordinate[below=1mm of GI.center] (GI label);
    \sankeyadvance{GI}{5mm}
    \sankeynodestart{397.8}{-90}{I}{4,0}
    \coordinate[below=1mm of I.center] (I label);
    \sankeyadvance{I}{5mm}

    \sankeynode{542.3}{-90}{EI}{2.86,-1}
    \sankeyfork{EI}{397.8/Ia,137.3/GIa,7.2/Ba}
    \path (I) to[sankey flow] (Ia);
    \path (GI) to[sankey flow] (GIa);
    \path (B) to[sankey flow] (Ba);
    \sankeyadvance{EI}{5mm}
    \coordinate (EI label) at (EI);
    \sankeyadvance{EI}{5mm}

    \sankeyfork{EI}{63.1/EB,479.2/P}

    \sankeyturn{EB}{90}
    \sankeyadvance{EB}{2cm}
    \coordinate (EB label) at (EB.center);
    \sankeyadvance{EB}{2cm}
    \sankeynodeend{63.1}{0}{EB}{EB}

    \sankeyadvance{P}{10mm}
    \coordinate (P label) at (P);
    \sankeyadvance{P}{5mm}

    \sankeyfork{P}{33.5/NV,445.7/P}

    {
      \tikzset{sankey fill/.append style={cyan!80!lime!50!gray}}
      \sankeyturn{NV}{90}
      \sankeyadvance{NV}{2cm}
      \coordinate (NV label) at (NV);
      \sankeyadvance{NV}{2cm}
      \sankeynodeend{33.5}{0}{NV}{NV}
    }

    \sankeyadvance{P}{10mm}

    \sankeyfork{P}{118.1/U,327.6/P}

    {
      \tikzset{sankey fill/.append style={orange!70!gray!50}}
      \sankeyturn{U}{90}
      \sankeyadvance{U}{2cm}
      \coordinate (U label) at (U);
      \sankeyadvance{U}{2cm}
      \sankeynodeend{118.1}{0}{U}{U}
    }

    \sankeyadvance{P}{10mm}

    \sankeyfork{P}{327.2/P,0.4/SD}

    {
      \sankeyturn{SD}{-90}
      \sankeyadvance{SD}{15mm}
      \coordinate (SD label) at (SD);
      \sankeyadvance{SD}{15mm}
      \sankeynodeend{0.4}{0}{SD}{SD}
    }

    \sankeyadvance{P}{8mm}

    \sankeyfork{P}{18.8/VE,308.4/E}

    {
      \tikzset{sankey fill/.append style={orange!70!gray!30}}
      \sankeyturn{VE}{90}
      \sankeyadvance{VE}{2cm}
      \coordinate (VE label) at (VE);
      \sankeyadvance{VE}{2cm}
      \sankeynodeend{18.8}{0}{VE}{VE}
    }

    \sankeyadvance{E}{8mm}
    \coordinate (E label) at (E);
    \sankeyadvance{E}{20mm}

    \sankeyfork{E}{135.1/H+GHD,87.2/V,86.1/In}

    \sankeyturn{In}{-90}
    \sankeyadvance{In}{10mm}
    \sankeyturn{In}{90}
    \sankeyadvance{In}{5mm}
    \coordinate (In label)  at (In);
    \sankeyadvance{In}{10mm}
    \sankeynodeend{86.7}{-90}{In}{In}

    \sankeyadvance{V}{19mm}
    \coordinate (V label) at (V);
    \sankeyadvance{V}{10mm}
    \sankeynodeend{87.2}{-90}{V}{V}

    \sankeyturn{H+GHD}{90}
    \sankeyadvance{H+GHD}{10mm}
    \sankeyfork{H+GHD}{47.0/GHD,88.1/H}

    \sankeyturn{H}{-90}
    \sankeyadvance{H}{.5mm}
    \coordinate (H label) at (H);
    \sankeyadvance{H}{10mm}
    \sankeynodeend{88.1}{-90}{H}{H}

    \sankeyadvance{GHD}{30mm}
    \sankeyturn{GHD}{-90}
    \sankeyadvance{GHD}{8.5mm}
    \coordinate (GHD label) at (GHD);
    \sankeyadvance{GHD}{10mm}
    \sankeynodeend{47}{-90}{GHD}{GHD}



    % labels
    \tikzset{
      label/.style={
        fill=white,inner sep=.5mm,text=cyan!50!blue!50!black,
        font=\sffamily\bfseries\small,inner sep=1mm,
        align=center,
      },
    }
    \node[label,anchor=north] (B label) at (B label) {7.1};
    \node[label,left=1mm of B label] {Bestands-\\entnahme};
    \node[label,anchor=north] at (GI label) {137.3};
    \node[label,above=5mm of GI label] {Gewinnung\\im Inland};
    \node[label,anchor=north] at (I label) {397.8};
    \node[label,above=5mm of I label] {Import};

    \node[label] at (EI label) {542.3\\Energieaufkommen im Inland};

    \node[label,anchor=center] (EB label) at (EB label) {63.1};
    \node[label,above=1mm of EB label] {Export und\\Bunkerung};

    \node[label] at (P label) {479.1\\Primärenergieverbrauch};

    \node[label,anchor=center] (NV label) at (NV label) {33.5};
    \node[label,above=0mm of NV label] {Nichtenergetischer Verbrauch};

    \node[label,anchor=center] (U label) at (U label) {118.1};
    \node[label,below=4mm of U label] {Umwandlungsverluste};

    \node[label,anchor=center] (SD label) at (SD label) {0.4};
    \node[label,above=0mm of SD label] {Statistische\\Differenzen};

    \node[label,anchor=center] (VE label) at (VE label) {18.8};
    \node[label,below=0mm of VE label] {Verbrauch in den\\Energiesktoren};

    \node[label,anchor=north] (E label) at (E label) {308.4\\Endenergieverbrauch};

    \node[label,anchor=north] (In label) at (In label) {86.1};
    \node[label,anchor=north,below=1cm of In label] {Industrie};

    \node[label,anchor=north] (V label) at (V label) {87.2};
    \node[label,anchor=north,below=1cm of V label] {Verkehr};

    \node[label,anchor=north] (H label) at (H label) {87.2};
    \node[label,anchor=north,below=1cm of H label] {Haushalte};

    \node[label,anchor=north] (GHD label) at (GHD label) {47.0};
    \node[label,anchor=north,below=1cm of GHD label] {Gewerbe, Handel\\Diensleistungen};
 \end{sankeydiagram}
\end{tikzpicture}
\end{document}