Search

The study was conducted in the semi-arid northern Ethiopia aimed at selecting appropriate water harvesting techniques (WHTs) for implementation. A plot-scale experiment was set up, in the Gule catchment, on a farmland to monitor the effect of in-situ WHTs such as tied ridges and straw mulch mainly on event-based runoff, soil-moisture, and soil and nutrient losses. The off-site effect of WHTs such as check dams and percolation ponds on catchment-scale event-based runoff and sediment yield was also monitored in the Gule catchment (~12 km2) and Misbar sub-catchment (~2.4 km2), northern Ethiopia. First, a decision support approach was developed to aid the selection of WHTs in arid and semi-arid areas. The decision support approach was validated with a case study for WHTs in the upper Geba watershed in northern Ethiopia. Using the decision support methodology, eight potential WHTs were pre-selected for implementation in the watershed. Next, using suitability indicators for WHTs and a GIS-based multi-criteria analysis, suitable areas were identified for three of these WHTs, namely check dams, percolation ponds and bench terraces and suitability maps were generated. The multi-criteria analysis was validated by comparing the predicted suitable areas with the already existing locations of WHTs in the watershed. The result was that 90% of the existing check dams and 93% of the percolation ponds in the upper Geba watershed were correctly identified by the approach. The field study showed runoff reduction by WHTs from farmland between 40 to 88% and soil loss between 60 to 90%. Nutrient loss reduction from farmland by WHTs also ranged between 52 and 86%. Soil-moisture also improved due to the use of the in-situ WHTs. Model-based simulation at the Gule and Misbar outlets using LISEM showed that the current WHTs applied in the catchment are able to decrease event-based runoff by 41 and 45%, respectively. Similarly, sediment yield was reduced at both the Gule outlet and Misbar sub-outlet, by 67 and 55%, respectively. This study has verified that in semi-arid areas, such as the northern Ethiopian highlands, in-situ and catchment-scale WHTs can be used to improve the efficiency of rainwater harvesting and water availability for agricultural uses. Furthermore, these WHTs help to mitigate land degradation by decreasing soil and nutrient losses from farmland and sediment yield from catchments.

In a context of future population increase and intensification of water cycle by climate change, water demand for irrigation is projected to double. However, freshwater resources have been degraded the last decades especially in rivers via fragmentation, dam contraction and pollution. Flow alteration and degradation lead to 80% of freshwater ecosystem species loss. In this thesis, a robust and reliable Environmental Flow (EF) method was developed for global scale: the Variable Monthly Flow (VMF) method. This method allowed estimating EF deficit at global scale including its origin, timing, frequency and magnitude. By setting EFRs as priority user in a global vegetation and hydrological model (LPJmL), irrigation loss due to EFRs implementation were assessed at 30% leading to 5% global calorie loss. To maintain water allocation to humans and ecosystems under global change, food imports would require to increase by 15% especially from Latin America to South of Asia.

In dit artikel worden de beschikbaarheid en het ( mogelijke meervoudige) gebruik van water als grondstof geschetst, toegespitst op de sectoren industrie en landbouw. Dit alles geplaatst in een mondiaal kader van groeiende schaarste en oplopende kosten van grondstoffen, en een dreigende monopolisering ervan. Dit artikel geeft de hoofdlijnen van de inaugurele rede (2006, bijzonder hoogleraarschap Wageningen)

Klimaatverandering en verstedelijking zijn wereldwijd bepalend voor de waterbeschikbaarheid, economische ontwikkeling en gezondheid. Aangezien veel steden kampen met droogte of overstromingen is het noodzakelijk om het stedelijk waterbeheer ingrijpend te verbeteren. De City Blueprint bestaat uit 24 indicatoren waarmee het stedelijk waterbeheer van 45 steden en regio’s in 27 landen is beoordeeld. De Blue City Index (BCI) is het gemiddelde van deze 24 indicatoren en correleert significant met het bruto nationaal product, bestuurlijke ambities, governance-indicatoren van de Wereldbank en met publieke participatie. De resultaten laten zien dat integrale langetermijnplanning en kennisuitwisseling cruciaal zijn voor duurzame oplossingen. - See more at: https://www.h2owaternetwerk.nl/index.php/vakartikelen/460-city-blueprints-duurzaamheidsanalyse-van-de-stedelijke-waterketen-in-45-steden#sthash.mVblFefI.dpuf

PhD candidate: Eman Rahamtalla Ahmed ElsheikhDepartment of Water Science and EngineeringChair Group Land and Water DevelopmentUNESCO-IHE institute for water educationWestvest 7, DelftSunflower has become an important crop for both farmers and consumers in Sudan. It is a crop that fits well in the local cropping system and is considered one of the most important oil crops of the country. Regular irrigation intervals could be reduced in order to increase total yield and maximize water productivity. In contrast prolonged irrigation intervals during sensitive growth stages may result in reduction in total yield. The application of water below the evapotranspiration requirements is termed deficit irrigation (DI). The experiments were conducted at Gezira Research Station Farm, WadMedani, Sudan, in a randomized complete block design with three replications. In this study irrigation intervals every week during the whole growing period, 10, 15 and 20 days intervals after flowering stage and 10, 15 and 20 days intervals after the seed filling stage were applied to study the effect of full and deficit irrigation on yield and yield components of sunflower during the two growing periods 2011/2012 and 2012/2013. Results showed that water stress decreased the number of filled seeds per head, weight of full seed and seed yield. The highest seed yield of (3130 and 3140 kg/ha) was obtained from the full irrigation treatment and the lowest seed yield of 2082 and 2130 kg/ha was obtained from irrigation every 20 days after the flowering stage in the first and second season respectively. Results indicated that there were no-significant differences on head diameter, plant height and stem diameter when the water deficit occurred after the flowering stage. Lower water productivity of 0.21-0.26 and 0.21-0.27 kg/m3 were obtained when sunflower was irrigated every 20 days after the flowering and seed filling stages in the first and second season respectively. Results revealed that water productivity was low under Gezira conditions.In addition, the AquaCrop model was used to simulate seed yield and water productivity under different irrigation strategies. AquaCrop simulated seed yield accuratley with a root mean square error (RMSE) that ranged between 0.01 and 0.12 t/ha and 0.04 to 0.16 t/ha for the sunflower varieties Hysun 33 and Bohooth-1 respectively. The corresponding values of d-index of agreement ranged between 0.89 - 0.99 and 0.92-0.99 respectivley in 2012 and 2013. Results revealed that the AquaCrop model can be adequately applied to simulate seed yield response to water deficit and to explore the best irrigation stratgies that can maximize yield under current climatic conditions.&nbsp

Voedselzekerheid en voedselveiligheid staan hoog op de agenda in het Midden-Oosten sinds de voedselcrisis in 2007-2008. Voedsel wordt voor een groot deel geïmporteerd uit omliggende landen, maar ook uit Nederland. Vooral in de zomermaanden zijn de prijzen van versproducten in deze landen hoog, omdat er dan weinig in de regio zelf wordt geproduceerd. Vanwege de hoge prijzen en de lage kwaliteit van producten uit omliggende landen zijn er verschillende programma’s gestart om het productiesysteem te verbeteren. Hierbij is ook veel aandacht voor waterbesparing, aangezien water een zeer schaars product is in een groot deel van deze regio.

Voedselzekerheid en voedselveiligheid staan hoog op de agenda in het Midden-Oosten sinds de voedselcrisis in 2007-2008. Voedsel wordt voor een groot deel geïmporteerd uit omliggende landen, maar ook uit Nederland. Vooral in de zomermaanden zijn de prijzen van versproducten in deze landen hoog, omdat er dan weinig in de regio zelf wordt geproduceerd. Vanwege de hoge prijzen en de lage kwaliteit van producten uit omliggende landen zijn er verschillende programma’s gestart om het productiesysteem te verbeteren. Hierbij is ook veel aandacht voor waterbesparing, aangezien water een zeer schaars product is in een groot deel van deze regio.

Water and resource availability in sufficient quantity and quality for anthropogenic needs represents one of the main challenges in the coming decades. To prepare for upcoming challenges such as increased urbanization and climate change related consequences, innovative and improved resource management concepts are indispensable. In recent years we have developed and applied the Urban Harvest Approach (UHA). The UHA proposes to model and quantify the urban water cycle on different temporal and spatial scales. This approach allowed us to quantify the impact of the implementation of water saving measures and new water treatment concepts in cities. In this paper we will introduce the UHA and present for urban water cycles. Furthermore, we will show first results for an extension to energy cycles and highlight future research items (e.g., nutrients, water-energy-nexus). Key words | Resource cycles, Water management, Water-Energy Nexus, Decision-Support

PhD candidate: Eman Rahamtalla Ahmed ElsheikhDepartment of Water Science and EngineeringChair Group Land and Water DevelopmentUNESCO-IHE institute for water educationWestvest 7, DelftSunflower has become an important crop for both farmers and consumers in Sudan. It is a crop that fits well in the local cropping system and is considered one of the most important oil crops of the country. Regular irrigation intervals could be reduced in order to increase total yield and maximize water productivity. In contrast prolonged irrigation intervals during sensitive growth stages may result in reduction in total yield. The application of water below the evapotranspiration requirements is termed deficit irrigation (DI). The experiments were conducted at Gezira Research Station Farm, WadMedani, Sudan, in a randomized complete block design with three replications. In this study irrigation intervals every week during the whole growing period, 10, 15 and 20 days intervals after flowering stage and 10, 15 and 20 days intervals after the seed filling stage were applied to study the effect of full and deficit irrigation on yield and yield components of sunflower during the two growing periods 2011/2012 and 2012/2013. Results showed that water stress decreased the number of filled seeds per head, weight of full seed and seed yield. The highest seed yield of (3130 and 3140 kg/ha) was obtained from the full irrigation treatment and the lowest seed yield of 2082 and 2130 kg/ha was obtained from irrigation every 20 days after the flowering stage in the first and second season respectively. Results indicated that there were no-significant differences on head diameter, plant height and stem diameter when the water deficit occurred after the flowering stage. Lower water productivity of 0.21-0.26 and 0.21-0.27 kg/m3 were obtained when sunflower was irrigated every 20 days after the flowering and seed filling stages in the first and second season respectively. Results revealed that water productivity was low under Gezira conditions.In addition, the AquaCrop model was used to simulate seed yield and water productivity under different irrigation strategies. AquaCrop simulated seed yield accuratley with a root mean square error (RMSE) that ranged between 0.01 and 0.12 t/ha and 0.04 to 0.16 t/ha for the sunflower varieties Hysun 33 and Bohooth-1 respectively. The corresponding values of d-index of agreement ranged between 0.89 - 0.99 and 0.92-0.99 respectivley in 2012 and 2013. Results revealed that the AquaCrop model can be adequately applied to simulate seed yield response to water deficit and to explore the best irrigation stratgies that can maximize yield under current climatic conditions.&nbsp

Een golfbaan in Drenthe heeft na hevige regenval, oktober 1998, langdurig onder water gestaan. Begin 2005 werd Alterra verzocht om modelmatig feitelijk aan te tonen, dat de inundatie het gevolg was van de regenbuien. Geconcludeerd wordt, dat de golfbaan 18 tot 23 dagen onder water moet hebben gestaan; door eerdere regenval stond het golfterrein al onder water; als de hevige buien van eind oktober niet gevallen waren, zou er slechts van 4 dagen wateroverlast sprake zijn geweest

To meet the food demand of a growing global population, agricultural production will have to more than double in this century. Agricultural land expansion combined with yield increases will therefore be required. This thesis investigates whether enough water resources will be available to sustain the future food production. Using a global scale hydrology and crop growth model, the combined effect of climate change and socio economic changes on water scarcity and food production were quantified. The first thing to explore was where water for agriculture is currently extracted. Reservoirs behind large dams are found to be very important for agriculture and contribute around 18% of the total irrigation water today. It is shown however that with current reservoir capacities and irrigation efficiencies, not enough water can be supplied to sustain an increased food production. Irrigation water shortage can lead to a loss of 20% of the irrigated crop production globally, but with important regional differences. Regions particularly at risk include basins in Southern Africa and South Asia, where production losses on irrigated cropland can become over 50%. This means that unless major investments are made towards improving irrigation efficiency and increasing storage capacity, water shortage will put a serious constraint on future food production.

Dit werkpakket gaat over terugwinnen van grondstoffen uit zij- en eindstromen van de Biobased Economy en het veilig en duurzaam hergebruik daarvan bij de productie of verwerking van biomassa, of bij herstellen van de natuurlijke balans van bodem- en watersystemen. De focus van dit werkpakket ligt op water, mineralen en koolstof, en de effecten op biodiversiteit.

Dit rapport geeft een tussentijds overzicht van ‘state of the art’ kennis uit lopend onderzoek van het consortium ‘Climate Proof Fresh Water Supply’ (CPFWS) dat in het kader van het onderzoeksprogramma Kennis voor Klimaat wordt uitgevoerd. De focus van dit onderzoek naar een klimaatbestendige zoetwatervoorziening ligt op lokale en regionale oplossingen in Laag Nederland voor land- en tuinbouw en natuur. De zoetwatervoorziening van dit gebied wordt naast droogte vooral bedreigd door verzilting van grond- en oppervlaktewater. In zes samenhangende werkpakketten wordt geanalyseerd hoe dit gebied meer zelfvoorzienend kan worden én hoe aanpassingen in het (hoofd)watersysteem kunnen bijdragen aan de watervoorziening van het gebied. Centraal in de aanpak zijn een 3-tal casestudies in de Hotspots Haaglanden, Rotterdam Regio en Zuidwestelijke delta.

Dit rapport geeft een tussentijds overzicht van ‘state of the art’ kennis uit lopend onderzoek van het consortium ‘Climate Proof Fresh Water Supply’ (CPFWS) dat in het kader van het onderzoeksprogramma Kennis voor Klimaat wordt uitgevoerd. De focus van dit onderzoek naar een klimaatbestendige zoetwatervoorziening ligt op lokale en regionale oplossingen in Laag Nederland voor land- en tuinbouw en natuur. De zoetwatervoorziening van dit gebied wordt naast droogte vooral bedreigd door verzilting van grond- en oppervlaktewater. In zes samenhangende werkpakketten wordt geanalyseerd hoe dit gebied meer zelfvoorzienend kan worden én hoe aanpassingen in het (hoofd)watersysteem kunnen bijdragen aan de watervoorziening van het gebied. Centraal in de aanpak zijn een 3-tal casestudies in de Hotspots Haaglanden, Rotterdam Regio en Zuidwestelijke delta.

To meet the food demand of a growing global population, agricultural production will have to more than double in this century. Agricultural land expansion combined with yield increases will therefore be required. This thesis investigates whether enough water resources will be available to sustain the future food production. Using a global scale hydrology and crop growth model, the combined effect of climate change and socio economic changes on water scarcity and food production were quantified. The first thing to explore was where water for agriculture is currently extracted. Reservoirs behind large dams are found to be very important for agriculture and contribute around 18% of the total irrigation water today. It is shown however that with current reservoir capacities and irrigation efficiencies, not enough water can be supplied to sustain an increased food production. Irrigation water shortage can lead to a loss of 20% of the irrigated crop production globally, but with important regional differences. Regions particularly at risk include basins in Southern Africa and South Asia, where production losses on irrigated cropland can become over 50%. This means that unless major investments are made towards improving irrigation efficiency and increasing storage capacity, water shortage will put a serious constraint on future food production.

Heeft de verwachte klimaatverandering invloed op de frequentie en omvang van laagwater in de zomer in de Maas. Modelstudies op grond van klimaatscenario's en analyse van historische data m.b.t. neerslag en waterafvoer tonen aan dat er, met de huidige behoefte aan Maaswater, een grote kans is dat aanzienlijke economische schade ontstaat als gevolg van langdurig lage afvoeren (zelfs zonder klimaatverandering)

Arid areas are characterized by a seasonal climate with a long dry period. In such stressful environment, resource availability is driven by longterm and shorterm rainfall pulses. Arbuscular Mycorrhizal (AM) fungi enhance access to moisture and nutrients and thereby influence plant performance. In this dissertation I applied field observations and greenhouse experiments to address four questions: 1) What are the major environmental factors influencing AM incidence in the Boswellia-dominated dry deciduous woodlands? 2) How do Boswellia seedlings respond when they are exposed to AM fungi and water pulses? 3) How do AM fungi, water deficit and soil fertility influence the growth and gas exchange of Boswellia and Acacia seedlings? 4) Does the AM symbiosis influence competition between Acacia and Boswellia seedlings at different water pulse levels? The present study showed that almost all woodland plants in northern Ethiopia are colonized by AM fungi. Root colonization levels in dry and wet seasons demonstrated that in the sites with the harshest conditions, AM plants and fungi respond to pulsed resource availability by temporally disconnecting carbon gain by the plant and carbon expenditure by the fungus. Consequently, we studied below-ground processes in conferring adaptation to highly pulsed resources in Boswellia seedlings. The strong interactive AM fungi and water pulse showed that mycorrhizal Boswellia benefits from drought pulses during the short rainy season. Boswellia acquires carbon and water after rain events and store probably carbon and water in coarse roots, suggesting conservative strategy. From this observation we carried out an experiment to test whether other trees (Acacias) than Boswellia in this habitat also show this conservative acquisition strategy, or whether more acquisitive strategies may also be beneficial under such climates. My study show that acquisitive and conservative species both benefit from the AM symbiosis, but that the acquisitive Acacias mainly benefit at higher water availability, whereas the conservative Boswellia benefits at water or nutrient-stressed conditions. I also investigate on how mycorrhiza and water availability affect competition between plants with different resource acquisition strategies in these drylands. Seedlings of Boswellia are competitively inferior to seedlings of Acacia, and neither the presence of AM fungi nor a stronger water limitation (through pulsing) affected this outcome.

In July 2011 a survey was carried out in five field vegetable producing areas in Tanzania. The aim of the survey was to learn about the conditions for field vegetable production in these areas and to learn about production methods and marketing.

The report provides information based on which the Royal Netherlands Embassy in Cairo can detail its strategy for broadening the cooperation between Egypt and the Netherlands in the area of water management and agriculture. The mounting problems in the field of water resources management combined with the ambitious plans of the Egyptian government to develop the agricultural sector offer a wide variety of opportunities for the Dutch private sector and research institutes. However, seizing the opportunities will require strategic and careful planning of using the programmes and facilities available to promote Dutch–Egyptian cooperation. Strategic decisions on where to focus on and how to make optimal use of the programmes and facilities available have are still to be made by the embassy.

In het stroomgebied van de Inkomati-rivier in zuidelijk Afrika, maken partijen uit drie landen aanspraak op het rivierwater. LEI, Alterra en adviesbureau WaterWatch ontwikkelden met lokale partners een tool die betrokkenen laat zien wat ander landgebruik betekent voor de beschikbaarheid van dat water.

In het stroomgebied van de Inkomati-rivier in zuidelijk Afrika, maken partijen uit drie landen aanspraak op het rivierwater. LEI, Alterra en adviesbureau WaterWatch ontwikkelden met lokale partners een tool die betrokkenen laat zien wat ander landgebruik betekent voor de beschikbaarheid van dat water.

In July 2011 a survey was carried out in five field vegetable producing areas in Tanzania. The aim of the survey was to learn about the conditions for field vegetable production in these areas and to learn about production methods and marketing.

The report provides information based on which the Royal Netherlands Embassy in Cairo can detail its strategy for broadening the cooperation between Egypt and the Netherlands in the area of water management and agriculture. The mounting problems in the field of water resources management combined with the ambitious plans of the Egyptian government to develop the agricultural sector offer a wide variety of opportunities for the Dutch private sector and research institutes. However, seizing the opportunities will require strategic and careful planning of using the programmes and facilities available to promote Dutch–Egyptian cooperation. Strategic decisions on where to focus on and how to make optimal use of the programmes and facilities available have are still to be made by the embassy.

KEY-WORDS: Bolivia, drought tolerance, shade tolerance, functional traits, trade-offs, ecophysiology, species distribution Tropical forests occur under rainfall regimes that vary greatly in the rainfall pattern and frequency and intensity of drought. Consequently water availability is one of the most important environmental factors influencing community structure, species composition, and plant functioning across large-scale rainfall gradients and small-scale topographic gradients within forests. The relative success of tree species to establish along these gradients of water availability and their success in dealing with future changes in water availability will depend on how they are adapted to tolerate drought. In this dissertation I applied a multi-species, multi-trait approach in field studies and a controlled experiment to give detailed information on the mechanisms of drought-tolerance of a large set of tropical dry and moist forest tree species. The following research questions were addressed; 1) How do dry and moist forests differ in soil water availability? 2) How are dry and moist forest species adapted to drought and what different drought-strategies can be distinguished? 3) Is there a trade-off between drought- and shade-tolerance? and 4) How do drought- and shade-tolerance determine local and regional tree species distribution? Dry season soil water availability is clearly lower in the dry forest than in the moist forest. Especially in the dry forest there is a lot of temporal and spatial variation in soil water availability. Temporal variation depends on the annual cycle of precipitation. Spatial heterogeneity is two-dimensional; 1) water availability varies with topography of the landscape; elevated crests are dry in comparison to slopes and low valleys, and 2) soil water is vertically redistributed with soil depth; in the dry season more water is available in deep soil layers while in the wet season most water is found in the top soil. When combining temporal and spatial dimensions, a complex mosaic of soil water availability emerges that shows great potential for niche partitioning among species at various levels, if species are adapted to exploit this variation. Seedlings of dry forest species have evolved mechanisms that enhance their access to water in deep soil layers, increase drought-induced cavitation resistance and increase water conservation. Seedlings of moist forest species show adaptations that improve their light foraging capacity and increase nutrient and water acquisition. Associations among functional traits show that there are three major drought strategies among tropical tree species, 1) physiological drought-tolerance, 2) drought-intolerance and 3) drought-avoidance. No conclusive evidence for a direct trade-off between species drought- and shade-tolerance was found, and the association between drought- and shade-tolerance is mainly subject to the scale of observation. On small scales, within the dry forest, drought- and shade-tolerance are positively related, as species hydraulic properties are integrally linked with niche differentiation for both light and water. This implies that in their distribution, light-demanding species will be restricted to habitats that combine high light and high moisture availability, while shade-tolerant species will be the better competitors in drier and shadier habitats. On larger scales a strong trade-off between above and belowground biomass allocation was found, which should in theory have resulted in a trade-off between drought- and shade-tolerance, but in practice it did not. Plants can compensate for a low root mass fraction by producing relatively cheap roots with a large specific root length and compensate for a low leaf mass fraction by making cheap leaves with a large specific leaf area. Drought- and shade-tolerance thus depend largely on different suites of morphological traits and can be uncoupled. Species distribution along the rainfall gradient was not directly explained by species drought survival, mainly because deciduousness was the most important factor contributing to survival and deciduous species are well represented in both dry and moist forests. The occurrence of evergreen species at the dry end of the rainfall gradient largely depends on drought related traits as a high wood density and a large biomass allocation to deep roots. Species occurrence at the moist end of the rainfall gradient was mainly determined by traits related to light-demand, as a high leaf mass fraction and long, branched root systems. In conclusion, I propose that at small scales, within forests, species distribution along water gradients depends on the interaction between species drought- and shade-tolerance while at larger scales distribution of (evergreen) species is mainly determined by their drought-tolerance.

Recently, large-scale surface-water or canal irrigation systems have been termed ‘a sunset industry’ (Rijsberman 2003). Handing over this sunset industry by means of irrigation management transfer (IMT) policies and the creation of water user associations (WUAs) has three main objectives: to increase efficiency, equity, and empowerment. The Uzbek government, together with the international organizations, the United States Agency for International Development (USAID), and the International Water Management Institute (IWMI), is currently promoting IMT and the creation of WUAs nationwide. The onset of the policy seemed to be a rational development since the former state and collective farms, which were also responsible for water management on their territories, were disintegrating, and new private farms were emerging rapidly. This study seeks to assess the potential of IMT policies by examining the broader physical, organizational, socio-economic, and political factors that might facilitate or hinder the main objectives of IMT and the creation of WUAs. These factors are addressed and analyzed separately through eight case study chapters that address questions on basin water management, the organizational capacities, and the socio-political dependencies of the district water management departments, the potential for multi-stakeholder platforms (MSPs), the politics of social network structures, and the process of land reforms. The study concludes that none of the external factors is conducive to the introduction of IMT policies and for creating WUAs. The implication is that IMT policies will not increase efficiency, equity, and empowerment, but could even worsen the water management situation. Furthermore, these policies will not increase the empowerment of either the WUAs or their members. Hence, under the current conditions, handing over the ‘sunset industry’ will not lead to a new sunrise for irrigation in Uzbekistan.

Recently, large-scale surface-water or canal irrigation systems have been termed ‘a sunset industry’ (Rijsberman 2003). Handing over this sunset industry by means of irrigation management transfer (IMT) policies and the creation of water user associations (WUAs) has three main objectives: to increase efficiency, equity, and empowerment. The Uzbek government, together with the international organizations, the United States Agency for International Development (USAID), and the International Water Management Institute (IWMI), is currently promoting IMT and the creation of WUAs nationwide. The onset of the policy seemed to be a rational development since the former state and collective farms, which were also responsible for water management on their territories, were disintegrating, and new private farms were emerging rapidly. This study seeks to assess the potential of IMT policies by examining the broader physical, organizational, socio-economic, and political factors that might facilitate or hinder the main objectives of IMT and the creation of WUAs. These factors are addressed and analyzed separately through eight case study chapters that address questions on basin water management, the organizational capacities, and the socio-political dependencies of the district water management departments, the potential for multi-stakeholder platforms (MSPs), the politics of social network structures, and the process of land reforms. The study concludes that none of the external factors is conducive to the introduction of IMT policies and for creating WUAs. The implication is that IMT policies will not increase efficiency, equity, and empowerment, but could even worsen the water management situation. Furthermore, these policies will not increase the empowerment of either the WUAs or their members. Hence, under the current conditions, handing over the ‘sunset industry’ will not lead to a new sunrise for irrigation in Uzbekistan.

KEY-WORDS: Bolivia, drought tolerance, shade tolerance, functional traits, trade-offs, ecophysiology, species distribution Tropical forests occur under rainfall regimes that vary greatly in the rainfall pattern and frequency and intensity of drought. Consequently water availability is one of the most important environmental factors influencing community structure, species composition, and plant functioning across large-scale rainfall gradients and small-scale topographic gradients within forests. The relative success of tree species to establish along these gradients of water availability and their success in dealing with future changes in water availability will depend on how they are adapted to tolerate drought. In this dissertation I applied a multi-species, multi-trait approach in field studies and a controlled experiment to give detailed information on the mechanisms of drought-tolerance of a large set of tropical dry and moist forest tree species. The following research questions were addressed; 1) How do dry and moist forests differ in soil water availability? 2) How are dry and moist forest species adapted to drought and what different drought-strategies can be distinguished? 3) Is there a trade-off between drought- and shade-tolerance? and 4) How do drought- and shade-tolerance determine local and regional tree species distribution? Dry season soil water availability is clearly lower in the dry forest than in the moist forest. Especially in the dry forest there is a lot of temporal and spatial variation in soil water availability. Temporal variation depends on the annual cycle of precipitation. Spatial heterogeneity is two-dimensional; 1) water availability varies with topography of the landscape; elevated crests are dry in comparison to slopes and low valleys, and 2) soil water is vertically redistributed with soil depth; in the dry season more water is available in deep soil layers while in the wet season most water is found in the top soil. When combining temporal and spatial dimensions, a complex mosaic of soil water availability emerges that shows great potential for niche partitioning among species at various levels, if species are adapted to exploit this variation. Seedlings of dry forest species have evolved mechanisms that enhance their access to water in deep soil layers, increase drought-induced cavitation resistance and increase water conservation. Seedlings of moist forest species show adaptations that improve their light foraging capacity and increase nutrient and water acquisition. Associations among functional traits show that there are three major drought strategies among tropical tree species, 1) physiological drought-tolerance, 2) drought-intolerance and 3) drought-avoidance. No conclusive evidence for a direct trade-off between species drought- and shade-tolerance was found, and the association between drought- and shade-tolerance is mainly subject to the scale of observation. On small scales, within the dry forest, drought- and shade-tolerance are positively related, as species hydraulic properties are integrally linked with niche differentiation for both light and water. This implies that in their distribution, light-demanding species will be restricted to habitats that combine high light and high moisture availability, while shade-tolerant species will be the better competitors in drier and shadier habitats. On larger scales a strong trade-off between above and belowground biomass allocation was found, which should in theory have resulted in a trade-off between drought- and shade-tolerance, but in practice it did not. Plants can compensate for a low root mass fraction by producing relatively cheap roots with a large specific root length and compensate for a low leaf mass fraction by making cheap leaves with a large specific leaf area. Drought- and shade-tolerance thus depend largely on different suites of morphological traits and can be uncoupled. Species distribution along the rainfall gradient was not directly explained by species drought survival, mainly because deciduousness was the most important factor contributing to survival and deciduous species are well represented in both dry and moist forests. The occurrence of evergreen species at the dry end of the rainfall gradient largely depends on drought related traits as a high wood density and a large biomass allocation to deep roots. Species occurrence at the moist end of the rainfall gradient was mainly determined by traits related to light-demand, as a high leaf mass fraction and long, branched root systems. In conclusion, I propose that at small scales, within forests, species distribution along water gradients depends on the interaction between species drought- and shade-tolerance while at larger scales distribution of (evergreen) species is mainly determined by their drought-tolerance.

Vietnam is located in typical monsoon climate region and therefore river are very abundant water. However, about 2/3 of water resources is originated from neighboring countries. Moreover, uneven spatial distribution and huge seasonal change are additional reasons that make Vietnam ranked low compared to other South East Asian countries in term of water resource availability (the index of water availability per capital in Vietnam is 4,170m3/s compared to 4,900 m3/s in South East Asian region). In Vietnam, there is dense network of river systems, out of which about 2,360 river have length of 10km or more with total volume of 835 billion m3. However, the flow during 6 or 7 months of dry season is counted for only 15-30% of total annual flow. As a result, every yeas, drought and water shortage have always occurred in many areas of different basins. To cope with this situation and also to meet increasing water demand, number of reservoirs has been built for water resource regulation. After many years of development, many large exploitation work systems have been constructed and operated in all the basins thought the country, such as dams, reservoirs, weirs, embankments and so on. Those systems are to supply water for all kinds of use, including: irrigation, drainage, and hydropower generation, households, industry and flood control. Those works have been played an important role in water supply for major social-economic development sectors of the country, such as irrigation, hydropower generation, domestic and industrial used.

Vietnam is located in typical monsoon climate region and therefore river are very abundant water. However, about 2/3 of water resources is originated from neighboring countries. Moreover, uneven spatial distribution and huge seasonal change are additional reasons that make Vietnam ranked low compared to other South East Asian countries in term of water resource availability (the index of water availability per capital in Vietnam is 4,170m3/s compared to 4,900 m3/s in South East Asian region). In Vietnam, there is dense network of river systems, out of which about 2,360 river have length of 10km or more with total volume of 835 billion m3. However, the flow during 6 or 7 months of dry season is counted for only 15-30% of total annual flow. As a result, every yeas, drought and water shortage have always occurred in many areas of different basins. To cope with this situation and also to meet increasing water demand, number of reservoirs has been built for water resource regulation. After many years of development, many large exploitation work systems have been constructed and operated in all the basins thought the country, such as dams, reservoirs, weirs, embankments and so on. Those systems are to supply water for all kinds of use, including: irrigation, drainage, and hydropower generation, households, industry and flood control. Those works have been played an important role in water supply for major social-economic development sectors of the country, such as irrigation, hydropower generation, domestic and industrial used.

This paper analyses the different impacts that biofuel production will have on water use and availability.

This paper analyses the different impacts that biofuel production will have on water use and availability.