31:T5ce,{ let cap = `Fig 2. Mean monthly rainfall at Mwinilunga and Mongu. The pattern of rainfall at Mwinilunga in the north of the catchment is similar to the pattern at Mongu in the South but the rain season starts earlier, finishes later and there is higher overall rainfall in the north of the basin.` rainCalMonthly.sort((e1, e2) => e1.RainMonth - e2.RainMonth); var data = [ { y: rainCalMonthly.map(month => Math.round(month.Mongu_mean)), x: [ 'Jul', 'Aug','Sep', 'Oct', 'Nov', 'Dec','Jan','Feb','Mar','Apr','May', 'Jun' ], mode: 'lines+markers', name: 'Mongu', line: { shape: 'spline', width: 3 },marker: { color: colr_c(2), size: 7 }, type: 'line' }, { y: rainCalMonthly.map(month => Math.round(month.Mwinilunga_mean)), x: [ 'Jul', 'Aug','Sep', 'Oct','Nov','Dec','Jan','Feb', 'Mar','Apr','May','Jun' ], mode: 'lines+markers', name: 'Mwinilunga', line: { shape: 'spline', width:3 }, marker: { color: colr_c(5), size: 7 }, type: 'line' } ]; var layout = { width: width>800?770:width-30, height: 270, font: font, showlegend: true, margin: {t:5, b:40, l:70, r:10}, legend: {x: 0.04, xanchor: 'left', y: 1}, xaxis: {showgrid: false, zeroline: false, ticks: 'outside'}, yaxis: {title: 'Rainfall (mm)', zeroline: false, showline: false } } const div=container(cap, width>800?790:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}); return div }32:T483,{ let cap = `Fig 3. Box plots of annual rainfall for various locations from the south to the north of the catchment showing a gradual increase in total annual rainfall going from the south to the north of the catchment. Variability in annual rainfall is similar across the catchment.` function buildTrace(station,i){ return { y: rainYearly.map(y=>y[station]===null?null:Math.round(y[station])), type: 'box', boxmean: true, hoverinfo:'none', name: station + " " + Math.round(Math.abs(rainStationDict[station].Lat)) + "\u00B0S", marker: {color: colr_c(i)}, } } var data = [ buildTrace('Livingstone',1), buildTrace('Mongu',2), buildTrace('Kaoma',3), buildTrace('Zambezi',4), buildTrace('Luena',5),buildTrace('Mwinilunga',6) ]; var layout = { showlegend: false, width: width>1000?970:width-30, height:300, font:font, margin: {t:5, b:40, l:70, r:10}, yaxis: { title: "Annual Rainfall (mm)", separatethousands:true, range:[250,2000] } } const div=container(cap, width>1000?990:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}); return div }33:T773,rainandflowchart={ let cap = "Fig 4. Due to the attenuating effect of the Barotse Floodplains the peak river flow is around 4 months later than the peak rainfall period." var data = [{ y: rainCalMonthly.sort((m1,m2)=>{return m1.WaterMonth-m2.WaterMonth}).map(month=>month.Mwinilunga_mean), text: rainCalMonthly.sort((m1,m2)=>{return m1.WaterMonth-m2.WaterMonth}).map(month=>d3.format(',.0f')(month.Mwinilunga_mean)+'mm'), x: rainCalMonthly.sort((m1,m2)=>{return m1.WaterMonth-m2.WaterMonth}).map(month=>month.WaterMonth), name:'Mwinilunga Rainfall', hoverinfo: 'text', marker: {color: colr_c(3,0.8)}, type: 'bar' }, { y: calMonthly.map(month=>month.flowMean), text: calMonthly.map(month=>formatFlow(month.flowMean)), x: calMonthly.map(month=>month.waterMonth), hoverinfo: 'text', yaxis: 'y2', mode: 'lines+markers', name:'Ngonye Falls Mean Flow', line: {shape: 'spline', width: 3}, marker: {color: colr_b(3), size: 7}, type: 'scatter' }] var layout = { width: width>800 ? 770 : width-30, margin: {t:10, b:40, l:70, r:70}, height: 300, font: font, showlegend: true, legend: {x: 1,xanchor: 'right',y: 1}, xaxis: { showgrid: false, zeroline: false, ticks:'outside', tickvals: [ 1,2,3,4,5,6,7,8,9,10,11,12 ], ticktext: ['Oct','Nov','Dec','Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep'], }, yaxis: { title: 'Rainfall (mm)', zeroline: false, showline: false, showgrid: false, }, yaxis2: { title: 'Flow (m\u00B3/s)', zeroline: false, showline: false, showgrid: false, overlaying: 'y', separatethousands: true, side: 'right' } } const div=container(cap, width>800?790:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}) return div }34:T655,meanFlow={ var data = [ { y: calmonthlyFDCs.map(month=>month.flows[25]), x: calmonthlyFDCs.map(month=>month.waterMonth), mode: 'lines', name:'P25', hoverinfo:'none', line: {shape: 'spline',color: colr_b(4),dash:'dashdot', width:0.5}, type: 'scatter' }, { y: calmonthlyFDCs.map(month=>month.flows[50]), x: calmonthlyFDCs.map(month=>month.waterMonth), text: calmonthlyFDCs.map(month=>formatFlow(month.flows[50])), mode: 'lines+markers', name:'Median (P50)',hoverinfo:'text', line: {shape: 'spline', width:3}, marker: {color: colr_b(3), size:7}, type: 'scatter' }, { y: calmonthlyFDCs.map(month=>month.flows[75]), x: calmonthlyFDCs.map(month=>month.waterMonth), mode: 'lines', name:'P75',hoverinfo:'none', line: {shape: 'spline',color: colr_b(4),dash:'dashdot', width:0.5}, type: 'scatter' }]; var layout = { width: width>700?670:width-30, height: 200, margin:{t:10,b:30,l:70,r:5}, font: font, showlegend: true, legend: {x: 1,xanchor: 'right',y: 1}, xaxis: { showgrid: false, zeroline: false, ticks:'outside', tickvals: [ 1,2,3,4,5,6,7,8,9,10,11,12 ], ticktext:['Oct','Nov','Dec','Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep'], }, yaxis: { title: 'Flow (m\u00B3/s)', zeroline: false, showline: false, separatethousands:true, } }; const div=container(`Zambezi River flow at Ngonye Falls in a typical hydrological year. `) plt.newPlot(div, data, layout,{displayModeBar: false}); return div }35:Ta2b,flowTimeseries={ let cap= `Historic flow at Ngonye Falls based on the record at Victoria Falls since 1924. Horizontal lines show flood return flows. Certain hydrological 'representative years' used for design of the power station are highlighted.` var data = [{ x: monthly.map(month=>month.year + '-' + month.month + '-01'), y: monthly.map(month=>month.flowMax), mode: 'lines', name:'Flow', type: 'scatter', showlegend: false, line: {color: colr_b(3),width:1.5}, }]; flood_return.map(fr=>{ if (fr.Flow<10000 && fr.Flow>5000) { data.push( { x:[1924,2022], y:[fr.Flow,fr.Flow], text:[fr.ReturnYears + ' year flood. ' + d3.format(',.2r')(fr.Flow) + ' m\u00b3/s' ,''] , textposition:'top-right', textfont:{size:12, color: colr(3)}, type:'scatter', line:{width:.5,color: colr(3)}, showlegend:false, mode: 'lines+text' }) } }) var layout = { width: width>1100 ? 1070 : width-30, margin: {t:10, b:30, l:70, r:10}, height: 350, font: font, legend: {x: 1,xanchor: 'right',y: 1}, xaxis: { showgrid: true, zeroline: true, ticks:'outside', range:["1924-01-01","2024-10-01"] }, yaxis: { title: 'Flow (m\u00B3/s)', zeroline: false, showgrid: false, tickformat: ',.2r', showline: false }, annotations: [ { x: '1968-03-15', y: 6000, arrowcolor:"#6f6f6f", arrowwidth:1.5, bgcolor:'white', text: 'Very Wet', showarrow: true,arrowhead: 2,ax: 0,ay: -80,xref: 'x',yref: 'y', }, { x: '2014-03-15', y: 4000, arrowcolor:"#6f6f6f", arrowwidth:1.5, bgcolor:'white', text: 'Wet', showarrow: true,arrowhead: 2,ax: 0,ay: -40,xref: 'x',yref: 'y', }, { x: '2003-03-15', y: 4500, arrowcolor:"#6f6f6f", arrowwidth:1.5, bgcolor:'white', text: 'Median', showarrow: true,arrowhead: 2,ax: 0,ay: -70,xref: 'x',yref: 'y', }, { x: '1991-03-15', y: 2600, arrowcolor:"#6f6f6f", arrowwidth:1.5, bgcolor:'white', text: 'Dry', showarrow: true,arrowhead: 2,ax: 0,ay: -60,xref: 'x',yref: 'y', }, { x: '1997-03-15', y: 2000, arrowcolor:"#6f6f6f", arrowwidth:1.5, bgcolor:'white', text: 'Very Dry', showarrow: true,arrowhead: 2,ax: 0,ay: -100,xref: 'x',yref: 'y', }, ] } const div=container(cap, width>1100?1090:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}) return div }36:T4b3,{ function histo(hData,name,pdiv,i){ var data = [{ y: hData, type: 'box', boxmean: true, name: name, marker: {color: colr_b(i)}, }]; var layout = { showlegend: false, margin:{t:10,b:20,l:70,r:30}, width:250, height:260, font:font, yaxis: { title: "Flow (m\u00B3/s)", separatethousands:true }, }; plt.newPlot(pdiv, data, layout,{staticPlot: true}); } const div=document.createElement('div') div.setAttribute('style','display:flex;') const h1=document.createElement('div') h1.setAttribute('style','flex:33%;') const h2=document.createElement('div') h2.setAttribute('style','flex:33%;') const h3=document.createElement('div') h3.setAttribute('style','flex:33%;') div.appendChild(h1) div.appendChild(h2) div.appendChild(h3) histo(yearly.map(yr=>yr.flowMin),'Annual Min',h1,1) histo(yearly.map(yr=>yr.flowMean),'Annual Mean',h2,3) histo(yearly.map(yr=>yr.flowMax),'Annual Max',h3,5) let cap = `Box plot for minimum, mean and maximum annual flow of the Zambezi River at Ngonye Falls.` const cont=container(cap, width>1100?1090:width-10) cont.prepend(div) return cont }37:T62e,{ let cap=`Hydrographs for five representative flow years ranging form Very Dry to Very Wet.` function yeardata(year,i){ return { x: selected_years.filter(yr=>yr.year==year)[0].weeks.map(mn=>mn.waterWeek), y: selected_years.filter(yr=>yr.year==year)[0].weeks.map(mn=>mn.flowMean), mode: 'lines', name: year, showlegend:false, type: 'scatter', line: {shape: 'spline', width:1.5, color: 'rgba(100,100,100,0.7)'} } } var data = selected_years.map((yr,i)=>yeardata(yr.year,i)); data.push({ x: selected_year.weeks.map(week=>week.waterWeek), y: selected_year.weeks.map(week=>week.flowMean), mode: 'lines', name: selected_year.WaterYear, type: 'scatter', showlegend:false, line: { shape: 'spline', color: colr_b(3), width: 4 }, }) var layout = { width: width>650 ? 620 : width-30, margin: {t:10, b:30, l:70, r:10}, height: 230, legend: {x: 1,xanchor: 'right',y: 1}, font: font, xaxis: { showgrid: false, zeroline: false, ticks:'outside', range: [0, 53], tickvals:[3,8,12,16,21,25,29,33,38,42,46,51], ticktext:['Oct','Nov','Dec','Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep'] }, yaxis: { title: 'Flow (m\u00B3/s)', zeroline: false, tickformat: ',.2r', showline: false, range: [0, 6000] } } const div=container(cap, width>650?640:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}) return div }38:T607,{ var data = [{ y: fdc.map(f=>f.flow), x: fdc.map(f=>f.exceedance), text: fdc.map(f=>d3.format(',.0%')(f.exceedance) + ', ' + formatFlow(f.flow)), mode: 'lines', hoverinfo:'text', line: {shape: 'spline', color: colr_b(3), width: 3}, type: 'scatter' },{ y: [100, 1130], x: [0.3, 0.3], mode: 'lines', hoverinfo:'text', line: {width: 1, color: colr(2)}, type: 'scatter' },{ y: [1130, 1130], x: [0, 0.3], mode: 'lines', hoverinfo:'text', line: {width: 1, color: colr(2)}, type: 'scatter' }]; var layout = { height: 280, margin:{t:10,b:50,l:70,r:50}, width: width>800?770:width-30, font: font, showlegend: false, legend: {x: 1,xanchor: 'right',y: 1}, xaxis: { showgrid: true, zeroline: false, tickformat: ',.0%', ticks:'outside', title:'Exceedance' }, yaxis: { title: 'Flow (m\u00B3/s)', type:'log', zeroline: false, showline: false, separatethousands:true, } }; const div=container(`Flow Duration Curve - FDC or Exceedance curve for the Zambezi River at Ngonye Falls showing the proportion of time in each year that flow exceeds the given value. The flow exceeds ${d3.format(',.3r')(fdc.find(f=>f.exceedance>=0.29).flow)} m\u00b3/s for 30% of all days in the year on average. Median flow (P50) is ${d3.format(',.3r')(fdc.find(f=>f.exceedance>=0.50).flow)} m\u00b3/s`) plt.newPlot(div, data, layout,{displayModeBar: false}); return div }39:T57a,{ let cap='Mean annual flow in the Zambezi River at Ngonye Falls since 1924.' let mean = d3.mean(yearly.map(yr=>yr.flowMean)) let movingAv = movingAverage(yearly.map(yr=>yr.flowMean), 15) var data = [{ y: yearly.map(yr=>yr.flowMean), x: yearly.map(yr=>yr.waterYear), text: yearly.map(yr=>formatFlow(yr.flowMean)), showlegend:false, name: '', hoverinfo:'x+text', marker: {color: colr_b(3,0.5)}, type: 'bar' },{ y: movingAv, x: yearly.map(yr=>yr.waterYear), name:'15yr moving average', mode: 'lines', hoverinfo:'none', line: {width:3,color: colr_b(3)}, type: 'scatter' },{ x: [1924, 2022], y: [mean, mean], mode: 'lines', line: {color: 'rgba(0,0,0,0.8)', width:1, dash:'dashdot'}, type: 'scatter', hoverinfo:'none', name: '1924-2022 average ' + formatFlow(mean) }]; var layout = { width: width-50, height:240, font: font, showlegend: true, margin: {t:5,b:40,l:70,r:5}, legend: {orientation: 'h', x: 0, xanchor: 'left', y: -0.15}, xaxis: { showgrid: false, zeroline: false, ticks:'outside', range:[1923,2022]}, yaxis: { title: 'Mean Flow (m\u00B3/s)', zeroline: false, tickformat: ',.0f', showline: false}, }; const div=container(cap, width-10) plt.newPlot(div, data, layout, {displayModeBar: false}); return div }3a:T43d,floodReturns={ var data = [{ x: flood_return.map(fr=>fr.ReturnYears), y: flood_return.map(fr=>fr.Flow), text: flood_return.map(fr=> fr.YearsSince ? fr.YearsSince + 'yrs' : ''), textposition: 'top', showlegend:false, marker: {color: colr_b(3), size: 15}, type: 'scatter', mode: 'markers+text', textfont: {color:'rgb(10,10,10)', size: 12}}, ]; var layout = { width: width>900?870:width-30, margin: {t:5,b:60,l:70,r:5}, height:350, font: font, showlegend: true, legend: {x: 1, xanchor: 'right', y: 1}, xaxis: { type: 'log', title: 'Return Period (years)', showgrid: false, zeroline: false, ticks:'outside', }, yaxis: { title: 'Flow (m\u00B3/s)', zeroline: false, tickformat: ',.2r', showline: false } } let cap=`Flood return flows. The years since the last flood of each flow is shown against flood up to R100.` const div=container(cap, width>900?890:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}) return div }3b:T539,{ var data = [ { x:[4000,9700], y:[42,10], mode:'lines', line:{color: colr_b(5,0.6),width:1}, hoverinfo:'skip', }, { x: flood_return.map(fr=>fr.Flow), y: flood_return.map(fr=>fr.MeanDays), text: flood_return.map(fr=> fr.ReturnYears + 'yrs'), textposition: 'right', showlegend:false, hoverinfo:'x+y+text', marker: {color: colr_b(3), size: 15}, type: 'scatter', mode: 'markers+text', textfont: {color:'rgb(10,10,10)', size: 12}}, ]; var layout = { width: width>900?870:width-30, margin: {t:5,b:60,l:70,r:5}, height:350, font: font, showlegend: false, legend: {x: 1, xanchor: 'right', y: 1}, xaxis: { title: 'Flow (m\u00B3/s)', showgrid: false, zeroline: false, ticks:'outside', tickformat:',0f', range:[3000,10500] }, yaxis: { title: 'Average Flood Period (days)', zeroline: false, tickformat: ',.2r', showline: false } } let cap=`Average duration of floods at Ngonye Falls for floods with return periods 2yrs upto 100yrs. The durations include the period where flow is higher than the given retrun period.` const div=container(cap, width>900?890:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}) return div }3c:T457,dailyChange={ var data = [ { y: calMonthly.map(month=>-month.dailyFlowChangePercentMean), x: calMonthly.map(month=>month.waterMonth), textposition:'top center', mode: 'lines+markers', name:'Mean', line: {shape: 'spline', width:3, color: colr_b(3)}, marker: {size: 8}, type: 'scatter' }]; var layout = { width: width>900?870:width-30, height: 300, margin: {t:5,b:60,l:70,r:5}, font: font, showlegend: false, legend: {x: 1,xanchor: 'right',y: 1}, xaxis: { showgrid: false, zeroline: false, ticks:'outside', tickvals: [ 1,2,3,4,5,6,7,8,9,10,11,12 ], ticktext:['Oct','Nov','Dec','Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep'], }, yaxis: { title: 'Daily Change in Flow', tickformat: ',.0%', zeroline: false, showline: false, separatethousands:true, } }; let cap=`Average daily change in flow by calendar month.` const div=container(cap, width>900?890:width-10) plt.newPlot(div, data, layout,{displayModeBar: false}) return div }3d:T5ca,function build_tree(param,pct_param,unit) { const root = treemap2(catchments,param); const svg = d3.create("svg") .attr("width", 300) .attr("viewBox", [0, 0, 300, 300]) .style("font", "10px sans-serif"); const leaf = svg.selectAll("g") .data(root.leaves()) .join("g") .attr("transform", d => `translate(${d.x0},${d.y0})`); leaf.append("title") .text(d => `${d.ancestors().reverse().slice(1,).map(d => d.data.name).join(" - ")}\n${d3.format(",d")(d.value)} ${unit}`); leaf.append("rect") .attr("id", d => (d.leafUid = DOM.uid("leaf")).id) .attr("fill", d => { var e=d; while (e.depth > 1) e = e.parent; return e.data.name=='Zambia'?blues(d.data[pct_param]/100+0.5):oranges(d.data[pct_param]/100+0.3); }) .attr("fill-opacity", 0.6) .attr("width", d => d.x1 - d.x0) .attr("height", d => d.y1 - d.y0); leaf.append("clipPath") .attr("id", d => (d.clipUid = DOM.uid("clip")).id) .append("use") .attr("xlink:href", d => d.leafUid.href); leaf.append("text") .attr("clip-path", d => d.clipUid) .selectAll("tspan") .data(d => d.data.name.split(/(?=[A-Z][a-z])|\s+/g).concat(d3.format(".0%")(d.data[pct_param]/100))) .join("tspan") .attr("x", 3) .attr("y", (d, i, nodes) => `${(i === nodes.length - 1) * 0.3 + 1.1 + i * 0.9}em`) .attr("fill-opacity", (d, i, nodes) => i === nodes.length - 1 ? 0.7 : null) .text(d => d); return svg.node(); }3e:[{"id":"b9dcbae9da9966128704eb37db0791cc37f72d07c2d52e40105dc0615ac3f038b6ddf769259cc465209ffef30d2c799cc0484cadc5e7b5a239f2798a74c71fe2","href":"https://static.observableusercontent.com/files/b9dcbae9da9966128704eb37db0791cc37f72d07c2d52e40105dc0615ac3f038b6ddf769259cc465209ffef30d2c799cc0484cadc5e7b5a239f2798a74c71fe2","name":"Screenshot 2024-05-22 110742.png","type":"image/png","lastModified":1716368933084.602,"size":385790},{"id":"600e5250aaeb2890c52bf6d5306514d4cbbf2f8384de9d5c0ecf77088e43265b89514b7334a79b56230c2a2f27fba25cf0fb27e6d10cf5e5d21ed88bdfecde11","href":"https://static.observableusercontent.com/files/600e5250aaeb2890c52bf6d5306514d4cbbf2f8384de9d5c0ecf77088e43265b89514b7334a79b56230c2a2f27fba25cf0fb27e6d10cf5e5d21ed88bdfecde11","name":"Screenshot 2024-05-22 110950.png","type":"image/png","lastModified":1716369062254.713,"size":366501},{"id":"08bd72cb751bfcf7b1a2f8207b8245301210acdb3ca41dbd4a68eca7cb5caf4556bb7b1dc72722913cccabcbead0afc8b5c2c9d7ee65e50289cf409add4b1adc","href":"https://static.observableusercontent.com/files/08bd72cb751bfcf7b1a2f8207b8245301210acdb3ca41dbd4a68eca7cb5caf4556bb7b1dc72722913cccabcbead0afc8b5c2c9d7ee65e50289cf409add4b1adc","name":"barotse.JPG","type":"image/jpeg","lastModified":1581163511163.348,"size":57748}] 2f:{"title":"Catchment Hydrology","cells":[{"id":0,"value":"html`\n

Catchment Hydrology

Ngonye Falls Hydroelectric Project

\n
\n${book_index('catchment-hydrology')}\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2339,"value":"

Summary

","pinned":false,"hidden":false,"mode":"html"},{"id":2344,"value":"html `\nThe Ngonye Falls run-of-river hydroelectric project will generate electricity using the flows in the Zambezi river and the head provided by the Ngonye Falls at Sioma in the Western Province of Zambia.\n

\nThe Zambezi River catchment upstream of the project site is very large at 315,500km\\u00B2\\ (similar to the area of Norway) of which 53% is in Zambia and 47% in Angola. \n

\nAlthough there are no existing dams or reservoirs upstream of the project site, the very large catchment size combined with the attenuating and regulating effect of the Barotse Floodplain mean that the flows in the river are very stable and predictable and follow a regular seasonal pattern based on seasonal rainfall patterns. \n

\nThere is however a large seasonal variation in flows, with an average maximum flow of ${formatFlow(mean_max_flow)} around April each year and average minimum flow of ${formatFlow(mean_min_flow)} in September - October.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":133,"value":"md`\n## Catchment\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":124,"value":"html`\n

\n\n \n\n

Interactive map of the catchment on the Zambezi River of the proposed Ngonye Falls power project. Click here for a fullscreen version.

\n\n\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1849,"value":"html`\nThe Ngonye Falls are around 1,000km downstream of the source of the Zambezi river - near Mwinilunga in Zambia. The total catchment size is 315,500km\\u00B2\\ (similar to the area of Norway) of which 53% is in Zambia and 47% in Angola.\n

\nAlthough the Upper Zambezi sub-basin makes up only 32% of the total catchment area it provides 63% of the runoff ot the Ngonye Falls.\n

\nThe catchment upstream of Ngonye Falls has no man-made regulation (no existing dams or reservoirs) but there is significant natural regulation provided by the Barotse Floodplains described in more detail below.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1791,"value":"treechart = {\n return html`\n

\n \n

Angola

Zambia

Catchment Areas

\n ${build_tree('area','area_pct','km\\u00B2')}\n

Runoff

\n ${build_tree('runoff','runoff_pct','Mm\\u00B3')}\n

\n\n

Fig 1. Breakdowns of catchment area and runoff at Ngonye Falls by country and sub-basin. Catchment in Zambia in blue and catchment in Angola in orange. Adapted from: The World Bank, 2010.

\n\n `;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":179,"value":"html`\n

Rainfall

\n\nRainfall follows the same pattern across the whole of the basin with a cold, dry season lasting at least six months (April - Sept) with no rain followed by a hotter, wet season (Oct - March) when all of the rainfall occurs.\n\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":335,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":349,"value":"html`\nThe wet season starts earlier and lasts longer further north in the basin. Total rainfall is also higher in the north of the basin than in the south.\n

\nMean annual rainfall is around 900mm at Ngonye Falls (Mongu) and nearly 1,400mm in Mwinilunga around the source of the Zambezi.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":357,"value":"$32","pinned":false,"hidden":false,"mode":"ojs"},{"id":1014,"value":"md`\n## The Barotse Floodplains\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":499,"value":"html`\n

The Barotse Floodplain on the Zambezi River

\n The seasonal pattern of rainfall across the basin leads to a similar annual pattern of flood and drought flow in the river. \n

\n However, the attenuating effect of the Barotse Floodplain, a vast area of seasonal wetlands which extends more than 400km across Zambia's Western Province north from Ngonye Falls to the border with Angola, means that the flood peak of the river is 3 months or more later than the peak rainfall. \n

\n\n

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2139,"value":"html`\n

Annual Flow Pattern

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":440,"value":"$33","pinned":false,"hidden":false,"mode":"ojs"},{"id":1017,"value":"html`\n The seasonal pattern of rainfall combined with the attenuating and regulating effect of the Barotse Floodplain leads to a significant variation of flow through the year. \n

\nAt Ngonye Falls flows vary on average by more than one order of magnitde through the year with average maximum flow of ${formatFlow(mean_max_flow)} and average minimum of ${formatFlow(mean_min_flow)}.\n

\nFollowing the onset of rain in the upper catchment, flows generally begin to rise in December and reach a peak in March or April before falling again to a minimum in September through to November.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":527,"value":"$34","pinned":false,"hidden":false,"mode":"ojs"},{"id":877,"value":"html`\n

Historic Annual Flows

\nThe historic record of daily river flows at Victoria Falls has been maintained since 1924. At Ngonye a gauge has been operated by Zambezi River Authority since 2005. By correlation of the overlapping period, a 98 year synthetic daily flow series has been produced for Ngonye Falls. The derivation of this synthetic flow data is described in detail here.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":31,"value":"$35","pinned":false,"hidden":false,"mode":"ojs"},{"id":2246,"value":"html`\nAs well as the natural annual cycle of low flow and flood flows in the Zambezi river, there is also a significant variation in the peak flow (and to a lesser extent minimum flows) from one year to the next. This interannual variability can be seen from the long-term hydrology record where the 100 year maximum flood in early 1958 was close to ${formatFlow(10000)} whearas the maximum flood flow in 1996 was only ${formatFlow(840)}.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":602,"value":"$36","pinned":false,"hidden":false,"mode":"ojs"},{"id":2378,"value":"html `\nFor the period of the flow record since 1924, the mean annual minimum flow at Ngonye Falls is ${formatFlow(d3.mean(yearly, v=>v.flowMin))}, the mean annual mean flow is ${formatFlow(d3.mean(yearly, v=>v.flowMean))} and the mean annual maximum flow is ${formatFlow(d3.mean(yearly, v=>v.flowMax))}.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1023,"value":"md`\n## Representative Years\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":646,"value":"html`\nSelected years from the historic record have been identified as being representative of particular flow conditions to help see the range of flows that can occur in both extream - wet and dry - and 'average' conditions.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":632,"value":"table = {\n const tbl = d3.select(html`

`);\n\n //headers\n tbl\n .append('thead')\n .selectAll('th')\n .data(selected_years_display.columns)\n .join('th')\n .text(d => d.replace(\"_\", \" \"));\n\n //rows\n const rows = tbl\n .selectAll('tr')\n .data(selected_years_display)\n .join('tr')\n .attr('style', d =>\n d[0] == selected_year.year\n ? 'background-color:' + colr_b(3,0.2) + ';color:black !important;font-weight:bold;'\n : ''\n )\n\n const cells = rows\n .selectAll('td')\n .data(d => Object.entries(d))\n .join('td')\n .text(d => (isNaN(d[1]) ? d[1] : Math.round(d[1])));\n\n return tbl.node();\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":673,"value":"$37","pinned":false,"hidden":false,"mode":"ojs"},{"id":2325,"value":"html`\nThe representitive years hydrographs not only have different levels and timings for the flood peak but also very different overall shapes. Unlike storage type hydroelectric power stations that produce energy proportional the the area under the annual hydrograph, run-of-river hydroelectric power stations generate power based on the instantaneous flow of water in the river and so rely more on the shape of the annual hydrograph.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2261,"value":"html`\n

Flow Duration Curve

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2406,"value":"$38","pinned":false,"hidden":false,"mode":"ojs"},{"id":2448,"value":"html`\nFlow Duration Curves are a commonly used tool that show the average hydrology for a particular river location in a single curve. The exceedance chart shows the flow that is met or exceeded for a given proportion of the year.\n

\nA usual rule of thumb for run-of-river hydroelectric plants is to size their installed capacity to use the flow at the 30% exceedance. For Ngonye Falls this is around ${formatFlow(1100)}.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1026,"value":"

Long-term Patterns in Annual Flow

","pinned":false,"hidden":false,"mode":"html"},{"id":967,"value":"html`\nAs with the annual peak flood flow, annual average flows for the Zambezi River at Ngonye Falls show significant variation from one year to the next with flood years such as 1957-58 having average annual flow of over ${formatFlow(2000)} and drought years such as 1994-95 and 1995-96 having average annual flow of less than ${formatFlow(420)}.\n

\nAs well as this overall variation, a long-period moving average of average annual flow shows a cyclical pattern with long periods of above and below average flows. The period from 1950 to 1980 saw generally above average flows and from 1980 to 2005 there was a period of below average flows. This pattern has been observed in other rivers in Africa and in the long-term climate record evidenced form tree ring data.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":897,"value":"$39","pinned":false,"hidden":false,"mode":"ojs"},{"id":819,"value":"{\n let movingAv = movingAverage(yearly.map(yr=>yr.flowMeanVariance), 15)\n \n var data = [{\n y: yearly.map(yr=>yr.flowMeanVariance),\n x: yearly.map(yr=>yr.waterYear),\n name:'Mean Annual Flow',\n marker: {color: colr_b(3,0.5)},\n type: 'bar'\n },{\n y: movingAv,\n x: yearly.map(yr=>yr.waterYear),\n name:'15yr moving average',\n mode: 'lines', hoverinfo:'none',\n line: {width:3,color: colr_b(3)},\n type: 'scatter'\n }\n ];\n \n var layout = {\n width: width-50,\n height:200,\n font: font,\n showlegend: false,\n legend: {x: 1, xanchor: 'right', y: 1},\n margin: {t:0,b:30,l:70,r:5},\n xaxis: {\n showgrid: false,\n zeroline: false,\n ticks:'outside',\n },\n yaxis: {\n zeroline: false,\n showline: false,\n tickformat:'.0%'\n }\n };\n\n let cap = `Percent variation from the longterm mean of mean annual flow.`\n const div=container(cap, width-10)\n plt.newPlot(div, data, layout, {displayModeBar: false});\n return div\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":1032,"value":"html `\n

Frequency and Duration of Floods

\nThe frequency of natural flooding events are critical to inform the design and operation of any hydroelectric power station, particularly as this relates to public safety considerations.\n

\nThe flood return estimates for Ngonye Falls have been determined using standard statistical methods based on the 98 years of available historic hydrology records. The analysis shows that the 100 year flood is approximately ${formatFlow(10000)}.\nThe area has not experienced a 10 year flood level (6,200m\\u00b3/s) for the last 42 years and has not seen a 20 year flood level (7,200m\\u00b3/s) for 51 years.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1049,"value":"$3a","pinned":false,"hidden":false,"mode":"ojs"},{"id":1901,"value":"$3b","pinned":false,"hidden":false,"mode":"ojs"},{"id":2611,"value":"$3c","pinned":false,"hidden":false,"mode":"ojs"},{"id":1822,"value":"md`\n## References\n\nThe World Bank, 2010. The Zambezi River Basin A Multi-Sector Investment Opportunities Analysis.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2025,"value":"","pinned":false,"hidden":false,"mode":"ojs"},{"id":4,"value":"html` \n

\n

Appendix

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1799,"value":"md`\n## Trees\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1798,"value":"$3d","pinned":false,"hidden":false,"mode":"ojs"},{"id":1805,"value":"treemap2 = (data,property_name) => d3.treemap()\n .tile(d3.treemapBinary)\n .size([300, 300])\n .padding(1)\n .round(true)\n (d3.hierarchy(data)\n .sum(d => d[property_name])\n .sort((a, b) => b[property_name] - a[property_name]))","pinned":false,"hidden":false,"mode":"ojs"},{"id":1807,"value":"blues=d3.scaleSequential(d3.interpolateBlues);","pinned":false,"hidden":false,"mode":"ojs"},{"id":1809,"value":"oranges=d3.scaleSequential(d3.interpolateOranges);","pinned":false,"hidden":false,"mode":"ojs"},{"id":1036,"value":"md`\n## Flood Returns\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1047,"value":"flood_return = (await d3.csv(server + '/other/ngonye_floods.csv?' + Math.floor(Math.random() * 100),d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":194,"value":"md`## Rainfall and Catchments`","pinned":false,"hidden":false,"mode":"ojs"},{"id":153,"value":"catchments = (await d3.json(\"https://gis.westernpower.org/data/input_data/catchments.json?\" + Math.floor(Math.random() * 1000),d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":201,"value":"rainCalMonthly= (await d3.csv(\"https://gis.westernpower.org/data/output_data/rainfall_calmonthly.csv\",d3.autoType)).map(mo=>{\n mo['WaterMonth']=mo['Month']>=10 ? mo['Month']-9 : mo['Month']+3\n return mo\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":253,"value":"rainStations= (await d3.csv(\"https://gis.westernpower.org/data/output_data/rainfall_stations.csv\",d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":395,"value":"\nrainStationDict = rainStations.reduce(function(map, obj) {\n map[obj.Station] = obj;\n return map;\n}, {});","pinned":false,"hidden":false,"mode":"ojs"},{"id":363,"value":"rainYearly= (await d3.csv(\"https://gis.westernpower.org/data/output_data/rainfall_yearly.csv\",d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":191,"value":"md `## Monthly Flow`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2,"value":"monthly = (await d3.csv(hydrologyFolder + 'monthly.csv',d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":444,"value":"md`## Calender Months Flow`","pinned":false,"hidden":false,"mode":"ojs"},{"id":449,"value":"calMonthly = (await d3.csv(hydrologyFolder + 'calMonthly.csv?' + Math.floor(Math.random() * 500),d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":2569,"value":"calMonthlyExceedances = (await d3.csv(hydrologyFolder + 'calMonthlyFlowExceedance.csv',d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":2548,"value":"md`## FDC`\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":1468,"value":"fdc = (await d3.csv(hydrologyFolder + 'fdc.csv?' + Math.floor(Math.random() * 1000),d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":2578,"value":"calmonthlyFdc_raw = (await d3.csv( hydrologyFolder + \"\tcalMonthlyFlowExceedance.csv?\" + Math.floor(Math.random() * 1000),d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":2582,"value":"calmonthlyFDCs = Array.from({ length: 12 }, (v, i) => {\n return {\n waterMonth: i+1,\n flows: calmonthlyFdc_raw.map(l=>l[i+1]),\n exceedance: calmonthlyFdc_raw.map(l=>l.exceedance),\n }\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":551,"value":"md`## Yealry Flows`\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":754,"value":"yearly = (await d3.csv(hydrologyFolder + 'yearly.csv?' + Math.floor(Math.random() * 1000),d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":759,"value":"yearlyDict = yearly.reduce(function(map, obj) {\n map[obj.waterYear.toString()] = obj;\n return map;\n}, {});","pinned":false,"hidden":false,"mode":"ojs"},{"id":630,"value":"selected_years_raw = (await d3.csv(server + '/other/selected_years.csv',d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":1624,"value":"selected_years=selected_years_raw.map(yr=>{\n yr.weeks=weekly.filter(wk=>wk.waterYear==yr.year)\n yr.yearStats=yearly.find(y=>y.waterYear==yr.year)\n return yr\n})\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":698,"value":"\nselected_year = {\n var index=0\n while (true) {\n yield new Promise(resolve => {\n setTimeout(() => {\n index = (index + 1) % 5;\n resolve(selected_years[index])\n }, 2000);\n });\n }\n}\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":1211,"value":"selected_years_display = {\n const d = selected_years.map(y => {\n return [\n y.year,\n y.class,\n d3.format(',.0%')(y.yearStats.flowMeanExceedance),\n y.yearStats.flowMin,\n y.yearStats.flowMean,\n y.yearStats.flowMax\n ];\n });\n d['columns'] = [\n 'Water Year',\n 'Class',\n 'Flow Exceedance',\n 'Flow Min',\n 'Flow Mean',\n 'Flow Max'\n ];\n\n return d;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":1626,"value":"\nweekly=(await d3.csv(hydrologyFolder + 'weekly.csv',d3.autoType))","pinned":false,"hidden":false,"mode":"ojs"},{"id":562,"value":"mean_max_flow=d3.mean(yearly.map(y=>y.flowMax))","pinned":false,"hidden":false,"mode":"ojs"},{"id":565,"value":"mean_min_flow=d3.mean(yearly.map(y=>y.flowMin))","pinned":false,"hidden":false,"mode":"ojs"},{"id":2511,"value":"

Data Source

","pinned":false,"hidden":false,"mode":"html"},{"id":2516,"value":"hydrologyFolder = `${server}/syntheticFlowSeries/${hydrologySet}/processed/`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2518,"value":"hydrologySet='2024'","pinned":false,"hidden":false,"mode":"ojs"},{"id":2513,"value":"server='https://data.westernpower.org'","pinned":false,"hidden":false,"mode":"ojs"},{"id":664,"value":"","pinned":false,"hidden":false,"mode":"ojs"},{"id":282,"value":"md `## Styling`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2250,"value":"function formatFlow(flow) {\n return d3.format(',.2r')(flow) + ' m\\u00b3/s'\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":2187,"value":"function colr_c(i = 1, a = 1) {\n return d3hsv.hsv(160, 0.85, ((6 - i + 1.5) * 15)/100, a).toString();\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":2094,"value":"function colr_b(i = 1, a = 1) {\n return d3hsv.hsv(215, 1, ((6 - i + 1.5) * 15)/120, a).toString();\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":2098,"value":"function colr(i = 1, a = 1) {\n return d3hsv.hsv(26, 0.85, ((6 - i + 1.5) * 15)/100, a).toString();\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":2083,"value":"container = function(captionText, width_over) {\n const div=DOM.element('div')\n div.setAttribute(\"class\",\"border m-2 p-2\")\n div.setAttribute(\"style\",`width: ${width_over?width_over:(width>800?800:width)}px`)\n if (captionText) {\n const caption=DOM.element('figcaption')\n caption.setAttribute(\"style\",\"max-width:100%\")\n caption.append(captionText)\n div.append(caption)\n }\n return div\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":1309,"value":"html`\n\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2091,"value":"style=html`css `","pinned":false,"hidden":false,"mode":"ojs"},{"id":1609,"value":"import {book_index} from \"@andyflem/commonlibrary\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":1307,"value":"import {commonStyle} from \"@andyflem/commonlibrary\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":189,"value":"md `## Libraries `","pinned":false,"hidden":false,"mode":"ojs"},{"id":1295,"value":"margin","pinned":false,"hidden":false,"mode":"ojs"},{"id":1333,"value":"import {plotTitle} from \"@andyflem/commonlibrary\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":1284,"value":"import {margin} from \"@andyflem/commonlibrary\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":1278,"value":"import {font} from \"@andyflem/commonlibrary\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":908,"value":"import {movingAverage} from \"@andyflem/commonlibrary\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":7,"value":"d3 = require(\"d3@5\",\"d3-hsv@0.1\")\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":13,"value":"plt = require(\"https://cdn.plot.ly/plotly-latest.min.js\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":2096,"value":"d3hsv = require(\"d3-hsv@0.1\")","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W3e","stdlib":"1","titling":"auto"}