The Drentsche Aa catchment in The Netherlands, which has nearly untouched natural river valleys, is a designated Natura 2000 area.Agriculture is practiced on the adjacent higher-lying ground.A set of measures was drafted to achieve climate-proof solutions in the short term by reducing the effects of a drier climate on nature and agriculture.These measures must have no adverse effects.In order to check this, the Hunze and Aa's Water Board investigated the feasibility of using groundwater for sprinkler irrigation in parts of the catchment.In the study, the SIMulation of GROundwater and surface water levels (SIMGRO) hydrological model was used in order to model future scenarios with different water level strategies and climate scenarios.The modelling examined various measures in the nature and agricultural areas to optimise the hydrological situation for both land use functions.In addition, the effect on the nature areas of abstracting groundwater for irrigation was determined for buffer zones of different widths.The findings have indicated the policy direction to be taken by both the water board and the province, as well as offer them opportunities to deal with the requests for withdrawals in the near future by the means of future-proof general rules.

Boosting the productivity of smallholder farming systems continues to be a major need in Africa. Challenges relating to how to improve irrigation are multi‐factor and multisectoral, and they involve a broad range of actors who must interact to reach decisions collectively. We provide a systematic reflection on findings from the research project EAU4Food, which adopted a transdisciplinary approach to irrigation for food security research in five case studies in Ethiopia, Mali, Mozambique, South Africa and Tunisia. The EAU4Food experiences emphasize that actual innovation at irrigated smallholder farm level remains limited without sufficient improvement of the enabling environment and taking note of the wider political economy environment. Most project partners felt at the end of the project that the transdisciplinary approach has indeed enriched the research process by providing different and multiple insights from actors outside the academic field. Local capacity to facilitate transdisciplinary research and engagement with practitioners was developed and could support the continuation and scaling up of the approach. Future projects may benefit from a longer time frame to allow for deeper exchange of lessons learned among different stakeholders and a dedicated effort to analyse possible improvements of the enabling environment from the beginning of the research process. © 2020 The Authors. Irrigation and Drainage published by John Wiley & Sons Ltd on behalf of International Commission for Irrigation and Drainage

Devastating floods adversely affect human life and infrastructure. Various regions of the Hindukush-Karakoram-Himalayas receive intense monsoon rainfall, which, together with snow and glacier melt, produce intense floods. The Kabul river basin originates from the Hindukush Mountains and is frequently hit by such floods. We analyses flood frequency and intensity in Kabul basin for a contemporary period (1981–2015) and two future periods (i.e., 2031–2050 and 2081–2100) using the RCP4.5 and RCP8.5 scenarios based on four bias-corrected downscaled climate models (INM-CM4, IPSL-CM5A, EC-EARTH, and MIROC5). Future floods are modelled with the SWAT hydrological model. The model results suggest an increasing trend due to an increasing precipitation and higher temperatures (based on all climate models except INM-CM4), which accelerates snow and glacier-melt. All of the scenario results show that the current flow with a 1 in 50 year return period is likely to occur more frequently (i.e., 1 in every 9–10 years and 2–3 years, respectively) during the near and far future periods. Such increases in intensity and frequency are likely to adversely affect downstream population and infrastructures. This, therefore, urges for appropriate early precautionary mitigation measures. This study can assist water managers and policy makers in their preparation to adequately plan for and manage flood protection. Its findings are also relevant for other basins in the Hindukush-Karakoram-Himalayas region.

Abstract. The Naga Foundation aims to implement durable re-greening interventions to increase local soil sustainability and regional water availability. When this is done on a large enough scale such landscape changes may also lead to positive regional climate impacts. Naga is developing a plan to re-green 15 large areas in Eastern Africa, creating a so-called hydrological corridor. Four potential hydrological corridors have been identified in Kenya and Tanzania, all four of them around Mount Kilimanjaro. To select the most promising corridor, a method was developed to support a decision in a situation where few data are available. The method is based on maps, models and literature from four different disciplines concerning soil, water, climate and social institutions. The findings favour the Tanzanian corridors and especially the Tanzania-East one, to start with re-greening projects. In that region many applicable land management options combine with a high potential for restoring soil organic matter, the highest rainfall recycling potential exists in the more favourable long rains season, while finally also the Tanzanian governments both at national and at local level seem more dependable for supporting hydrological corridor implementation.

Abstract The aim of this study was to analyse the impact of selected small water retention measures on surface and groundwater level in river basins. The study was limited to the analysis of measures like small water reservoirs, restoration of bogs and reconstruction of drainage systems in the river valleys. A few study cases were described. Dutch SIMGRO numerical model describing the regional surface water and groundwater flow has been used for simulation modelling of different cases. The result of the study has shown that small retention measures are a good and effective method to increase the ability to retain water in the small river basins. Construction of small water reservoirs and weirs on ditches and creeks and restoration of drained bogs can limit the fast outflow of precipitation and melting water from the catchment. The study has proved that the small water retention measures can be helpful for flood protection and in decreasing of drought threats in small river basins.

ABSTRACTThe assessment of the ecological status of water bodies, as requires by the European Water Framework Directive, can raise a number of problems when applied to temporary streams. These problems are because of the particular physical, chemical and biological conditions resulting from the recurrent cessation of flow or even the complete drying of the stream beds. In such non‐permanent water bodies, the reference quality standards developed for permanent streams may only be applicable under certain circumstances or may not be applicable at all. Work conducted within the collaborative EU‐funded project Mediterranean Intermittent River ManAGEment (MIRAGE) has addressed most of these difficulties and has used diverse approaches to solve them. These approaches have been brought together in the so‐called MIRAGE Toolbox. This toolbox consists of a series of methodologies that are designed to be used in a sequential manner to allow the establishment of the ecological and chemical status of temporary streams and to relate these findings to the hydrological status of the streams. The toolbox is intended to serve the following purposes: (i) the determination of the hydrological regime of the stream; (ii) the design of adequate schedules for biological and chemical sampling according to the aquatic state of the stream; (iii) the fulfillment of criteria for designing reference condition stations; (iv) the analysis of hydrological modifications of the stream regime (with the definition of the hydrological status); and (v) the development of new methods to measure the ecological status (including structural and functional methods) and chemical status when the stream's hydrological conditions are far from those in permanent streams. Copyright © 2014 John Wiley & Sons, Ltd.

In order to apply the EU Water Framework Directive for temporary streams, it is important to quantify the space-time development of different aquatic states. We report on research on the development of aquatic states for temporary streams in the Evrotas basin, Greece. The SIMGRO regional hydrological model was used in a GIS framework to generate flow time series for the Evrotas River and all major tributaries. Five flow phases were distinguished: flood conditions, riffles, connected pools, isolated pools and dry bed conditions. Thresholds based on local hydraulic characteristics were identified per stream reach and flow phase, enabling the frequency of flow phases per month and the average frequencies for all streams to be derived. Three historical scenarios within the 20th century, marking periods of major changes in water management, were investigated. Additionally, a climate scenario for the 2050s was analysed. Simulations revealed that low flows are now much lower, mainly because more groundwater is abstracted for irrigation. The consequence is that stretches of the river fall dry during several months, causing the ecological status to deteriorate.

Hourly water level measurements were used to investigate the flood characteristics of a semi-arid river in Greece, the Evrotas. Flood events are analysed with respect to flood magnitude and occurrence and the performance of Curve Number approach over a period of 2007–2011. A distributed model, Soil and Water Assessment Tool, is used to simulate the historic floods (1970–2010) from the available rainfall data, and the performance of the model assessed. A new flood classification method was suggested the Peaks-Duration Over Threshold method that defines three flood types: ‘usual’, ‘ecological’ and ‘hazardous’. We classify the basin according to the flood type for the most serious past simulated flood events. The proportion of hazardous floods in the main stream is estimated to be 5–7% with a lower figure in tributaries. Flood Status Frequency Graphs and radar plots are used to show the seasonality of simulated floods. In the Evrotas, the seasonality pattern of hazardous flood is in agreement with other studies in Greece and differs from other major European floods. The classification in terms of flood types in combination with flood type seasonality is identified as an important tool in flood management and restoration.

In Noord-Nederland steeg door stevige regenval het waterpeil in de boezem sinds de jaarwisseling enorm. Een belemmerende factor was dat dit overtollige water nauwelijks op zee geloosd kon worden vanwege de aanhoudende harde tot stormachtige noordwestenwind en daardoor zeer hoge waterstanden in de Waddenzee. De inzet van bergingsgebieden moest de extreem hoge waterstanden verlagen. Het is de allereerste keer dat de noordelijke waterschappen met succes gebruik maakten van deze voorzieningen. Erik Querner en Cees Kwakernaak pleiten voor het bovenstrooms vasthouden van water, waarmee overlast te vermijden is.

The survival of peat meadows in the Netherlands is threatened by soil subsidence, less favourable conditions for farming and rising costs of water management. To support policy-making, a study examined possible future strategies for these meadows in the west of the Netherlands. Future scenarios with different water level strategies and climate scenarios were modelled with the SIMGRO regional hydrological model. The analysis focused on water level control strategies, in combination with subsurface drains, with the aim of reducing subsidence and minimising the water supply in dry periods. Subsurface drains were found to be a good measure to reduce subsidence, but more water had to be supplied. Based on the simulated water level control strategies an optimal scenario was found; it minimises the negative effects of the increased water supply. A scenario simulating the anticipated climate change appeared to have a great impact on the peat meadows. In the future the subsidence rate will increase and more water will have to be supplied to maintain the target surface water levels.

Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The structure and composition of biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. Therefore, the structural and functional characteristics of aquatic fauna to assess the ecological quality of a temporary stream reach cannot be used without taking into account the controls imposed by the hydrological regime. This paper develops methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the transient sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: Hyperrheic, Eurheic, Oligorheic, Arheic, Hyporheic and Edaphic. When the hydrological conditions lead to a change in the aquatic state, the structure and composition of the aquatic community changes according to the new set of available habitats. We used the water discharge records from gauging stations or simulations with rainfall-runoff models to infer the temporal patterns of occurrence of these states in the Aquatic States Frequency Graph we developed. The visual analysis of this graph is complemented by the development of two metrics which describe the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of temporary streams in four aquatic regimes in terms of their influence over the development of aquatic life is updated from the existing classifications, with stream aquatic regimes defined as Permanent, Temporary-pools, Temporary-dry and Episodic. While aquatic regimes describe the long-term overall variability of the hydrological conditions of the river section and have been used for many years by hydrologists and ecologists, aquatic states describe the availability of mesohabitats in given periods that determine the presence of different biotic assemblages. This novel concept links hydrological and ecological conditions in a unique way. All these methods were implemented with data from eight temporary streams around the Mediterranean within the MIRAGE project. Their application was a precondition to assessing the ecological quality of these streams.

De zoetwatervoorziening in de Veenkolonien gaat problemen opleveren als het klimaat verandert en er minder aanvoerwater vanuit het IJsselmeer beschikbaar komt. In het plan De Verscholen Bron wordt een aantal maatregelen genoemd die het gebied onafhankelijk(er) kunnen maken van waterinlaat van buiten de Veenkolonien. Om een eerste indruk te krijgen van de haalbaarheid van de voorgestelde maatregelen zijn berekeningen uitgevoerd met het model SIMGRO. De uitkomsten laten zien dat water vasthouden, extra beregenen of het aanleggen van waterbergingsgebieden goede perspectieven bieden. Het globale karakter van de studie maakt wel dat de resultaten nog een indicatief karakter hebben.

Dit rapport is onderdeel van de studie Droogtebestendig West-Nederland die is uitgevoerd in opdracht van de provincies Zuid-Holland, Noord-Holland en Utrecht, Waternet, Hoogheemraadschap van Rijnland, Hoogheemraadschap De Stichtse Rijnlanden en Hoogheemraadschap van Schieland en de Krimpenerwaard. Door het afwateren van de veenweidegebieden daalt daar de bodem. Toepassing van onderwaterdrains kan de bodemdaling halveren, maar zal door een betere infiltratie in het veenweideperceel en een doorgaande gewasverdamping in droge perioden leiden tot een grotere watervraag van het veenweidegebied. Uit dit verkennend onderzoek blijkt dat door toepassing van onderwaterdrains de watervraag tot 15% extra kan toenemen. Door slim peilbeheer kan deze toename van de watervraag echter sterk worden gereduceerd.

Tools were developed to quantify space time development of different flow phases on a river basin scale. Such information is needed for the Water Framework Directive (WFD). The spatial development of temporary streams was investigated in the Evrotas basin, Greece. We used the regional hydrological model SIMGRO in a GIS framework to generate flow time series for all major streams. For a stream reach five flow phases are distinguished, being: floods; riffles; connected flow; pools and dry conditions. For each stream and flow phase, thresholds were identified based on local characteristics. The analysis shows the frequency of the flow phases per month. For all streams in the Evrotas basin the average frequency of the flow phase dry and pools are presented. The aim is that GIS helps to better understand the link between dry streams and spatially-distributed catchment characteristics. Local morphological conditions and roughness of the bed need to be considered in defining appropriate threshold levels for the flow phases.

Het klimaat verandert en dat heeft de nodige consequenties voor de zoetwatervoorziening en de verwerking van neerslagpieken. Inmiddels wordt al volop gewerkt aan plannen om Nederland klimaatbestendiger te maken, onder meer in het Deltaprogramma. In deze fase worden strategische keuzen rond lange termijn veiligheid en zoetwatervoorziening voorbereid. In dat kader past ook het verkennende onderzoek naar de watervoorziening in de Gronings-Drentse Veenkolonien. Met een hydrologisch model is nagegaan of water vasthouden in regionale retentiegebieden een realistisch alternatief kan bieden voor het verminderen of zo mogelijk volledig stoppen van wateraanvoer vanuit het IJsselmeer.