Water companies are required to produce a Water Resources Management Plan (WRMP) every five years which sets out how the company intends to provide a secure and sustainable supply of water to their customers, whilst protecting the environment. Recent guidance from Ofwat required a partial update of the tables. We'll provide a full and comprehensive update at a later date. Lehner, B., Verdin, K. & Jarvis, A. New global hydrography derived from spaceborne elevation data. Eos, Transactions American Geophysical Union 89, 93–94 (2008). Yamazaki, D. et al. MERIT Hydro: A high-resolution global hydrography map based on latest topography dataset. Water Resources Research. 55(6), 5053–5073 (2019).

Arnold, J. G., Srinivasan, R., Muttiah, R. S. & Williams, J. R. Large area hydrologic modeling and assessment part I: model development 1. JAWRA Journal of the American Water Resources Association. 34(1), 73–89 (1998). NASA/METI/AIST/Japan Spacesystems, U.S./Japan ASTER Science Team. ASTER Global Digital Elevation Model. NASA EOSDIS Land Processes DAAC https://doi.org/10.5067/ASTER/ASTGTM.002 (2009). Yan, D. et al. A data set of inland lake catchment boundaries for the Qiangtang Plateau. Scientific data. 6(1), 1–11 (2019). Ciais, P. et al. Europe-wide reduction in primary productivity caused by the heat and drought in 2003. Nature 437, 529 (2005). On registering their interest, third parties will be registered on Thames Water’s IASTA SmartSource portal within two weeks and provided access to complete an initial pre-qualification (PQQ1) survey.

We chose HydroSHED 9 and HDMA 11 databases for accuracy comparison. They are two widely used global hydrological data sets in which the secondary products (HydroRIVERS 34 and Stream layers) can provide us with an objective comparison. We refer to the comparison method in GRNWRZ V1.0 to compare the accuracy of our RN with HydroRIVERS and Stream layers. It should be noted that few rivers in Stream layers can meet the criteria for rivers at level 7 in GRNWRZ V2.0, so the rivers in Stream layers cannot completely cover the comparison points. Therefore, we only compare with HydroRIVERS at level 7. The comparison is made in the following way: Step 1. We randomly selected 400 rivers from L2-L7 RN of each continent, and three randomly points were generated at each river by ArcGIS (because the Level 1 RN consists of all Level 2 RN that flow into the same ocean, they are essentially the same rivers but divided by different criteria). Step 2. We imported these random points into Google Earth and manually marked the center point of natural rivers nearest to the random point. Step 3. We calculate the deviation distances from the center point obtained in step 2 to rivers in the other two data sets by ArcGIS. Then, we performed statistics in Excel to derive the comparison results. Li, X. et al. Hydrological cycle in the Heihe River Basin and its implication for water resource management in endorheic basins. Journal of Geophysical Research: Atmospheres. 123(2), 890–914 (2018). Lehner, B. & Grill, G. Global river hydrography and network routing: baseline data and new approaches to study the world’s large river systems. Hydrological Processes 27, 2171–2186 (2013).

Many people think there’s plenty of water in the UK, but the South East of England is one of its driest regions and London gets less rain than Rome, Istanbul and even Sydney. The water resources we rely on are under pressure, and this is increasing all the time. We must find ways to adapt to our changing climate, supply water to more people as our population grows and reduce the amount of water we take from our rivers to protect the environment. Developing a plan for the South East region The combined WRZ: The combined WRZ was defined as a region which contains several rivers flowing into the sea or lake, mainly small watersheds distributed in coastal areas, such as the east coast rivers in the South America. The rivers at L2, L3, and L4 levels in this combined WRZ are shown as follows (Fig. 3b). Where δ is the relative error, V 2 is the distance between the center point of natural rivers and the river network in GRNWRZ V2.0, and V 1 is the distance between the center point of natural rivers and the river network in GRNWRZ V1.0. The distance between the center point of natural rivers and the river network is obtained in the same way as steps 1–3 mentioned above.Ostrom, E. A general framework for analyzing sustainability of social-ecological systems. Science 325, 419–422 (2009).

The river at level 3 (L3 river) refers to the river that flows into the L2 river, and its confluence area is larger than one hundredth of the L2 river or 1000 km 2. Updating information about individual schemes such as costs, delivery dates and environmental information

Our Water Resources Management Plan 2024

HydroSHEDS has been developed by the Conservation Science Program of World Wildlife Fund (WWF), in partnership with the USGS, the International Centre for Tropical Agriculture (CIAT), The Nature Conservancy (TNC), and the Center for Environmental Systems Research (CESR) of the University of Kassel, Germany. HydroSHEDS is a mapping product that provides hydrographic information for regional and global-scale applications in a consistent format. HydroSHEDS is based on SRTM DEM data. However, not all of the data has been completed and released, such as the river network is at 15 arc-second resolution 26. Cohen, S., Wan, T., Islam, M. T. & Syvitski, J. P. M. Global river slope: A new geospatial dataset and global-scale analysis. Journal of Hydrology 563, 1057–1067 (2018). Our Water Resources Management Plan 2024 (WRMP24) builds on our current plan ( WRMP19) and reflects the South East regional plan. It sets out how we'll keep taps flowing for customers like you over the next 50 years, looking ahead to 2075.

Yan, D. et al. A data set of global river networks and corresponding water resources zones divisions. figshare, https://doi.org/10.6084/m9.figshare.8044184.v6 (2019). Stein, J. L. An enhanced Pfafstetter catchment reference system. Water Resources Research 54, 9951–9963 (2018). It is worth pointing out that the WRZ in our study is different from the Basin levels (1-12) in HydroSHEDS and the EU’s River Basin District (RBD) concept. Our new method could divide each basin into 99 sub-basins maximumly, according to the stem-branch topology, as shown in Fig. 4. By contrast, the watershed of HydroSHEDS are divided into 9 parts following the topological concept of the Pfafstetter coding system 10. The river basin district in EU refers to the area of land and sea, made up of one or more neighboring river basins together with their associated groundwaters and coastal waters 23. And the boundaries of river basin district in EU were obtained from different countries, without uniform data source and code number. Treatment for small “wolf-tooth” coastal area This enables third parties, who can either be other incumbents or independent third parties, to identify opportunities to provide new water resources; and identify and provide demand management and leakage services. Each spreadsheet contains key market information as well as the WRZ’s water resources position as detailed in our final WRMP19. Falorni, G., Teles, V., Vivoni, E. R., Bras, R. L. & Amaratunga, K. S. Analysis and characterization of the vertical accuracy of digital elevation models from the Shuttle Radar Topography Mission. Journal of Geophysical Research: Earth Surface. 110, F2 (2005).In response to the above problems, we developed a data set entitled ‘A data set of global river networks and corresponding water resources zones’ (GRNWRZ V1.0) 22 with a spatial resolution of 90 m based on the SRTM and the ASTER Global Digital Elevation Model (ASTER GDEM) 23 in 2019. The RN in this dataset has been extensively verified manually in combination with natural rivers in Google Earth, and it is relatively accurate compared to other data sets, especially in plain and inland areas 24. Each basin is divided into 99 sub-basins maximumly through the coding method determined according to the stem-branch topology, which solves the problem of the upper limit of the number of sub-basins. At the same time, the code numbers of reaches and corresponding sub-basins are unified to ensure that both have the same code number. However, GRNWRZ V1.0 still has some limitations for application in the more widely used sub-basin based distributed hydrological models (e.g., SWAT 25, 26, WEP-L 27). Firstly, hydrological simulation and water resources evaluation of super-large WRZ (>10000 km 2) and ultra-small WRZ (<100 km 2) are hindered. For super-large WRZ, many small sub-basins in the main stream reaches do not match their level in GRNWRZ V1.0, affecting the efficiency of the hydrological simulation. For ultra-small WRZ, the flow concentration relationship between sub-basins is unclear, affecting the accuracy of water resources evaluation results. Secondly, the flow concentration relationship represented by the code numbers among sub-basins in the coastal region is not emphasized. Lastly, GRNWRZ V1.0 does not consider that those exorheic rivers eventually flow to different oceans when they define rivers, affecting global terrestrial water resources estimation.