HYDRO/Flood_Statistics_Henderson_Collins

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Service Description: Layer used in public web app <a href='https://niwa.maps.arcgis.com/apps/webappviewer/index.html?id=933e8f24fe9140f99dfb57173087f27d' rel='nofollow ugc' target='_blank'>https://niwa.maps.arcgis.com/apps/webappviewer/index.html?id=933e8f24fe9140f99dfb57173087f27d </a> to provide Flood Estimation for New Zealand<p><b> 1. Modelled flood frequency estimates on river lines.</b></p><ul><li><div style='margin-right: 0px;'>NZREACH NZ digital network 1 ID no.</div></li><li><div style='margin-right: 0px;'>River name where available</div></li><li><div style='margin-right: 0px;'>Areakm2 catchment area draining to the downstream end of this reach (square kilometres)</div></li><li><div style='margin-right: 0px;'>q100_reach ratio of Q100 (1% aep flood) to mean annual flood</div></li><li><div style='margin-right: 0px;'>H&C18_MAF mean annual flood (cumecs)</div></li><li><div style='margin-right: 0px;'>H&C18_5-yr 5-yr (20% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>H&C18_10y 10-yr (10% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>H&C18_20y 20-yr (5% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>H&C18_50y 50-yr (2% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>H&C18_100y 100-yr (1% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>H&C18_1000y 1000-yr (0.1% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>HCse_MAF standard error of mean annual flood (cumecs)</div></li><li><div style='margin-right: 0px;'>HCse_5y standard error of 5-yr (20% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>HCse_10y standard error of 10-yr (10% aep) flood (cumecs) </div></li><li><div style='margin-right: 0px;'>HCse_20y standard error of 20-yr (5% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>HCse_50y standard error of 50-yr (2% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>HCse_100y standard error of 100-yr (1% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>HCse_1000y standard error of 1000-yr (0.1% aep) flood (cumecs)</div></li><li><div style='margin-right: 0px;'>Strm_Order Strahler stream order (1=headwater, two ones join to make an order 2, etc.) 2.</div></li></ul><p><b> 2. At-site flood statistics at flow recorders used in the model development</b></p><ul><li> Siteno NIWA reference number for flow recorder </li><li>Name Flow recorder name generally 'river' at 'location' </li><li>NZTM_E NZTM easting NZTM_N NZTM northing</li><li>Region Regional council or unitary authority territory</li><li>Operator Organisation that oprates the flow recorder Funder Organisation that funds the flow recorder (can be more than one)</li><li>Area_km2 catchment area draining to the flow recorder (square kilometers)</li><li>No_years Number of years in the annual flood series (allowing for years with missing data)</li><li>L1_mean Mean of the annual flood series (linear moment 1)</li><li>L2 Linear moment 2 of the annual flood series (analogous to standard deviation)</li><li>Lcv Linear CV of the annual flood series (L2/L1) </li><li>T3_Lskew Linear skew ratio of the annual flood series </li><li>T4_Lkurt Linear kurtosis ratio of the annual flood series </li><li>Gumb_u Gumbel distribution u of the annual flood series </li><li>Gumb_alpha Gumbel distribution alpha of the annual flood series </li><li>GEV_u Generalised Extreme Value u of the annual flood series</li><li>GEV_alpha Generalised Extreme Value alpha of the annual flood series </li><li>GEV_k Generalised Extreme Value k of the annual flood series </li><li>GEV_z Hosking-Wallis normal standard variate to test significance of GEV-k (is the at-site distribution Gumbel or not?)</li><li>Data 2.33y mean annual flood (2.33-yr assuming Gumbel, or 43% aep)</li><li>Data 5y 5-yr (20% aep) flood (cumecs)</li><li>Data 10y 10-yr (10% aep) flood (cumecs)</li><li>Data 20y 20-yr (5% aep) flood (cumecs)</li><li>Data 50y 50-yr (2% aep) flood (cumecs)</li><li>Data 100y 100-yr (1% aep) flood (cumecs)</li><li>Data 250y 250-yr (0.4% aep) flood (cumecs)</li><li>Data 500y 500-yr (0.2% aep) flood (cumecs) </li><li>Data 1000y 1000-yr (0.1% aep) flood (cumecs)</li><li>se_2.33y standard error of mean annual flood (%) </li><li>se_5y standard error of 5-yr (20% aep) flood (%)</li><li>se_10y standard error of 10-yr (10% aep) flood (%)</li><li>se_20y standard error of 20-yr (5% aep) flood (%)</li><li>se_50y standard error of 50-yr (2% aep) flood (%)</li><li>se_100y standard error of 100-yr (1% aep) flood (%)</li><li>se_250y standard error of 250-yr (0.4% aep) flood (%)</li><li>se_500y standard error of 500-yr (0.2% aep) flood (%) </li><li>se_1000y standard error of 1000-yr (0.1% aep) flood (%)</li></ul><p><b> 3. Return period estimates of the area-rain intensity values for small catchments. Where results display '-1' the catchment is greater than 30 square kilometres and no answer is available. Numbers need to be multiplied by the Rational Method 'C' factor to give the required flood magnitude.</b> </p><ul><li>NZREACH NZ digital network 1 ID no. </li><li>AREA_km2 catchment area draining to the flow recorder (square kilometers)</li><li>QIA_5y 5-yr (20% aep) IA estimate</li><li>QIA_10y 10-yr (10% aep) IA estimate </li><li>QIA_20y 20-yr (5% aep) IA estimate</li><li>QIA_50y 50-yr (2% aep) IA estimate</li><li>QIA_100y 100-yr (1% aep) IA estimate </li><li>QIA_1000y 1000-yr (0.1% aep) IA estimate</li></ul><p><b>4. Annual data values at flow recorders used in the model development. Layer coming later.</b></p><p><b><br /></b></p><p><br /></p><p><span style='font-weight: bold;'>Spatial Reference: New Zealand Transverse Mercator (NZTM) </span><br /></p><p>EPSG:2193 (2193) <br /></p>XMin: 1090154.6277<br /> YMin: 4748852.6367<br /> XMax: 2089112.8753000004<br /> YMax: 6193369.0554

Map Name: NZ Flood Statistics Henderson Collins V2 Layer

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Copyright Text: National Institute of Water and Atmosphere (NIWA)

Spatial Reference: 2193 (2193) LatestVCSWkid(0)

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HYDRO/Flood_Statistics_Henderson_Collins_V2 (MapServer)