Hydrology is still, and for good reasons, an inexact science (for a recent discussion, see Beven, 2019a), even if evolving hydrological understanding has provided a basis for improved water management for at least the last three millennia. The limitations of that understanding have, however, become much more apparent and important in the last century as the pressures of increasing populations, and the anthropogenic impacts on catchment forcing and responses, have intensified (see Abbott et al., 2019; Montanari et al., 2013; Sivapalan, Savenije, & Blöschl, 2012; Srinivasan et al., 2017; Wagener et al., 2010; Wilby, 2019). At the same time, the sophistication of hydrological analyses and models has been developing rapidly, often driven more by the availability of computational power and geographical data sets than any real increases in understanding of hydrologicalprocesses. This sophistication has created an illusion of real progress, but a case can be made that we are still rather muddling along, limited by the significant uncertainties in hydrological observations, knowledge of catchment characteristics, and related gaps in conceptual understanding, particularly of the subsurface. These knowledge gaps are illustrated by the fact that for many catchments, we cannot close the water balance without significant uncertainty (e.g.,

Five satellite-based rainfall estimation algorithms (TRMM 3B42, CMORPH, TAMSAT, RFE 2.0 and PERSIANN) are assessed against historical monthly rainfall statistics from raingauges within four regions of Uganda. Results are discussed in terms of the accuracy of the products, the effect of climate variability, and differences between products. Products are able to reasonably reflect seasonal patterns in rainfall, and also the spatial patterns in rainfall between regions. Patterns in the occurrence of rainfall are better reflected than patterns in rainfall amounts. There is significant scope for improving the estimation of amounts by calibration to the raingauge data. TRMM 3B42, CMORPH and TAMSAT show most promise in this application followed by RFE 2.0 and the PERSIANN system. However, the relative performance of the products depends on what aspects of the rainfall regime are being considered. Differences between the products are large and the use of more than one product for any application is recommended.Key words rainfall estimation; satellites; Uganda; TRMM; CMORPH; TAMSAT; RFE; PERSIANN Evaluation de cinq produits satellitaires pour l'estimation des précipitations en OugandaRésumé Cinq algorithmes d'estimation par satellite des précipitations (TRMM 3B42, CMORPH, TAMSAT, RFE 2.0 et PERSIANN) sont confrontés aux statistiques mensuelles historiques de pluviomètres répartis dans quatre régions d'Ouganda. Les résultats sont discutés en termes de précision des estimations, de sensibilité à la variabilité climatique, et de différences entre les produits. La saisonnalité des précipitations ainsi que leur distribution géographique entre régions sont convenablement reproduites. Les structures d'occurrence sont mieux représentées que les structures de hauteur de pluie. La marge d'amélioration de l'estimation des hauteurs d'eau par calage avec les données au sol est significative. Cette application est plus prometteuse avec TRMM 3B42, CMORPH et TAMSAT qu'avec RFE 2.0 et PERSIANN. Les performances relatives des produits dépendent cependant des caractéristiques du régime pluviométrique qui sont considérées. Les résultats diffèrent largement entre les produits et une utilisation combinée est recommandée quelle que soit l'application.

In December 2015, northern England experienced two major flooding events with extreme, even in some locations unprecedented, rainfalls and flooding. New 24-, 36-, and 48-hour UK rainfall records were created of 341.4, 401.4, and 405.2 mm, respectively. Three river-flow gauging stations, with flows of around 1,700 m3/s exceeded the previous peak flow record for England and Wales. There was widespread flooding, including major towns and cities, some of which had recent flood alleviation schemes. In Cumbria, the flood events in 2005, 2009 and 2015 compared with previous and historical events raise questions about the stationarity of the flood data and flood-producing mechanisms. These possible effects are less apparent elsewhere in northern England. This paper discusses whether present methods of estimating flood risk are able to cope with such extreme events and suggests topics for future research. In the meantime, for studies where flood estimates are important, practical hydrologists are faced with the difficult task of producing design flood estimates which fit with our understanding of these events.

In addition to population increases, water use in the Santa basin may change. Higher temperatures and lower precipitation in the dry season could lead to more of the flow in the dry season being extracted for irrigation purposes. Economic development in the Santa basin may also increase pressure on the water supply, especially if agriculture in the basin is developed and new intakes for irrigation are planned from the river upstream of the CHAVIMOCHIC intake.

A ‘roadmap’ for the future of UK flood hydrology over the next 25 years has been published, based on a wide-ranging and inclusive co-creation process involving more than 270 individuals and 50 organisations from different sectors and disciplines. This paper highlights key features of the roadmap and its development as a community-owned initiative. The roadmap's relationship with hydrological research and practice is discussed, as is its context within the wider flood risk management innovation landscape, including funding. While the paper has a focus on UK flood hydrology, reflecting the scope of the roadmap, it is also considered in the context of advances in hydrology internationally.

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